The GROOP effect: groups mimic group actions.

Research on perception-action links has focused on an interpersonal level, demonstrating effects of observing individual actions on performance. The present study investigated perception-action matching at an inter-group level. Pairs of participants responded to hand movements that were performed by two individuals who used one hand each or they responded to hand movements performed by an individual who used both hands. Apart from the difference in the number of observed agents, the observed hand movements were identical. If co-actors form action plans that specify the actions to be performed jointly, then participants should have a stronger tendency to mimic group actions than individual actions. Confirming this prediction, the results showed larger mimicry effects when groups responded to group actions than when groups responded to otherwise identical individual actions. This suggests that representations of joint tasks modulate automatic perception-action links and facilitate mimicry at an inter-group level.