How do we know who has a mind?

According to responses to an online survey conducted by the Harvard Psychology Department, we believe people with minds boast two attributes: agency and experience.

“The common perception was that an adult human had the most mind and there’s a little less when you get to a baby, even less when you get to a man in a vegetative state, all the way down to a dead person when there’s no one there at all,” said Professor of Psychology and the senior author of the study Daniel M. Wegner.

But the findings, published in the Feb. 2 issue of the academic journal Science, modify the view that minds are judged on a continuum from greater to lesser, revealing instead that they are evaluated based on assumptions about the individual’s ability for doing, in combination with his or her capacity to feel sensations like hunger and pride.

The authors of the study suggest that their findings conform to classical theories of morality and responsibility.

“How we view a character’s moral worth really depends on how much experience we perceive them to have. The more experience and worth, the more we would worry about hurting them,” said Kurt J. Gray, a Ph.D candidate in psychology and the study’s co-author. “Determining if someone has agency dictates if we hold them accountable for their actions.”

Participants in the survey were asked to rank fictional characters based on what they believed the characters’ capacities were for sensations like rage and desire as well as their abilities to exercise self-control and thought.

For example, one question asked respondents to evaluate whether a five-year-old girl would be more or less likely to feel pain when compared to a chimpanzee.

The study used 13 different characters, including a fetus, an adult woman, a man in a persistent vegetative state, a frog, God, and a robot.

Respondents said human adults possessed high amounts of both agency and experience. In contrast, while they said dogs ranked similarly to humans in terms of experience, they ranked low in agency.

Interestingly, respondents—who typically identified themselves as Christians—said that while God had agency, he lacked experience, ranking at the level of a robot and below a dead person.

“It was stricking for us to see that people perceived God as capable of taking action yet God was incapable of sharing human emotions or desires,” said Wegner.

—Staff writer Xianlin Li can be reached at li3@fas.harvard.edu.