Recognition of Facial Expression
The argument that facial expression serves to elicit a response from the observer may have merit from an evolutionary standpoint. In primates, smiling is actually a display of threat, intended to warn other primates to keep away. Take time to bring your awareness to your own facial expressions. Do your facial expressions accurately reflect how you feel inside, or are you trying to elicit a response from others?
How many muscles are in the human face?
Repeat the experiment by testing for gender differences. Use two sets of photographs, males and females.
"What is in the face" from the American Psychological Association at http://www.apa.org/monitor/jan00/sc1.aspx