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What Does the Bible Say About Spiritual Blindness?

♫ Tuesday, May 14th, 2019

2 Corinthians 4:4ESV / 4,056 helpful votesHelpfulNot Helpful

In their case the god of this world has blinded the minds of the unbelievers, to keep them from seeing the light of the gospel of the glory of Christ, who is the image of God.

Let them alone; they are blind guides. And if the blind lead the blind, both will fall into a pit.

And even if our gospel is veiled, it is veiled only to those who are perishing. In their case the god of this world has blinded the minds of the unbelievers, to keep them from seeing the light of the gospel of the glory of Christ, who is the image of God.

For God, who said, Let light shine out of darkness, has shone in our hearts to give the light of the knowledge of the glory of God in the face of Jesus Christ.

Jesus said, For judgment I came into this world, that those who do not see may see, and those who see may become blind.

The natural person does not accept the things of the Spirit of God, for they are folly to him, and he is not able to understand them because they are spiritually discerned.

Again Jesus spoke to them, saying, I am the light of the world. Whoever follows me will not walk in darkness, but will have the light of life.

The Spirit of the Lord is upon me, because he has anointed me to proclaim good news to the poor. He has sent me to proclaim liberty to the captives and recovering of sight to the blind, to set at liberty those who are oppressed,

For you say, I am rich, I have prospered, and I need nothing, not realizing that you are wretched, pitiable, poor, blind, and naked.

But whoever hates his brother is in the darkness and walks in the darkness, and does not know where he is going, because the darkness has blinded his eyes.

He has blinded their eyes and hardened their heart, lest they see with their eyes, and understand with their heart, and turn, and I would heal them.

The Lord opens the eyes of the blind. The Lord lifts up those who are bowed down; the Lord loves the righteous.

Jesus said, For judgment I came into this world, that those who do not see may see, and those who see may become blind. Some of the Pharisees near him heard these things, and said to him, Are we also blind? Jesus said to them, If you were blind, you would have no guilt; but now that you say, We see, your guilt remains.

But you are a chosen race, a royal priesthood, a holy nation, a people for his own possession, that you may proclaim the excellencies of him who called you out of darkness into his marvelous light.

I will bring distress on mankind, so that they shall walk like the blind, because they have sinned against the Lord; their blood shall be poured out like dust, and their flesh like dung.

For at one time you were darkness, but now you are light in the Lord. Walk as children of light

Lest you be wise in your own sight, I want you to understand this mystery, brothers: a partial hardening has come upon Israel, until the fullness of the Gentiles has come in.

Woe to you, blind guides, who say, If anyone swears by the temple, it is nothing, but if anyone swears by the gold of the temple, he is bound by his oath.

The light shines in the darkness, and the darkness has not overcome it.

Open my eyes, that I may behold wondrous things out of your law.

Then the eyes of the blind shall be opened, and the ears of the deaf unstopped;

To open their eyes, so that they may turn from darkness to light and from the power of Satan to God, that they may receive forgiveness of sins and a place among those who are sanctified by faith in me.

For the mind that is set on the flesh is hostile to God, for it does not submit to God's law; indeed, it cannot.

He answered, Whether he is a sinner I do not know. One thing I do know, that though I was blind, now I see.

But seek first the kingdom of God and his righteousness, and all these things will be added to you.

As he passed by, he saw a man blind from birth. And his disciples asked him, Rabbi, who sinned, this man or his parents, that he was born blind? Jesus answered, It was not that this man sinned, or his parents, but that the works of God might be displayed in him. We must work the works of him who sent me while it is day; night is coming, when no one can work. As long as I am in the world, I am the light of the world. ...

Whoever says he is in the light and hates his brother is still in darkness.

For since, in the wisdom of God, the world did not know God through wisdom, it pleased God through the folly of what we preach to save those who believe.

But to this day the Lord has not given you a heart to understand or eyes to see or ears to hear.

Knowing this first of all, that scoffers will come in the last days with scoffing, following their own sinful desires.

But for those who are self-seeking and do not obey the truth, but obey unrighteousness, there will be wrath and fury.

Whom have you mocked and reviled? Against whom have you raised your voice and lifted your eyes to the heights? Against the Holy One of Israel!

And no wonder, for even Satan disguises himself as an angel of light.

To the choirmaster. Of David. The fool says in his heart, There is no God. They are corrupt, they do abominable deeds, there is none who does good.

They said to you, In the last time there will be scoffers, following their own ungodly passions.

The one who rejects me and does not receive my words has a judge; the word that I have spoken will judge him on the last day.

This is why I speak to them in parables, because seeing they do not see, and hearing they do not hear, nor do they understand.

And I will lead the blind in a way that they do not know, in paths that they have not known I will guide them. I will turn the darkness before them into light, the rough places into level ground. These are the things I do, and I do not forsake them.

For this people's heart has grown dull, and with their ears they can barely hear, and their eyes they have closed, lest they should see with their eyes and hear with their ears and understand with their heart and turn, and I would heal them.

And you shall grope at noonday, as the blind grope in darkness, and you shall not prosper in your ways. And you shall be only oppressed and robbed continually, and there shall be no one to help you.

But Jesus went to the Mount of Olives. Early in the morning he came again to the temple. All the people came to him, and he sat down and taught them. The scribes and the Pharisees brought a woman who had been caught in adultery, and placing her in the midst they said to him, Teacher, this woman has been caught in the act of adultery. Now in the Law Moses commanded us to stone such women. So what do you say? ...

And the Word became flesh and dwelt among us, and we have seen his glory, glory as of the only Son from the Father, full of grace and truth.

And as Jesus passed on from there, two blind men followed him, crying aloud, Have mercy on us, Son of David. When he entered the house, the blind men came to him, and Jesus said to them, Do you believe that I am able to do this? They said to him, Yes, Lord. Then he touched their eyes, saying, According to your faith be it done to you. And their eyes were opened. And Jesus sternly warned them, See that no one knows about it.

You are of your father the devil, and your will is to do your father's desires. He was a murderer from the beginning, and has nothing to do with the truth, because there is no truth in him. When he lies, he speaks out of his own character, for he is a liar and the father of lies.

Yes, to this day whenever Moses is read a veil lies over their hearts.

They have neither knowledge nor understanding, they walk about in darkness; all the foundations of the earth are shaken.

As it is written, God gave them a spirit of stupor, eyes that would not see and ears that would not hear, down to this very day.

To open the eyes that are blind, to bring out the prisoners from the dungeon, from the prison those who sit in darkness.

He has delivered us from the domain of darkness and transferred us to the kingdom of his beloved Son,

Hear, you deaf, and look, you blind, that you may see!

Jesus heard that they had cast him out, and having found him he said, Do you believe in the Son of Man? He answered, And who is he, sir, that I may believe in him? Jesus said to him, You have seen him, and it is he who is speaking to you. He said, Lord, I believe, and he worshiped him. Jesus said, For judgment I came into this world, that those who do not see may see, and those who see may become blind. ...

No one can come to me unless the Father who sent me draws him. And I will raise him up on the last day.

And the great dragon was thrown down, that ancient serpent, who is called the devil and Satan, the deceiver of the whole worldhe was thrown down to the earth, and his angels were thrown down with him.

Paul, a servant of Christ Jesus, called to be an apostle, set apart for the gospel of God, which he promised beforehand through his prophets in the holy Scriptures, concerning his Son, who was descended from David according to the flesh and was declared to be the Son of God in power according to the Spirit of holiness by his resurrection from the dead, Jesus Christ our Lord, through whom we have received grace and apostleship to bring about the obedience of faith for the sake of his name among all the nations, ...

In order that all may be condemned who did not believe the truth but had pleasure in unrighteousness.

But to all who did receive him, who believed in his name, he gave the right to become children of God, who were born, not of blood nor of the will of the flesh nor of the will of man, but of God.

He answered, The man called Jesus made mud and anointed my eyes and said to me, Go to Siloam and wash. So I went and washed and received my sight.

Bring out the people who are blind, yet have eyes, who are deaf, yet have ears!

Jesus heard that they had cast him out, and having found him he said, Do you believe in the Son of Man?

But when one turns to the Lord, the veil is removed.

And this is the judgment: the light has come into the world, and people loved the darkness rather than the light because their works were evil.

And this is the judgment: the light has come into the world, and people loved the darkness rather than the light because their works were evil. For everyone who does wicked things hates the light and does not come to the light, lest his works should be exposed.

So that we would not be outwitted by Satan; for we are not ignorant of his designs.

In the beginning was the Word, and the Word was with God, and the Word was God.

Now this I say and testify in the Lord, that you must no longer walk as the Gentiles do, in the futility of their minds. They are darkened in their understanding, alienated from the life of God because of the ignorance that is in them, due to their hardness of heart. They have become callous and have given themselves up to sensuality, greedy to practice every kind of impurity.

That is why many of you are weak and ill, and some have died.

Put on the whole armor of God, that you may be able to stand against the schemes of the devil.

For the mind that is set on the flesh is hostile to God, for it does not submit to God's law; indeed, it cannot. Those who are in the flesh cannot please God.

For whoever lacks these qualities is so nearsighted that he is blind, having forgotten that he was cleansed from his former sins.

Then Jesus said to the crowds and to his disciples, The scribes and the Pharisees sit on Moses' seat, so practice and observe whatever they tell youbut not what they do. For they preach, but do not practice. They tie up heavy burdens, hard to bear, and lay them on people's shoulders, but they themselves are not willing to move them with their finger. They do all their deeds to be seen by others. For they make their phylacteries broad and their fringes long, ...

The brothers immediately sent Paul and Silas away by night to Berea, and when they arrived they went into the Jewish synagogue. Now these Jews were more noble than those in Thessalonica; they received the word with all eagerness, examining the Scriptures daily to see if these things were so.

In that day you will know that I am in my Father, and you in me, and I in you. Whoever has my commandments and keeps them, he it is who loves me. And he who loves me will be loved by my Father, and I will love him and manifest myself to him. Judas (not Iscariot) said to him, Lord, how is it that you will manifest yourself to us, and not to the world? Jesus answered him, If anyone loves me, he will keep my word, and my Father will love him, and we will come to him and make our home with him.

For the Lord has poured out upon you a spirit of deep sleep, and has closed your eyes (the prophets), and covered your heads (the seers).

For the word of the cross is folly to those who are perishing, but to us who are being saved it is the power of God.

Saul rose from the ground, and although his eyes were opened, he saw nothing. So they led him by the hand and brought him into Damascus.

But if your eye is bad, your whole body will be full of darkness. If then the light in you is darkness, how great is the darkness!

For we do not have a high priest who is unable to sympathize with our weaknesses, but one who in every respect has been tempted as we are, yet without sin.

Whoever loves his brother abides in the light, and in him there is no cause for stumbling.

But blessed are your eyes, for they see, and your ears, for they hear.

And he said, Who are you, Lord? And he said, I am Jesus, whom you are persecuting.

He is the image of the invisible God, the firstborn of all creation. For by him all things were created, in heaven and on earth, visible and invisible, whether thrones or dominions or rulers or authoritiesall things were created through him and for him.

Again he appoints a certain day, Today, saying through David so long afterward, in the words already quoted, Today, if you hear his voice, do not harden your hearts.

And they may come to their senses and escape from the snare of the devil, after being captured by him to do his will.

Finally, be strong in the Lord and in the strength of his might. Put on the whole armor of God, that you may be able to stand against the schemes of the devil. For we do not wrestle against flesh and blood, but against the rulers, against the authorities, against the cosmic powers over this present darkness, against the spiritual forces of evil in the heavenly places. Therefore take up the whole armor of God, that you may be able to withstand in the evil day, and having done all, to stand firm. Stand therefore, having fastened on the belt of truth, and having put on the breastplate of righteousness, ...

For since the message declared by angels proved to be reliable, and every transgression or disobedience received a just retribution, how shall we escape if we neglect such a great salvation? It was declared at first by the Lord, and it was attested to us by those who heard, while God also bore witness by signs and wonders and various miracles and by gifts of the Holy Spirit distributed according to his will.

Be sober-minded; be watchful. Your adversary the devil prowls around like a roaring lion, seeking someone to devour. Resist him, firm in your faith, knowing that the same kinds of suffering are being experienced by your brotherhood throughout the world.

Whoever confesses that Jesus is the Son of God, God abides in him, and he in God.

By this we know that we abide in him and he in us, because he has given us of his Spirit.

Do not love the world or the things in the world. If anyone loves the world, the love of the Father is not in him. For all that is in the worldthe desires of the flesh and the desires of the eyes and pride in possessionsis not from the Father but is from the world.

Those who are in the flesh cannot please God. You, however, are not in the flesh but in the Spirit, if in fact the Spirit of God dwells in you. Anyone who does not have the Spirit of Christ does not belong to him.

So that we may no longer be children, tossed to and fro by the waves and carried about by every wind of doctrine, by human cunning, by craftiness in deceitful schemes.

You are to deliver this man to Satan for the destruction of the flesh, so that his spirit may be saved in the day of the Lord.

Do not deprive one another, except perhaps by agreement for a limited time, that you may devote yourselves to prayer; but then come together again, so that Satan may not tempt you because of your lack of self-control.

Therefore God gave them up in the lusts of their hearts to impurity, to the dishonoring of their bodies among themselves, because they exchanged the truth about God for a lie and worshiped and served the creature rather than the Creator, who is blessed forever! Amen. For this reason God gave them up to dishonorable passions. For their women exchanged natural relations for those that are contrary to nature; and the men likewise gave up natural relations with women and were consumed with passion for one another, men committing shameless acts with men and receiving in themselves the due penalty for their error. And since they did not see fit to acknowledge God, God gave them up to a debased mind to do what ought not to be done. ...

Go to this people, and say, You will indeed hear but never understand, and you will indeed see but never perceive. For this people's heart has grown dull, and with their ears they can barely hear, and their eyes they have closed; lest they should see with their eyes and hear with their ears and understand with their heart and turn, and I would heal them.

Simon Peter answered him, Lord, to whom shall we go? You have the words of eternal life, and we have believed, and have come to know, that you are the Holy One of God.

If you love me, you will keep my commandments. And I will ask the Father, and he will give you another Helper, to be with you forever, even the Spirit of truth, whom the world cannot receive, because it neither sees him nor knows him. You know him, for he dwells with you and will be in you.

And since they did not see fit to acknowledge God, God gave them up to a debased mind to do what ought not to be done. They were filled with all manner of unrighteousness, evil, covetousness, malice. They are full of envy, murder, strife, deceit, maliciousness. They are gossips, slanderers, haters of God, insolent, haughty, boastful, inventors of evil, disobedient to parents, foolish, faithless, heartless, ruthless. Though they know God's decree that those who practice such things deserve to die, they not only do them but give approval to those who practice them.

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What Does the Bible Say About Spiritual Blindness?

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National Blindness Professional Certification Board

♫ Friday, April 26th, 2019

The National Blindness Professional Certification Board (NBPCB) was created to certify qualified specialists in work with the blind. At present, the Certification Board oversees four certifications - the National Orientation and Mobility Certification (NOMC), the National Certification in Rehabilitation Teaching for the Blind (NCRTB), the National Certification in Literary Braille (NCLB), and the National Certification in Unified English Braille (NCUEB).

The National Orientation and Mobility Certification (NOMC) emphasizes nonvisual instruction, and Structured Discovery Cane Travel .

The National Certification in Rehabilitation Teaching for the Blind (NCRTB) emphasizes nonvisual instruction through Structured Discovery Rehabilitation Teaching methods and principles.

The National Certification in Literary Braille (NCLB) is specifically intended for teachers working with blind children or adults. All those who are certified will hold valid certification until their expiration date; however, it is no longer offered and has been replaced with the NCUEB.

The National certification in Unified English Braille (NCUEB) is specifically intended for professionals working with blind children or adults.

The NBPCB has also developed an approval process for orientation training centers who utilize Structured Discovery methodology throughout their programs and a consumer-focused approach.

Subscribe to the O&M Announcement List

Subscribe to the Braille Announcement list

For details regarding how to schedule any of our certification exams in your area, please contact us atadmin@nbpcb.org.

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National Blindness Professional Certification Board

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Blindness – askjan.org

♫ Sunday, April 21st, 2019

The Disability Management Employer Coalition (DMEC) is committed to providing focused education for absence management professionals. From face-to-face conferences to helpful tools and resources, we give you what you need to reduce costs, minimize lost work time, and increase staff productivity.

Presenters:

The National APSE Conference is the only national conference focused solely on the advancement of Employment First. The Association of People Supporting Employment First (APSE) National Conference brings together more than 1,000 community leaders, businesses, and individuals with disabilities from across the country and around the world to network and discuss state-of-the-art strategies to ensure equitable employment for all citizens with disabilities.

The EXCEL Training Conference is sponsored by the EEOC's Training Institute. In its 21st year, EXCEL is the premier national training conference for federal and private sector EEO managers, supervisors, practitioners, HR professionals, attorneys and Alternative Dispute Resolution (ADR) specialists. Private and public sector employees will gain invaluable knowledge for making those tough HR decisions!

Presenters:

The 2018 ILG National Conference held in Anaheim California is the premier meeting ground in 2018 for employers involved and interested in OFCCP compliance and EEOC issues. The 2018 ILG National Conference convenes industry experts, HR, compensation, legal and talent acquisition professionals to discuss the latest issues and information impacting affirmative action and equal opportunity employment and diversity and inclusion.

Presenters:

Slides - Tools, Techniques, and Technologies for Creating Inclusive Workplaces

Handout - Tools, Techniques, and Technologies for Creating Inclusive Workplaces

Presenters:

Slides - Tools, Techniques, and Technologies for Creating Inclusive Workplaces

Handout - Tools, Techniques, and Technologies for Creating Inclusive Workplaces

At the 2018 DMEC Annual Conference, youll connect with 700+ like-minded absence, disability, and return-to-work professionals who are looking to tackle strategic workforce issues facing their organizations.And with 40+ sessions and events, you will:Gain insights from those on the front line, giving you expert knowledge on how to address the complex leave and disability issues you are facing in your organization.Share ideas with peers and executive thought leaders from across the country.Take back proven strategies, actionable ideas, and tested program models to assist with the development of cost-saving programs in your company."

