Abstract
Introduction: Sensory symptoms are part of the core phenotype of autism, but their underlying mechanisms are unknown. We examined whether altered perception of magnitude in autism arises from modulations in biases and contextual effects known to calibrate perceptual sensitivity in neurotypicals. Specifically, we asked whether calibration of duration perception by context is generalized across modalities or rather mediated by within-modality specific mechanisms. Sensitivity of duration perception for visual and auditory stimuli was tested when context was manipulated within- and between the sensory modalities. Method: Individuals with and without autism preformed a two-interval forced choice task to determine the longer of two temporal signals either visual or auditory. Participants performed the task under three conditions: 1) the central standard was presented in two types of modalities: visual or auditory; 2) the contextual standards formed either a wide or a narrow contextual range around the central standard; 3) the contextual standards were presented in two modalities: visual or auditory independent of the central standard, forming “same-modality” or “between-modality” conditions. Thresholds were determined using two staircase methods: constant stimuli and QUEST. Results: For neurotypicals, thresholds determined in the auditory domain were smaller than in vision, suggesting an auditory specialization. Importantly, the narrower context enhanced sensitivity for standards within the same modality but had no effect on standards of different modality, suggesting that perceptual magnitude normally follows a modality specific calibration process. For individuals with autism, thresholds were similar in the auditory and visual domains suggesting no auditory specialization. Context only mildly affected sensitivity and in a similar magnitude for between- and within-modalities context, suggesting an amodal general calibration mechanism. These results suggest that contrary to the specialized, modality specific calibration processes in neurotypicals, overall reduced and less specialized (amodal) calibration process is shown in autism, that may account for sensory dysregulations and symptoms.