UNOBSERVABLE FACIAL ACTIONS AND EMOTION

Surface electromyographic recordings in humans were first made less than 70 years ago, and the electromyographic study of covert facial actions during affect and emotion has less than a 20-year history. Despite the relative youth of facial electromyography, its use in combination with autonomic measures and comprehensive overt facial action coding systems has provided a sensitive and effective armamentarium for investigating emotion and affect-laden information processing. Research over the past decade has demonstrated that facial electromyographic activity varies as a function of the intensity, valence, and sociality of emotional stimuli and shows that facial electromyographic activity is slightly different in deliberately manipulated and spontaneous expressions of emotion. The multiply determined nature of facial actions and expressions, however, has limited the inferences that can be made about the psychological significance of facial electromyographic responses. These limitations have begun to recede in recent years as a result of advances in the psychometric properties of facial electromyographic measurements, the quantification of electromyographic waveforms and patterns, the conjoint measurement of facial electromyographic and electrocortical activity, the conceptualization of psychophysiological relations, and the formalization of psychophysiological inference.