International Journal of Comparative Psychology

In the handful of existing comparative false belief studies, chimpanzees have consistently failed tests that 5- to 6-year-old children have passed. However, those tests were either explicitly cooperative communicativeor competitive, both of which are problematic for different reasons. We therefore devised a new change-of-contents false belief test for children and chimpanzees that did not include these problematic elements. Nevertheless, chimpanzees showed no evidence of understanding false beliefs (consistent with past research, however, children showed a clear improvement in test performance from 3.5 to 4.5 years of age). Our results suggest that the cooperative-communicative or competitive nature of previous false belief tests was not solely responsible for chimpanzees’ failure. That chimpanzees have now also failed a more socially neutral test supports the conclusion that chimpanzees may simply not recognize false belief states in others. Additionally, our test departs from a near exclusive reliance on the change-of-location paradigm in false belief research. It therefore expands the repertoire of methods available for testing false belief understanding with minimally verbal and nonverbal procedures.