Action word understanding and overt motor behavior.

Is the motor system involved in language processing? In order to clarify this issue, we carried out three behavioral experiments, using go-no-go and choice paradigms. In all the experiments, we used a semantic decision task with an early delivery of the go signal (during processing language material). Italian verbs expressing hand actions, foot actions or an abstract content served as stimuli. Participants executed intransitive (Experiment 1) or transitive (Experiment 2) actions with their right hand in response to the acoustic presentation of action-related verbs and refrained from responding to abstract verbs. The kinematics of the actions was slowed down by hand action-related verbs when compared with foot action-related verbs. In Experiment 3, hand-related and foot-related verbs were presented. Participants responded to hand-related and foot-related verbs with their hand and their foot (compatible condition) and in another block of trials they responded to hand-related and foot-related verbs with their foot and their hand (incompatible condition), respectively. In the compatible condition, the beginning of the action was faster, whereas the kinematics of the action was slower. The present findings suggest complete activation of verb-related motor programs during language processing. The data are discussed in support of the hypothesis that this complete activation is necessary requisite to understand the exact meaning of action words because goal and consequence of the actions are represented.