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Great Apes Understand That Others May Hold False Beliefs, a First in Nonhuman Animals

David Jennings
7th October, 2016

Researchers have now shown that great apes, including bonobos and chimpanzees, can tell when an individual holds a false belief. The ability to comprehend that others are acting based on what they think is happening, rather than what’s actually true, has never been seen in a nonhuman animal. The details are in a paper that was just published in the journal Science. Theory of mind is the ability of an animal to attribute mental states both to themselves and other individuals. One important milestone in theory of mind development is the ability to understand that other’s knowledge and beliefs differ from one’s own perception of the world. Being able to anticipate that others will act based on their own beliefs, even if false, has previously only been shown in humans. Researchers from Duke University, the Max Planck Institute for Evolutionary Anthropology, and Kyoto University collaborated in a study of great apes. The team studied bonobos, chimpanzees, and orangutans to look for signs of theory of mind development. The researchers had the apes watch videos and used eye-tracking technology to see what the animals focused on. In one short movie, a person dressed like King Kong hides in a haystack while another man watches. The man leaves and King Kong runs away. When the man returns, he looks for King Kong behind the haystacks. In a similar movie, the man sees King Kong hide a rock in a box. The man later comes back to get the rock but King Kong has already stolen it when he wasn’t looking. The point of these films was to see where the apes would look; if the apes understood false beliefs, they would look to where the man expected to find the rock or King Kong—not where they actually were. All three great ape species passed the test. The team’s findings show, for the first time, that nonhuman primates understand the concept of false beliefs. Chimpanzees, bonobos, and orangutans all anticipated where a man would look even though it went against the apes’ own knowledge. Future experiments are planned and may change our understanding of primate cognition. REFERENCE Krupenye et al. Great Apes Anticipate That Other Individuals Will Act According to False Beliefs. Science (2016).