Facial asymmetries in the spontaneous response to positive and negative emotional arousal.

Facial asymmetries during emotional arousal were studied under conditions designed to produce spontaneous responses. Subjects who performed a difficult verbal task reported unpleasant emotions, tested high on state anxiety and showed greater changes in left than right-sided composite photographs compared to the relaxed state. Subjects who performed an easy version of the same task reported positive emotions, tested significantly lower on state anxiety and showed greater changes in right sided composites. The pattern of results is consistent with the lateralization of function for positive and negative emotions and not for cognitive task variables, however, a cognitive basis for these results cannot be categorically excluded. The role of arousal in the appearance of facial asymmetries is discussed.