Chimp Facial Action Coding: An Important Forward Brachiation in Method

Abstract

(1872) The Expression of the Emotions in Man and Animals. This work not only helped establish the conceptual basis of nonverbal behavior and communication but also sketched out the comparative method. In turn, comparing species on structure and function has played a key role in the development of the fields of physiology, neuroanatomy, ethology, and others, especially including nonverbal communication. One of the key benefits of cross-species comparisons is of course in providing insight into the functional value of particular communicative behavior (Marler & Vandenbergh, 1979). Animals living dense forests or dark waters or who are nocturnal are more likely to find their mates and alert their conspecifics with calls and other auditory cues than they are to rely on visual communication. There is thus also a significant selected increase in auditory acuity. Dogs and wolves, highly territorial and with their noses near the ground, use urine markers. Homo sapiens, with generally excellent visual acuity, detect their mates and potential aggressors mostly with visual cues rather than through sniffing. Such gross comparisons, tremendously important over the past century (Ekman, 1973), have become increasingly refined as particular nonverbal movements are better studied. Progress and refinements in the study of nonverbal behavior have often depended on methodological advances. Use of film and video, slow motion, the point-light technique, sound recordings and spectrograms, as well as statistical advances in coding and judgments have led to huge swings forward in understanding. Notably, in the area of facial behavior, the Facial Action Coding System (FACS), developed by Paul Ekman and colleagues, provided a standardized, neuro-anatomically based technique for the reliable coding and analysis of facial movement and expression (Ekman, Friesen, & Hager, 2002; Ekman & Rosenberg, 2005). The paper by Vick, Waller, Parr, Smith Pasqualini, and Bard (2007) in this issue describes a modification of the FACS for describing chimpanzee facial movement.