The Cafe Wall Illusion 7/52

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The café wall illusion is a geometrical-optical illusion in which the parallel straight dividing lines between staggered rows with alternating black and white "bricks" appear to be sloped.

It was first described under the name Kindergarten illusion in 1898,[1] and re-discovered in 1973 by Richard Gregory.[2] According to Gregory, this effect was observed by a member of his laboratory, Steve Simpson, in the tiles of the wall of a café at the bottom of St Michael's Hill, Bristol. It is a variant of the shifted-chessboard illusion originated by Hugo Münsterberg.[3]

The precise cause of the illusion is not well understood, although it appears to involve interactions between the neurons in the visual cortex which code for orientation. It is unclear whether some inhibitory mechanism is at play, or if there is a kind of computational filter acting on input from cells operating at different spatial frequencies, i.e. taking their inputs from larger or smaller areas of the visual field (Takeuchi 2005).

Philosophers have also been interested in what illusions like this illusion can tell us about the nature of experience. For example, in the case of experiencing the Café Wall Illusion, it would seem to be that the one can know that the lines are parallel whilst at the same time one experiences them as unparallel. If so, then this might count against the claim the perceptual states are belief-like, because if perceptual states were belief like then, when experiencing the Café Wall Illusion one would simultaneously believe that the lines were, and were not, parallel. This would seem to entail that one was being irrational, because one would simultaneously be holding contradictory beliefs. But it seems highly implausible that one is being irrational when under going this illusion. For discussion of this general point about whether perceptions are like beliefs, see Crane & French (2016).

 
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The Orbison Illusion 6/52

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The Orbison Illusion 6/52

I love optical illusions so I thought I would share a few of my favorite and with many people opting to take up 365 day challenges i thought i would try a 52 week challenge in which i will share with you a different Illusion every week. so if you have any you would like me to feature get in touch.

The Orbison Illusion was created by William Orbison (1912 - 1952), an American psychologist. Orbison first published the illusion in the American Journal of Psychology, in 1939. 

The Orbison Illusion is one among a number of illusions where a central aspect of a simple line image – e.g. the length, straightness, or parallelism of lines – appears distorted by other aspects of the image – e.g. other background/foreground lines, or other intersecting shapes. These are sometimes called ‘geometrical optical illusions’.

What are the best optical illusions you've found on the web? Do you have more amazing examples you don't see here?

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The Troxler effect 5/52

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I love optical illusions so I thought I would share a few of my favorite and with many people opting to take up 365 day challenges i thought i would try a 52 week challenge in which i will share with you a different Illusion every week. so if you have any you would like me to feature get in touch.

The Troxler Effect Week 5

If you focus on one tiny point, and the rest of the scene doesn't move, your eyes sort of become desensitised to it, and fade it into the background.

It's called the Troxler effect, or Troxler flading - named for physician Ignaz Paul Vital Troxler, who discovered in 1804 that if he focussed his eyes on a fixed spot, the surrounding image would gradually disappear from view.

So now you know something about the way your brain can lie to you about the information right in front of your eyes. We think there's a life lesson somewhere in there for all of us.

The Troxler Effect is named after Swiss physician and philosopher Ignaz Paul Vital Troxler (1780-1866).

What are the best optical illusions you've found on the web? Do you have more amazing examples you don't see here?

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Peripheral Drift Illusions 4/52

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I love optical illusions so I thought I would share a few of my favorite and with many people opting to take up 365 day challenges i thought i would try a 52 week challenge in which i will share with you a different Illusion every week. so if you have any you would like me to feature get in touch.

Week 4

Peripheral Drift Illusion

The peripheral drift illusion is a perception of movement in a static image; the illusion is caused by the brain's interpretation of patterns seen outside of the eye's area of focus. Certain repeated patterns of black and white and simple color patterns can elicit the illusory effect.Rotating Snakes

Rotating snakes is an optical illusion developed by Professor Akiyoshi Kitaoka in 2003.[1]

At first this optical illusion picture may be hard to see, but if you begin to scan back and forth across the image you will notice that the squares in your periphery begin to rotate. As soon as your eyes stop moving, however, rotation will cease.

Below are several examples of Peripheral Drift Illusions

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What are the best optical illusions you've found on the web? Do you have more amazing examples you don't see here?

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Ninio's Extinction Illusion 3/52

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52 weeks 52 different Optical Illusions

I love optical illusions so i thought i would share a few of my favorite and with many people opting to take up 365 day challenges i thought i would try a 52 week challenge in which i will share with you a different Illusion every week. so if you have any you would like me to feature get in touch.

Week 3

Ninio's Extinction Illusion

This illusion shows 12 black dots on a gray-and-white grid. However, it is impossible to see all 12 dots at once. If the grid wasn't in the picture, people could see all 12 dots. French scientist and visual perception specialist Jacques Ninio created the illusion in 2000 and published a detailed study explaining how it tricks the mind.

"When the white disks in a scintillating grid are reduced in size, and outlined in black, they tend to disappear," wrote Ninio. "One sees only a few of them at a time, in clusters which move erratically on the page. Where they are not seen, the gray alleys seem to be continuous, generating gray crossings that are not actually present."

This illusion is a prime example of how only see certain things in the center of our vision. Our brain compensates for things we can't see. Therefore, viewers know there are 12 dots in total on the grid but visually only see a few at a time.

This illusion is a variation on the Hermann Grid, which has sort of the opposite effect of the Ninio's Extinction Illusion. In the Hermann Grid, all of the dots are white, but some appear black based on where your eyes travel.

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What are the best optical illusions you've found on the web? Do you have more amazing examples you don't see here?

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The Ebbinghaus illusion 2/52

 
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52 weeks 52 different Optical Illusions

I love optical illusions so i thought i would share a few of my favorite and with many people opting to take up 365 day challenges i thought i would try a 52 week challenge in which i will share with you a different Illusion every week. so if you have any you would like me to feature get in touch.

Week 2

The Ebbinghaus Illusion 2/52

Observe the two sets of circles below. Which of the orange circles is larger?

 
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You may be surprised to find out that they are exactly the same size. The deception occurs because of the size of the surrounding blue circles and their relative distance from the central orange circle.

These adjustments cause the brain's visual perception system to distort the relative size of the inner circles. Another factor at play is the "completeness" of the surrounding circles; if we removed a few of the blue dots or spaced them out, the illusion would not persist.

The two orange circles appear to be different sizes, but they are the same. The one on the left appears larger because of its context within the grey outlined circle. The Ebbinghaus illusion was discovered by the German psychologist Hermann Ebbinghaus (1850–1909).The illusion was popularized by Edward B. Titchener in a 1901 textbook, in English, which is why the illusion is sometimes called "Titchener circles".

The Ebbinghaus illusion is one of several size contrast illusions to have been studied by both philosophers and cognitive scientists. Bela Julesz (1928-2003), a Hungarian neuroscientist and experimental psychologist hypothesised that the illusory effect of the Ebbinghaus discs cannot be explained entirely in terms of retinal processes (Julesz 1971).

The illusion is similar to a Delboeuf Illusion, shown below. 

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The two black circles appear to be different sizes, but they are the same. The one on the left appears larger because of its context within the white outlined circle. 

Interestingly, these illusions are perceived differently by adults and children, which provides evidence that they are context-sensitive. Because adults have higher sensitivity to context, illusions of this type fool them more often and more easily. Since children are not as context-sensitive, they are less often deceived by this kind of illusion.

What are the best optical illusions you've found on the web? Do you have more amazing examples you don't see here?

Share your thoughts with us in the comments section below.