Is seeing really believing?

#1
My debut post for the monstrosity which is the 'Are you religious?' thread consisted of something about dogs being colour blind, not being able to see rainbows and therefore we shouldn't limit our experience of the world to senses. I quickly got out of my depth as the cleverer chaps started discussing the finer technicalities of vision and to my surprise my innocent musing was still bubbling to the surface a year and a half later. It seems we never really did clear up what exaclty vision is, how it works and how we see things.

Then I saw this and as it's quite relevant I'd like to share it with you:

This might come as a shock, but everything you think is wrong. Much of what you take for granted about day-to-day existence is largely a figment of your imagination. From your senses to your memory, your opinions and beliefs, how you see yourself and others and even your sense of free will, things are not as they seem. The power these delusions hold over you is staggering, yet, as Graham Lawton discovers, they are vital to help you function in the world

Your senses are your windows on the world, and you probably think they do a fair job at capturing an accurate depiction of reality. Don't kid yourself. Sensory perception - especially vision - is a figment of your imagination. "What you're experiencing is largely the product of what's inside your head," says psychologist Ron Rensink at the University of British Columbia in Vancouver, Canada. "It's informed by what comes in through your eyes, but it's not directly reflecting it."

Given the basic features of your visual system, it couldn't be any other way. For example, every 5 seconds or so, you blink. Yet unless you're thinking about it, as you probably are right now, you don't notice the blackouts because your brain edits them out.



Blinking is just the tip of the iceberg. Even when your eyes are open they're only taking in a fraction of the visual information that is available.

In the centre of your retina is a dense patch of photoreceptor cells about 1 millimetre across. This is the fovea, the visual system's sweet spot where perception of detail and colour is at its best. "When you move away from the fovea, visual acuity falls away really quickly, and colour vision disappears," says Rensink. About 10 degrees to the side of the fovea, visual acuity is only about 20 per cent of the maximum.

What that means is you can only capture a tiny percentage of the visual field in full colour and detail at any one time. Hold your hand at arm's length and look at your thumbnail. That is roughly the area covered by the fovea. Most of the rest is captured in fuzzy monochrome.

And yet vision doesn't actually feel like this: it feels like a movie. That, in part, is because your eyes are constantly flitting over the visual scene, fixing on one spot for a fraction of a second then moving on. These jerky eye movements are called saccades and they happen about 3 times a second and last up to 200 milliseconds. With each fixation your visual system grabs a bite of high-resolution detail which it somehow weaves together to create an illusion of completeness.

That's remarkable given that during saccades themselves, you are effectively blind. Your eyes don't stop transmitting information as they lurch from one fixation to the next, but for about 100 milliseconds your brain is not processing it.

Look in the mirror and deliberately flick your eyes from left to right and back again. You won't see your eyes move - not because the movement is too fast (other people's saccades are visible), but because your brain isn't processing the information.

Given that you perform approximately 150,000 saccades every day, that means your visual system is "offline" for a total of about 4 hours during each waking day even without blinking (Trends in Cognitive Sciences, vol 12, p 466). Yet you don't notice anything amiss.

Exactly how your brain weaves such fragmentary information into the smooth technicolour movie that we experience as reality remains a mystery. One leading idea is that it makes a prediction and then uses the foveal "spotlight" to verify it. "We create something internally and then we check, check, check," says Rensink. "Essentially we experience the brain's best guess about what is happening now."

In conjuring up this "now", the visual system has to do something even more remarkable: predict the future. Information striking the fovea cannot be relayed instantaneously to conscious perception: first it has to travel down the optic nerve and be processed by the brain. This takes several hundred milliseconds, by which time the world has moved on. And so the brain makes a prediction about what the world will look like about 200 milliseconds into the future, and that is what you see. Without this future projection you would be unable to catch a ball, dodge moving objects or walk around without crashing into things.

There's another huge hole in the visual system that can render you oblivious to things that should be unmissable. The jerky movements that shift your fovea around the visual scene don't happen at random - they are directed by your brain's attentional system. Sometimes you consciously decide what to attend to, such as when you read. At other times your attention is grabbed by a movement in your peripheral vision or an unexpected noise.

The problem with attention is that it is a limited resource. For reasons that remain unknown, most people are unable to keep track of more than four or five moving objects at once. That can lead your visual system to be oblivious to things that are staring you in the face.

The most famous demonstration of this "inattention blindness" is the invisible gorilla, a video-based experiment created by Daniel Simons and Christopher Chabris at the University of Illinois at Urbana-Champaign. Viewers are asked to pay close attention to a specific aspect of a basketball game, and around half completely fail to see a person in a gorilla suit walk slowly across the screen, beat their chest and walk off again.
The grand delusion: What you see is not what you get - life - 16 May 2011 - New Scientist

So it appears that we all live in an imaginary world after all.

