Flower illusion

The picture below was taken about a month ago in our garden. Can you say what colour the flower is?

I bet you can. Below, you can find the same picture with some colour modifications. Stare at the dot in the middle for 30 seconds, then move your mouse pointer over the picture and you ought to be able to tell what the colour is!

True, it is not that novel or innovatory, but I was interested to see how it all works. Note also that you see the colour on the black and white image only as long as you don’t move your eyes. The moment you do that, your brain re-evaluates what it sees, realizes that there is no colour there, and reverts back to perceiving a black and white image.

About a year ago I read a rather interesting (and popularised) book on neurology by V. S. Ramachandran, titled Phantoms in the Brain. It discusses these matters and many other related assumptions your brain often makes about the world around us (including, for example, how and why people “feel” an arm that has been amputated).

If you want to know how this particular trick is done, see John Sadowski’s tutorial. It’s all pretty simple, actually.