What can asymmetry and laterality in EMG tell us about the face and brain?

This paper will review the use of the electromyographic (EMG) technique for studying asymmetry and laterality in facial behavior. My discussion will include several issues: (1) a review of the neurology of facial expression with respect to asymmetry/laterality; (2) a compendium of models of cerebral hemispheric participation in emotion and in facial motor control that imply asymmetry-laterality in facial behavior; (3) a summary of facial asymmetry-laterality findings to date; and (4) uses and abuses of EMG techniques in inferring asymmetry-laterality in facial behavior. I conclude with (5) recommendations for future facial asymmetry-laterality research in general.