Automatic imitation or 'imitative compatibility' is thought to be mediated by the mirror neuron system and to be a laboratory model of the motor mimicry that occurs spontaneously in naturalistic social interaction. Imitative compatibility and spatial compatibility effects are known to depend on different stimulus dimensions - body movement topography and relative spatial position. However, it is not yet clear whether these two types of stimulus-response compatibility effect are mediated by the same or different cognitive processes. We present an interactive activation model of imitative and spatial compatibility, based on a dual-route architecture, which substantiates the view they are mediated by processes of the same kind. The model, which is in many ways a standard application of the interactive activation approach, simulates all key results of a recent study by Catmur and Heyes (2011). Specifically, it captures the difference in the relative size of imitative and spatial compatibility effects; the lack of interaction when the imperative and irrelevant stimuli are presented simultaneously; the relative speed of responses in a quintile analysis when the imperative and irrelevant stimuli are presented simultaneously; and the different time courses of the compatibility effects when the imperative and irrelevant stimuli are presented asynchronously. Automatic imitation occurs when a task-irrelevant action stimulus facilitates the performance of a topographically matching response and/or interferes with performance of a topographically non-matching response (see Heyes, 2011, for a review). For example, in one of the first experimental demonstrations of automatic imitation (Stuermer, Aschersleben & Prinz, 2000), participants were asked to open and close their hands in response to a color cue (red or blue; the 'task-relevant' stimulus dimension) superimposed on a video of an opening or closing hand (the 'task-irrelevant' stimulus dimension). Correct responses were initiated faster when the irrelevant action stimulus was response-compatible (i.e. when an open hand response was made in the presence of an opening hand stimulus, and a close hand response
['Richard P. Cooper', 'Caroline Catmur', 'Cecilia Heyes']
Are automatic imitation and spatial compatibility mediated by different processes