Perceptual asymmetry for happy-sad chimeric faces: effects of mood.

Happy-sad chimeric face drawings were viewed in free vision by normal subjects. A significant and reliable perceiver bias toward the left hemiface when judging facial expression was found in right-handers whereas no consistent bias was found in non-right handers. This bias tended to be more pronounced in females. Subjects' current mood influenced their choice of facial affect but not their perceptual bias. In a further experiment, subjects were tested during induced elation and once more during induced depression. Again, though these moods increased the number of happy and sad choices respectively, the magnitude of the left hemifacial bias remained unchanged. The results are best explained by stable properties of the right hemisphere rather than arousal mechanisms. The implications of these findings are discussed in the light of the proposed hemispheric asymmetries in emotional perception and the possible lateralized effects of depressed mood on cognition.