Performing hand actions assists the visual discrimination of similar hand postures

Recent theoretical work has suggested that internal predictive signals are used for motor control and coordination. The predictive signal - proposed to be the output of a forward model - would be a sensory representation of action. Hence, these sensory representations could potentially influence other sensory processes. We report here how performance of hand actions assisted the visual discrimination of target hand postures presented at random times within an on-going series of hand images. Reaction times to discriminate the targets were significantly shorter when the displayed images were both sequential and congruent with the action being performed. Hence, the planning or execution of action appears to allow better prediction of a displayed series of congruent images. In further control experiments, we show that the motor-visual priming effect is unlikely to be due to differential attentional demands and it is specific to a first person perspective display; it is short lasting, being lost if a 500 ms delay is introduced between successive stimulus presentations. The data are interpreted as evidence supporting the hypothesis that forward models in the motor system provide action-specific sensory predictions that are available to cognitive processes.