Delays in recognizing facial expressions resulting from prolonged viewing of adaptation face stimuli

The main purpose of the present study was to investigate the mechanism underlying fundamental dimensions in recognition of facial expressions, using the prolonged viewing method. Pictures of female faces were used, which displayed one of the following six: happiness, sadness, surprise, anger, disgust, and neutral expressions. In Experiment 1, the mean ratings of each expression on each picture were analyzed with principal component analysis (PCA). In Experiment 2, subjects orally judged the expressions of test faces following either one or 25 seconds of viewing of an adaptation face. Significant delays occurred in the prolonged viewing condition only when the adaptation face had a higher absolute value on 'pleasantness,' the first component of PCA, than the test face. In contrast, adaptation faces that were high only on 'arousal,' the second component, produced no such effects. It was suggested that there are at least two subsystems involved in the recognition of facial expressions and that each system has different temporal characteristics.