Joint attention: inferring what others perceive (and don't perceive).

Research has shown that observers automatically align their attention with another's gaze direction. The present study investigates whether inferring another's attended location affects the observer's attention in the same way as observing their gaze direction. In two experiments, we used a laterally oriented virtual human head to prime one of two laterally presented targets. Experiment 1 showed that, in contrast to the agent with closed eyes, observing the agent with open eyes facilitated the observer's alignment of attention with the primed target location. Experiment 2, where either sunglasses or occluders concealed the agent's eye direction, showed that only the agent with the sunglasses facilitated the observer's alignment of attention with the target location. Taken together, the data demonstrate that head orientation alone is not sufficient to trigger a shift in the observer's attention, that gaze direction is crucial to this process, and that inferring the region to which another person is attending does facilitate the alignment of attention.