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Blindness - askjan.org

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WebAIM: Visual Disabilities – Color-blindness

♫ Wednesday, March 27th, 2019

You are here: Home > Articles > Visual Disabilities > Page 4: Color-blindness

Before getting into the details of the types of color-blindness, you should know that the following explanations are simplified versions of the complete picture. Color-blindness is a fascinating topic precisely because of its complexity. You do not need to understand all of the details of color-blindness to know how to create web content that is accessible to those who are color-blind. Here is an important fact to understand right off the bat:

Important

The key principle of web accessibility for users with color-blindness is:

The colors with which they have difficulty distinguishing depend upon their type of color-blindness, but red-green deficiencies are the most common.

The most common broad category of color-blindness is often called red-green color-blindness, but this does not mean that these people cannot see reds or greens. They simply have a harder time differentiating between them. Not all reds and greens are indistinguishable. It would be easy for someone with a red-green deficiency to tell the difference between a light green and a dark red, for example. A lot dependsat least in parton how dark the colors are. If the red is approximately as dark as the green, there is a greater likelihood that the colors will be confused.

Also, there is some evidence that people with red-green color-blindness see reds and greens as yellows, oranges and beiges. This means that yellows, oranges, and beiges can be confused with greens and reds. The colors least affected are the blues.

When designing web content for people who are color-blind you do NOT have to convert all of your images to black and white or get rid of your images entirely. In fact, you may not have to change any of your images at all. Here is the key:

Important

Make sure that colors are not your only method of conveying important information.

Most of the time when people put images on the web, the fact that they are in color at all is irrelevant. It may be nicer to see the colors, but the viewer can understand the image just fine even with all of the colors removed. If, however, the purpose of posting the image is to communicate something about the colors in that image, then it is important to provide some other way of understanding the information. For example, if the image shows the routes of the London Underground, where the routes are distinguished only by the color of the lines, as in the graphic below, you would want to somehow annotate either the graphic itself (and supply the appropriate alt text) or the text in the web page to supplement the color-dependent method of distinguishing between routes.

Incidentally, people with color-blindness are not the only ones who will benefit from this technique. Those who are blind are also unable to distinguish between colors, and so are in need of the extra cues given through other methods.

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WebAIM: Visual Disabilities - Color-blindness

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Colblindor All about Color Blindness

♫ Friday, February 8th, 2019

Color blindness (or colour blindness or more specific color vision deficiency (CVD)) is well known but hard to imagine if you are not suffering from it. So usually people are either looking for more information to learn about color blindness and all its details, would like to better understand the vision by simulating it or want to test themselves with some form of color blindness test. All this you can be found here on color-blindness.com and much more.

Color blindness affects approximately every 1 in 12 men (8%) and 1 in 200 women (0.5%). This means there is definitely one in your neighborhood or school class affected by it. Most of them are male, because the most common form called red-green color blindness (a term wich is also misleading) is encoded on the x-chromosome and therefore sex-linked. As red-green color blindness is inherited from a mother to her son, a father never passes this type of color blindness on to his children.

The term red-green color blindness is often used but actually not quite correct. Ever type of color vision deficiency affects the whole color spectrum and therefore can not be reduced to just certain colors. Of course, for the most often encountered types Protanomly (the milder form or red-weakness) or Protanopia (missing red cones, red-blindness) and Deuteranomaly (green-weakness) or Deuteranopia (green-blindness) the colors red and green are the most problematic and misinterpreted or indistinguishable ones. But people suffering from any of those forms have issues with the red or green part in every color, so the whole spectrum of colors is affected.

Besides red-green color blindness, which is encoded on the x-chromosome (sex-linked) and therefore much more common for men, there are also forms of color vision deficiency which are evenly distributed between male and female like Tritanomaly (blue-weakness) or Tritanopia (blue-blindness) and the real color blindness Achromatopsia (monochromacy) or the so called blue-cone monochromacy (only blue cones).

Color blindness simulation is fascinating! If you are not colorblind it is so hard to imagine what it looks like to be colorblind: Which color do you see? Do you see any at all? What does it mean not to be able to see red? and so on. My COlor BLIndness Simulator is a handy tool which allows you to use your own images and try out all the different simulation types. It is even possible to save any simulated image and have a one-by-one comparison.

Online color blindness testing is often done but unfortunately no yet as good as it could be. Usually youll find out about color blindness at school or when visiting an eye specialist and want to confirm this with some online tools. There are online color blindness tests available, but most of them are not reliable and cannot compensate a visit at your eye specialist. There is a new form of color blindness test coming up: Color Blind Check uses a new method and its results look very promising. But this new form still needs more time to develop and calibration to count as a trustable color blindness test.

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Colblindor All about Color Blindness

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Inattentional blindness – Wikipedia

♫ Tuesday, January 15th, 2019

Inattentional blindness, also known as perceptual blindness, is a psychological lack of attention that is not associated with any vision defects or deficits. It may be further defined as the event in which an individual fails to perceive an unexpected stimulus that is in plain sight. When it simply becomes impossible for one to attend to all the stimuli in a given situation, a temporary blindness effect can take place as a result; that is, individuals fail to see objects or stimuli that are unexpected and quite often salient.[1] The term was coined by Arien Mack and Irvin Rock in 1992 and was used as the title of their book of the same name, published by MIT press in 1998,[2] in which they describe the discovery of the phenomenon and include a collection of procedures used in describing it.[3] A famous study that demonstrated inattentional blindness asked participants whether or not they noticed a gorilla walking through the scene of a visual task they had been given.[1]

Research on inattentional blindness suggests that the phenomenon can occur in any individual, independent of cognitive deficits. However, recent evidence shows that patients with ADHD performed better attentionally when engaging in inattentional blindness tasks than control patients did,[4] suggesting that some mental deficits may decrease the effects of this phenomenon. Recent studies have also looked at age differences and inattentional blindness scores, and results show that the effect increases as humans age.[5][6][7] There is mixed evidence that consequential unexpected objects are noticed more: Some studies suggest that we can detect threatening unexpected stimuli more easily than nonthreatening ones,[8][9] but other studies suggest that this is not the case.[10][11][12] There is some evidence that objects associated with reward are noticed more.[12]

Numerous experiments[13] and art work [14][15][16][17] has demonstrated that inattentional blindness also has an effect on people's perception.

The following criteria are required to classify an event as an inattentional blindness episode: 1) the observer must fail to notice a visual object or event, 2) the object or event must be fully visible, 3) observers must be able to readily identify the object if they are consciously perceiving it,[3] and 4) the event must be unexpected and the failure to see the object or event must be due to the engagement of attention on other aspects of the visual scene and not due to aspects of the visual stimulus itself.[3] Individuals who experience inattentional blindness are usually unaware of this effect, which can play a subsequent role on behavior.

Inattentional blindness is related to but distinct from other failures of visual awareness such as change blindness, repetition blindness, visual masking, and attentional blink. The key aspect of inattentional blindess which makes it distinct from other failures in awareness rests on the fact that the undetected stimulus is unexpected.[18] It is the unexpected nature of said stimulus that differentiates inattentional blindness from failures of awareness such as attentional failures like the aforementioned attentional blink. It is critical to acknowledge that occurrences of inattentional blindness are attributed to the failure to consciously attend to an item in the visual field as opposed the absence of cognitive processing.

Findings such as inattentional blindness the failure to notice a fully visible but unexpected object because attention was engaged on another task, event, or object has changed views on how the brain stores and integrates visual information, and has led to further questioning and investigation of the brain and importantly of cognitive processes.

Cognitive capture or, cognitive tunneling, is an inattentional blindness phenomenon in which the observer is too focused on instrumentation, task at hand, internal thought, etc. and not on the present environment. For example, while driving, a driver focused on the speedometer and not on the road is suffering from cognitive capture.[a]

One of the most foremost conflicts among researchers of inattentional blindness surrounds the processing of unattended stimuli. More specifically, there is disagreement in the literature about exactly how much processing of a visual scene is completed before selection dictates which stimuli will be consciously perceived, and which will not be (i.e. inattentional blindness). There exists two basic schools of thought on the issue those who believe selection occurs early in the perceptual process, and those who believe it occurs only after significant processing.[19] Early selection theorists propose that perception of stimuli is a limited process requiring selection to proceed. This suggests that the decision to attend to specific stimuli occurs early in processing, soon after the rudimentary study of physical features; only those selected stimuli are then fully processed. On the other hand, proponents of late selection theories argue that perception is an unlimited operation, and all stimuli in a visual scene are processed simultaneously. In this case, selection of relevant information is done after full processing of all stimuli.[20]

While early research on the topic was heavily focused on early selection, research since the late 1970s has been shifted mainly to the late selection theories. This change resulted primarily from a shift in paradigms used to study inattentional blindness which revealed new aspects of the phenomenon.[21] Today, late selection theories are generally accepted, and continue to be the focus of the majority of research concerning inattentional blindness.

A significant body of research has been gathered in support of late selection in the perception of visual stimuli.

One of the popular ways of investigating late selection is to assess the priming properties (i.e. influencing subsequent acts[22]) of unattended stimuli. Often used to demonstrate such effects is the stem completion task. While there exist a few variations, these studies generally consist of showing participants the first few letters of words, and asking them to complete the string of letters to form an English word.[22] It has been demonstrated that observers are significantly more likely to complete word fragments with the unattended stimuli presented in a trial than with another similar word.[2] This effect holds when stimuli are not words, but instead objects. When photos of objects are shown too quickly for participants to identify, subsequent presentation of those items lead to significantly faster identification in comparison to novel objects.[22]

A notable study by Mack and Rock has also revealed that showing a word stimulus differing from the participant's name by one letter did not generally call conscious attention. By simply changing a character, transforming the presented word into the observer's first name, the now highly meaningful stimulus is significantly more likely to be attended to. This suggests that the stimuli are being extensively processed, at least enough to analyze their meaning. These results point to the fact that attentional selection may be determined late in processing.[2]

The evidence outlined above suggests that even when stimuli are not processed to the level of conscious attention, they are nonetheless perceptually and cognitively processed, and can indeed exert effects on subsequent behavior.[23]

While the evidence supporting late selection hypotheses is significant and has been consistently reproduced, there also exists a body of research suggesting that unattended stimuli in fact may not receive significant processing.

For example, in an functional magnetic resonance imaging (fMRI) study by Rees and colleagues, brain activity was recorded while participants completed a perceptual task. Here they examined the neural processing of meaningful (words) and meaningless (consonant string) stimuli both when attended to, and when these same items were unattended. While no difference in activation patterns were found between the groups when the stimuli were unattended, differences in neural processing were observed for meaningful versus meaningless stimuli to which participants overtly attended. This pattern of results suggests that ignored stimuli are not processed to the level of meaning, i.e. less extensively than attended stimuli.[24] Participants do not seem to be detecting meaning in stimuli to which they are not consciously attending.

This particular hypothesis bridges the gap between the early and late selection theories. Authors integrate the viewpoint of early selection stating that perception is a limited process (i.e. cognitive resources are limited), and that of the late selection theories assuming perception as an automatic process.[20] This view proposes that the level of processing which occurs for any one stimulus is dependent on the current perceptual load. That is, if the current task is attentionally demanding and its processing exhausts all the available resources, little remains available to process other non-target stimuli in the visual field. Alternatively, if processing requires a small amount of attentional resources, perceptual load is low and attention is inescapably directed to the non-target stimuli.[19]

The effects of perceptual load on the occurrence of inattentional blindness is demonstrated in a study by Fougnie and Marois. Here, participants were asked to complete a memory task involving either the simple maintenance of verbal stimuli, or the rearrangement of this material, a more cognitively demanding exercise. While subjects were completing the assigned task, an unexpected visual stimulus was presented. Results revealed that unexpected stimuli were more likely to be missed during manipulation of information than in the more simple rehearsal task.[25]

In a similar type of study, fMRI recordings were done while subjects took part in either low-demand or high-demand subtraction tasks. While performing these exercises, novel visual distractors were presented. When task demands were low and used a smaller portion of the finite resources, distractors captured attention and sparked visual analysis as shown by brain activation in the primary visual cortex. These results, however, did not hold when perceptual load was high; in this condition, distractors were significantly less often attended to and processed.[19]

Thus, higher perceptual load, and therefore more significant use of attentional resources, appears to increase the likelihood of inattentional blindness episodes.

The theory of inattentional amnesia provides an alternative in the explanation of inattentional blindness in suggesting that the phenomenon does not stem from failures in capture of attention or in actual perception of stimuli, but instead from a failure in memory. The unnoticed stimuli in a visual scene are attended to and consciously perceived, but are rapidly forgotten rendering them impossible to report.[26] In essence, inattentional amnesia refers to the failure in creating a lasting explicit memory: by the time a subject is asked to recall seeing an item, their memory for the stimulus has vanished.[27]

While it is difficult to tease apart a failure in perception from one in memory, some research has attempted to shed light on the issue. In a now-classic study of inattentional blindness, a woman carrying an umbrella through a scene goes unnoticed. Despite stopping the video while she is walking through and immediately asking participants to identify which of two people they have seen leaving as little delay as possible between presentation and report observers very often fail to correctly identify the woman with the umbrella. No differences in performance were identified whether the video was stopped immediately after the unexpected event or moments later. These findings would seem to oppose the idea of inattentional amnesia, however advocates of the theory could always contend that the memory test simply came too late and that the memory had already been lost.[28]

The very phenomenon of inattentional blindness is defined by a lack of expectation for the unattended stimulus. Some researchers believe that it is not inattention that produces blindness, but in fact the aforementioned lack of expectation for the stimuli.[23] Proponents of this theory often state that classic methods for testing inattentional blindness are not manipulating attention per se, but instead the expectation for the presentation of a visual item.[29]

Studies investigating the effect of expectation on episodes of inattentional blindness have shown that once observers are made aware of the importance of the stimuli to be presented, for example stating that one will later be tested on it, the phenomenon essentially disappears.[2] While admitting to possible ambiguities in methodology, Mack, one of the foremost researchers in the field, holds strongly that inattentional blindness stems predominantly from a failure of attentional capture. She points out that if expectation does not mediate instances of very closely linked phenomena such as attentional blink and change blindness (whereby participants have difficulty identifying the changing object even when they are explicitly told to look for it), it is unlikely that inattentional blindness can be explained solely by a lack of expectation for stimulus presentation.[23]

The perceptual cycle framework has been used as another theoretical basis for inattentional blindness. The perceptual cycle framework describes attention capture and awareness capture as occurring at two different stages of processing. Attention capture occurs when there is a shift in attention due to the salience of a stimuli, and awareness capture refers to the conscious acknowledgement of stimuli. Attentional sets are important because it is composed of characteristics of stimuli an individual is processing. Inattentional blindness occurs when there is an interaction between an individual's attentional set and the salience of the unexpected stimulus. Recognizing the unexpected stimulus can occur when the characteristics of the unexpected stimulus resembles the characteristics of the perceived stimuli. The attentional set theory of inattentional blindness has implications for false memories and eyewitness testimony. The perceptual cycle framework offers four major implications about inattentional blindness 1) environmental cues aid in the detection of stimuli by providing orienting cues but is not enough to produce awareness, 2) perception requires effortful sustained attention, interpretation, and reinterpretation, 3) implicit memory may precede conscious perception, and 4) visual stimuli that is not expected, explored, or interpreted may not be perceived.[30]

Other bases for attentional blindness include top down and bottom up processing.

To test for inattentional blindness, researchers ask participants to complete a primary task while an unexpected stimulus is presented. Afterwards, researchers ask participants if they saw anything unusual during the primary task. Arien Mack and Irvin Rock describe a series of experiments that demonstrated inattentional blindness in their 1998 book, Inattentional Blindness.

The best-known study demonstrating inattentional blindness is the Invisible Gorilla Test, conducted by Daniel Simons of the University of Illinois at Urbana-Champaign and Christopher Chabris of Harvard University. This study, a revised version of earlier studies conducted by Ulric Neisser, Neisser and Becklen in 1975, asked subjects to watch a short video of two groups of people (wearing black and white T-shirts) passing a basketball around. The subjects are told either to count the passes made by one of the teams or to keep count of bounce passes vs. aerial passes. In different versions of the video a person walks through the scene carrying an umbrella (as discussed above) or wearing a full gorilla suit. After watching the video, the subjects are asked whether they noticed anything out of the ordinary taking place. In most groups, 50% of the subjects did not report seeing the gorilla (or the person with the umbrella). Failure to perceive the anomalies is attributed to failure to attend to it while engaged in the difficult task of counting passes of the ball. These results indicate that the relationship between what is in one's visual field and perception is based much more on attention than was previously thought.[31]

Out 228 participants of the tests, only 194 those who did count the passes correctly were used for statistical purposes further. The percentage was even as low as 8% in one of the 16 tests performed.[32][33]

The basic Simons and Chabris study was reused on British television as a public safety advert designed to point out the potential dangers to cyclists caused by inattentional blindness in motorists. In the advert the gorilla is replaced by a moon-walking bear.[34]

In 1995, Officer Kenny Conley was chasing a shooting suspect. An undercover officer was in the same vicinity and was mistakenly taken down by other officers while Conley ran by and failed to notice. A jury later convicted Officer Conley of perjury and obstruction of justice, believing he had seen the fight and lied about it to protect fellow officers, yet he stood by his word that he had, in fact, not seen it.[35]

Christopher Chabris, Adam Weinberger, Matthew Fontaine and Daniel J. Simons took it upon themselves to see if this scenario was possible. They designed an experiment in which participants were asked to run about 30 feet behind an experimenter, and count how many times he touched his head. A fight was staged to appear about 8 meters off the path, and was visible for approximately 15 seconds. The procedure in its entirety lasted about 2 minutes and 45 seconds, and participants were then asked to report the number of times they had seen the experimenter touch his head with either hand (medium load), both hands (high load), or were not instructed to count at all (low load). After the run, participants were asked 3 questions: 1) If they had noticed the fight; 2) if they had noticed a juggler, and 3) if they had noticed someone dribbling a basketball. Questions 2) and 3) were control questions, and no one falsely reported these as true.

