Abstract
Previous research has shown that individuals unintentionally mimic the actions of an interaction partner. This phenomenon has been explained in terms of ideomotor theory, which suggests that upon perceiving an action, a tendency to perform this action is activated. In line with this claim, neurophysiological and brain imaging research has shown that perceiving somebody performing an action activates the representational structures involved in one's own planning and execution of this action. What happens when one observes the actions of a person who has difficulties achieving her action goal, as for example, when one observes a soccer player trying to score a goal from a difficult position? We conducted a series of studies to investigate whether in such a situation, the unintentional movements of an observer reflect the observed movements or whether the observer performs compensatory movements that are in accordance with the actor's intention rather than her actual movements. Participants viewed movies of a person balancing on a foam roller. The movies ended before the actor had reached the end of the roller, and the participants' task was to indicate how likely they thought it was that the actor would reach the end of the foam roller. Using a motion capture system, we measured the participants' unintentional movements while observing the movies. We varied the perspective from which the actor was filmed (front and back) and the task instructions. Our results show that participants mimicked the observed actions a large amount of the time. They also made corrective movements with their bodies (e.g., leaning to the right when the actor was almost falling off to the left). These “intentional ideomotor movements” were modulated by the perspective and by the task instruction. Our findings provide evidence that unintentional movements occur not only as the result of a direct perception-action link, but are also influenced by shared representations of intentions.