Atypical Cross-Modal Contextual Calibration of Sensory Evidence in Autism

Sensory perception is often described as atypically calibrated in autism, yet the underlying mechanisms remain unclear. We tested whether temporal magnitude perception in autism relies on amodal or modality-specific processes using an adapted range-of-standards paradigm. Autistic and nonautistic adults judged auditory and visual durations in blocks that varied in contextual range and whether the contextual standards were presented in the same modality as the central standard. Non-autistic participants showed clear auditory specialization and larger context effects within than between modalities, consistent with modality-specific coding. Autistic adults, however, showed reduced auditory specialization and similar effects across modalities, suggesting broader and less differentiated temporal calibration. To determine whether these patterns could be explained by synesthetic cross-modal tendencies, we tested an additional group of adults with synesthesia. Synesthetes showed calibration patterns that resembled the non-autistic group, indicating that the unique cross-modal context effects observed in autism cannot be attributed to synesthetic mechanisms.