CAMBRIDGE, Mass. -- Through an online survey of more than 2,000 people, psychologists at Harvard University have found that we perceive the minds of others along two distinct dimensions: agency, an individual's ability for self-control, morality and planning; and experience, the capacity to feel sensations such as hunger, fear and pain.
The findings, presented this week in the journal Science, not only overturn the traditional notion that people see mind along a single continuum, but also provide a framework for understanding many moral and legal decisions and highlight the subjective nature of perceiving mental attributes in others.
"Important societal beliefs, such as those about capital punishment, abortion, and the legitimacy of torture, rest on perceptions of these dimensions, as do beliefs about a number of philosophical questions," says co-author Kurt Gray, a doctoral student in Harvard's Department of Psychology. "Can robots ever have moral worth? What is it like to be God? Is the human experience unique?"
Gray worked alongside fellow psychologists Heather Gray and Daniel Wegner on the study, which presented respondents with 13 characters: 7 living human forms (7-week-old fetus, 5-month-old infant, 5-year-old girl, adult woman, adult man, man in a persistent vegetative state, and the respondent himself or herself), 3 non-human animals (frog, family dog, and wild chimpanzee), a dead woman, God, and a sociable robot.
Participants were asked to rate the characters on the extent to which each possessed a number of capacities, ranging from hunger, fear, embarrassment, and pleasure to self-control, morality, memory and thought. Their analyses yielded two distinct dimensions by which people perceive the minds of others, agency and experience.
These dimensions are independent: An entity can be viewed to have experience without having any agency, and vice versa. For instance, respondents viewed the infant as high in experience but low in agency -- having feelings, but unaccountable for its actions -- while God was viewed as having agency but not experience.
"Respondents, the majority of whom were at least moderately religious, viewed God as an agent capable of moral action, but without much capacity for experience," Gray says. "We find it hard to envision God sharing any of our feelings or desires."
Respondents viewed themselves and other "normal" human adults as highest in both dimensions, possessing both experience and agency; perhaps not surprisingly, they attributed neither dimension to the dead person. Some characters, such as the fetus and the man in a persistent vegetative state had little agency, and ranked somewhere in the middle on experience, which suggests that people disagree on whether these entities are truly capable of experience.
"The perception of experience to these characters is important, because along with experience comes a suite of inalienable rights, the most important of which is the right to life," Gray says. "If you see a man in a persistent vegetative state as having feelings, it feels wrong to pull the plug on him, whereas if he is just a lump of firing neurons, we have less compunction at freeing up his hospital bed."
If attributing experience to another entity is the key to imbuing them with moral worth, he says, attributing agency is the key for holding them responsible for their actions.
"When we perceive agency in another, we believe they have the capacity to recognize right from wrong and can punish them accordingly," Gray says. "The legal system, with its insanity and reduced capacity defenses, reflects the fact that people naturally assess the agency of individuals following a moral misdeed."
Gray, Gray, and Wegner's research was supported by the National Institute of Mental Health and the Canadian Social Sciences and Humanities Research Council. Their online survey is available at http://mind.