The Body Action Coding System I: muscle activations during the perception and expression of emotion.

Body postures provide clear signals about emotional expressions, but so far it is not clear what muscle patterns are associated with specific emotions. This study lays the groundwork for a Body Action Coding System by investigating what combinations of muscles are used for emotional bodily expressions and assessing whether these muscles also automatically respond to the perception of emotional behavior. Surface electromyography of muscles in the arms (biceps and triceps) and shoulders (upper trapezius and deltoids) were measured during both active expression and passive viewing of fearful and angry bodily expressions. The biceps, deltoids, and triceps are recruited strongly for the expression of anger and fear expression predominantly depends on the biceps and the deltoids. During passive viewing, all muscles automatically activate during the passive viewing of anger. During fear perception, a clear activation can be seen in the trapezius, deltoid, and triceps muscles, whereas the biceps shows inhibition. In conclusion, this study provides more insight into the perception and expression of emotions in the body.