Is repulsive serial bias in visual perception driven by adaptation mechanisms?

Reported perception can exhibit a repulsive bias away from a task-irrelevant prior stimulus. Previous research has suggested that this repulsive serial bias is driven by low-level adaptation, such that the prior stimulus repels the representation of the new stimulus during encoding. To test this account, the present study compared the repulsive serial bias with another perceptual bias that is known to be driven by an adaptation mechanism (e.g., the tilt aftereffect). We measured the repulsive serial bias using a common location delayed estimation task and the adaptation-driven bias using a location estimation task with an inducer stimulus. We found that, although both repulsive serial bias and adaptation-driven bias were evident, the two biases were not correlated. In addition, only the repulsive serial bias was associated with a response time effect, where responses were slower when the bias was stronger. Moreover, mouse-tracking data for the repulsive serial bias exhibited a pattern that started with a stronger repulsion and ended with smaller repulsion, which cannot be explained by an adaptation mechanism alone. Taken together, our findings suggest that repulsive serial bias in continuous estimation tasks involves post-perceptual decisional processes that are not present in the adaptation-driven bias.