Participants were significantly more likely to notice the fight when the experiment was done during the day as opposed to in the dark. Additionally, sightings of the fight were most likely to be reported in the low load condition (72%) than in either the medium load (56%), or high load conditions (42%).[36] These results exemplify a real world occurrence of inattentional blindness, and provide evidence that officer Conley could indeed have missed the fight because his attention was focused elsewhere. Moreover, these results add to the body of knowledge suggesting that as perceptual load increases, less resources remain to process items not explicitly focused on, and in turn episodes of inattentional blindness become more frequent.

Another experiment was conducted by Steven Most, along with Daniel Simons, Christopher Chabris and Brian Scholl. Instead of a basketball game, they used stimuli presented by computer displays. In this experiment objects moved randomly on a computer screen. Participants were instructed to attend to the black objects and ignore the white, or vice versa. After several trials, a red cross unexpectedly appeared and traveled across the display, remaining on the computer screen for five seconds. The results of the experiment showed that even though the cross was distinctive from the black and white objects both in color and shape, about a third of participants missed it. They had found that people may be attentionally tuned to certain perceptual dimensions, such as brightness or shape. Inattentional blindness is most likely to occur if the unexpected stimuli presented resembles the environment.[37]

One interesting experiment displayed how cell phones contributed to inattentional blindness in basic tasks such as walking. The stimulus for this experiment was a brightly colored clown on a unicycle. The individuals participating in this experiment were divided into four sections. They were either talking on the phone, listening to an mp3 player, walking by themselves or walking in pairs. The study showed that individuals engaged in cell phone conversations were least likely to notice the clown. This experiment was designed by Ira E. Hyman, S. Matthew Boss, Breanne M. Wise, Kira E. Mckenzie and Jenna M. Caggiano at Western Washington University.[38]

Daniel Memmert conducted an experiment which suggests that an individual can look directly at an object and still not perceive it. This experiment was based on the invisible gorilla experiment. The participants were children with an average age of 7.7 years. Participants watched a short video of a six-player basketball game (three with white shirts, three with black shirts). The participants were instructed to watch only the players wearing black shirts and to count the times the team passed the ball. During the video a person in a gorilla suit walks through the scene. The film was projected onto a large screen (3.2 m X 2.4 m) and the participants sat in a chair 6 meters from the screen. Participants' eye movement and fixations were recorded during the video, and afterward the participants answered a series of questions.

Only 40% of the participants reported seeing the gorilla. There was no significant difference in accuracy of the counting between the two groups. Analyzing the eye movement and fixation data showed no significant difference in time spent looking at the players (black or white) between the two groups. However, the 60% of participants who did not report seeing the gorilla spent an average of 25 frames (about one second) fixated on the gorilla, despite not perceiving it.[39]

A more common example of blindness despite fixation is illustrated in the game of Three-card Monte.

Another experiment conducted by Daniel Memmert tested the effects of different levels of expertise can have on inattentional blindness. The participants in this experiment included six different groups: Adult basketball experts with an average of twelve years of experience, junior basketball experts with an average of five years, children who had practiced the game for an average of two years, and novice counterparts for each age group. In this experiment the participants watched the invisible gorilla experiment video. The participants were instructed to watch only the players wearing white and to count the times the team passed the ball.

The results showed that experts did not count the passes more accurately than novices but did show that adult subjects were more accurate than the junior and child subjects. A much higher percentage of experts noticed the gorilla compared with novices and even the practiced children. 62% of the adult experts and 60% of the junior experts noticed the gorilla, suggesting that the difference between five and twelve years of experience has minimal effect on inattentional blindness. However, only 38% of the adult, 35% of the junior, and none of the child novices noticed the gorilla. Only 18% of the children with two years of practice noticed. This suggests that both age and experience can have a significant effect on inattentional blindness.[39]

Arien Mack and Irvin Rock's concluded in 1998 that no conscious perception can occur without attention.[2] Evidence through research on inattentional blindness contemplates that it may be possible that inattentional blindness reflects a problem with memory rather than with perception.[2] It is argued that at least some instances of inattentional blindness are better characterized as memory failures than perceptual failures. The extent to which unattended stimuli fail to engage perceptual processing is an empirical question that the combination of inattentional blindness and other various measures of processing can be used to address.[3]

The theory behind inattentional blindness research suggests that we consciously experience only those objects and events to which we directly attend.[2] That means that the vast majority of information in our field of vision goes unnoticed. Thus if we miss the target stimulus in an experiment, but are later told about the existence of the stimulus, this sufficient awareness allows participants to report and recall the stimulus now that attention has been allocated to it.[3] Mack and Rock, and their colleagues discovered a striking array of visual events to which people are inattentionally blind.[2] However the debate arises whether this inattentional blindness was due to memory or perceptual processing limitations.

Mack and Rock note that explanations for inattentional blindness can reflect a basic failure of perceptual processes to be engaged by unattended stimuli. Or that it may reflect a failure of memorial processes to encode information about unattended stimuli. It is important to note that the memory failure does not have to do with forgetting something that has been encoded by losing access to the memory of the stimulus from time of presentation to time of retrieval, rather that the failure is attributed to information not being encoded when the stimulus was present.[2] It seems that inattentional blindness can be explained by both memory and perceptual failures because in experimental research participants may fail to report what was on display due to failures in encoded information (memory) or a failure in perceptually processed information (perception).[2]

There are similarities in the types of unconscious processing apparent in inattentional blindness and in neuropsychological syndromes such as visual neglect and extinction. The analogy between these phenomenon's seems to generate more questions as well as answers. These answers are fundamental for our understanding of the relationship between attention, stimulus coding and behavior.

Research has shown that some aspects of the syndrome of unilateral visual neglect appear to be similar to normal subjects in a state of inattentional blindness. In neglect, patients with lesions to the parietal cortex fail to respond to and report stimuli presented on the side of space contralateral to damage.[23][40] That is, they appear to be functionally blind to a range of stimuli. Since such lesions do not result in any sensory deficits, shortcomings have been explained in terms of a lack of attentional processing, for which the parietal cortex plays a large role.[41] These phenomena draw strong parallels to one another, as in both cases stimuli are perceptible but unreported when unattended.

In the phenomenon of extinction, patients can report the presence of a single stimulus presented on the affected side, but then fail to detect it when a second stimulus is presented simultaneously on the "good" (ipsilateral) side.[42] Here the stimulus on the affected side seems to lose under conditions of attentional competition from stimuli in the ipsilesional field.[42] The consequence of this competition is that the extinguished items may not be detected.

Similar to studies of inattentional blindness, there is evidence of processing taking place in the neglected field. For example, there can be semantic priming from a stimulus presented in the neglected field, which affects responses to stimuli subsequently presented on the unimpaired side.[43] Apparently in both neglect and inattentional blindness, there is some level processing of stimuli even when they are unattended.[43] However one major difference between neuropsychological symptoms such as neglect and extinction, and inattentional blindness concerns the role of expectation.[43] In inattentional blindness, subjects do not expect the unreported stimulus. In contrast, in neglect and extinction, patients may expect a stimulus to be presented on the affected side but still fail to report it when another it may be that expectation affects reportability but not the implicit processing of stimuli.[43]

Further explanations of the phenomenon of inattentional blindness include inattentional amnesia, inattentional agnosia and change blindness.

An explanation for this phenomenon is that observers see the critical object in their visual field but fail to process it extensively enough to retain it. Individuals experience inattentional agnosia after having seen the target stimuli but not consciously being able to identify what the stimuli is. It is possible that observers are not even able to identify that the stimuli they are seeing are coherent objects.[44] Thus observers perceive some representation of the stimuli but are actually unaware of what that stimulus is. It is because the stimulus is not encoded as a specific thing, that it later is not remembered. Individuals fail to report what the stimuli is after it has been removed. However, despite a lack in ability to fully process the stimuli, experiments have shown a priming effect of the critical stimuli. This priming effect indicates that the stimuli must have been processed to some degree, this occurs even if observers are unable to report what the stimuli is.[45]

Inattentional blindness is the failure to see a stimulus, such as an object that is present in a visual field. However, change blindness is the failure to notice something different about a visual display. Change blindness is a directly related to memory, individuals who experience the effects of change blindness fail to notice something different about a visual display from one moment to the next.[18] In experiments that test for this phenomenon participants are shown an image that is then followed by another duplicate image that has had a single change made to it. Participants are asked to compare and contrast the two images and identify what the change is. In inattentional blindness experiments, participants fail to identify some stimulus in a single display, a phenomenon that doesn't rely on memory the way change blindness does.[18] Inattentional blindness refers to an inability to identify an object all together whereas change blindness is a failure to compare a new image or display to one that was previously stored in memory.[18]

In 2006, Daniel Memmert conducted a series of studies in which he tested the how age and expertise of participants affect inattentional blindness. Using the gorilla video, he tested 6 different groups of participants. There were 2 groups of children (average age=7) half with no experience in basketball, and the other half with 2 years experience; 2 groups of juniors (average age=13) half with no experience in basketball, and the other half with 5 years of experience; and 2 groups of adults (average age = 24) half with no experience in basketball, the other half with over 12 years of experience. He then instructed all the groups to keep track of how many passes the people on the black team made.

Overall, the children with or without any basketball experience failed to perceive the gorilla more than the juniors or the adults. There were no significant difference between the inexperienced junior and adult groups, or between the experienced junior and adult groups.[39] This pattern of results suggests that until the approximate age of 13, presumably because certain aspects of cognition are still under development, inattentional blindness occurrences are more frequent, but become consistent throughout the remainder of the life span.

Additionally, the juniors with basketball experience noticed the gorilla significantly more than the juniors with no basketball experience; and the group of experienced adults noticed the gorilla significantly more than the non-experienced adults. This suggests that if one has had much experience with the stimuli in a visual field, they are more likely to consciously perceive the unexpected object.

In 2011, Elizabeth Graham and Deborah Burke conducted a study that assessed whether or not older adults are more susceptible to inattentional blindness than younger adults by having 51 younger-aged participants (17 to 22 years) and 61 older-aged participants (61 to 81 years) watch the classic gorilla video. Overall, they found that younger-aged participants were more likely to notice the unexpected gorilla than older-aged participants.[5]

In a 2015 study,[6] Cary Stothart, Walter Boot, and Daniel Simons attempted to replicate and extend the findings from both Graham and Burke's 2011 study and Steven Most and colleague's 2000 study[46] on Amazon Mechanical Turk using a sample of 515 participants that varied in age. In this study, participants were tasked with counting the number of times a number of white moving objects crossed the vertical midpoint of a display while ignoring a number of black moving objects. The unexpected object in this case was a gray cross that moved horizontally across the display at various distances from the vertical midpoint (this was manipulated between participants). Overall, they found that inattentional blindness susceptibility increases with age, which replicates the finding from Graham and Burke. In fact, they found that every 10 years of age was associated with a 1.3 fold increase in the probability of displaying inattentional blindness. They also found that the probability of inattentional blindness increases as the distance between the observer's focus of attention and the unexpected object increases, which replicates the finding from Most and colleagues. However, they also found that the relationship that age has with inattentional blindness does not change as a function of the unexpected object's distance from the focus of attention, suggesting that useful field of view does not mediate the relationship between age and inattentional blindness.

A series of studies conducted to test how similarity can influence the perception of a present stimulus. In the study, they asked participants to fixate on a central point on a computer screen and count how many times either white or black letters bounced off the edges of the screen. The first 2 trials did not contain an unexpected event, but the third trial was the critical trial in which a cross that had the same dimensions as the letters and varied in colour (white/light gray/dark gray/black) moved from the right side of the screen to the left side and passed through the central point. The results revealed the following: during the critical event, the more similar the colour of the cross was to the colour of the attended letters, the more likely the participants were to perceive it, and the less similar the colour of the cross was to the attended colour decreased the likelihood of the cross being noticed. For the participants attending to the black letters, 94% perceived the black cross; 44% perceived the dark gray cross; 12% perceived the light gray cross, and only 6% perceived the white cross. Similarly, if the participant was attending to the white letters, they were more likely to notice the cross it was white (94%) than if it was light gray (75%), dark gray (56%), or black (0%).[31] This study demonstrates that the more similar an unexpected object is to the attended object, the more likely it is to be perceived, thus reducing the chance of inattentional blindness.

A large experiment conducted on 794 participants by Schofield, Creswell and Denson[47] found evidence that completing a brief mindfulness exercise reduced rates on inattentional blindness, but did not improve the depth of encoding of the unexpected distractor. Participants in this experiment engaged in a guided-audio task of mindfully eating a raisin, a well-known task introduced by Kabat-Zinn in his mindfulness-based stress reduction program, or listened to factual descriptions about raisins. The audio recordings used to manipulate mindful states in this experiment are freely available online.[48] Participants who completed the raisin-eating task had 41% greater odds of noticing an unexpected red cross that floated across the screen. Participants were then asked to select the shape that had unexpectedly appeared (i.e., the red cross) out of a line-up of 3 red and 3 green shapes. Those in the mindfulness condition were no better than those in the control condition at selecting the red cross out of the line-up. This was true regardless of whether or not detection of the unexpected distractor was statistically controlled. This experiment demonstrated that not only does mindfulness affect inattentional blindness, but that detailed encoding of the unexpected distractor can be dissociated from the detection of the unexpected distractor.

The research that has been done on inattentional blindness suggests that there are four possible causes for this phenomenon. These include: conspicuity, mental workload, expectations, and capacity.[22]

Conspicuity refers to an object's ability to catch a person's attention. When something is conspicuous it is easily visible. There are two factors which determine conspicuity: sensory conspicuity and cognitive conspicuity. Sensory conspicuity factors are the physical properties an object has. If an item has bright colors, flashing lights, high contrast with environment, or other attention-grabbing physical properties it can attract a person's attention much easier. For example, people tend to notice objects that are bright colors or crazy patterns before they notice other objects. Cognitive conspicuity factors pertain to objects that are familiar to someone. People tend to notice objects faster if they have some meaning to their lives. For example, when a person hears his/her name, their attention is drawn to the person who said it. The cocktail party effect describes the cognitive conspicuity factor as well. When an object isn't conspicuous, it is easier to be inattentionally blind to it. People tend to notice items if they capture their attention in some way. If the object isn't visually prominent or relevant, there is a higher chance that a person will miss it.

Mental workload is a person's cognitive resources. The amount of a person's workload can interfere with processing of other stimuli. When a person focuses a lot of attention on one stimulus, he/she focuses less attention on other stimuli. For example, talking on the phone while driving the attention is mostly focused on the phone conversation, so there is less attention focused on driving. The mental workload could be anything from thinking about tasks that need to be done to tending to a baby in the backseat. When people have most of their attention focused on one thing, they are more vulnerable to inattentional blindness. However, the opposite is true as well. When a person has a very small mental workload he/she is doing an everyday task the task becomes automatic. Automatic processing can lessen one's mental workload, which can lead to a person to missing the unexpected stimuli.

Working memory also contributes to inattentional blindness. Cognitive psychologists have examined the relationship between working memory and inattention, but evidence is inconclusive. The rate of this phenomenon can be impacted by a number of factors. Researchers have found evidence for a number of components that may play a role. These include features of the object and the current task, where an individual's attention lies relative to the object, and mental workload as mentioned above. Researchers Kreitz, Furley, and Memmery in 2015, asserted that working memory capacity is not an indicator of susceptibility to inattentional blindness. Instead, it is a combination of what stimulus the attention is directed to as well as the individual's personal expectations. There are individual differences that can play a role, but some argue those disparities are separate from capacity for working memory.[49] On the other hand, there are researchers who consider differences between individuals and their working memory capacity to be a stronger determinant of inattentional blindness. Seegmiller, Watson, and Strayer in 2011 for example, studied individual differences in working memory capacity and how that overall impacted their attention on a given task. They utilized the same Invisible Gorilla video Simons and Chabris did (as mentioned above), but they additionally had participants complete a mathematics test to measure their capacity. From their results, they were able to find a high correlation between an individual's working memory capacity and their susceptibility to inattentional blindness. Those who were calculated to have a lower capacity, more often experienced the blindness.[50]

In a follow up study the same year, Kreitz and her team looked specifically at the cognitive abilities between individuals. Her team employed a variety of tasks, both static and dynamic, to compare the participants who had their cognitive capacity measured beforehand. Even though they included different tasks to test individuals, there was not a measurable relationship between the cognitive abilities of a participant and their attention performance. They did, however, find evidence to support the idea that noticing a certain stimuli was better in those demonstrating expertise in the task subject (referenced above). Overall, Kreitz concluded that cognitive/working memory capacity might not be an accurate measure for inattentional blindness. Instead, they determined that the rate of noticing might be both circumstantial and dependent on the requirements of the task.[51]

There are also researchers who subscribe to the idea that working memory does not play a measurable role in attentional blindness. This is different from the study by Kreitz and her team finding that individual differences in cognitive abilities might not be relative to noticing rates. Bredemeier and Simons conducted two studies in 2012. The first involved identifying the location of letters as well as counting how many times a group of shapes touched one another. These served as spatial and attention tasks respectively. The second study utilized the same tasks as the previous, but included a verbal one. Participants had to solve math problems and then remember a particular letter that followed each equation. From their results, the two researchers questioned if there was a relationship between noticing a particular stimuli and cognitive abilities. Instead of other factors contributing to the working memory of an individual's noticing, Bredemeier and Simons postulated that external variables establish the appearance of this relationship. Finally, the two researchers attempted to explain why studies were yielding conflicting results. The reason for why this research seems particularly inconclusive might be a result of disparities between the design of the actual research. Essentially, a variety of confounded variables might be prevalent across the studies when considering methodology and sampling processes. A more regulated, large-scale experiment could lead to more conclusive findings.[52]

When a person expects certain things to happen, he/she tends to block out other possibilities. This can lead to inattentional blindness. For example, person X is looking for their friend at a concert, and that person knows their friend (person Y) was wearing a yellow jacket. In order to find person Y, person X looks around for people wearing yellow. It is easier to pick a color out of the crowd than a person. However, if person Y took off the jacket, there is a chance person X could walk right past person Y and not notice because he/she was looking for the yellow jacket. Because of expectations, experts are more prone to inattentional blindness than beginners. An expert knows what to expect when certain situations arise. Therefore, that expert will know what to look for. This could cause that person to miss out on other important details that he/she may not have been looking for.

