A couple of researchers at Harvard have investigated people’s perceptions of other people’s minds. Volunteers had to consider 13 different entities: “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.” (For some reason that pairing of God and a sociable robot at the end makes me laugh.) For each of these 13 cases, the volunteers had to specify the degree to which they thought the being had various abilities or capacities such as memory, the ability to feel pain, self-control, etc.
Their responses indicated that their perceptions of another person’s mind involve two independent dimensions: agency, which is the ability to plan and take responsibility for actions, and experience, the ability to feel things. (Because they’re independent, you could have entities with agency but no experience–which is how the volunteers viewed God–or experience but no agency–like babies.) This press release has more info. It doesn’t use the word “personhood” but it sounds like that’s more or less what it’s describing, because it mentions the implications for questions about rights and responsibilities, and how our answers could be based on our beliefs about someone’s degrees of agency and experience.
The volunteers in this experiment scored normal adult humans the highest on both scales and rated dead people at zero on both, with the other cases at various places in between. I guess “personhood” isn’t quite the right word, now that I think about it, because dead people, while lacking agency and experience, are definitely still persons and it even feels sometimes like they have rights. (If someone dies and leaves behind diaries that you know they don’t want you to read, for example, it would still feel, at least to me, like the dead person has a right to privacy and that it wouldn’t be right to read the diaries.)
