Publications of Pomiechowska, B.

Rationality in joint action: Maximizing co-efficiency in coordination

When people perform simple actions, they often behave efficiently, minimizing the costs of movement for the expected benefit. The present study addressed the question whether this efficiency scales up to dyads working together to achieve a shared goal: do people act efficiently as a group, or do they minimize their own or their partner’s individual costs even if this increases the overall cost for the group? We devised a novel, touchscreen-based, sequential object transfer task to measure how people choose between different paths to coordinate with a partner. Across multiple experiments, we found that participants did not simply minimize their own or their partner’s movement costs but made co-efficient decisions about paths, which ensured that the aggregate costs of movement for the dyad were minimized. These results suggest that people are able and motivated to make co-efficient, collectively rational decisions when acting together.

Motor activation during action perception depends on action interpretation

Since the discovery of motor mirroring, the involvement of the motor system in action interpretation has been widely discussed. While some theories proposed that motor mirroring underlies human action understanding, others suggested that it is a corollary of action interpretation. We put these two accounts to the test by employing superficially similar actions that invite radically different interpretations of the underlying intentions. Using an action-observation task, we assessed motor activation (as indexed by the suppression of the EEG mu rhythm) in response to actions typically interpreted as instrumental (e.g., grasping) or referential (e.g., pointing) towards an object. Only the observation of instrumental actions resulted in enhanced mu suppression. In addition, the exposure to grasping actions failed to elicit mu suppression when they were preceded by speech, suggesting that the presence of communicative signals modulated the interpretation of the observed actions. These results suggest that the involvement of sensorimotor cortices during action processing is conditional on a particular (instrumental) action interpretation, and that action interpretation relies on inferential processes and top-down mechanisms that are implemented outside of the motor system.