Your brain's recognition system is neither simple nor always predictable. Have you ever felt sure you'd seen your friend's face in a crowd only to realize that you'd just creeped out a stranger by staring too long?
Did you ever look at your husband or wife and feel that person is an impostor? Janet, a 24-year-old graduate student, came home from a stressful day at school and found a man she thought was a stranger in her bed.