Premack and Woodruff introduced the term “theory of mind” in 1978 for the ability to attribute mental states—such as beliefs, desires, intentions, and knowledge—to oneself or another individual.
The phrase appeared in their influential paper “Does the Chimpanzee Have a Theory of Mind?” The paper asked whether chimpanzees could understand that another being might have goals, perceptions, or knowledge different from their own. That question helped establish theory of mind as a major concept in comparative psychology and developmental psychology.
In humans, researchers study theory of mind through tasks involving deception, false beliefs, perspective-taking, and the recognition of intentions. Animal researchers have explored related abilities in chimpanzees, bonobos, corvids, dogs, goats, and other species.
The term does not mean that an animal literally possesses a scientific theory. It refers to an inferred cognitive capacity to represent another mind. Researchers still disagree about how convincingly nonhuman animals demonstrate full theory of mind, because sophisticated behavior can sometimes be explained by simpler learning or attention-reading mechanisms.