The role of the motor system in conceptual processing: effects of object affordances beyond response interference.

Numerous behavioral and neuro-imaging studies have demonstrated that the motor system is activated when people are presented with manipulable objects. However it remains a matter of debate whether these results should be interpreted as evidence that certain conceptual processes employ motor programs. In order to address this issue, we conducted two experiments which required participants to assess the functions of tool-like objects and respond verbally. The results demonstrate that action affordances may constrain performance in tasks which are not based on the stimulus-response compatibility paradigm. We argue that this finding supports the causal role of the motor system in conceptual processing and that it cannot be explained by spreading of activation and response interference.