Attentional capacity, or neurological salience, is a measure of how much attention must be focused to complete a task. For example, an expert pianist can play a piano without thinking much, but a beginner would have to consciously think of every note they hit. This capacity can be lessened by drugs, alcohol, fatigue, and age. With a small capacity, it is more possible to miss things. Therefore, if a person is drunk, he/she will probably miss more than a sober person would. If your attentional capacity is large, you are less likely to experience inattentional blindness.

William James addressed the benefits of attention by saying, "Only those items which I notice shape my mind without selective interest, experience is utter chaos".[53] Humans have a limited mental capacity that is incapable of attending to all the sights, sounds and other inputs that rush the senses every moment. Inattentional blindness is beneficial in the sense that it is a mechanism that has evolved with attention to help filter out irrelevant input, allowing only important information to reach consciousness.[53] Several researchers, notably James J. Gibson, have argued that, even before the retina, perception begins in the ecology, which has turned perceptual processes into informational relationships in the environment through evolution.[54] This allows humans to focus our limited mental resources more efficiently in our environment. For example, New et al. maintain that survival required monitoring animals, both human and non-human, to become part of the evolutionary adaptiveness of the human species. They found that when participants were shown an image with a rapidly altering scene where the scene change included an animate or inanimate object that the participants were significantly better at identifying humans and animals. New et al. argue that better performance in detecting animals and humans is not a factor of acquired expertise, rather it is an evolved survival mechanism in human perception.[54]

Inattentional blindness is also beneficial as a response to advertising overload.[55] Irrelevant marketing makes it more likely for consumers to ignore initiatives that aim at capturing their attention. This phenomenon called 'purposeful blindness' has a compelling illustration regarding banner ads. Banner blindness shows that consumers can adopt fast and become good at ignoring marketing messages that are not relevant.

Although the bulk of inattentional blindness research has been conducted in laboratory studies, the phenomenon occurs in a variety of everyday contexts. Depending upon the context, the occurrence of inattentional blindness could range from embarrassing and/or humorous to potentially devastating.

Several recent studies of explicit attention capture have found that when observers are focused on some other object or event, they often experience inattentional blindness.[26] This finding has potentially tragic implications for distracted driving. If a person's attention is focused elsewhere while driving, carrying on a conversation or text messaging, for example, they could fail to notice salient and distinctive objects, such as a stop sign, which could lead to serious injury and possibly even death. There have also been heinous incidents attributed to inattentional blindness behind the wheel. For example, a Pennsylvania highway crew accidentally paved over a dead deer that was lying on the road. When questioned regarding their actions, the workers claimed to have never seen it.[30]

Many policies are being implemented around the world to decrease the competition for explicit attention capture while operating a vehicle. For example, there are legislative efforts in many countries aimed at banning or restricting the use of cell phones while driving. Research has shown that the use of both hands-free and hand-held cellular devices while driving results in the failure of attention to explicitly capture other salient and distinctive objects, leading to significantly delayed reaction times, as well as inattentional blindness.[56] A study published in 1997, based on accident data in Toronto, found the risk involved in driving while using a cell phone to be similar to that of driving drunk. In both cases, the risk of a collision was three to six times higher compared to a sober driver not using a cell phone.[57] Moreover, Strayer et al. (2006) found that when controlling for driving difficulty and time on task, cell-phone drivers exhibited greater impairment than intoxicated drivers, using a high-fidelity driving simulator.[58]

Inattentional blindness is also prevalent in aviation. The development of heads-up display (HUD) for pilots, which projects information onto the windshield or onto a helmet-mounted display, has enabled pilots to keep their eyes on the windshield, but simulator studies have found that HUD may cause runway incursion accidents, where one plane collides with another on the runway.[53] This finding is particularly concerning because HUDs are being employed in automobiles, which could lead to potential roadway incursions.[53] When a particular object or event captures attention to the extent to which the beholders' attentional capacity is completely absorbed, the resulting inattentional blindness has been known to cause dramatic accidents. For example, an airliner crew, engrossed with a blinking console light, failed to notice the approaching ground and register hearing the danger alarm sounding before the airliner crashed.[53]

Collaborative efforts to establish links between science and illusion have examined the relationship of the processes underlying inattentional blindness and the concept of misdirectiona magician's ability to manipulate attention in order to prevent his/her audience from seeing how a trick was performed. In several misdirection studies, including Kuhn and Tatler (2005),[59] participants watch a "vanishing item" magic trick. After the initial trial, participants are shown the trick until they detect the item dropping from the magician's hand. Most participants see the item drop on the second trial. The critical analyses involved differences in eye movements between the detected and undetected trials. These repetition trials are similar to the full-attention trial in the inattentional blindness paradigm, as both involve the detection of the unexpected event and, by detecting the unexpected event on the second trial, demonstrate that the event is readily perceivable.[60]

The main difference between inattentional blindness and misdirection involves how attention is manipulated. While inattentional blindness tasks require an explicit distractor, the attentional distraction in misdirection occurs through the implicit yet systematic orchestration of attention.[60] Moreover, there are several varieties of misdirection and different types are likely to induce different cognitive and perceptual processes, which vary the misdirection paradigm's resemblance to inattentional blindness.[60]

Although the aims of magic and illusion differ from those of neuroscience, magicians wish to exploit cognitive weaknesses, whereas neuroscientists seek to understand the brain and the neuronal significance of cognitive functions. Several researchers have argued that neuroscientists and psychologists can learn from incorporating the real world experience and knowledge of magicians into their fields of research. The techniques developed over centuries of stage magic by magicians may also be utilized by neuroscience as powerful probes of human cognition.[61]

When a police officer's version of events differs from video or forensic evidence, inattentional blindness has been used by defense lawyers as a possibility.[62] The criticism of this defense is that this view could be used to defend nearly any police shooting.[63]

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Inattentional blindness - Wikipedia

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With river blindness, ‘you never sleep’ – CNN

♫ Wednesday, December 19th, 2018

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See the article here:
With river blindness, 'you never sleep' - CNN

♫ Posted in Blindness | | Comments Off»

End Times – Life, Hope & Truth

♫ Friday, November 30th, 2018

Who is he? What does this strange-sounding term mean? How can you avoid being a victim of the end-time Antichrists deception?

God is the only One who can predict the futureand make His predictions come true. What does He want you to know about Bible prophecies of the end times?

The religious leaders of Jesus day asked Him for a miraculous sign, but He chided them for not discerning the signs of the times. What did He mean? Can we discern them?

Doomsday prophets always talk about the end of the world. What does the Bible really say about end-time prophecy? And why is Gods message called good news?

Many people have heard of the four horsemen of the Apocalypse, but not as many really know what they are. What do they tell us about end times prophecy?

Many believe when Jesus returns, He will approach secretly to snatch away all believers and children in a rapture to protect them. Is this biblical?

Many people describe the final battle at the end of the world as the battle of Armageddon. But is that really what the Bible teaches?

What did Jeremiah mean by the time of Jacobs trouble? How does this unequaled time of trouble for Israels descendants relate to the Great Tribulation?

Russia always seems to find its way into the middle of world affairs. Historically, who are the Russians? Do they have a role to play in biblical prophecy?

The Bible says that Jesus is going to come back to earth. But given all the advancements in our modern world, is Christs second coming really necessary?

Jesus knew that we would want to know when He is coming back. He wants us to eagerly await that day! But does He want us to know exactly when He will return?

The world desperately needs the return of Christ. But the Bible warns there will be conflicting messages about when and where He will return. Whats the truth?

God will use supernatural heavenly signs to signal the beginning of His intervention to punish humanity for our sinsand to rescue us from self-destruction.

Fluctuations in the world economy have plagued mankind for thousands of years. Why do economic crises happen? Is there a biblical solution?

Jesus Christ pointed out the importance of understanding the signs of the times. Why did He say this, and what are the warning signs of the end times?

Why do we have the WorldWatch section in Discern? What does the Bible tell us to watch, and how do we choose which news items and trends to share?

Just before He returns, Christ says, the earth will be dominated by gentile nations. Who are these gentiles, and what will be the result of their influence?

The Bible speaks of wonderful future times of comfort and joy. When will these times of refreshing be, and how can true believers experience them?

Bible prophecy foretells the times of restoration of all things. What will be restored to its former state? When will this longed-for renewal occur?

Jesus said that end-time events would parallel those in the days before Sodom and Gomorrahs destruction. What were those conditions, and why is it important?

Jesus Christ said that end-time events would be like those during the time of Noah. What were those conditions like, and why should we be concerned?

Earthquakes have caused widespread destruction and the deaths of millions of people. What does the Bible say about earthquakes in the end times? How should we respond?

The Bible describes terrible end-time plagues on the earths water systems; but after Jesus Christs return, fresh water will bring life even to barren lands.

What is happening to our water supplies? Will shortages affect our health, economy and lead to more conflict? What does the Bible say about future water woes?

Many wars have been fought since World War II. Has man learned how to avoid world war or are we living on borrowed time? Does the Bible predict World War III?

In spite of our unquenchable optimism, the solution to our brokenness is out of reach. Its going to take far more than elbow grease to fix the mess weve made.

Millions of people are feverishly preparing for the end of the world as we know it. Many of the fears are real. But is there a better way to prepare?

There is so much bad news today, good news can seem unbelievable or at least overblown. But utopia is realand its coming soon.

Terrifying curses were pronounced millennia ago, and their effects are being felt to this day. Why? And how will they finally be removed?

Thanksgiving and its opposite dont seem that important to most people. But God looks at things differently. Ingratitude is one of the symptoms of society on the brink.

As concerns over weapons of mass destruction (WMD) escalate, what does the Bible say about end-time events in which these devices may be used?

As corruption, violence and evil increase, our world teeters on the brink of self-destruction. Jesus Christs promise to come again offers our only real hope.

In the last days, the Bible warns of times of stress that can turn people cold as ice. Consider four points to help keep your love from growing cold.

On the Mount of Olives Jesus answered His disciples questions about the temple and end-time events. His prophecy remains a vital message for today.

Why is the world facing epidemic after epidemic of new and reemerging infectious diseases? What are we doing wrong, and how will the ultimate healing come?

How close are we to the end of the world? Is it even possible to know?

Unrest, war, poverty and extreme ideological divides are multiplying around the globe. How did we get in this mess? Is there a way out?

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Messiah’s Message: Repent – Life, Hope & Truth

♫ Friday, November 30th, 2018

The first two statements of explanation that Jesus gave as He preached the gospel of the Kingdom of GodThe time is fulfilled and the kingdom of God is at handwere covered in previous articles in this series. We now come to the first of the two commands Jesus issued: Repent (Mark 1:15).

In the previous article we noted that flesh and blood cannot inherit the kingdom of God (1 Corinthians 15:50). Our human body must be changed to a spiritual body (verse 44) if we are to be part of this Kingdom.

Obeying Christs command to repent is the first step in the process that prepares us for change from flesh and blood to spirit. This change is necessary in order for us to become members of Gods immortal family and rulers within His eternal Kingdom (John 1:12; Revelation 1:6; 5:10).

Encouraging people to repent of their sins was an integral part of the gospel Jesus preached. Commenting on two occasions where people had lost their lives, Jesus said, I tell you, no; but unless you repent you will all likewise perish (Luke 13:3, 5, emphasis added throughout). Later, He began to rebuke the cities in which most of His mighty works had been done, because they did not repent (Matthew 11:20).

The historical record shows that the disciples Jesus trained also preached that people should repent (Mark 6:12). As Peter explained, repentance and then baptism were the initial steps Christians must take when they respond to the gospel (Acts 2:38).

The Greek word that is translated repent in the New Testament means to change ones way of life as the result of a complete change of thought and attitude with regard to sin and righteousness (J.P. Louw and Eugene Nida, Greek-English Lexicon of the New Testament Based on Semantic Domains, 1988). A person who repents realizes that he or she has been sinningbreaking Gods holy and beneficial lawand that he or she needs to change.

Key Steps in Repentance

What specific steps must one take in order to repent? The Bible reveals several actions that are integral to this important process:

Admit to God that you have sinned. Although Scripture teaches that everyone has sinned (Romans 3:23), we do not like to personally acknowledge that we have broken Gods holy and beneficial law. Hard as it is, this fundamental act is the first step we must take in order to repent.

Ask God for help. Although we like to think we can do anything we set our minds to, the truth iswe need Gods assistance in order to repent. Repentance is a gift from God (2 Timothy 2:25). He is the One who leads people to repentance (Romans 2:4).

Start living in accordance with Gods laws. Our natural, carnal nature does not want to obey God, but we must rule over this rebellious nature and keep Gods commandments (Romans 8:7, 13; Matthew 19:17).

Continue to repent. Even after we are baptized and receive the Holy Spirit, we still occasionally sin. When we do, we must confess our sins to God (1 John 1:7-10) and determine not to continue in them (Romans 6:1-2).

For further study on the actions involved in repentance, see the article How to Repent.

The calling and stimulus for wanting to repentto change our livescomes from God the Father (John 6:44). As Paul wrote to members at Rome, Do you despise the riches of His goodness, forbearance, and longsuffering, not knowing that the goodness of God leads you to repentance? (Romans 2:4).

Although the realization of our need to change may come in various waysa key moment in life, a time of contemplation, hearing a specific message, the example of a friendit is always marked by a change of heartthat is, our way of thinking (Acts 2:37). Instead of ignoring Gods instructions as we had been doing, the primary focus in our lives becomes earnestly learning Gods law and living in accordance with it. Gods way of life is now our life. We love Gods instructions and want to do what He expects of us (1 John 5:3).

Understanding that a dramatic change in thinking occurs when people repent of their sins, some have referred to this event as giving your heart to the Lord. And while our hearts are indeed at the center of thisprocess, we must also understand that repentance is far more than simply an emotional moment. When we truly repent, we will also act differentlythat is, by living righteouslyand we will continue living righteously for the remainder of our lives.

Genuine repentance is not a one-time event. It is an ongoing way of thinking and living in accordance with Gods instructions found in His Wordthe Holy Bible.

If we are going to obey Jesus command to repent, we must also understand what He expects us to repent of. The obvious answer is that we must repent of our sinsthe times we have broken or ignored Gods law. As Peter told the crowd in Jerusalem, Repent therefore and be converted, that your sins may be blotted out (Acts 3:19).

The Bible says sin is lawlessness, specifically meaning transgressing Gods laws (1 John 3:4). In light of this, what would have been some of the sins Christ commanded the people of the first century and us today to repent of? Here are a few sins to consider.

Sadly, many within mainstream Christianity no longerunderstand what sin is. Many teach or condone some of the things Jesus expects people to repent of. The honorable traits of tolerance, love and respect have been so distorted and misapplied that many now think Jesus approves of the very things that were sins in the first century and that continue to be sins today.

Though their hearts and emotions may indeed be touched by the Messiahs message, too many have mistakenly continued living in opposition to Gods teaching. Those who neglect or fail to understand this more complete understanding of repentancethat it includes our minds and our obedience to Gods instructions in the Bibleare not properly responding to the Messiahs command to repent.

God hasnt changed His mind about what is and isnt sin (Malachi 3:6; Hebrews 13:8). In order to truly repent, we must accept Gods definitions of sin and then alter our conduct accordingly.

While our hearts are indeed at the center of this process, we must also understand that repentance is far more than simply an emotional moment.

The biblical response to real, genuine repentance is baptism. As Peter told the crowd gathered in Jerusalem on the Day of Pentecost in A.D. 31, Repent, and let every one of you be baptized in the name of Jesus Christ for the remission of sins; and you shall receive the gift of the Holy Spirit (Acts 2:38).

Baptism represents our sins being washed away (Acts 22:16). The Holy Spirit helps us understand Gods timeless instruction in spite of religious confusion in the world around us (John 16:13; 1 John 5:19). This power from God (Luke 24:49) strips away spiritual blindness (2 Corinthians 3:14-16; Ephesians 4:18); and when we receive it via baptism, it identifies us as children of God (Romans 8:9, 14, 16).

In addition to these wonderful benefits of having Gods Spirit, there is still another important blessing that God extends when His Spirit is present within us. It is the guarantee of receiving eternal life. As Paul wrote, But if the Spirit of Him who raised Jesus from the dead dwells in you, He who raised Christ from the dead will also give life to your mortal bodies through His Spirit (Romans 8:11).

The new life we will receive will be eternal. As Paul further explained, this life will come when we are changed from natural bodies formed from the dust of the earth to ones that are immortal and similar to God in composition (1 Corinthians 15:35-53; 1 John 3:1-2).

Repenting of our sins and being baptized for the forgiveness of those sins so we can receive the Holy Spirit are thus necessary steps for us to enter the Kingdom of God. Again, as Jesus stated, Unless you repent you will all likewise perish (Luke 13:3).

In the concluding article in this series we will examine Christs command to believe in the gospel (Mark 1:15).

For further study on repentance, see the Life Hope & Truth article What Is Repentance? and the ones in the section on baptism.

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Color Blindness Tests Colblindor

♫ Wednesday, November 21st, 2018

Many people are looking for a possibility to test their color vision on the web. Unfortunately there arent many color blindness tests available online. So this page shall bring together a series of tests to check your personal type of color vision deficiency and the severity of it.

Please be aware that your personal computer display settings, ambient light and other factors can affect your test result. If you want to get an accurate diagnosis of your color vision deficiency, please visit your local eye specialist.

The often called Ishihara plates were introduced by Dr. Shinobu Ishihara from Japan long time ago. Since then this test is the most well known all around the world.

This test consists of 38 different pseudoisochromatic plates. Each of them hides a number or line behind colorful dots. Based on what you can see and what not, it is possible to check if you are suffering from some form of red-green color blindness.

As the test is usually executed in a booklet, it is not the best possibility to online test your type and severity of color blindness. Other tests like the arrangement tests below show better results.

This famous color vision testwhich is based on 88 colored plates and not 100 as the name suggestwas introduced in 1943 by Farnsworth.

The test will show you four batches of 22 mixed colored plates. What you have to do is to arrange the for rows of plates in a correct order. Thats all.

All misplacements will be summed up to your personal total error score. The higher your TES is, the more severely colorblind you are. On the other hand you can also get some information on the type of your color vision deficiency based on the area around your biggest error points.

