Substantial evidence links perception of others' bodies and mental representation of the observer's own body; however, the overwhelming majority of this evidence is unidirectional, showing influence from perception to action. It has been proposed that the influence also runs from action to perception, but to date the evidence is scant. Here we report that ordinary motor actions performed by the subject affect concurrent psychophysical judgments of human-body stimuli. Subjects remained unaware of the connection between the action and the main task. The results show that perception can change as a result of the observer's ongoing actions. (Contains 2 figures.)