Tap Your Hands if You Don’t Know It

Kluge alert! Yesterday, The New York Times described a fascinating but little-known study by Elizabeth Newton. According to the Times report

“[Newton] gave one set of people, called “tappers,” a list of commonly known songs from which to choose. Their task was to rap their knuckles on a tabletop to the rhythm of the chosen tune as they thought about it in their heads. A second set of people, called “listeners,”were asked to name the songs.
 Before the experiment began, the tappers were asked how often they believed that the listeners would name the songs correctly. On average, tappers expected listeners to get it right about half the time. In the end, however, listeners guessed only 3 of 120 songs tapped out, or 2.5 percent.”

Why? People mistake what they know for what other people know. Psychologists call this “curse of knowledge“. Another powerful illustration of this phenomenon comes from the lab of University of Chicago psychologist Boaz Keysar, who asked undergraduates to read aloud a bunch of ambiguous sentences — and then guess whether they’d made themselves clear. Almost everybody overestimated their own effectiveness, even when they were fully aware that the sentences were in principle ambiguous.