Emotional Face Processing Of Brain Function Lateralization And Interaction Between The Two Hemispheres: Effects Of Titer And Arousal

Objective:The aim of this paper is exploring the influence of arousal and valence on the emotional faces processing hemispheric laterality and the subliminal faces processing of the contralateral hemisphere how to affect this effect.Methods:Using the tachistoscopic visual half-field technique presenting happy or fear emotional expressions by unilateral and bilateral ways. In the unilateral presenting condition we only present a supraliminal face at one side as target stimulus. In the bilateral presenting condition we present a supraliminal face at one side and present a subliminal face at the other side. This study use a 2(valence: happy?fear)×2(arousal:high?low)×2(visual field:left?right)×2(stimulus present condition:unilateral?bilateral)four factors within-subject design. And in the bilateral present conditions, the valence and arousal all include 2(consistency:consistent? inconsistent). The task of subjects is to judge the supraliminal faces'valence.Results:(1) When the target expression was presented in the left visual field, the reaction in unilateral and bilateral conditions are faster than in the right side and processing unilateral faces were faster than bilateral ones; but, when the target expression was presented in the right visual field, if the faces were high-arousal level, the reaction time for happy were faster than for fear; if the faces were low-arousal level, the reaction time for fear were faster than for happy; When the target expression was high-arousal level, processing unilateral faces were faster than bilateral ones.(2)In the bilateral valence consistent condition, when the happy faces were presented in the left visual field, the reaction time was significant faster than in the right visual field, but overall in the inconsistent condition.(3) In the bilateral arousal consistent condition, When the target expression was high-arousal happy, the reaction time in the inconsistent condition was significantly faster than the consistent condition; when the target expression was presented in the right visual field, the reaction time for the low-arousal fear was significantly faster than the low-arousal happy.Conclusions:(1)The right hemisphere superiority for all emotional expressions, and this advantage is very stable. Although the left hemisphere processing subliminal emotional faces may disturb the right hemisphere processing emotional faces, the superiority for right hemisphere emotional processing still exsit.(2) The emotion processing not only influenced by the valence, the arousal also can influence the processing of emotional valence. (3) The approach and withdrawal motivational tendencies of valence and arousal influence the two brain hemispheric processing the emotional expressions. (4) In the high-arousal level, the unconscious fear can facilitate the processing of the conscious emotional expressions.