How does imitation occur? How can the motor plans necessary for imitating an action derive from the observation of that action? Imitation may be based on a mechanism directly matching the observed action onto an internal motor representation of that action (“direct matching hypothesis”). To test this hypothesis, normal human participants were asked to observe and imitate a finger movement and to perform the same movement after spatial or symbolic cues. Brain activity was measured with functional magnetic resonance imaging. If the direct matching hypothesis is correct, there should be areas that become active during finger movement, regardless of how it is evoked, and their activation should increase when the same movement is elicited by the observation of an identical movement made by another individual. Two areas with these properties were found in the left inferior frontal cortex (opercular region) and the rostral-most region of the right superior parietal lobule.

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Here we show that if an adult demonstrates a new way to execute a task to a group of infants aged 14 months, the children will use this action to achieve the same goal only if they consider it to be the most rational alternative. Our results indicate that imitation of goal-directed action by preverbal infants is a selective, interpretative process, rather than a simple re-enactment of the means used by a demonstrator, as was previously thought.

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We used measures of the human event-related brain potential (ERP) to investigate the neural mechanisms underlying error processing during action observation. Participants took part in two conditions, a task execution condition and a task observation condition. We found that activity in both the medial frontal cortex and the motor cortices, as measured via the error-related negativity and the lateralized readiness potential, respectively, was modulated by the correctness of observed behavior. These data suggest that similar neural mechanisms are involved in monitoring one's own actions and the actions of others.

The view that the motor program activated during imitation is organized by goals was investigated by asking pre-school children to imitate a set of hand gestures of varying complexity that were made by an experimenter sitting in front of them. In Experiments 1 and 3, children reached for the correct object (one of their own ears or one of two dots on a table) but preferred to use the ipsilateral hand. This ipsilateral preference was not observed when hand movements were made to only one ear (Experiment 2), or when movements were directed at space rather than physical objects (Experiment 3). The results are consistent with the notion that imitation is guided by goals and provide insights about how these goals are organized.

We review a series of behavioural experiments on imitation in children and adults that test the predictions of a new theory of imitation. Most of the recent theories of imitation assume a direct visual-to-motor mapping between perceived and imitated movements. Based on our findings of systematic errors in imitation, the new theory of goal-directed imitation (GOADI) instead assumes that imitation is guided by cognitively specified goals. According to GOADI, the imitator does not imitate the observed movement as a whole, but rather decomposes it into its separate aspects. These aspects are hierarchically ordered, and the highest aspect becomes the imitator's main goal. Other aspects become sub-goals. In accordance with the ideomotor principle, the main goal activates the motor programme that is most strongly associated with the achievement of that goal. When executed, this motor programme sometimes matches, and sometimes does not, the model's movement. However, the main goal extracted from the model movement is almost always imitated correctly.