In 1947 Farnsworth released the D-15 dichotomous test. This is to this day one of the most famous color vision deficiency test and definitely the most famous color arrangement test.

You simply have to arrange the given colors in the correct order of colors. If you are suffering from some form of color blindness, you will arrange them quite differently compared to persons with normal color vision.

With this test is not only possible to check the type of your color vision deficiency but also its severity. Unfortunately the test results are not completely reliable, which is a base problem for all types of online color vision tests. But the result will be a good indicator of your correct color vision abilities, specially if you take it under different conditions.

This is my first try to develop a simple red-green color blindness test. It is based on the idea of the real anomaloscope, made from two different light sources which have to be brought to a match.

Just match the left color to the right one using the slider below the box. If you can match several of them you are definitely red-green colorblind. Originally I wanted to retrieve more detailed information from the test results. But it didnt work outyet.

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Blindness – kidshealth.org

♫ Monday, September 24th, 2018

Have you ever put on a blindfold and pretended that you couldn't see? You probably bumped into things and got confused about which way you were going. But if you had to, you could get adjusted and learn to live without your sight.

Lots of people have done just that. They have found ways to learn, play, and work, even though they have trouble seeing or can't see at all.

Your eyes and your brain work together to see. The eye is made up of many different parts, including the cornea, iris, lens, and retina. These parts all work together to focus on light and images. Your eyes then use special nerves to send what you see to your brain, so your brain can process and recognize what you're seeing. In eyes that work correctly, this process happens almost instantly.

When this doesn't work the way it should, a person may be visually impaired, or blind. The problem may affect one eye or both eyes.

When you think of being blind, you might imagine total darkness. But most people who are blind can still see a little light or shadows. They just can't see things clearly. People who have some sight, but still need a lot of help, are sometimes called "legally blind."

Vision problems can develop before a baby is born. Sometimes, parts of the eyes don't form the way they should. A kid's eyes might look fine, but the brain has trouble processing the information they send. The optic nerve sends pictures to the brain, so if the nerve doesn't form correctly, the baby's brain won't receive the messages needed for sight.

Blindness can be genetic (or inherited), which means that this problem gets passed down to a kid from parents through genes.

Blindness also can be caused by an accident, if something hurts the eye. That's why it's so important to protect your eyes when you play certain sports, such as hockey.

Some illnesses, such as diabetes, can damage a person's vision over time. Other eye diseases, such as cataracts (say: KAH-tuh-rakts), can cause vision problems or blindness, but they usually affect older people.

A kid who has serious trouble with vision might see an ophthalmologist (say: af-thal-MAH-luh-jist), a doctor who specializes in eye problems. Even babies might see an ophthalmologist if their parents think they might be having trouble seeing.

At the doctor visit, the doctor will talk with the parents and the kid (if the kid is old enough to describe what's going on). A doctor might use an eye chart to find out how well the kid can see. You've probably seen these charts that contain letters of different sizes. It's a way of testing how well a person can see. Someone with really good vision would be able to read certain letters from 20 feet (6 meters) away.

Eyesight this good is called 20/20 vision, although some people can see even better than that. The numbers change depending on how clearly a person can see. The larger or closer something needs to be in order for it to be seen, the worse a person's vision is.

Many times, glasses or contact lenses are all that's needed to help kids see better. But if glasses and contact lenses can't make someone's vision any better and the person needs to get really close to something to see it he or she may be considered blind. For instance, someone with good vision might be able to see an object from 200 feet (61 meters) away, but someone is considered blind if he or she needs to be 20 feet (6 meters) away to see the same object.

Babies and little kids won't be able to use the eye chart, but doctors can check their vision by doing special vision tests or something as simple as putting a toy in front of the child to see if he or she can focus on it.

The ophthalmologist also will examine the kid's eyes using special medication and lighting that allows him or her to see into the eyeballs. The ophthalmologist will look at each part of the eye to check for problems, such as a cataract (cloudiness of the eye's lens). Once the doctor knows what's causing the vision problem, he or she can begin planning how to treat it.

In some cases, an operation can help improve a kid's vision. For example, if a kid has a cataract, doctors may do surgery to remove it.

A baby who is blind can still learn and develop normally. But the baby's parents will need the help of specialists who know how to help blind children. It's often a great idea for the child to attend special learning programs designed just for little kids who have trouble seeing. These programs would make the most of the senses that the kid does have, such as touch, hearing, smell, and taste.

Touch comes in handy when a child is older and wants to read books. Kids who are visually impaired can learn to read by using a special system called braille. Braille is a way of expressing letters, words, and thoughts. To read braille, a person feels a series of little bumps that are associated with letters in the alphabet. For instance, "A" is represented as one bump. Computer programs and other devices that can "see" turn the words on a page into braille.

Hearing is another important sense if a kid has vision problems. Some devices can read out loud what's written on a page. With special equipment, a visually impaired kid can read almost anything. These kinds of technologies can be helpful in learning. Kids who are blind might attend a special school, or they might attend regular classes, aided by special devices and specialists.

Kids who have vision problems will get help from their parents, doctors, and teachers. When they are older, some of them may get a hand or should we say a paw? from a guide dog. These helper dogs are trained to be a blind person's eyes. That means the dog learns to be very alert to surroundings so he or she can be a good guide for the person.

Not only are these dogs great friends, they give blind people independence, so they can accomplish what they want to accomplish.

Many blind people have gone on to do amazing things in many different fields, including music, the arts, and even sports. Serious vision problems didn't stop runner Marla Runyan. She was the first legally blind person to ever qualify for the Olympics!

Date reviewed: September 2016

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AARP’s Health Tools

♫ Tuesday, August 28th, 2018

Blindness is the inability to see anything, even light. Ifyoure partially blind, you have limited vision. For example, you may haveblurry vision or the inability to distinguish the shapes of objects. Completeblindness means that you cant see at all and are in total darkness. Legalblindness refers to vision thats highly compromised. What a person withhealthy eyes can see from 200 feet away a legally blind person can see onlyfrom 20 feet away.

Seek medical attention right away if you suddenly lose theability to see. Have someone bring you to the emergency room for treatment. Dontwait for your vision to return. Depending on the cause of your blindness,immediate treatment may increase your chances of restoring your vision.Treatment may involve surgery or medication.

If youre completely blind, you can see nothing. If yourepartially blind, you might experience the following symptoms:

Your childs visual system begins to develop in the womb,but it wont be fully formed until about 2 years of age. By 6 to 8 weeks ofage, your baby should be able to fix their gaze on an object and follow itsmovement. By 4 months of age, their eyes should be properly aligned and notturned inward or outward.

The symptoms of visual impairment in young children can include:

The following eye diseases and conditions can causeblindness:

Blindness is a potential complication if you have diabetesor have a stroke. Birth defects, eye injuries, and complications from eyesurgery are other common causes of blindness.

The following conditions can impair vision or cause blindnessin infants:

The following categories of people are at risk of blindness:

A thorough eye exam by an optometrist will help to determinethe cause of your blindness or partial loss of vision. Your eye doctor willadminister a series of tests that measure the clarity of your vision, thefunction of your eye muscles, and how your pupils react to light. Theyllexamine the general health of your eyes using a slit lamp, which is a low-powermicroscope paired with a high-intensity light.

A pediatrician will screen your baby for eye problemsshortly after birth. At 6 months of age, you should have an eye doctor orpediatrician check your child again for visual acuity, focus, and eyealignment. The doctor will look at your babys eye structures and see whetherthey can follow a light or colorful object with their eyes.

Your child should be able to pay attention to visual stimuliby 6 to 8 weeks of age. If your child doesnt react to light shining in theireyes or focus on colorful objects by 2 to 3 months of age, have their eyesexamined right away. You should have their eyes examined if you notice crossedeyes or any other symptoms of impaired vision.

In some cases of vision impairment, one or more of thefollowing may help to restore your vision:

If you experience partial blindness that cant be corrected,your doctor will provide guidance on how to function with limited vision. Forexample, you can use a magnifying glass to read, increase the text size on yourcomputer, and use audio clocks and audiobooks.

Complete blindness requires approaching life in a new wayand learning new skills. For example, you may need to learn how to:

You may also need to have handrails installed in yourbathroom.

The long-term outlook for restoring vision and slowingvision loss is better when treatment is preventive and sought immediately.Cataracts can be treated effectively with surgery and dont necessarily resultin blindness. Early diagnosis and treatment are also important in cases ofglaucoma and macular degeneration to help slow down or stop your vision loss.

To detect eye diseases and help prevent vision loss, getregular eye examinations. If youre diagnosed with certain eye conditions, suchas glaucoma, treatment with medication can help prevent blindness.

Have your childs eyes examined at 6 months of age, 3 yearsof age, and every two years between the ages of 6 and 18 years old to helpprevent vision loss. If you notice symptoms of vision loss between routinevisits, make an appointment with their eye doctor immediately.

Written by: Chitra Badii and Marijane LeonardMedically reviewed on: Mar 09, 2016: Mark R. Laflamme, MD

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Blindness (Harvest Book): Jose Saramago, Giovanni Pontiero …

♫ Wednesday, August 22nd, 2018

This is a shattering work by a literary master.The Boston Globe

This is an important book, one that is unafraid to face all of the horrors of the century.The Washington Post

Symphonic . . . [There is] a clear-eyed and compassionate acknowledgment of things as they are, a quality that can only honestly be termed wisdom. We should be grateful when it is handed to us in such generous measure.The New York Times Book Review

Saramago's surreal allegory explores the ability of the human spirit to prevail in even the most absurdly unjust of conditions, yet he reinvents this familiar struggle with the stylistic eccentricity of a master.The New Yorker

Extraordinarily nuanced and evocative . . . This year's most propulsive, and most profound, thriller.The Village Voice

Like Jonathan Swift, Saramago uses airily matter-of-fact detail to frame a bitter parable; unlike Swift he pierces the parable with a dart of steely tenderness . . . out of leisurely prose, the ferocity and tenderness shoot suddenly: arrows set alight. . . . Enchanting, sinuous dialogue.TheLos Angeles Times

Blindness may be as revolutionary in its own way and time as were, say, The Trial and The Plague in theirs. Another masterpiece.Kirkus Reviews (starred review)

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Loss of Vision and Blindness in Your Dog

♫ Wednesday, August 8th, 2018

I cannot see you Mommy, when you cuddle me so near.And yet I know you love me, it's in the words I hear.I cannot see you Daddy, when you hold me by your sideBut still I know you love me when you tell me so with pride.I cannot see to run and play out in the sun so brightFor here inside my tiny head it's always dark as night.I cannot see the treats you give when I am extra goodBut I can wag my tail in Thanks just like a good dog should."She cannot see. The dogs no good" is what some folks might say"She can't be trained, she'll never learn, She must be put away."But not you, Mom and Daddy, You know that it's alrightBecause I love you just as much as any dog with sight.You took me in, you gave me love and we will never partBecause I'm blind with just my eyes, I see you in my heart.

Sherrill Wardrip

Causes and Treatments

The causes of vision loss and blindness in dogs range from normal aging and heredity to disease and injury. Vision problems ranging from hazy vision to complete blindness occur in many dogs as part of the aging process. An untreated eye infection or stroke may result in temporary or permanent blindness. Blindness is sometimes a secondary symptom to other canine diseases such as heart, liver, and kidney ailments or systemic diseases such as diabetes.

Diabetes in dogs is on the rise. Its estimated that one in 10 dogs worldwide will eventually become diabetic. Heredity plays a large factor, and larger, older dogs and breeding females are at a higher risk. Poor nutrition and obesity are other risk factors. Three out of four dogs with diabetes will develop cataracts within a year of being diagnosed, which may result in partial or total blindness. In fact, development of cataracts may be the first indication that a dog is diabetic. Other symptoms include extreme thirst, more frequent urination possibly with accidents in the house, sudden unexplained weight loss, lethargy or depression, and abdominal pain. If your dog shows any of these signs, seek veterinary treatment immediately. As with humans, treatment for diabetes can range from a change of diet and exercise to daily insulin shots and, as with any disease, the prognosis is better with early intervention.

Cataracts, a condition where the normally transparent lens turns cloudy preventing light from reaching the retina, can result in partial or total blindness. It can be inherited or caused by infections, injury, and other diseases as well as diabetes. Cataracts can develop very quickly. Early intervention through surgery may save a dogs sight. However, if caused by diabetes, healing may be slowed and scarring could result in less than optimal results. If left untreated, cataracts can sometimes cause an inflammation called Lens-Induced Uveitis (LIU) causing glaucoma. And if the LIU is untreated and glaucoma develops, cataract surgery might not be possible.

Glaucoma a painful condition where fluid pressure increases inside the eye causing damage to the retina and optic nerves resulting in partial or total blindness. The pain is similar to that of a migraine headache. Symptoms include dilation of one or both pupils, green or yellow discharge from the eye(s), delayed response to bright light, or bloodshot eyes. Seek veterinary care as soon as possible if you notice any of these symptoms. Both medical and surgical treatments are available, but are more successful with early intervention.

Progressive Retinal Atrophy (PRA) is an inherited condition where the cells of the retina deteriorate causing blindness. Although not painful, both eyes are affected. It is found most often in Collies, Poodles, Schnauzers and Cocker Spaniels. The first sign of PRA is decreased night vision. Your dog may become more reluctant to go out after dark or become disoriented in low light situations. This is a degenerative disease with no cure. However, there are some antioxidant supplements available to slow the deterioration of your dog's sight.

Perhaps the most tragic and scariest of conditions is Suddenly Acquired Retinal Degeneration Syndrome (SARDS). Much like PRA, it involves the deterioration of the retina, usually affects both eyes, and causes no pain. Unlike PRA, the blindness is sudden rather than gradual, with total blindness occurring over a few days to several weeks. Older dogs, females, and overweight dogs appear to be more at risk. The disease is diagnosed by a lack of electrical activity within the retina. Initial observation of the eye shows no structural damage, but the retina degenerates quickly over a short period of time. University of Iowa College of Veterinary Medicine has had some success in restoring the sight of dogs, but treatments are still the experimental stages. Long-term prognosis is still unknown and the costs are high. Again, successful treatment required quick intervention. For more information on SARDS, click here.

Other conditions and diseases that affect vision include high blood pressure, Cushings disease, epilepsy, tumors, heart, liver, and kidney diseases. Regardless of what you may suspect as a cause, if your dog appears to be having trouble with his vision, you should seek veterinary treatment immediately.

Vision Impairment and Blindness

Dogs do not rely on their sense of vision to the same extent as do humans. The dog's vision is also not as highly developed as it is in humans. Dogs also cannot focus well on near objects, are partially color blind, and have poor detail vision. Canine vision is superior to human vision for detecting moving objects in dim light. This vision suits their original need as nocturnal hunters. Since the majority of domesticated dogs no longer hunt to survive, blindness does not interfere with their domesticated primary function--being a companion and pet.

The Animal Ophthalmology Center

Dogs who are blind from birth are unaware that they are different from other dogs. They interact with the world much like any other puppy; they just go about it differently. Blind dogs rely on their senses of smell and hearing to compensate for the lack of sight, and those senses become more acute over time. Without proper socialization, however, a dog may become fearful and stressed in unfamiliar situations. Therefore early and frequent socialization with other animals and humans is important and should continue throughout life. It allows the dog to develop self-confidence and dog and his owner to bond more closely. The dog will experience a richer life with exposure to a variety of new people, situations, and experiences.

Most dogs with vision loss and blindness experience a gradual loss of vision over time. Frequently owners rush to the veterinarian with a claim of sudden blindness when examination indicates that the animal has been blind for some time. The dog has managed to compensate so well, its only when there is a change in their home environment or exposure to a new situation that the problem becomes apparent. These dogs are far better equipped to deal with the vision loss/blindness than the owners. The owners sense of grief and loss is understandable, but usually the pet has moved on and is coping just fine. Many people consider euthanizing their blind pets, thinking that their quality of life will be diminished.

What I say to people is, look, your dog couldnt read, write or drive a car, anyway. Hes already got four other senses that are better than yours. As long as you take good care of him, hell be okay.

Nick Whelan, Canine ophthalmologist, Ontario Veterinary College

Sudden onset blindness can be much harder for both the dog and owner than a gradual loss of vision. Even then, most dogs can adjust, but the adjustment period is likely to be longer and harder. Where a dog whose vision gradually diminishes has the opportunity to work on mapping out his environment and developing coping strategies without the owners help or knowledge, a dog with sudden onset blindness is plunged into darkness without warning. He is more likely to experience depression, nervousness, and anxiety. The owner will have to take more precautions, such as adding baby gates or otherwise blocking off stairs and other hazards, removing or padding sharp corners on furniture, and make other accommodations until the dog has adjusted to his condition and mapped his environment. You may need to limit access to one or two rooms at a time until the dog is comfortable there, before expanding his access to the rest of the house. Once he has mastered those, add another room or two. You may need to walk him around the rooms and show him obstaclesplacement of furniture and other objects, and the location of his food and water bowls and bed or crate.

How well your dog will cope with blindness will depend on the dog. Young dogs will adapt better than old dogs, but may require more vigilance because their exuberance can lead them to dangerous situations. Indoor pets are likely to adjust more easily than those allowed to run free. A dominant dog in a multi-dog environment may have more difficult adjusting than a single dog, especially if the other dogs challenge his pack position. Or his companions may help him with adjusting. If blindness is caused by a painful condition such as glaucoma or a systemic disease such as diabetes, the dog may have more difficulty adjusting until the underlying condition is treated.

Even dogs who adapt well otherwise may experience some personality changes. Many dogs will develop some degree of separation anxietythey are more dependent on their owners and will become distressed when the owner leaves. This can be addressed through training and behavioral modification, but it will be more challenging because the underlying condition, blindness, cannot be changed.

Training is good for any dog. It increases bonding between the dog and owner and gets him accustomed to taking direction from the owner. For a blind dog, it can be a lifesaver. The wait command can save your dog from injury or even death when facing hazards he cant see. If the dog was trained before going blind, he will have an easier time learning the additional commands you will need to teach him to help him navigate his darkened world.

Perhaps the most important factor in how well a dog copes with his new condition is the owner. Giving your dog the love and support he needs during his adjustment is crucial. If you must give in to your emotions, do it away from the dog. It is important to remain upbeat and positive in his presence.

