The role of spatial attention during action observation: the case of complementary actions

Background: Interactive social contexts often require to perform actions dissimilar to those observed (i.e., complementary actions). To date, the role of attention in this endeavor is still unexplored. Methods: In the present research we aimed to study the role of spatial attention during action observation. The stimuli used were action sequences eliciting (or not) complementary responses in the participant’s hand. Spatial attention was manipulated by means of a red dot cue superimposed on the video clips. First, eye-tracking procedures were used to measure the spontaneous allocation of overt spatial attention during action observation. Second, we recorded motor-evoked potentials (MEPs) to transcranial magnetic stimulation (TMS) to assess the excitability of corticospinal projections to hand muscles while participants were observing the action stimuli. Results: Results showed that the allocation of spatial attention plays no role when the observed action evokes an interactive complementary motor response. Overall, the present research provides one of the first evidence that social motor preparation is impervious to spatial attentional allocation.