Electromyographic specificity during simple physical and attitudinal tasks: location and topographical features of...

Integrated electromyographic (IEMG) activity was recorded using surface mini-electrodes placed over the corrugator supercilii, zygomatic major, levator labii superioris, masseter, obicularis oris and superficial forearm flexors muscle regions while subjects imagined or performed simple physical or attitudinal tasks. In the physical tasks, subjects either imagined they lifted or actually lifted a 16 gram or 35 gram weight. In the attitudinal tasks, subjects adopted either an agreeable or disagreeable attitudinal set as they silently read neutral text or imagined reading an editorial. Each task was performed for 12 sec on five separate occasions, and tasks were ordered randomly across the experimental trials. Following each trial, subjects provided self-reports regarding the extent to which the task was stressful, arousing and vivid. Multivariate analyses of the topographical features of each IEMG response were performed to determine the effects of the tasks on changes in IEMG response waveforms, and univariate analyses were conducted to assess the features of the waveform that were altered by tasks. Results support the efficacy of electromyographic studies of covert affective processing given that subjects are generally quiescent, unobtrusively observed, unaware that somatic activity is being recorded and involved in the task. The implications of these data for the somatic representation of affect are discussed.