The Invisible Gorilla

Christopher Chabris and Daniel Simons conducted an experiment at Harvard University more than a decade ago that became infamous in psychology circles. Their book The Invisible Gorilla popularized it. And you may be one of the millions of viewers who made their Selective Attention Test one of YouTubes’s most-watched videos.

The two researchers filmed students passing basketballs while moving in a circular fashion. In the middle of the short film, a woman dressed in a gorilla suit walks into the frame, beats her chest, and walks out of the frame. The sequence takes nine seconds…