Posing for success: clenching a fist facilitates approach.

A clenched fist is a gesture often seen both within and outside sports that seems to communicate success or to function in self-encouragement or the encouragement of others. This "encouragement gesture" involves the contraction of forearm flexors, similar to the grasping action that is part of acquisitive approach actions. This gesture may be part of a physiological feedback mechanism that functions to increase or sustain levels of approach in challenging situations by signaling the sufficiency of resources (muscle strength). Here we show that for pleasant but not unpleasant words, subjects were faster in categorizing words while contracting their forearm flexors rather than their forearm tensors. This effect dissipated during the first minute of performance, which may reflect habituation of interoceptive feedback. The data further suggest that the effect is larger when experimenter and subject are of opposite sexes. The facilitated responding to pleasant stimuli suggests that contraction of the forearm flexors promotes approach.