As researchers led by Fumihiro Kano of Japan’s Kyoto University report in Proceedings of the National Academy of Sciences, the findings add to a growing body of evidence indicating non-human animals possess “theory of mind,” or the ability to attribute mental states—including beliefs, desires and knowledge—to oneself and others.
According to Cosmos’ Tanya Loos, the study builds on a 2016 investigation also co-authored by Kano. The previous paper, published in the journal Science, showed that great apes are capable of recognizing when others are operating under a false set of assumptions—a key component of theory of mind.
To determine primates’ capacity for understanding false belief, Kano, lead coauthor Christopher Krupenye of Duke University and their colleagues conducted a series of anticipatory looking tests. In the 2016 experiment, great apes watched videos of humans—one dressed as a gorilla—hiding an object and then guessing where it was. One video showed the gorilla-suit actor hiding an object while another human watched. The person then had to guess where the object was hidden. A second video showed the gorilla-suit actor hiding an object after the other human left the room. When the person returned, they had to guess where the object was hidden.