Detecting Loss of Vision

Some signs that your dog may be experiencing vision loss or blindness include general clumsiness, bumping into walls and furniture, startling easily and apprehensive behavior, inability to find toys or food and water bowls, reluctance to go out at night, excessive sleeping or loss of playfulness, disorientation or confusion, or changes in the appearance of the eyes. If you notice these behaviors in your dog, you should seek immediate veterinary care.

Your veterinarian will likely conduct a thorough physical exam to determine the cause and extent of the dogs vision loss. This may include blood work, neurological exam, cerebral spinal fluid test, MCR or CT scan, and ophthalmologic exam. You may be referred to a veterinary ophthalmology specialist. Treatment of the condition will depend on the cause. And while the vision loss may not be reversible, your dog can still live a fulfilling life after adjusting to his new condition.

How Do I Help My Pet Adjust to Vision Loss or Blindness?

Naturally, you are going to be distressed at your pets vision loss. Remember that animals key in to your emotions, and that the best thing you can do for your pet is to maintain a calm, upbeat, positive attitude. Dogs can adjust to vision loss or blindness rather quicklyassuming you help, rather than hinder, the adjustment. Coddling or babying your pet usually results in a much longer adjustment period, loss of self-confidence, and may increase his dependence on you increasing his stress level. If you have a small pet, you may want to pick her up to take her to her bed or food and water bowls, or just to comfort her. Try to avoid this. It disorients her. If you do pick her up for petting and snuggling, return her to the same spot and facing the same direction. Talk to your dog when entering and exiting rooms, and prior to touching her when she is sleeping. Let her figure things out for herself. You will be surprised at how well and quickly she will adjust.

This doesnt mean you shouldnt make changes to your behavior, home and routine to accommodate your blind pet. There are a number of actions you can and should take to make to keep your pet safe and increase his confidence.

Establishing schedules and routines will be helpful to your blind pet. Feeding should be done on a set schedule and food and water bowls should not be movedeven by inches. Use adhesive stars or dots to mark locations. Some veterinarians recommend placing a small rug under food bowls and using a scent on it, a drop of peppermint or vanilla, to help her navigate to it. It usually isnt necessary as long as you keep the food and water bowl in the same place. Call your pet to dinner with the same words and tone of voice every time. Do check to make sure your pet is eating and drinking, and lead her to her bowls if she is not. If she still doesnt eat or drink, seek veterinary care immediately.

When walking a blind dog, he may be more comfortable if you walk the same route every time while he adjusts to his blindness. The smells, textures, and sounds will be familiar and comforting to him. You may want to give him more sniffing time in safe areas than you would a sighted dog. Many animals are less open to new experiences after becoming blind or experiencing vision loss. Introduce them to changes slowly and pace changes to the pets comfort level.

You can use aromas in your home to help your pet navigate. You may just elect to use twoone to signal good and one to signal bad. For example, use a drop a vanilla on food bowls, on doorways (get both sides of the doorframe so can navigate between the two) and at the top and bottom of stairs, and bitter apple on stoves, fireplaces, and rooms he would be best avoiding. Some experts suggest using a different plug-in air fresher fragrance in each room. You need to be certain to use the same fragrance in each room every time and keep a back-up supply on hand in case your local store runs out of a particular fragrance.

Talking to your dog can relieve the sense of isolation brought on by blindness. Talk to her frequently. Discuss the weather, current events, the garden, or what your mother or children said on the phone. Even taboo subject such as politics and religion, she really doesnt care! Talking to your dog will provide comfort, lessen her sense of isolation, and let her know you are there regardless of what you are saying!

Home Hazards

To the extent possible, dont rearrange the furniture in your house. After eating, move dining room chairs back to their original positions. Again, you can do this with the use of adhesive dots or stars. Keep objects off the floor and train your family members to do the same. Laundry baskets, toys and shoes left on the floor create an obstacle course that your blind dog cant see to navigate. Use your dots or stars to mark the locations of furniture and other object you move when cleaning or vacuuming. Some dogs can map a house down to within inches. Be sure to close cabinet doors and drawers so your dog doesnt bump into them.

Be especially vigilant of hazards along the walls of your home. A newly blind pet may have a tendency to hug the walls in order to avoid obstacles in the middle of the room. Your pet may become tangled up in cords for electrical appliances, blinds and drapes and be unable to free himself.

Pad the sharp corners on coffee tables and other furniture with sharp corners, especially those at your pets head height or treat them with bitter apple until he is comfortably navigating around them. You may want to use runners in rooms to indicate a clear path from one room to another, and rugs at the top and bottom of stairs. Be sure to anchor them. You will be amazed at how quickly your pet adapts and dislocates them running up and down stairs or tearing through rooms. Stairs, both indoors and out, should be blocked off until the dog learns their locations and can navigate them easily without assistance.

When turning off televisions and stereos return them to the lowest volume so that you dont startle your pet when you turn them back on. Train your teenagers to do this if they listen to music at a high volume. Gradually increase the volume when you turn them back on. Your pet will thank you!

Outdoor Hazards

You should never allow a blind pet to run loose outside a fenced area until he has perfectly mastered recall. Even then, you want to limit off-leash time to situations where you are absolutely certain he will not encounter any hazards. In the yard, trim low branches on bushes and trees in your yard and keep fallen branches picked up. Make sure childrens toys are put away or stored in a regular place. Decks and porches need to have railings low enough to keep your pet from falling off if you are going to let him out in these areas. You can use chicken wire or screening to block openings below rail level. Cedar chips, mulch, landscaping rocks, and paving stones can be placed to create a zone around obstacles such as trees, bushes, and outdoor furniture.

If you have a ground level door, it might be easier to have him always go out that door until he is fully adjusted to his disability, rather than deal with steps, porches, or raised decks without low railings. Just like a dog who can see, hes going to be excited to go outside and it might be better to take a few extra precautions to keep him safe, especially when hes newly blind.

Buy bells and attach them to the collars of your other pets or make sure their tags make noise when they are running. At a walk, most blind dogs and cats can pick up the scent of a familiar animal approaching. At a run, they may not. Blind dogs enjoy running and playing as much as sighted dogsthe noise your other pets make will help him follow his friends lead. Your other dogs are probably going to sense that he is special pretty fast and, if they are like most dogs, they will help him out.

Training

When training a blind dog, conduct your initial training sessions for any new command in a familiar place free from any obstacles and distractions. You want the dog as relaxed and at ease as possible, as this will be more conducive to learning. The sit, down, stays and recall/come commands are taught to a blind dog in the same manner as a sighted dog. Stays may be a bit more challenging for a blind dog. You should reward the dog for stays of a second or two and slowly increase the time while by her side, and do the same for increasing distance. For the recall/come command, be sure you have a large area free from any obstacles in case your dog goes a little off-course. You may need to keep talking to him until he finds you at first or in noisy situations. While walking your dog, you may find that a halter gives you more control than a leash and that your dog is more comfortable with it than a regular collar. Teaching a heel is much the same for other dogs. You should, however, work at the commands left, right and slow to let your dog know where you want her to go since she cant see you turning. These are taught by luring her with a treat just as you do when teaching a heel. For more information on basic training, click here.

The Wait and Slow commands, in addition to sits and recalls are especially important for a blind dog. These are the primary commands you can use to protect your dog from danger. You may want to use a sit instead of a recall in some situations, especially if he is likely to encounter hazards coming back to you. I cant overemphasize practicing in non-threatening situations so when a real emergency comes along, both your action and your dogs reactions are instinctive and immediate.

Wait (or Halt)

What you are really teaching here is stop, but if you are like most people, you use the word stop frequently for other purposes. Use whatever word you are comfortable with, but be consistent. Use this command when you open the front door, when getting your dog out of the car, or when he is about the wander into the street. Put your dog on a leash and begin walking with him. Tell him Wait (or halt, or whatever word you choose) while applying steady but gentle pressure on the lease until he stops. Praise and reward the second he stops. Practice this until he is responding reliably, both indoors and out, and with distractions. Then practice off lead in the house, then outside in an enclosed area and slowly add distractions. Always release your dog from wait with a release command such as Freeeeee!

Slow

Use this command to alert your dog that he's there is an obstacle is his way. Put your dog on a leash and begin walking with him. Tell him Slow while applying steady but gentle pressure on the lease until he slows. Praise and reward the second he slows. Practice this until he is responding reliably both inside and out, and with distractions. Use the Slow command if you see your dog is about to run into something.

Home

Use the home command to reorient your dog if he gets confused about where he is in the house or yard. You should have a home base both inside and out. Whatever place you pick, stay consistent. You may want to select the area where his food and water bowls are in the house or the back door outside. Lead him to home, and say home.

Stairs

If your dog has handled steps in the past, these commands may be a fairly simple for her to learn or maybe not! If she has not gone up or down stairs before (or you dont know if she has), start with a short flight of stairs or a single one if you can find it. Find stairs without an open back if possible. A street curb in an area free from traffic may be your best starting point. Going up stairs will be easier for her than going down, so start with that. Have the dog on a leash and walking beside you. As you approach the stair, say Up and lure her up one step with a treat while tapping the tread. Keep the treat close to the tread of the upper step. When she gets her paws on the step, reward and praise, and continue luring until she gets up on the step, reward and praise again. Repeat with the next step or steps. If she is reluctant, dont push her. It may take several days. If she is willing, next try going down the stairs. If she is tired, save it for another day! Lure the dog to around to face the steps. Tap the lower step, say Step and lure her with the treat. You do not want to say Step Down because she might confuse this with the down command. Going downstairs is very scary to a blind dog. Let her take as long as needed to learn this. It may take a week or more. Just be patient. Do not force her. If after a week or so, she is still reluctant to go down stairs, try to find some shallower steps or use a street curb in an area free from traffic. Going down stairs where it feels like there is nothing underneath her is the ultimate act of trust. Be understanding. Work on longer staircases only after your dog has mastered short ones comfortably. Introduce her to each set of stairs in and around your house. Block them off until she is comfortable with them.

Sudden Noise Alert

Your blind dog will be startled by loud and unexpected noisesa car starting, a door slamming, or vacuum or other appliance turned on. To the extent possible, you can minimize this by teaching her an unexpected noise is about to happen. You can use any word or words you want, maybe Uh Oh! prior to the noise occurring.

Toys and Games and Other Activities for Your Blind Pet

Keep your blind dog physically and mentally challenged to avoid him sinking into depression. Walk him often and allow him plenty of sniffing exploration breaks. At first, he may be reluctant to explore new places. If so, keep your walks to familiar routes. Give him time to adjust, and extend your walk by just a little each day. Soon exploring new places and smells will be a favorite activity.

Just like any dog, blind dogs love to play with toys and play with you. As stated before, their sense of hearing and smell will grow more acute over time. Consider these when selecting toys. Kongs filled with smelly treats are a wonderful way to keep your dog entertained. You can play fetch with a tennis ball scented with lemon oil or vanilla extract or a ball that makes noise when it bounces, but you may need to limit the distance you are throwing it. Be sure to have a clear space with no obstacles. Tennis balls inside a kiddie pool, with or without water, can be fun for your dog to chase, and they wont be able to get away from him. You can use rope toys to play tug of war. For other ideas on toys and games for your blind dog, click here and here.

Remember that blind dogs enjoy having fun, just like any dog. Click here to see the inspiring video, "Riddle's Song".

For a really fun and challenging activity, and one that depends on your blind dogs keen sense of smell, teach your dog scent tracking. Its both physically and mentally challenging for the dog, and it will simply amaze your friends. For details on training your dog to track, click here.

And, of course, snuggling and massages are fun activities for any dog, sighted or blind!

Additional resources that you might find helpful:

One of the best resources for Blind Dogs: "Living With Blind Dogs" by Caroline D. Levin RN

Other books and DVDS: http://www.petcarebooks.com

Owners of Blind Dogs website: http://www.blinddogs.com/

For information on cataracts, click here.

Read about two Great Danes (Lily is blind, while Maddison serves as her guide dog)! Click here for the original story about them, when they were up for adoption, and click here for the story about their adoption!

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Blindness by Jos Saramago – goodreads.com

♫ Saturday, July 28th, 2018

From Nobel Prizewinning author Jos Saramago, a magnificent, mesmerizing parable of loss

A city is hit by an epidemic of "white blindness" that spares no one. Authorities confine the blind to an empty mental hospital, but there the criminal element holds everyone captive, stealing food rations and assaulting women. There is one eyewitness to this nightmare who guides her chargesamong them a boy with no mother, a girl with dark glasses, a dog of tearsthrough the barren streets, and their procession becomes as uncanny as the surroundings are harrowing. As Blindness reclaims the age-old story of a plague, it evokes the vivid and trembling horrors of the twentieth century, leaving readers with a powerful vision of the human spirit that's bound both by weakness and exhilarating strength.

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Blindness by Jos Saramago - goodreads.com

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Cortical blindness – MedLink

♫ Wednesday, July 18th, 2018

Sashank Prasad MD(Dr. Prasad of Brigham and Women's Hospital in Boston, Massachusetts, has no relevant financial relationships to disclose.) Jonathan D Trobe MD,editor.(Dr. Trobe of the University of Michigan has no relevant financial relationships to disclose.)Originally released July 14, 1997; last updated June 6, 2018; expires June 6, 2021

This article includes discussion of cortical blindness, Anton syndrome, Anton-Babinski syndrome, cerebral blindness, cortical visual impairment, and geniculocalcarine dysfunction. The foregoing terms may include synonyms, similar disorders, variations in usage, and abbreviations.

Overview

Cortical blindness refers to visual loss due to bilateral lesions of the geniculocalcarine pathways in the brain. Patients with cortical blindness may or may not be aware of their visual deficits. When they are unaware of the extent of visual loss (often confabulating their responses), the clinical presentation is termed Anton syndrome. Etiologies of cortical blindness are numerous and diverse. In this article, the author discusses the diagnosis of cortical blindness and its various causes.

Key points

Cortical blindness is a term used to encompass visual loss from lesions of the retrogeniculate pathways. Pupillary responses are spared in a patient with cortical blindness because they rely on synaptic reflexes through the brainstem and do not require cortical inputs.

Patients with cortical blindness due to occipital lesions may be unaware of their visual deficits. If so, the clinical presentation is termed Anton syndrome.

Brain MRI is an important diagnostic test to determine the cause of cortical blindness, but not all causes produce MRI abnormalities.

When infarction is suggested by MRI, the diagnostic work-up should be aimed at identifying cardioembolism and other causes of stroke.

Posterior reversible encephalopathy syndrome may cause cortical blindness and is associated with severe preeclampsia or eclampsia, hypertension, and use of certain medications.

Nonorganic visual loss should be considered a diagnosis of exclusion but can be suggested by examination findings that violate physiological patterns of visual loss.

Historical note and terminology

"Cortical blindness" is generally used to refer to visual loss due to bilateral dysfunction of the occipital visual cortex (striate cortex or V1). Some patients will exhibit unawareness of the extent of visual loss; this remarkable clinical state is termed "Anton syndrome" in reference to Gabriel Anton, who described this phenomenon in 1899 (Anton 1899). For lesions not isolated to the cortex, including the subcortical visual pathways, the term "cerebral blindness" may be more appropriate. The term "cortical visual impairment" has also been introduced (particularly in the pediatric population) when visual deficits are incomplete (Good et al 1994). Nevertheless, because the term "cortical blindness" continues to be in common use, it will be retained in this discussion.

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Cortical blindness - MedLink

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One Nation, One Poll proposal is completely blind to the …

♫ Wednesday, July 18th, 2018

Editor's note: This is the second article in a two-part series on the ongoing stakeholder discussions regarding the One Nation, One Poll proposal, called for by the Law Commission. Read part I here

***

The proposal to conduct Lok Sabha and State Assembly elections simultaneously, presently undergoing stakeholder consultation, led by the Law Commission of India, is yet to reckon with the question of whether simultaneous elections would damage the federal structure or any other basic feature of the Constitution.

Leaving this question open, at the tail-end of its Draft Working Paper, the Law Commission has laid out ways to ensure concurrent terms for the Lok Sabha and Assemblies (how to stave off dissolution of the House when a no-confidence motion is passed, or when there is a hung verdict in the election), and proposed some election scheduling options (all elections are held either together in 2019 and 2024, alongside the Lok Sabha elections, or in 2019 and 2021-22, such that elections are held every two and a half years, with state Assembly terms accordingly modified). Without testing the proposal against constitutional principles like democracy or federalism, the Law Commission has put the cart before the horse by suggesting amendments on the logistics of how to conduct simultaneous elections.

So what if we had simultaneous elections at the birth of India?

But first, it is crucial to address the Law Commission's and NITI Aayog's oft-repeated claim that simultaneous elections are somehow acceptable because "elections to Lok Sabha and all state Legislative Assemblies were held simultaneously between 1951 and 1967." To use our history in this way is flatly inaccurate and incorrect. First, several states had to go to polls in between the General Elections of 1951-52, 1957, 1962 and 1967 due to varied circumstances. Moreover, it is one thing for concurrent elections to take place organically, by virtue of the Centre and the states having commenced their democratic existence together under the Indian Constitution, and quite another, for simultaneous elections to be enforced, inorganically, in the way that is presently sought.

The birth of the Republic of India, was not a "coming together" of States as autonomous, pre-existing political units. As BR Ambedkar explained to the Constituent Assembly, "... though India was to be a federation, the Federation was not the result of an agreement by the States to join in a Federation and that the Federation not being the result of an agreement no State has the right to secede from it."

Representational image. AP

This statement is best understood in contrast with the United States of America, which was born from thirteen colonies coming together to sign the Declaration of Independence. Of the 50 states presently part of the United States, only eleven ratified the Constitution in 1787-88, two ratified the Constitution well after the first Congress was elected and convened, and other territories entered a country that was already governed by the US Federal Constitution. On the other hand, the Indian situation represents a "holding together" or unification of many socio-politically and culturally disparate political units under the terms of the Constitution of India. The Constitution took effect at the same time (more or less) for the princely States, the British provinces as well as the newly constituted Union Government Sikkim being the exception.

