Perception of Human Age from Faces: Symmetric Versus Asymmetric Movement

Dynamic movements of a face affect human perception of a person's identification, emotional expression, speech, and so on. Findings of studies related to age perception, however, have mainly been obtained from static features of texture such as wrinkles and spots on the skin. Our goal is to investigate the perception of human age related to dynamic information. Systematically manipulated bilateral symmetric and asymmetric facial movements were utilized as stimuli in the age perception experiment. All images were low-pass filtered so that the judgment would not depend on detailed texture information. In the experiment, viewers judged the age level (the first half (indicating 20-24 and 60-64) or the latter half (indicating 25-29 and 65-69) of two age groups: 20's and 60's. Results revealed that faces with symmetric dynamic movements of expression (from a neutral face to one pronouncing i) were not only judged at the level of chance, but were also perceived to be statistically significantly younger than faces with asymmetric dynamic movements. It was also found that types of asymmetry were also effective in age perception, which might be a reflection of laterization of facial processing in a human brain.