Superiority of the left hemisphere in the recognition of emotional faces.

Thirty-two right-handed university students (16 males and 16 females) participated in a choice reaction time study assessing the perception of hemispheric differences in positive (happiness, surprise) and negative (anger, disgust) facial affect. Subjects were exposed to slides of facial expressions in either the left or right visual field, and latency of affect identification was measured by having each subject move a lever forward or backward in a specified direction to indicate the emotion perceived. An analysis of variance with repeated measures over hand used, visual field, and affect across sex of subject revealed significant main effects for visual field, affect and sex of subject. In contrast to prior studies, the emotional faces were perceived faster in the right visual field than in the left visual field. This finding is explained in terms of the more demanding analytical task chosen in contrast to previous research which typically employed a holistic matching or recognition task. The faster perception of positive affect may be attributed to the increased salience of the facial cues present in those faces displaying happiness or surprise. Finally, the faster response of males supports existing data suggesting greater cerebral lateralization in the male brain.