Serial dependence in orientation is weak at the perceptual stage but intact at the response stage in autistic adults.

Recent studies have suggested that autistic perception can be attributed to atypical Bayesian inference; however, it remains unclear whether the atypical Bayesian inference originates in the perceptual or post-perceptual stage or both. This study examined serial dependence in orientation at the perceptual and response stages in autistic and neurotypical adult groups. Participants comprised 17 autistic and 23 neurotypical adults. They reproduced the orientation of a Gabor stimulus in every odd trial or its mirror in every even trial. In the similar-stimulus session, a right-tilted Gabor stimulus was always presented; hence, serial dependence at the perceptual stage was presumed to occur because the perceived orientation was similar throughout the session. In the similar-response session, right- and left-tilted Gabor patches were alternately presented; thus serial dependence was presumed to occur because the response orientations were similar. Significant serial dependence was observed only in neurotypical adults for the similar-stimulus session, whereas it was observed in both groups for the similar-response session. Moreover, no significant correlation was observed between serial dependence and sensory profile. These findings suggest that autistic individuals possess atypical Bayesian inference at the perceptual stage and that sensory experiences in their daily lives are not attributable only to atypical Bayesian inference.