Koga, K., Groner, M. T., Bischof, W. F., and Groner, R. (1998). Motion trajectory illusion and eye movements. Swiss Journal of Psychology,
We describe a visual illusion where a moving target produces an illusory trajectory. Previously it has been suggested that this illusion is related to eye movements, but the exact nature of the relation, as well as relevant stimulus conditions and eye movements were unknown. In two experiments, we varied critical stimulus conditions, recorded eye movements and judgment of trajectories. In experiment 1, a visual cue lead to a reduction of the illusion; however if a saccadic eye movement preceded the targets change of direction within a critical interval, assessed by SacOA (Saccade Onset Asynchrony). In experiment 2, an analogous result was found under conditions of sudden velocity changes. The results are explained by a critical timing between smooth pursuit and different phases of saccadic eye movements.
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