| Summary: | In four experiments, we investigated the role of motion in gaze perception. In Experiment 1, we developed and evaluated a comprehensive stimulus set of small eye movements at three different gaze angles (1, 2 and 3 degrees visual angle) and demonstrated that observers were able to detect and discriminate these small eye movements with a high degree of fidelity. In Experiments 2 and 3, we evaluated discrimination accuracy and confidence to dynamic and static gaze stimuli. We demonstrated that the reason for the high sensitivity to gaze in Experiment 1 was due predominantly to the presence of the motion signal in the video stimuli. Accuracy to dynamic gaze was significantly higher than accuracy to static gaze. In addition, the size of the gaze angle (i.e. signal strength) increased accuracy for static gaze despite the fact that confidence for these stimuli was consistently moderate. This latter result suggests that the dynamic gaze signal is qualitatively different from the static gaze signal. In Experiment, 4 we tested this possibility by reversing the contrast polarity of half of the gaze stimuli. This manipulation has been shown to disrupt normal gaze processing. We reasoned that if the perception of static and dynamic gaze are fundamentally different, contrast reversal will differentially effect these two types of gaze stimuli. Indeed, contrast reversal impaired the perception of static, but not dynamic gaze, confirming that the perception of dynamic and static gaze are qualitatively different.
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