DC
 
#2
I actually like what I've just read. So when I look at the fittest bloke in my office and I like what I see - it's a lie, it's just my brain deceiving me into thinking "he is fit" when my eyes should be telling me "he's really an alien". I use this analogy cause the thought went through my brain on more than one occasion this week... So we could be over-run with aliens and we wouldn't spot them cause our brain assimilates the information from the eyes and assumes all 7' tall, gangly men are basketball players.

This could catch on. Discussion between 2 people. "Do you see what I see?", "no, seriously tell me what you're seeing" and "can we compare notes as I'm a bit worried my brain is deceiving me?".

D_C epic paranoia to follow...
 
#3
Yep. From a systems point of view, 'you' are a construct that is possibly the result of something like a predictor-corrector filter (eg, Kalman) with 'you' being the predicted state.
 
#4
DC,

Relax and don't worry too much about sight. The eye is only a detector and not a very good one. The small amount of information that it can see is sorted out in the brain...an evolutionary development. Eyesight is not foolproof...you can be tricked, or to be more precise you can trick yourself.

Reality is probably fairly close to what we see.... not always what we think we see. The imagination fills in gaps and in some cases deludes. Never take a ghost sighting or a supernatural claim seriously.

Bats use sound to navigate around stuff without any light at all and blind people can also develop sonar skills. Place a snooker ball in a blind persons hand and they have a pretty good idea about the reality of a snooker ball. Texture, weight and shape. A person with sight will see the same thing but with colour...But colour is not so important. Many animals have colour perception, it's not a human only feature.

Machines can mimic human sight and a whole lot more.
 
#5
The Humans With Super Human Vision | Senses | DISCOVER Magazine

The Humans With Super Human Vision
An unknown number of women may perceive 
millions of colors invisible to the rest of us. One British scientist is trying to track them down and understand their extraordinary power of sight.



An average human, utterly unremarkable in every way, can 
perceive a million different colors. Vermilion, puce, cerulean, periwinkle, chartreuse—we have thousands of words for them, but mere language can never capture our extraordinary range of hues. Our powers of color vision derive from cells in our eyes called cones, three types in all, each triggered by different wavelengths of light. Every moment our eyes are open, those three flavors of cone fire off messages to the brain. The brain then combines the signals to produce the sensation we call color.
Vision is complex, but the calculus of color is strangely simple: Each cone confers the ability to distinguish around a hundred shades, so the total number of combinations is at least 1003, or a million. Take one cone away—go from being what scientists call a trichromat to a dichromat—and the number of possible combinations drops a factor of 100, to 10,000. Almost all other mammals, including dogs and New World monkeys, are dichromats. The richness of the world we see is rivaled only by that of birds and some insects, which also perceive the ultraviolet part of the spectrum.
Researchers suspect, though, that some people see even more. Living among us are people with four cones, who might experience a range of colors invisible to the rest. It’s possible these so-called tetrachromats see a hundred million colors, with each familiar hue fracturing into a hundred more subtle shades for which there are no names, no paint swatches. And because perceiving color is a personal experience, they would have no way of knowing they see far beyond what we consider the limits of human vision.

Over the course of two decades, Newcastle University neuroscientist Gabriele Jordan and her colleagues have been searching for people endowed with this super-vision. Two years ago, Jordan finally found one. A doctor living in northern England, referred to only as cDa29 in the literature, is the first tetrachromat known to science. She is almost surely not the last.
The first hint that tetrachromats might exist came in a 1948 paper on color blindness. Dutch scientist HL de Vries was studying the eyes of color-blind men, who, along with two normal cones, possess a mutant cone that is less sensitive to either green or red, making it difficult for them to distinguish the two colors. He tested their vision by having them perform a basic matching task. Twiddling the dials on a lab instrument back and forth, the men had to mix red and green light so that the result, to their eyes, matched a standard shade of yellow. To compensate for their difficulty in discerning hues, color-blind men need to add more green or red than normal trichromats to make a match.
Out of curiosity, De Vries tested the daughters of one subject and observed that even though they were not color-blind—they seemed to distinguish red and green as well as anyone—they needed more red in their test light than normal people to make the match precise. If the women weren’t color-blind, what was going on?
Pondering the situation, De Vries thought he saw an explanation. Color blindness ran in families, affecting men but not women. While color-blind men had two normal cones and one mutant cone, De Vries knew that the mothers and daughters of color-blind men had the mutant cone and three normal cones—a total of four separate cones in their eyes. He suspected the extra cone could be why the women perceived color differently—not because they saw less than most people but because they saw more. He speculated that such women might be using the fourth cone to distinguish more colors than a trichromat, but he buried this insight on the last page of the paper. De Vries never wrote about four-coned women again.

