Facial expression and imagery in depression: an electromyographic study

When subjects are instructed to self-generate happy, sad, and angry imagery, discrete patterns of facial muscle activity can be detected using electromyographic (EMG) procedures. Prior research from this laboratory suggests that depressed subjects show attenuated facial EMG patterns during imagery conditions, particularly during happy imagery. In the present experiment, 12 depressed subjects and 12 matched normals were requested to generate happy and sad imagery, first with the instruction to simply "think" about the imagery, and then to self-regulate the affective state by "reexperiencing the feelings" associated with the imagery. Continuous recordings of facial EMG were obtained from the corrugator, zygomatic major, depressor anguli oris, and mentalis muscle regions. It was hypothesized that (a) these muscle sites would reliably differentiate between happy and sad imagery. (b) the instruction to self-generate the affective feeling state would produce greater EMG differences than the "think" instructions, and (c) the "think" instructions would be a more sensitive indicator of the difference between depressed and nondepressed subjects, especially for happy imagery. All three hypotheses were confirmed. The application of facial electromyography to the assessment of normal and clinical mood states, and the role of facial muscle patterning in the subjective experience of emotion, are discussed.