ABSTRACT
This chapter presents what is known about facial asymmetries during the expression of emotion, possible neuroanatomic substrates for these asymmetries, and methodological issues in the study of facial asymmetry. It reviews what is known about the innervation of the face. It reviews the studies that examine the phenomenon of facial asymmetry during emotional expression. The chapter describes what is currently known about the way in which facial expression is innervated. It presents an understandable, but abridged, description of the innervation of facial expression, rather than an exhaustive review. Having described some of the issues that must be considered in the study of facial asymmetry, it turns to a review of the literature on asymmetries during emotional expression. Overall, the data, when analyzed in terms of poser asymmetries, suggest that the left hemiface is involved more frequently than the right hemiface in the deliberate production of negative expressions.
