Optical Illusion of the Week: “Blue = Yellow = Gray”

Happy New Year!

This week’s illusion is based on the same concept as the Adelson Illusion (“Which Square Is Darker?”) we showed you back in October, but there’s an added twist to this one. Whereas the previous illusion appeared to be in shades of gray throughout, this week’s illusion, created by R. Beau Lotto of the Lottolab studio in London, features “colored” squares.

I’ve put “colored” in quotation marks, because the “blue” squares in the left image, while appearing to be blue, and the “yellow” squares in the right image, while appearing to be yellow, are actually neither color.

Instead, both sets of squares are not really of any color at all! Rather, they are actually all gray—and, moreover, of the same shade of gray. (In other words, the “blue” squares in the yellow-masked image [on the left] are identical in shade to the “yellow” squares in the blue-masked image [on the right].)

Skeptical? Take a look at the following composite image, where I’ve drawn connections between cut-outs of the “yellow” squares from the image on the right to the “blue” squares in the image on the left.

Also, check out Lotto’s original demo of the illusion, seen here: http://www.lottolab.org/illusiondemos/Demo%2012.html. Mouse over the ‘MASK’ graphic in the demo to reveal that the “blue” squares on the left are identical to the “yellow” squares on the right.