193 / Illusion, irrationality & the mind

On a recent interstate trip I picked up my in-flight-read at the airport (as ever, being convinced a good read is the best means to alleviate the tedium of impersonating a sardine on a plane), a book about the issue of irrationality of the mind, as explained with the help of psychological experiments, such as this one.

The book is Priceless (pun intended). One of the experiments I put to the test with my fellow travellers; the result was astonishing. I asked them which square in the illustration they thought was lighter, A or B. Everyone will agree that B seems lighter than A (it certainly appears to be lighter). So far so good, there's no point in arguing about appearances.

But what happens when you tell people unambiguously that they both are one as dark or light as the other? Like I said, the result is astonishing, because my two test subjects insisted that this was not true, even after repeatedly being told: no, B is not lighter than A, it's an optical illusion.

I am fascinated by the extend to which we can be irrational, and the book deals with the subject in a fascinating manner. A great read.

The two squares A and B are one as light (or dark) as the other. Not convinced?

Here are the two squares in isolation (unaltered, unretouched - I swear):

(This perceptual illusion was devised by MIT cognitive scientist Edward H. Alderson.)