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Monday, July 08, 2013

The Cafe Wall Illusion

This is one of my favorite illusions. It was discovered by Dr. Richard Gregory. The horizontal lines appear to be bent, but they are in fact parallel, straight, horizontal lines.


Alan said...

Wonderful! Thanks so much for this--I had never seen such a great illusion!

One great fact I discovered is that the effect of the illusion is additive if interaction is involved. Take a piece of paper and shield everything but the first line. Then move the paper down to the next, etc. The second line thus looks pretty parallel, but by the third, it's impossible (to me) to see them as all parallel. Move it along and the overall impression of the illusion is inescapable. Great!

Alan said...

And of course if you look at any one line--it looks straight.

So this is about gestalt consciousness?

Brit Brogaard said...

That's interesting! I don't know what the mechanism is yet. But what you say seems exactly right.

Christina said...

This is gorgeous!

Aaron Sloman said...

There's a version of this image with adjustable settings that enhance or diminish the illusion here:

Philosophers interested in such things need to learn how to design working perceivers.

Computational modelling research needs more philosophers.

Aaron Sloman

Alan said...

Thank you so much Aaron (if I may). That is a terrific site!

Lindsey H. said...

Ah! I love illusions but I'm so creeped out at the same time. How does it work?! I kind of like not knowing because it's like seeing the trick behind the magic, which usually ruins the fun, but still my perplexity always wins over. This was fun! Thanks!