

Perception trumps knowledge: optical illusion - RiderOfGiraffes
http://web.mit.edu/persci/people/adelson/checkershadow_illusion.html

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nazgulnarsil
WAY more dramatic for me: the blue and green spirals are the same color.
[http://blogs.discovermagazine.com/badastronomy/2009/06/24/th...](http://blogs.discovermagazine.com/badastronomy/2009/06/24/the-
blue-and-the-green/)

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JoeAltmaier
Not really the same; the blue and green areas are mixed with other colors; its
wellknown the eye sees finely mixed colors as different colors. The greyscale
illusion uses quite large areas which is remarkable.

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jamesbritt
"the eye sees finely mixed colors as different colors"

These are hardly finely mixed. I'm 1.5 feet form my 24" monitor, looking at
the thing, amazed at the illusion. I clearly see distinct stripes of color. I
have to block out the bordering color with my fingers to perceive the real
color.

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JoeAltmaier
Still they are one tenth the dimension of the b&w illusion.

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TheTarquin
What's even more interesting is how much of the image you can remove while
still maintaining the illusion. Block out almost all the image except for
squares A and B and just a VERY little bit of space around them. The two
squares still look different colors.

The brain can mess with perception in pretty significant ways based on very
little information.

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J_McQuade
I tried covering up bits with my hand, with bits of paper, and staring at it
with varying intensities - I still didn't believe it until I loaded it up in
Gimp and checked the colour values.

It seems our perception of colour could be like our perception of temperature
- comparative, rather than 'quantitative' in any way. Anyone here know of any
studies into this?

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evanrmurphy
I even got suspicious that the right image on the Proof page might have been
doctored, but it does pass the Gimp test. :)

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JoeAltmaier
Make a little circle with your index fingers and thumbs, put it over each
square, that breaks the spell.

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dskhatri
More illusions: <http://web.mit.edu/persci/gaz/gaz-teaching/index.html>

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bitwize
Once I was told they were the same color it became one of those "CAN'T UNSEE"
things.

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olegk
This is sooo old. HN shouldn't have this crap on the front page.

