Anatomy of a lying smile.
A smile can be deceiving, but can you tell the difference between a decoy and the real McCoy? According to psychologists at the University of California at San Francisco, there are subtle differences between smiles when people are truthful and when they lie about experiencing pleasant feelings.
Smiles that reflect actual enjoyment (left) include the activity of the outer muscle that circles the eye more often than when enjoyment is feigned, report Paul Ekman and his colleagues in the March JOURNAL OF PERSONALITY AND SOCIAL PSYCHOLOGY. Smiles intended to conceal strong negative emotions frequently include muscular action around the lips and eyes linked to disgust (right), fear, contempt or sadness.
The investigators studied videotapes of 31 student nurses. First, each subject was told to describe her feelings to an interviewer after seeing a pleasant nature film. Then they saw a film showing amputations and burns and were told to convince the interviewer they had seen a pleasant film. Descriptions of the young womens' facial muscle actions, such as pulling the brows together and wrinkling the nose, were made by two observers experienced in using a facial measurement technique developed by Ekman and his co-workers.
Although deceptive interviews produced significantly more "masking" smiles across the entire group, on an individual basis the face provided clues to deceit in fewer than half of the subjects. The researchers are now looking at how other behavioral signs, including body posture and speech content, may operate as clues to deceit in different people.
The spectrum of smiles that provide various social signals remains to be determined, add the scientists. For example, "phony" smiles that occur when nothing much is felt were not considered in their study.