On January 26th we posted a neat little eye and brain game on our Facebook page and our visitors had a lot of fun with it. We wanted to take a moment and explain the science behind how the game works.

Stare at the below picture for 30 seconds:

After 30 seconds look at a blank surface or piece of paper and blink your eyes in rapid succession to see the non-negative version of the photo. Did you see it?

This works because when you stare at an object long enough, your eye’s photoreceptors – especially the color-sensitive cone cells – become overstimulated and lose sensitivity. And when you shift your gaze to a blank surface the surrounding cone cells of your eyes send out a stronger signal to compensate for the difference. Your brain interprets this stronger signal discrepancy as looking at the exact opposite colors. This phenomenon is also known as negative afterimage.