Researcher: People are able to tell whether a person is extroverted just by looking at pictures in which the person has a neutral expression
Since people are also able to tell whether a chimpanzee behaves dominantly just by looking at a picture of the chimpanzee' s expressionless face, and since both humans and chimpanzees are primates, we conclude that this ability is probably not acquired solely through culture but rather as a result of primate biology
Some of the pictures of people used in the experiments were composites of several different people.