Two dimensions of mind perception.

Scientists want to figure out how individuals can tell whether someone or something else has a mental life. Controversial studies have addressed whether chimpanzees and children with autism are capable of making such an inference about others.

However, investigators shouldn't assume that organisms perceive another's mind as a single entity, assert psychologist Heather M. Gray of Harvard University and her colleagues. Instead, people attribute to others two distinct dimensions of mental activity, Gray's team reports in the Feb. 2 Science.

The researchers dub one dimension of mind perception "experience," meaning a capacity for feeling hunger, fear, pain, rage, desire, pride, embarrassment, and joy. This dimension also implies the presence of self-awareness and a distinctive personality.

The other dimension, "agency," refers to a capacity for self-control, morality, memory, emotion recognition, planning, communication, and thought.

The researchers surveyed 2,399 people via the Internet. Participants rated pairs of characters described on the survey on one of 18 mental capacities, for example, deciding which member of the pair was more able to feel pain. The pair members were also rated in six other ways, such as which was the more likable character. Characters included a frog, a chimpanzee, a human fetus, a baby, a 5-year-old girl, a man in a persistent vegetative state, an adult woman, God, and a robot that interacts with people.

Volunteers' responses often broke down along the two mind-perception dimensions. For instance, participants felt that characters rated high in agency--such as the active adults--deserved punishment for a mis-deed, but participants most wanted to avoid inflicting harm on the characters ranked high in experience, such as the young girl. Participants perceived God as having much agency but little experience.--B. B.