Attractive effects of previous form information on heading estimation from optic flow occur at perceptual stage.

When moving in the environment, optic flow and form (e.g., motion streaks) information generally appear simultaneously. Previous studies have shown that observers can estimate their heading by integrating the simultaneously presented form and optic flow information. Recent work also found that the previously seen optic flow affected the current heading estimation. The current study conducted two experiments to explore whether and how the heading estimation from optic flow was affected by the previously seen form information. We found that the current heading estimates from optic flow were biased toward the location of the focus of expansion of the previously seen form stimulus, showing an attractive effect of the previous form. Additionally, the results revealed that the attractive effect of the previous form occurred at the perceptual stage rather than postperceptual stages (e.g., working memory). Our findings suggest that our visual system can integrate dynamic optic flow and static form information across the temporal domain to estimate our heading direction.