Weather and Smiling Contagion: A Quasi Experiment with the Smiling Sunshine

Studies have shown that pleasant weather conditions (namely, sunshine) favor positive social relationships and improve moods. However, the effect of sunshine on one nonverbal expression that facilitates social relationships (namely, smiling) has never been studied. In a field experiment, men and women walking alone in the street were passed by a male or a female confederate who displayed a smile to the passersby. The contagion effect of smiling was measured. The study was carried out on days that were evaluated as being either sunny or cloudy, but precaution was taken to control the temperature and not to solicit participants when it rained. It was found that the display of a smile results in a smile more often on sunny days. The positive mood induced by the sun may explain such results.