Grasping the other's attention: the role of animacy in action cueing of joint attention.

The current experiment investigates the role of animacy on grasp-cueing effects as investigated in joint attention research. In a simple detection task participants responded to the colour change of one of two objects of identical size. Before the target onset, we presented a cueing stimulus consisting of either two human hands with a small and a large grip aperture (animate condition) or two comparable U-shaped figures with small and large aperture (inanimate condition). Depending on the size of the objects and the arrangement of the apertures (i.e., large aperture to the left and small aperture to the right or vice versa), either the left or right object matched the grasping hand or U-shapes. Our data show that biological grasping actions modulate the observer's attention whereas the perception of inanimate stimuli does not result in a comparable cueing effect. This strong impact of animacy on attentional priming suggests that grasp cueing represents a marker of a joint attention mechanism that involves spontaneous simulation of the observed motor behaviour.