Now, the Indian Constitution governs the States and the Centre alike withregard to elections and political representation, unlike the Constitution of the United States, which governs only the Federal Government. So, the simultaneity of Central and State elections, 1951 onwards, to whatever extent, was a result of the Indian Constitution becoming effective at the same moment for the States and the Union Government. That situation cannot be compared with the present effort to forcefully ensure elections are simultaneously held at the Centre and the states. The deliberate transition from status-quo back to concurrent elections, and the enforced nature of concurrent elections are unconstitutional, even if simultaneity of elections in and of itself is permissible.

Enforced concurrent elections

To enforce concurrent elections, premature dissolution of the Lok Sabha or state assemblies must be prevented. In the case of a successful motion of no-confidence, Law Commission proposes that movers of the no-confidence motion propose an alternative government through a "motion of confidence". Likewise, in the case of a hung verdict after elections, it is proposed that all parties decide the leader of the Housewhich would require a relaxation in the Tenth Schedule of the Constitution "only for formation of a stable government".

To permit the movers of a no-confidence motion to propose an alternative government, is to say that voters' choice only matters in deciding the origin of a government but not the continued survival of a government. This might appear to be democratic to the extent that the new government will be accountable to Parliament by winning a vote of confidence. But there is a second aspect of democratic accountability: the Parliament must answer to citizens, and needs to enjoy our continued confidence. In putting an alternate government into power through a "motion of confidence", parliamentarians will be forced to act according to the will of their political party. However, when MPs are answerable to their political parties, nothing ensures that they are similarly answerable to citizensthe voters who elected them into power, for the simple reason that political parties are not answerable to voters.

In India, citizens vote for candidates who contest polls on a party ticket they have obtained, unless they run as independents.There are no rules which dictate guidelines as to who might get the ticket.We do not have a system of party "primaries"wherein voters choose a candidate to ultimately contest the main General Electionson that party's ticket from the pool of candidates seeking that partys endorsement. In short, political parties are not democratic in their internal structure and organisation. To make matters worse, the Tenth Schedule forces all elected members of a House to vote in line with the party whip, on threat of disqualification from the House.

In effect, during elections, voters either choose the individual whose capabilities they trust, thus risking an implicit vote for the candidates political party, or they choose the political party they wish to see in government, thus risking an implicit vote for an incompetent candidate. No system exists for voters to choose which candidate gets a party ticket from the political party they wish to see in government. Political parties, therefore, are not anchored to voter preferences once their candidates are elected as parliamentarians, until the next election cycle.

With political parties being internally undemocraticand externally unanswerable to voters, creation of an alternate government through a motion of confidence is partisan and undemocratic, since the electorate has no say in the matter.Likewise, in the case of a hung verdict, the Law Commission proposes a relaxation of Tenth Schedule norms such that all parties can together choose a leader of their House without being restrained by the Whip. However, hung verdicts are where the threats of defections and loss of majority in the House loom largest on a party. Relaxing Tenth Schedule norms here is to permit parliamentarians to vote against their party affiliation and "defect" to another party.

However, parliamentarians can never know whether they won the election in their constituency based on votes for their individual worth or a vote to see their political party in power. Permitting defection is to ignore the electorates choice yet again, particularly that section of voters who chose candidates for the party she represented.

In short, enforced concurrent elections violates representative democracy, a basic feature of our Constitution.

The outcome of concurrent elections impairs federalism

The composition of the Rajya Sabha is determined by the composition of the States legislatures and is crucial for federalism because of its power to enable Parliament to make laws on matters in the State List.The interests of the State were assumed to be taken care of in the Upper House by virtue of itsstructure andcomposition andthe political process of election a feature of "cooperative federalism". Therefore, to alter this political process by holding elections concurrently at the Centre and in states, is to alter the feature that is meant to protect federalism in the Rajya Sabha.

Data - such as this study by IDFC - shows that scheduling of State elections determines the likelihood of the same party being elected both at the Centre and the state-level. Unfortunately, IDFC concludes that "when presented with an option to choose different parties for the Lok Sabha and state, with all other things being equal, a vast majority of voters did not exercise that choice. Leveraging this, NITI Aayog dismisses their concerns, suggesting self-assuredly, that unless simultaneity of elections can be established as the cause of the same party winning at both levels of government, the mere correlation between the two events is not good evidence.

However, studies have contradicted IDFCs assumptions of the non-discerning voter. Voters deliberately reward the same party at the Centre and State, depending on the timing of the election.

Timing is everything

Psephologists like Yogendra Yadav have found that the national ruling party gains support in state elections that are held earlier in their term during the honeymoon period but lose ground as their term progresses.

The explanation of this phenomenon runs thus: since "voters are likely to credit the state ruling party and not the national ruling party" when States spend more money on programmes, national ruling parties are inclined to spend more on states whose governments are controlled by their own party. As states get more funds when they are governed by the same party at the Centre, state voters deliberately ensure the same party holds power at both levels. However, their incentives to do so are highest when the Centre's term has just commenced, so as to maximise the States gains in the five years of the Centre's term.Two or three years into their term, state voters may not be sure if the national ruling party will return to power, and, therefore, may not be too inclined to vote for the same party at the state level.National ruling parties' advantage in state elections in the first two years, turns into a disadvantage by their third year in government."

Since timing of elections in state is crucial in deciding whether the national ruling party comes to power in states, holding simultaneous polls would ensure one party dominance over the nation.

Voters choice must be respected, even if the outcome of their vote hurts federalism. Normatively, there is no reason why a vote for the national incumbent at the state level is worse than a vote against it.However, with the knowledge that several studies show that timing of State elections is, in most cases, a determinant of the national ruling party's success in states, enforcing simultaneous elections would amount to wilful blindness to its federalism-impairing consequences.

With inputs from Krupakar Manukonda

The author is a Bangalore-based lawyer, currently working on teaching democracy and active citizenship through experiential learning. She tweets @MaLawdy

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Assessment | Face Blind UK

♫ Tuesday, July 10th, 2018

As part of current research, work is in progress to establish a formal definition for face blindness and to have the condition formally recognised

For many people with face blindness, once they become aware of the existence of this condition, their lived experience is sufficient proof that they are affected by it. You can check out some of the common indicators of face blindness are listed in our Quiz So you think you may be face blind

However, there are also a number of routes to getting an assessment of your face recognition abilities and difficulties.

There are online tests which can give a provisional indication of whether you may have face blindness.

Famous Faces recognitionhttp://www.faceblind.org/facetests

Test my brain research toolshttp://www.testmybrain.org

These tests can help you learn more about your particular abilities or difficulties, while also participating in scientific research

For a more indepth analysis of your specific difficulties, you can contact one of the research institutes nvestigating prosopagnosia.

However, when volunteering to participate in a research project, you should be aware that research tests and projects are designed primarily for the purpose of furthering specific areas of research, rather than to give you an insight into your particular difficulties, and there is unlikely to be any follow up support.

People with Acquired Prosopagnosia (following a brain injury or trauma), may be referred to a clinical neuropsychologist working within the NHS or private practice, as part of their aftercare.

The British Psychological Society hold a directory of chartered psychologists in private practice.

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Causes of Blindness BLIND, Inc.

♫ Thursday, July 5th, 2018

Vision loss and blindness can be caused by several factors. These factors can be genetic, environmental or accidental. In order to better comprehend how blindness can affect the individual, it is important to understand what blindness is.

A person is legally blind if his/her central visual acuity, that is (what they see in front of them), is less than 20/200 in their good eye after correction, such as glasses or contacts. 20/200 visual acuity means that a person can see at 20 feet what a person with 20/20 vision can at 200 feet. A person can also be considered legally blind if their visual field, that is what they perceive to either side of them is 20 degrees or less.

For the purposes of this article, we will look at the top five eye conditions that cause blindness: Cataracts, Glaucoma, Age-Related Macular Degeneration, Diabetic Retinopathy and Retinitis Pigmentosa. Other conditions do exist, however, they will not be discussed here.

Cataracts are caused by the clouding of the lens of the eye. This means that the light that comes through the pupil and passes through the lens to be focused to the retina is blurred. This will cause your vision to become cloudy, blurry and, or, dim. Colors may not seem as bright or vivid as before. Its like looking through the dirty windshield of a car. This condition occurs gradually and you may not notice it at first. Cataracts can be treated with surgery.

Glaucoma is a disease that damages your eyes optic nerve. It is caused by excess fluid in the eye which increases the eye pressure. This fluid is called aqueous humor. It is produced in the front portion of the eye and leaves the eye through the drainage angle. This keeps the intraocular pressure, at a healthy level. This pressure may vary from person to person. When the fluid does not leave the eye correctly, it will cause pressure to increase which will gradually damage the optic nerve.

There are several types of glaucoma. The two most common forms being: Primary Open-angle Glaucoma and Normal-tension Glaucoma. Open-angle Glaucoma is the most prevalent and happens when your eye can no longer drain fluid efficiently, causing the pressure to build. Open-angle Glaucoma has no early symptoms. As it progresses the optic nerve will become damaged, and you will start to notice blank spots in your field of vision. These spots will grow larger until all optic nerves are damaged, at which point, you will be blind.

Normal Tension Glaucoma is characterized by low pressure in the eye. This type of Glaucoma can also cause nerve damage and loss of vision. Treatment for both Open-angle Glaucoma and Normal tension Glaucoma is the same. The disease can be managed by prescription eye drops or surgery.

Unlike Primary Open-angle Glaucoma however, Primary Acute Closed-angle Glaucoma happens quite suddenly and should be attended to immediately. It results from a buildup of fluid because the drainage system is blocked and fluid can no longer drain from the eye.

Macular Degeneration destroys the light sensitive cells in the macula, the part of the eye that lets you see objects in great detail. Often, the progress of AMD is so slow that you do not notice any change in your vision, but it can progress quickly as well. There are two types of Macular Degeneration: wet and dry. Wet Macular Degeneration occurs when irregular blood vessels begin growing behind the retina under the macula. Dry Macular Degeneration is caused by the breakdown of light sensitive cells in the macula causing the central vision to blur. The treatment for Wet Macular Degeneration includes surgery. At this time, no treatment exists for Dry Macular Degeneration.

Diabetic Retinopathy is caused by diabetes. It affects the retina, the part of the eye sensitive to light. It is a result of high blood glucose, or sugar, over a prolonged period of time. High blood sugar prevents the blood vessels in the back of the eye from delivering the proper nutrients to the retina. Early on in the progress of the disease, these blood vessels will leak fluid and will cause site distortions. As the disease progresses, new blood vessels are formed around the retina and in the vitreous humor. These blood vessels will bleed making the vision cloudy and eventually causing the retina to detach. If not treated, a retinal detachment may cause permanent blindness. Vision loss caused by Diabetic Retinopathy can be prevented by laser surgery, a proper diet and controlling your blood glucose levels and blood pressure.

Retinitis Pigmentosa affects the retinas ability to respond to light. It is a geneticly inherited disease. The symptoms include loss of night vision and peripheral vision. The gradual degeneration of the retinas Photoreceptor cells (rods and cones) will eventually cause the individual to become blind As the disease progresses. While research is on-going, there is no cure at this time.

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Causes of Blindness BLIND, Inc.

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Color blindness – Wikipedia

♫ Thursday, June 21st, 2018

Color blindness, also known as color vision deficiency, is the decreased ability to see color or differences in color.[2] Simple tasks such as selecting ripe fruit, choosing clothing, and reading traffic lights can be more challenging.[2] Color blindness may also make some educational activities more difficult.[2] However, problems are generally minor, and most people find that they can adapt.[2] People with total color blindness (achromatopsia) may also have decreased visual acuity and be uncomfortable in bright environments.[2]

The most common cause of color blindness is an inherited problem in the development of one or more of the three sets of color sensing cones in the eye.[2] Males are more likely to be color blind than females, as the genes responsible for the most common forms of color blindness are on the X chromosome.[2] As females have two X chromosomes, a defect in one is typically compensated for by the other, while males only have one X chromosome.[2] Color blindness can also result from physical or chemical damage to the eye, optic nerve or parts of the brain.[2] Diagnosis is typically with the Ishihara color test; however, a number of other testing methods also exist.[2]

There is no cure for color blindness.[2] Diagnosis may allow a person's teacher to change their method of teaching to accommodate the decreased ability to recognize colors.[1] Special lenses may help people with redgreen color blindness when under bright conditions.[2] There are also mobile apps that can help people identify colors.[2]

Redgreen color blindness is the most common form, followed by blueyellow color blindness and total color blindness.[2] Redgreen color blindness affects up to 8% of males and 0.5% of females of Northern European descent.[2] The ability to see color also decreases in old age.[2] Being color blind may make people ineligible for certain jobs in certain countries.[1] This may include being a pilot, train driver and working in the armed forces.[1] The effect of color blindness on artistic ability, however, is controversial.[1] The ability to draw appears to be unchanged, and a number of famous artists are believed to have been color blind.[1]

In almost all cases, color blind people retain blueyellow discrimination, and most color-blind individuals are anomalous trichromats rather than complete dichromats. In practice, this means that they often retain a limited discrimination along the redgreen axis of color space, although their ability to separate colors in this dimension is reduced. Color blindness very rarely refers to complete monochromatism.[3]

Dichromats often confuse red and green items. For example, they may find it difficult to distinguish a Braeburn apple from a Granny Smith or red from green of traffic lights without other cluesfor example, shape or position. Dichromats tend to learn to use texture and shape clues and so may be able to penetrate camouflage that has been designed to deceive individuals with normal color vision.[4]

Colors of traffic lights are confusing to some dichromats as there is insufficient apparent difference between the red/amber traffic lights and sodium street lamps; also, the green can be confused with a grubby white lamp. This is a risk on high-speed undulating roads where angular cues cannot be used. British Rail color lamp signals use more easily identifiable colors: The red is blood red, the amber is yellow and the green is a bluish color. Most British road traffic lights are mounted vertically on a black rectangle with a white border (forming a "sighting board") and so dichromats can more easily look for the position of the light within the rectangletop, middle or bottom. In the eastern provinces of Canada horizontally mounted traffic lights are generally differentiated by shape to facilitate identification for those with color blindness.[citation needed] In the United States, this is not done by shape but by position, as the red light is always on the left if the light is horizontal, or on top if the light is vertical. However, a lone flashing light (e.g. red for stop, yellow for caution) is still problematic.

Color vision deficiencies can be classified as acquired or inherited.

Color blindness is typically an inherited genetic disorder. It is most commonly inherited from mutations on the X chromosome but the mapping of the human genome has shown there are many causative mutationsmutations capable of causing color blindness originate from at least 19 different chromosomes and 56 different genes (as shown online at the Online Mendelian Inheritance in Man (OMIM)). Two of the most common inherited forms of color blindness are protanomaly (and, more rarely, protanopia the two together often known as "protans") and deuteranomaly (or, more rarely, deuteranopia the two together often referred to as "deutans").[12] Both "protans" and "deutans" (of which the deutans are by far the most common) are known as "redgreen color-blind" which is present in about 8 percent of human males and 0.6 percent of females of Northern European ancestry.[13]

Some of the inherited diseases known to cause color blindness are:

Inherited color blindness can be congenital (from birth), or it can commence in childhood or adulthood. Depending on the mutation, it can be stationary, that is, remain the same throughout a person's lifetime, or progressive. As progressive phenotypes involve deterioration of the retina and other parts of the eye, certain forms of color blindness can progress to legal blindness, i.e., an acuity of 6/60 (20/200) or worse, and often leave a person with complete blindness.

Color blindness always pertains to the cone photoreceptors in retinas, as the cones are capable of detecting the color frequencies of light.

About 8 percent of males, and 0.6 percent of females, are red-green color blind in some way or another, whether it is one color, a color combination, or another mutation.[14] The reason males are at a greater risk of inheriting an X linked mutation is that males only have one X chromosome (XY, with the Y chromosome carrying altogether different genes than the X chromosome), and females have two (XX); if a woman inherits a normal X chromosome in addition to the one that carries the mutation, she will not display the mutation. Men do not have a second X chromosome to override the chromosome that carries the mutation. If 8% of variants of a given gene are defective, the probability of a single copy being defective is 8%, but the probability that two copies are both defective is 0.08 0.08 = 0.0064, or just 0.64%.

Other causes of color blindness include brain or retinal damage caused by shaken baby syndrome, accidents and other trauma which produce swelling of the brain in the occipital lobe, and damage to the retina caused by exposure to ultraviolet light (10300nm). Damage often presents itself later on in life.

Color blindness may also present itself in the spectrum of degenerative diseases of the eye, such as age-related macular degeneration, and as part of the retinal damage caused by diabetes. Another factor that may affect color blindness includes a deficiency in Vitamin A.[15]

Some subtle forms of colorblindness may be associated with chronic solvent-induced encephalopathy (CSE), caused by longtime exposure to solvent vapors.[16]

Redgreen color blindness can be caused by ethambutol,[17] a drug used in the treatment of tuberculosis.

Based on clinical appearance, color blindness may be described as total or partial. Total color blindness is much less common than partial color blindness.[18] There are two major types of color blindness: those who have difficulty distinguishing between red and green, and who have difficulty distinguishing between blue and yellow.[19][20]

Immunofluorescent imaging is a way to determine redgreen color coding. Conventional color coding is difficult for individuals with redgreen color blindness (protanopia or deuteranopia) to discriminate. Replacing red with magenta or green with turquoise improves visibility for such individuals.[21]

The different kinds of inherited color blindness result from partial or complete loss of function of one or more of the different cone systems. When one cone system is compromised, dichromacy results. The most frequent forms of human color blindness result from problems with either the middle or long wavelength sensitive cone systems, and involve difficulties in discriminating reds, yellows, and greens from one another. They are collectively referred to as "redgreen color blindness", though the term is an over-simplification and is somewhat misleading. Other forms of color blindness are much more rare. They include problems in discriminating blues from greens and yellows from reds/pinks, and the rarest forms of all, complete color blindness or monochromacy, where one cannot distinguish any color from grey, as in a black-and-white movie or photograph.

