The facial expression responses of adults to the display of facial expressions were examined in a variety of public settings
to test predictions from a contagion hypothesis, that the display of smiles and frowns results in smiles and frowns, and folk wisdom that the display of a smile will result in a smile but that a frown will not lead to a frown in response. It was also predicted that female subjects would smile more frequently than male subjects and that people would smile at females more than at males. The results supported the folk adage rather than the contagion hypothesis: Over half the subjects responded to a smile with a smile, whereas few subjects responded to a frown with a frown. The predicted effects of subjects'' and displayers'' gender were also observed. The results were interpreted in the context of internalized norms of reciprocity for brief encounters. The potential for enhanced affect as a result of the contagion of smiles is discussed.