Abstract
PURPOSE: How do facial expressions affect perception of a face? Previous research on binocular rivalry suggests that stimulus strength (e.g. amount of contour or luminance contrast) affects perceptual dominance and suppression of the stimulus during rivalry. Certain facial expressions may increase perceptual strength of a face because of their emotional information. We examined the influence of facial expressions on perception of faces by implementing binocular rivalry experiments. More specifically, we tested whether (a) emotional faces had dominance over neutral faces, and (b) a negative facial expression, as a result of evolutionary advantage, had dominance over a positive facial expression. METHODS: Three different facial expressions (happy, disgust, neutral) from two female models (i.e. a total of six faces) were chosen from Ekman and Matsumoto's (1993) Combined JACFEE and JACNeuF. Twenty-four observers viewed two faces presented on a calibrated CRT through a haploscopic mirror system. During 1-minute presentation, exclusive visible time for each face was measured. RESULTS: Faces with facial expressions of happiness (18±2 s) and disgust (17.2±1.8 s) had longer dominance duration than a neutral face (10.2±1.1 s) presented to the contralateral eye. When a happy face and a disgust face were presented to the two eyes, the happy face (19±1.8 s) had longer dominance duration than the disgust face (12.6±1.3 s). CONCLUSIONS: The experiments showed that emotional information from a face could affect perceptual dominance of the face, which suggested that facial expressions could change the strength of a face stimulus. The results are inconsistent with the perceptual advantage of negative facial expressions found in searching experiments. The results suggest the presence of a positivity bias, which is consistent with previous studies demonstrating higher accuracy for the decoding of happy faces in a variety of conditions.
This research was supported by a Psychology Research Grant from the University of Chicago