Protanopes, deuteranopes, and tritanopes are dichromats; that is, they can match any color they see with some mixture of just two primary colors (whereas normally humans are trichromats and require three primary colors). These individuals normally know they have a color vision problem and it can affect their lives on a daily basis. Two percent of the male population exhibit severe difficulties distinguishing between red, orange, yellow, and green. A certain pair of colors, that seem very different to a normal viewer, appear to be the same color (or different shades of same color) for such a dichromat. The terms protanopia, deuteranopia, and tritanopia come from Greek and literally mean "inability to see (anopia) with the first (prot-), second (deuter-), or third (trit-) [cone]", respectively.

Anomalous trichromacy is the least serious type of color deficiency.[22] People with protanomaly, deuteranomaly, or tritanomaly are trichromats, but the color matches they make differ from the normal. They are called anomalous trichromats. In order to match a given spectral yellow light, protanomalous observers need more red light in a red/green mixture than a normal observer, and deuteranomalous observers need more green. From a practical standpoint though, many protanomalous and deuteranomalous people have very little difficulty carrying out tasks that require normal color vision. Some may not even be aware that their color perception is in any way different from normal.

Protanomaly and deuteranomaly can be diagnosed using an instrument called an anomaloscope, which mixes spectral red and green lights in variable proportions, for comparison with a fixed spectral yellow. If this is done in front of a large audience of males, as the proportion of red is increased from a low value, first a small proportion of the audience will declare a match, while most will see the mixed light as greenish; these are the deuteranomalous observers. Next, as more red is added the majority will say that a match has been achieved. Finally, as yet more red is added, the remaining, protanomalous, observers will declare a match at a point where normal observers will see the mixed light as definitely reddish.[citation needed]

Protanopia, deuteranopia, protanomaly, and deuteranomaly are commonly inherited forms of redgreen color blindness which affect a substantial portion of the human population. Those affected have difficulty with discriminating red and green hues due to the absence or mutation of the red or green retinal photoreceptors.[12][23] It is sex-linked: genetic redgreen color blindness affects males much more often than females, because the genes for the red and green color receptors are located on the X chromosome, of which males have only one and females have two. Females (46, XX) are redgreen color blind only if both their X chromosomes are defective with a similar deficiency, whereas males (46, XY) are color blind if their single X chromosome is defective.[24]

The gene for redgreen color blindness is transmitted from a color blind male to all his daughters who are heterozygote carriers and are usually unaffected. In turn, a carrier woman has a fifty percent chance of passing on a mutated X chromosome region to each of her male offspring. The sons of an affected male will not inherit the trait from him, since they receive his Y chromosome and not his (defective) X chromosome. Should an affected male have children with a carrier or colorblind woman, their daughters may be colorblind by inheriting an affected X chromosome from each parent.[24]

Because one X chromosome is inactivated at random in each cell during a woman's development, deuteranomalous heterozygotes (i.e. female carriers of deuteranomaly) are potentially tetrachromats, because they will have the normal long wave (red) receptors, the normal medium wave (green) receptors, the abnormal medium wave (deuteranomalous) receptors and the normal autosomal short wave (blue) receptors in their retinas.[25][26][27] The same applies to the carriers of protanomaly (who have two types of short wave receptors, normal medium wave receptors, and normal autosomal short wave receptors in their retinas). If, by chance, a woman is heterozygous for both protanomaly and deuteranomaly she could be pentachromatic. This situation could arise if, for instance, she inherited the X chromosome with the abnormal long wave gene (but normal medium wave gene) from her mother who is a carrier of protanomaly, and her other X chromosome from a deuteranomalous father. Such a woman would have a normal and an abnormal long wave receptor, a normal and abnormal medium wave receptor, and a normal autosomal short wave receptor 5 different types of color receptors in all. The degree to which women who are carriers of either protanomaly or deuteranomaly are demonstrably tetrachromatic and require a mixture of four spectral lights to match an arbitrary light is very variable. In many cases it is almost unnoticeable, but in a minority the tetrachromacy is very pronounced.[25][26][27] However, Jameson et al.[28] have shown that with appropriate and sufficiently sensitive equipment all female carriers of red-green color blindness (i.e. heterozygous protanomaly, or heterozygous deuteranomaly) are tetrachromats to a greater or lesser extent.

Since deuteranomaly is by far the most common form of red-green blindness among men of northwestern European descent (with an incidence of 8%), then the carrier frequency (and of potential deuteranomalous tetrachromacy) among the females of that genetic stock is 14.7% (= [92% 8%] 2).[24]

Those with tritanopia and tritanomaly have difficulty discriminating between bluish and greenish hues, as well as yellowish and reddish hues.

Color blindness involving the inactivation of the short-wavelength sensitive cone system (whose absorption spectrum peaks in the bluish-violet) is called tritanopia or, loosely, blueyellow color blindness. The tritanope's neutral point occurs near a yellowish 570nm; green is perceived at shorter wavelengths and red at longer wavelengths.[31] Mutation of the short-wavelength sensitive cones is called tritanomaly. Tritanopia is equally distributed among males and females. Jeremy H. Nathans (with the Howard Hughes Medical Institute) demonstrated that the gene coding for the blue receptor lies on chromosome 7, which is shared equally by males and females. Therefore, it is not sex-linked. This gene does not have any neighbor whose DNA sequence is similar. Blue color blindness is caused by a simple mutation in this gene.

Total color blindness is defined as the inability to see color. Although the term may refer to acquired disorders such as cerebral achromatopsia also known as color agnosia, it typically refers to congenital color vision disorders (i.e. more frequently rod monochromacy and less frequently cone monochromacy).[33][34]

In cerebral achromatopsia, a person cannot perceive colors even though the eyes are capable of distinguishing them. Some sources do not consider these to be true color blindness, because the failure is of perception, not of vision. They are forms of visual agnosia.[34]

Monochromacy is the condition of possessing only a single channel for conveying information about color. Monochromats possess a complete inability to distinguish any colors and perceive only variations in brightness. It occurs in two primary forms:

The typical human retina contains two kinds of light cells: the rod cells (active in low light) and the cone cells (active in normal daylight). Normally, there are three kinds of cone cells, each containing a different pigment, which are activated when the pigments absorb light. The spectral sensitivities of the cones differ; one is most sensitive to short wavelengths, one to medium wavelengths, and the third to medium-to-long wavelengths within the visible spectrum, with their peak sensitivities in the blue, green, and yellow-green regions of the spectrum, respectively. The absorption spectra of the three systems overlap, and combine to cover the visible spectrum. These receptors are known as short (S), medium (M), and long (L) wavelength cones, but are also often referred to as blue, green, and red cones, although this terminology is inaccurate.[36]

The receptors are each responsive to a wide range of wavelengths. For example, the long wavelength "red" receptor has its peak sensitivity in the yellow-green, some way from the red end (longest wavelength) of the visible spectrum. The sensitivity of normal color vision actually depends on the overlap between the absorption ranges of the three systems: different colors are recognized when the different types of cone are stimulated to different degrees. Red light, for example, stimulates the long wavelength cones much more than either of the others, and reducing the wavelength causes the other two cone systems to be increasingly stimulated, causing a gradual change in hue.

Many of the genes involved in color vision are on the X chromosome, making color blindness much more common in males than in females because males only have one X chromosome, while females have two. Because this is an X-linked trait, an estimated 23% of women have a 4th color cone[25] and can be considered tetrachromats. One such woman has been reported to be a true or functional tetrachromat, as she can discriminate colors most other people can't.[26][27]

The Ishihara color test, which consists of a series of pictures of colored spots, is the test most often used to diagnose redgreen color deficiencies.[37] A figure (usually one or more Arabic digits) is embedded in the picture as a number of spots in a slightly different color, and can be seen with normal color vision, but not with a particular color defect. The full set of tests has a variety of figure/background color combinations, and enable diagnosis of which particular visual defect is present. The anomaloscope, described above, is also used in diagnosing anomalous trichromacy.

Position yourself about 75cm from your monitor so that the colour test image you are looking at is at eye level, read the description of the image and see what you can see!! It is not necessary in all cases to use the entire set of images. In a large scale examination the test can be simplified to six tests; test, one of tests 2 or 3, one of tests 4, 5, 6, or 7, one of tests 8 or 9, one of tests 10, 11, 12, or 13 and one of tests 14 or 15.[this quote needs a citation]

Because the Ishihara color test contains only numerals, it may not be useful in diagnosing young children, who have not yet learned to use numbers. In the interest of identifying these problems early on in life, alternative color vision tests were developed using only symbols (square, circle, car).

Besides the Ishihara color test, the US Navy and US Army also allow testing with the Farnsworth Lantern Test. This test allows 30% of color deficient individuals, whose deficiency is not too severe, to pass.

Another test used by clinicians to measure chromatic discrimination is the Farnsworth-Munsell 100 hue test. The patient is asked to arrange a set of colored caps or chips to form a gradual transition of color between two anchor caps.[38]

The HRR color test (developed by Hardy, Rand, and Rittler) is a redgreen color test that, unlike the Ishihara, also has plates for the detection of the tritan defects.[39]

Most clinical tests are designed to be fast, simple, and effective at identifying broad categories of color blindness. In academic studies of color blindness, on the other hand, there is more interest in developing flexible tests to collect thorough datasets, identify copunctal points, and measure just noticeable differences.[40]

There is generally no treatment to cure color deficiencies. The American Optometric Association reports a contact lens on one eye can increase the ability to differentiate between colors, though nothing can make you truly see the deficient color.[41]

Optometrists can supply colored spectacle lenses or a single red-tint contact lens to wear on the non-dominant eye, but although this may improve discrimination of some colors, it can make other colors more difficult to distinguish. A 1981 review of various studies to evaluate the effect of the X-chrom contact lens concluded that, while the lens may allow the wearer to achieve a better score on certain color vision tests, it did not correct color vision in the natural environment.[42] A case history using the X-Chrom lens for a rod monochromat is reported[43] and an X-Chrom manual is online.[44]

Lenses that filter certain wavelengths of light can allow people with a cone anomaly, but not dichromacy, to see better separation of colors, especially those with classic "red/green" color blindness. They work by notching out wavelengths that strongly stimulate both red and green cones in a deuter- or protanomalous person, improving the distinction between the two cones' signals. As of 2013, sunglasses that notch out color wavelengths are available commercially.[45]

Many applications for iPhone and iPad have been developed to help colorblind people to view the colors in a better way. Many applications launch a sort of simulation of colorblind vision to make normal-view people understand how the color-blinds see the world. Others allow a correction of the image grabbed from the camera with a special "daltonizer" algorithm.

The GNOME desktop environment provides colorblind accessibility using the gnome-mag and the libcolorblind software. Using a gnome applet, the user may switch a color filter on and off, choosing from a set of possible color transformations that will displace the colors in order to disambiguate them. The software enables, for instance, a colorblind person to see the numbers in the Ishihara test.

Color blindness affects a large number of individuals, with protanopia and deuteranopia being the most common types.[12] In individuals with Northern European ancestry, as many as 8 percent of men and 0.4 percent of women experience congenital color deficiency.[47]

The number affected varies among groups. Isolated communities with a restricted gene pool sometimes produce high proportions of color blindness, including the less usual types. Examples include rural Finland, Hungary, and some of the Scottish islands.[citation needed] In the United States, about 7 percent of the male populationor about 10.5 million menand 0.4 percent of the female population either cannot distinguish red from green, or see red and green differently from how others do (Howard Hughes Medical Institute, 2006[clarification needed]). More than 95 percent of all variations in human color vision involve the red and green receptors in male eyes. It is very rare for males or females to be "blind" to the blue end of the spectrum.[48]

The first scientific paper on the subject of color blindness, Extraordinary facts relating to the vision of colours, was published by the English chemist John Dalton in 1798[50] after the realization of his own color blindness. Because of Dalton's work, the general condition has been called daltonism, although in English this term is now used only for deuteranopia.

Color codes present particular problems for those with color deficiencies as they are often difficult or impossible for them to perceive.

Good graphic design avoids using color coding or using color contrasts alone to express information;[51] this not only helps color blind people, but also aids understanding by normally sighted people by providing them with multiple reinforcing cues.[citation needed]

Designers need to take into account that color-blindness is highly sensitive to differences in material. For example, a redgreen colorblind person who is incapable of distinguishing colors on a map printed on paper may have no such difficulty when viewing the map on a computer screen or television. In addition, some color blind people find it easier to distinguish problem colors on artificial materials, such as plastic or in acrylic paints, than on natural materials, such as paper or wood. Third, for some color blind people, color can only be distinguished if there is a sufficient "mass" of color: thin lines might appear black, while a thicker line of the same color can be perceived as having color.[citation needed]

Designers should also note that redblue and yellowblue color combinations are generally safe. So instead of the ever-popular "red means bad and green means good" system, using these combinations can lead to a much higher ability to use color coding effectively. This will still cause problems for those with monochromatic color blindness, but it is still something worth considering.[52]

When the need to process visual information as rapidly as possible arises, for example in an emergency situation, the visual system may operate only in shades of gray, with the extra information load in adding color being dropped.[citation needed] This is an important possibility to consider when designing, for example, emergency brake handles or emergency phones.

Color blindness may make it difficult or impossible for a person to engage in certain occupations. Persons with color blindness may be legally or practically barred from occupations in which color perception is an essential part of the job (e.g., mixing paint colors), or in which color perception is important for safety (e.g., operating vehicles in response to color-coded signals). This occupational safety principle originates from the Lagerlunda train crash of 1875 in Sweden. Following the crash, Professor Alarik Frithiof Holmgren, a physiologist, investigated and concluded that the color blindness of the engineer (who had died) had caused the crash. Professor Holmgren then created the first test using different-colored skeins to exclude people from jobs in the transportation industry on the basis of color blindness.[53] However, there is a claim that there is no firm evidence that color deficiency did cause the collision, or that it might have not been the sole cause.[54]

Color vision is important for occupations using telephone or computer networking cabling, as the individual wires inside the cables are color-coded using green, orange, brown, blue and white colors.[55] Electronic wiring, transformers, resistors, and capacitors are color-coded as well, using black, brown, red, orange, yellow, green, blue, violet, gray, white, silver, gold.[56]

Some countries have refused to grant driving licenses to individuals with color blindness. In Romania, there is an ongoing campaign to remove the legal restrictions that prohibit colorblind citizens from getting drivers' licenses.[57]

The usual justification for such restrictions is that drivers of motor vehicles must be able to recognize color-coded signals, such as traffic lights or warning lights.[52]

While many aspects of aviation depend on color coding, only a few of them are critical enough to be interfered with by some milder types of color blindness. Some examples include color-gun signaling of aircraft that have lost radio communication, color-coded glide-path indications on runways, and the like. Some jurisdictions restrict the issuance of pilot credentials to persons who suffer from color blindness for this reason. Restrictions may be partial, allowing color-blind persons to obtain certification but with restrictions, or total, in which case color-blind persons are not permitted to obtain piloting credentials at all.[citation needed]

In the United States, the Federal Aviation Administration requires that pilots be tested for normal color vision as part of their medical clearance in order to obtain the required medical certificate, a prerequisite to obtaining a pilot's certification. If testing reveals color blindness, the applicant may be issued a license with restrictions, such as no night flying and no flying by color signalssuch a restriction effectively prevents a pilot from holding certain flying occupations, such as that of an airline pilot, although commercial pilot certification is still possible, and there are a few flying occupations that do not require night flight and thus are still available to those with restrictions due to color blindness (e.g., agricultural aviation). The government allows several types of tests, including medical standard tests (e.g., the Ishihara, Dvorine, and others) and specialized tests oriented specifically to the needs of aviation. If an applicant fails the standard tests, they will receive a restriction on their medical certificate that states: "Not valid for night flying or by color signal control". They may apply to the FAA to take a specialized test, administered by the FAA. Typically, this test is the "color vision light gun test". For this test an FAA inspector will meet the pilot at an airport with an operating control tower. The color signal light gun will be shone at the pilot from the tower, and they must identify the color. If they pass they may be issued a waiver, which states that the color vision test is no longer required during medical examinations. They will then receive a new medical certificate with the restriction removed. This was once a Statement of Demonstrated Ability (SODA), but the SODA was dropped, and converted to a simple waiver (letter) early in the 2000s.[58]

Research published in 2009 carried out by the City University of London's Applied Vision Research Centre, sponsored by the UK's Civil Aviation Authority and the US Federal Aviation Administration, has established a more accurate assessment of color deficiencies in pilot applicants' redgreen and yellowblue color range which could lead to a 35% reduction in the number of prospective pilots who fail to meet the minimum medical threshold.[59]

Inability to distinguish color does not necessarily preclude the ability to become a celebrated artist. The 20th century expressionist painter Clifton Pugh, three-time winner of Australia's Archibald Prize, on biographical, gene inheritance and other grounds has been identified as a protanope.[60] 19th century French artist Charles Mryon became successful by concentrating on etching rather than painting after he was diagnosed as having a redgreen deficiency.[61]

A Brazilian court ruled that people with color blindness are protected by the Inter-American Convention on the Elimination of All Forms of Discrimination against Person with Disabilities.[62][63][64]

At trial, it was decided that the carriers of color blindness have a right of access to wider knowledge, or the full enjoyment of their human condition.

In the United States, under federal anti-discrimination laws such as the Americans with Disabilities Act, color vision deficiencies have not been found to constitute a disability that triggers protection from workplace discrimination.[65]

A famous traffic light on Tipperary Hill in Syracuse, New York, is upside-down due to the sentiments of its Irish American community,[66] but has been criticized due to the potential hazard it poses for color-blind persons.[67]

Some tentative evidence finds that color blind people are better at penetrating certain color camouflages. Such findings may give an evolutionary reason for the high rate of redgreen color blindness.[4] There is also a study suggesting that people with some types of color blindness can distinguish colors that people with normal color vision are not able to distinguish.[68] In World War II, color blind observers were used to penetrate camouflage.[69]

In September 2009, the journal Nature reported that researchers at the University of Washington and University of Florida were able to give trichromatic vision to squirrel monkeys, which normally have only dichromatic vision, using gene therapy.[70]

In 2003, a cybernetic device called eyeborg was developed to allow the wearer to hear sounds representing different colors.[71] Achromatopsic artist Neil Harbisson was the first to use such a device in early 2004; the eyeborg allowed him to start painting in color by memorizing the sound corresponding to each color. In 2012, at a TED Conference, Harbisson explained how he could now perceive colors outside the ability of human vision.[72]

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