Sex differences in perception of emotion intensity in dynamic and static facial expressions

Most research on the perception of emotional expressions is conducted using static faces as stimuli. However, facial displays of emotion are a highly dynamic phenomenon and a static photograph is its very unnatural representation. The goal of the present research was to assess the role of stimuli dynamics as well as subjects' sex in the perception of emotional expressions. In the experiment, subjects rated the intensity of expressions of anger and happiness presented as photographs (static stimuli) and animations (dynamic stimuli). The impact of both stimulus dynamics and emotion type on the perceived intensity was observed. The emotions on 'angry faces' were judged as more intense than on 'happy faces' and the intensity ratings were higher in the case of animation rather than photography. Moreover, gender differences in the rated intensity were found. For male subjects higher intensity ratings for dynamic than for static expressions were noted in the case of anger, whereas in the case of happiness, no differences were observed. For female subjects, however, differences for both anger and happiness were significant. The results suggest that the dynamic characteristic of facial display is an important factor in the perception of the intensity of emotional expressions. Its effect, however, depends on the subjects' sex and emotional valence.