Attentional Orientation Induced by Viewing the Back of Head: Spatial cueing, inhibition of return, and the Simon effect

Orienting your attention toward where another is looking at can provide you with important information about the environment. Social cues such as gaze or head orientation induce observers’ joint attention. But previous studies have used only front-view social cues, and little is known about whether joint attention is also triggered without face-to-face interaction. We test this by using the Posner paradigm. The cue, supraliminal/subliminal back of head, was followed by the target, which appeared on the faced-toward (valid) or the faced-away (invalid) side. Regardless of the cue visibility, we found a facilitatory cueing effect (faster RTs for valid-cue trials), inhibition of return (the reversed pattern), and the spatial Simon effect (faster RTs with congruent cued-side and response-hand). The current study expands the realm of social cues: Being a highly socialized species, even without face-to-face interaction, observers’ joint attention and action preparation can be triggered by viewing the back of others’ heads.