Abstract
Ample evidence supports the idea that social signals, such as eye gaze, influence our voluntary eye movements. However, people move their eyes constantly and most of these eye movements are irrelevant in a social context. It is thus to expect that even stronger shifts in overt attention should be induced by eye movements conveying a potentially relevant action.
We tested this hypothesis with a variation of the gaze cueing paradigm. Participants were required to perform a saccadic eye movement toward a target either to the left or to the right. A colored instruction cue signaled the direction of the saccade. Cueing with varying SOAs was induced either by an averted eye gaze and/or by a small hand gesture corresponding to the initial phase of a pointing movement towards one of the targets. These stimuli were provided either in isolation or in combination with each other. In the latter case, the cued direction could be either matched or unmatched. Participants were informed that the stimuli were spatially uninformative cues. As previously reported, gaze and hand cueing were effective at triggering the saccades in the opposite to the intended direction. A stronger gaze cueing effect was, however, observed when the gaze and hand cue were presented simultaneously. Interestingly, the proportion of saccades following the gaze cue increased irrespective of the hand cue direction.
Relevant actions are usually the product of combined eye and hand movements where the eyes select the target of interest. The mere presence of a sudden hand movement might have been interpreted as a sufficient indication of a forthcoming relevant action that consequently enhanced the saliency of the directional cue provided by the gaze. These findings thus suggest a process that prioritizes potentially relevant actions to which the visual system automatically responds.
Research supported by EU grant (FP7-ICT-217077-Eyeshots).