In the 1980s neuroscientist John Mollon of Cambridge University, then Jordan’s adviser there, was studying color vision in monkeys and became interested in De Vries’s note on tetrachromacy. Mollon and Jordan realized that since color blindness is common, four-coned women must be as well. Jordan estimates they make up as many as 12 percent of women. To find if tetrachromats were hidden in this group, the researchers sought out the mothers of color-blind sons and had them take matching tests similar to the one used by De Vries, but with a twist. If they were true tetrachromats, they would never be able to make a satisfactory match, because they would be able to sense color gradations beyond those available on the test.
No luck: Mollon and Jordan found that women with four cones could consistently make a match on the tests. Jordan began to have doubts. Perhaps the fourth cone was not active. Perhaps super-vision was not real. In 2007 Jordan, now at Newcastle, returned to testing using a new method. Sitting in a dark room, peering into a lab device, women saw three colored circles flash before their eyes. To a trichromat, they all looked the same. To a tetrachromat, though, one would stand out. That circle was not a pure color but a subtle mixture of red and green light randomly generated by a computer. Only a tetrachromat would be able to perceive the difference, thanks to the extra shades made visible by her fourth cone.
Jordan gave the test to 25 women who all had a fourth cone. One woman, code named cDa29, got every single question correct. “I was jumping up and down,” Jordan says. She had finally found her tetrachromat.

What would it be like to see through cDa29’s eyes? Unfortunately, she cannot describe how her color vision compares with ours, any more than we can describe to a dichromatic person what red looks like. “This private perception is what everybody is curious about,” Jordan says. “I would love to see that.” Jordan’s next challenge is discovering why cDa29 is different from the other women she tested. “We now know tetrachromacy exists,” Jordan says. “But we don’t know what allows someone to become functionally tetrachromatic, when most four-coned women aren’t.” Jay Neitz, a vision researcher at the University of Washington, thinks that potential tetrachromats may need practice to awaken their abilities. “Most of the things that we see as colored are manufactured by people who are trying to make colors that work for trichromats,” he says. “It could be that our whole world is tuned to the world of the trichromat.” He also suspects the natural world may not have enough variation in color for the brain to learn to use a fourth cone. Tetrachromats might never need to draw on their full capacity. They may be trapped in a world tailored to creatures with lesser powers. Perhaps if these women regularly visited a lab where they had to learn—really learn—to tell extremely subtle shades apart, they would awaken in themselves the latent abilities of their fourth cone. Then they could begin to see things they had never tried to see before, a kaleidoscope of colors beyond our imagining.
 
#6
The comment about dogs being colour blind is interesting and it is true to a great extent. During the initial training of our explosives search dogs we needed to:
a. Build the dogs confidence,
b. Get it to use it's nose for our purpose,
c. Get the dog to use its nose rather than its eyes for searching.

In the early stages the searches have to be easy so that the dog always wins. This means throwing a scent article out onto an easy location like a grass field. Initially the dog will run around looking for the search article and will often find it by sight rather than smell.

To overcome this reliance on sight we developed a procedure where we use a scent article which is coloured red, as dogs can't discriminate between red and green. When a red search article lands on the grass it is very difficult for the dog to see. And the dogs eyes/brain/distance configuration is designed for detecting movement rather than shapes, so a static article is difficult for it to detect.

Using these little tricks, we get the dog to find the article because of its scent rather than by shape or colour.
 

Fang_Farrier

LE
Kit Reviewer
Book Reviewer
#7
The comment about dogs being colour blind is interesting and it is true to a great extent. During the initial training of our explosives search dogs we needed to:
a. Build the dogs confidence,
b. Get it to use it's nose for our purpose,
c. Get the dog to use its nose rather than its eyes for searching.

In the early stages the searches have to be easy so that the dog always wins. This means throwing a scent article out onto an easy location like a grass field. Initially the dog will run around looking for the search article and will often find it by sight rather than smell.

To overcome this reliance on sight we developed a procedure where we use a scent article which is coloured red, as dogs can't discriminate between red and green. When a red search article lands on the grass it is very difficult for the dog to see. And the dogs eyes/brain/distance configuration is designed for detecting movement rather than shapes, so a static article is difficult for it to detect.

Using these little tricks, we get the dog to find the article because of its scent rather than by shape or colour.
Surely the "fzzzzzzzzzzzzzzzzzzzzzzz" of the fuze burning helps as well?
 

