The impact of response type on affordance and spatial compatibility effects in human and object interactions.

Everyday social interactions or goal-directed actions towards objects activate action plans appropriate to their affordances. The spatial compatibility of a stimulus and a response might interfere with the activation of these action plans. In the present study, we examined how framing of interactions affects the interplay between affordance and spatial compatibility effects towards humans and objects in two separate experiments. In a motor priming task designed to simultaneously assess these two effects, participants were presented with interactive hand gestures and objects with a single handle. Participants responded either with their left or right hand according to the colour mask of the stimulus, regardless of the spatial position or the affordance-related orientation of the stimulus. In Experiment 1, when responses were given by keypresses, we found independent affordance and spatial compatibility effects towards objects. Surprisingly, interactive hand gestures induced a reversed affordance effect, that is, imitative action tendencies. Changing the responses from keypresses to the performance of grasping actions in Experiment 2 drastically altered these findings, resulting in the enhancement of affordance and the elimination of spatial compatibility effects for both human and object interactions. These findings highlight the importance of contextual influences on the emergence of automatic action tendencies.