Movement observation affects movement execution in a simple response task

The present study was designed to examine the hypothesis that stimulus–response arrangements with high ideomotor compatibility lead to substantial compatibility effects even in simple response tasks. In Experiment 1, participants executed pre-instructed finger movements in response to compatible and incompatible finger movements. A pronounced reaction time advantage was found for compatible as compared to incompatible trials. Experiment 2 revealed a much smaller compatibility effect for less ideomotor-compatible object movements compared to finger movements. Experiment 3 presented normal stimuli (hand upright) and flipped stimuli (hand upside-down). Two components were found to contribute to the compatibility effect, a dynamic spatial compatibility component (related to movement directions) and an ideomotor component (related to movement types). The implications of these results for theories about stimulus–response compatibility (SRC) as well as for theories about imitation are discussed.