Side Bias in Facial Expression

Abstract

Although the bias is more clearly evident in paired organs (such as hand, foot, eye, and ear), it is also distinguishable in similarly arranged areas of non-paired organs like the face. Ordinarily, people are less aware of the differential involvement of the two sides of the face. This behaviour (referred generally as facedness) is conceived in terms of the relative intensity of expression and the extent of movement on the left and right sides of the face (Borod & Koff, 1990). Functionally, facedness is different from other indices of side bias (handedness, footedness, eyedness and earedness). Whereas the latter indices provide important cues to understand subjective preference or proficiency in unimanual activities of sensory or motor origin, the former index provides interpersonal cues important to understand social interaction. By definition, facial asymmetry refers to the fact that the left and right sides of human face during rest or movement are not identical. The