The Psychophysics of Dynamic Gaze-Following Saccades During Search

The ability to quickly and precisely follow another person’s gaze reflects important evolutionary mechanisms that underlie social interactions, such as attention modulation and prediction of future actions. Recent studies have shown that observers utilize gazer head direction and peripheral information to execute anticipatory saccades toward gaze goals. However, how anticipatory eye movements are influenced by the presence of multiple potential gaze goals, the absence of the gazer and the relative distance between the gazer and gaze goal has not been studied. In this work, we presented dynamic stimuli of gazers moving their heads to look at other individuals (gaze goals) in the scene and instructed observers to search for a target individual. We measured the accuracy of the first saccade end-point in locating the gaze goal. Firstly, we find that the absence of a gazer induces a significantly larger saccade error in estimating the goal location but only when the initial fixation location and the gaze goal location are far from each other (at least 9.07 dva apart). The first saccade’s amplitude and onset latency are significantly higher in gazer-present than in gazer-absent trials. Secondly, when multiple potential gaze goals were present in the visual periphery, the first saccade was directed to the individual closer to the initial fixation increasing the saccade accuracy in fixating closer gaze goals. Finally, we find that multiple potential gaze goals present in the visual periphery shorten saccade latencies and increase the frequency of anticipatory saccades executed prior to the completion of the gazer’s head movement. Taken together, our findings extend the understanding of eye movement control during gaze-following to complex and naturalistic scenarios.