I am familiar with studies in which children are tested for theory of mind. In one such experiment, a story is told: Betty is playing with her doll in the bedroom. Then she has to go to school, so she leaves the doll on her bed. While she is at school, her mom takes the doll and puts it on the kitchen counter. When Betty gets home, where will she look for the doll?
The correct answer is obviously "On the bed", because that's where she last saw the doll. But if the child says "On the kitchen counter", he or she does not yet possess a theory of mind - he or she doesn't understand that Betty doesn't know everything that her mother knows, and has no way of knowing that the doll was moved while Betty was at school.
If I'm not mistaken, children normally develop theory of mind around the age of 4 or 5. But are there any conditions or disorders unrelated to intelligence that might prevent an adult from possessing a "normal" theory of mind?