Great apes anticipate that other individuals will act according to false beliefs

Humans operate with a "theory-of-mind" with which they understand that others’ actions are driven not by reality but by beliefs about reality, even when those beliefs are false. Although great apes share with humans many social-cognitive skills, they have repeatedly failed experimental tests of such false belief understanding. Using an anticipatory looking test (originally developed for human infants), we show that three species of great apes reliably look in anticipation of an agent acting on a location where he falsely believes an object to be, even though they themselves know that it is no longer there. These results suggest that great apes also operate—at least on an implicit level—with an understanding of false beliefs.