Ratings of emotion in faces are influenced by the visual field to which stimuli are presented

This experiment was designed to assess the differential impact of initially presenting affective information to the left versus right hemisphere on both the perception of and response to the input. Nineteen right-handed subjects were presented with faces expressing happiness and sadness. Each face was presented twice to each visual field for an 8-sec duration. The electro-oculogram (EOG) was monitored and fed back to subjects to train them to keep their eyes focused on the central fixation point as well as to eliminate trials confounded by eye movement artifact. Following each slide presentation, subjects rated the intensity of the emotional expression depicted in the face and their emotional reaction to the face on a series of 7-point rating scales. Subjects reported perceiving more happiness in response to stimuli initially presented to the left hemisphere (right visual field) compared to presentations of the identical faces to the right hemisphere (left visual field). This effect was predominantly a function of ratings on sad faces. A similar, albeit less robust, effect was found on self-ratings of happiness (the degree to which the face elicited the emotion in the viewer). These data challenge the view that the right hemisphere is uniquely involved in all emotional behavior. The implications of these findings for theories concerning the lateralization of emotional behavior are discussed.