Facial EMG in an anger-provoking situation: individual differences in directing anger outwards or inwards

This study was designed to examine whether facial EMG reactions occurred while subjects experienced anger. All subjects (n = 60) were required to perform an intelligence test. Randomly chosen subjects (n = 40) received negative feedback irrespective of their actual test achievement. The remaining twenty subjects served as control group and received neutral feedback. While all subjects received their feedback, facial EMG was recorded over the mm. frontalis lateralis, corrugator supercilii, orbicularis oculi, and zygomaticus major. In addition, anger and fear self-reports were measured. Those subjects receiving negative feedback were post-hoc divided into two groups. One group comprised subjects verbally expressing their anger toward the experimenter (anger-out group, n = 19) while the other anger group comprised subjects who were angry with themselves (anger-in group, n = 18). Facial EMG reactions over the m. frontalis and m. corrugator were only evident for the anger-out group while they received negative feedback. In addition, intensity of anger self-reports were unrelated to facial EMG reactions. It is hypothesized that the anger-out group implicitly communicated with the experimenter by generating facial anger displays including mm. frontalis and corrugator EMG activity. Thus, these results were taken as evidence that facial displays are communicative tools used to communicate with an interactant although he/she is not physically present (implicit audience).