Previous research has shown that, after ruling out the center bias, which accounts for perceptual errors, the heading perception from an optic flow can either be attracted to the straight-ahead direction showing a center bias or repelled away from the previously seen heading (i.e., repulsive serial dependence). The question of whether serial reliance happens at the perceptual or post-perceptual phases (e.g., working memory) has been disputed in recent studies. 

The serial dependency in heading perception was reexamined in the current investigation, and it was determined if it happened at the perceptual or post-perceptual phases. To determine whether observers best merged the straight-ahead direction with the prior and present headings to perceive headings, an ideal observer model was also created. 

The findings demonstrated that when the center bias was eliminated, the perceived heading was skewed in favor of the heading that came before it, indicating an alluring serial reliance on heading perception. Both the perceptual and post-perceptual phases of this attractive serial dependency took place. Importantly, an ideal observer model accurately predicted the perceived heading, indicating that observers could best estimate their heading by fusing their perceptual observations of the present heading with their past knowledge of the straight-ahead direction and previous headings.