Digitizing the moving face during dynamic displays of emotion

Author(s): Bowers, D., Bauer, R. M., Heilman, K. M., Leonard, C. M.

Journal/Book: Neuropsychologia. 2000; 38: the Boulevard Langford Lane, Kidlington, Oxford Ox5 1GB, England. Pergamon-Elsevier Science Ltd. 1028-1039.

Abstract: Humans typically decode facial signals during dynamic interactions in which the face moves. In this study, we digitized real time video signals in order to examine movement asymmetries across the face during emotional and nonemotional expressions. Forty dextral males were tested. For each expression. A 400 ms video segment was analyzed for changes in signal value (pixel intensity) over consecutive frames. Thr upper and lower face regions were examined separately due to differences in the cortical enervation of facial muscles in the upper (bilateral) vs lower face (contralateral). Results revealed distinctly different movement asymmetries over the lower and upper hemiface. In the upper face, more movement occurred over the right side for most facial expressions, regardless of emotionality. The latter finding questions the assumption that muscles of the upper face are symmetrical and/or bilaterally enervated in a symmetrical manner. In the lower face, negative expressions linked to fight-flight emotions (i.e. Fear. Anger) were associated with greater left sided movement, whereas happiness tended to be associated with more right sided movement. No consistent pattern of movement asymmetry occurred for nonemotional expressions. Although the valence-related movement asymmetries in the lower face are consistent with neuropsychologial models of emotional expressivity, it remains unclear whether they reflect activation or inhibitory hemispheric mechanisms. Taken together, these data suggest that multiple factors may contribute to expressive movement asymmetries of the face.

Note: Article Bowers D, Univ Florida, Coll Hlth Profess, Inst Brain, Dept Clin & Hlth Psychol, POB 100165, Gainesville,FL 32601 USA

Keyword(s): hemiface; right hemisphere; laterality; negative emotions; BRAIN-DAMAGED PATIENTS; SPONTANEOUS FACIAL EXPRESSION; ASYMMETRY; LATERALIZATION; RESPONSES; IDENTITY; NEURONS; MONKEY

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