Abstract
Imitation involves matching the visual representation of another’s action onto the observer’s own motor program for that action. However, there has been some debate regarding the extent to which imitation is “automatic” – i.e., occurs without attention. Participants performed a perceptual load task in which images of finger movements were presented as distractors. Responses to target letter stimuli were performed via finger movements which could be imitatively compatible (requiring the same finger movement), or incompatible, with the distractor movements: in this common stimulus-response compatibility manipulation, the stimulus set comprises images of the response movements, producing an imitative compatibility effect. Attention to the distractor movements was manipulated by altering perceptual load through increasing the number of non-target letter stimuli. If imitation requires attention, then at high perceptual load, imitative compatibility should not affect response times. In contrast, imitative compatibility influenced response times at high perceptual load, demonstrating that distractor movements were processed. However, the compatibility effect was reversed, suggesting that longer response times at high perceptual load tap into an inhibitory stage of distractor movement processing. A follow-up experiment manipulating temporal delay between targets and distractor movements supported this explanation. Further experiments confirmed that non-movement distractor stimuli in the same configuration produced standard perceptual load effects, and that results were not solely due to effector compatibility. These data suggest that imitation can occur without attention.