September 16, 2008

Adelson’s Checker-Shadow Illusion Claims Another Victim

MIT professor Edward H. Adelson came up with this optical illusion in 1995. It’s a “shadow illusion”; that is, areas A and B are the same shade of gray. Weird, innit?
Courtesy of the good folks at


Lindsey Zehner said...

My IB Theory of Knowledge class just went over this.

The 2 squares are said to be the same color, however, my class refused to believe that it was true. I didn't quite see the resemblance either. Its a tricky one.

Bart King said...

I should have done this with the posting: Copy a section from both parts A and B, and compare. The proof is in the checker-shadow illusion's pudding!

Anonymous said...

I just went over this extensively in a Psych class. To prove that they are different, I photocopied the page it was on in the book, then cut out the two squares in question. When isolated from the rest of the image, they indeed are EXACTLY the same color. It's mind-boggling but true.