Attachments

#8
The Humans With Super Human Vision | Senses | DISCOVER Magazine

The Humans With Super Human Vision
An unknown number of women may perceive 
millions of colors invisible to the rest of us. One British scientist is trying to track them down and understand their extraordinary power of sight.

I'm not sure that the research will help very much, the way our senses work is already strange enough. Good luck if he is on a big budget. But put things into perspective... what is smell, touch and hearing? It's not difficult to understand how over millions of years life has adapted to this environment and it's not over yet. The brain is only a decoder and the evidence is that women are more subjective to senses because of their evolved roles... Men can get by with less and my guess is that massive areas of our brains are just switched off...Mrs HB will confirm. After a few months cooking, changing nappies and dusting, men will regain their enhanced perception of colour, agreed?...:)
 
#9
I'm not sure that the research will help very much, the way our senses work is already strange enough. Good luck if he is on a big budget. But put things into perspective... what is smell, touch and hearing? It's not difficult to understand how over millions of years life has adapted to this environment and it's not over yet. The brain is only a decoder and the evidence is that women are more subjective to senses because of their evolved roles... Men can get by with less and my guess is that massive areas of our brains are just switched off...Mrs HB will confirm. After a few months cooking, changing nappies and dusting, men will regain their enhanced perception of colour, agreed?...:)

You can't ever say with certainty the causes for evolutionary divergence, but I spose there's no harm in speculating the varying roles of men and women over a few hundred thousand years. One would assume people of a dark ethnicity have a different skin colour due to their habitat and the sun, whereas Caucasians have a whiter complexion due to temperate climes.

If women have a role of gathering berries, leaves and edible foods and men are involved in hunting perhaps women's vision evolved to spot bright coloured berries etc?

Now that survival of the fittest is no longer a requirement for the human race it's interesting to see whether we'll evolved further. Without an evolutionary need or advantage for breeding what will be the result?
 
#11
"Hey! Who you gonna believe, me or your lyin' eyes?"
 
#13
Did anyone catch Fry's English Delight on radio 4? Apparently some cultures have no word for blue. Someone deduced that includes the ancient Greeks from descriptions of the sky in the Iliad. The Italians, on the other hand, have 2 words for blue.

Our eyes have been selected by evolution, to work with our brains and improve our chances of survival, that's why we see what we need to - Perhaps the conclusion should be that the same applies to religious beliefs. If you can't see the fairies at the bottom of the garden the most likely explanation is they aren't there.
 
#14
why oh why oh why! do you have to be such a utter cnut
Perfectly excellent thread.

Where is Arrse's moderators gone to let children spam the good stuff?

You've got a series of Arrse Depressive Collectives spamming and flaming across the site with no action. If it's not damaging revenues now it will in time.
 

Bowmore_Assassin

MIA
Moderator
Book Reviewer
#15
Perfectly excellent thread.

Where is Arrse's moderators gone to let children spam the good stuff?

You've got a series of Arrse Depressive Collectives spamming and flaming across the site with no action. If it's not damaging revenues now it will in time.

Moderated as required as someone reported this thread to me...

For those contributers whose posts I deleted, please play in the NAAFI. Thanks.
 
#16
You can't ever say with certainty the causes for evolutionary divergence, but I spose there's no harm in speculating the varying roles of men and women over a few hundred thousand years. One would assume people of a dark ethnicity have a different skin colour due to their habitat and the sun, whereas Caucasians have a whiter complexion due to temperate climes.

If women have a role of gathering berries, leaves and edible foods and men are involved in hunting perhaps women's vision evolved to spot bright coloured berries etc?

Now that survival of the fittest is no longer a requirement for the human race it's interesting to see whether we'll evolved further. Without an evolutionary need or advantage for breeding what will be the result?
Probably going off topic DC but what we may evolve into is a great question. No doubt there are subtle changes taking place now such as resistance to disease, gains in average height and perhaps intelligence but the effects of 'civilisation' may also have odd results. Enter the stuff of science fiction... Personally I think that a new species is already among us...surviving on alcohol, nicotine and benefits... the Homoparasiticus! They are born wearing track suits and trainers, collect around betting shops and pubs, communicate via texting on pay as you go and worship the gods of soccer. It's not looking good mate...:hmm:
 
#17
[video=youtube;iPPYGJjKVco]http://www.youtube.com/watch?v=iPPYGJjKVco[/video]

Perhaps finally an answer to the colour problem?
 
#20
Also, as someone who works in the visual impairment field, I did work with a lady who would have been classed with Achromotopsia but for the sad fact that she also saw yellow. To her, the whole world was a Wolves supporter but she did not know it because until the hospital finally registered her as partially sighted, she had managed to live independently without realizing the world was actually quite colourful
 

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