Reduced monitoring of task performance is an effective biomarker of autism

Can reduced flexibility in autistics behavior be a reliable classifier of autism? We asked this question in the context of pitch discrimination, which is performed with similar accuracy by autistic and non-autistic participants, matched for cognitive skills. We found that three reliable, uncorrelated characteristics quantified reduced behavioral flexibility. Most non-autistic participants showed a clear feedback-related negativity (FRN) in their EEG when incorrect, larger EEG responses during feedback following difficult versus easy trials, and increased perceptual bias following correct and easy trials versus difficult ones. All three measures were weaker in autistic participants. To assess reliability, we replicated all three measures in an experiment approximately a year later. These measures were not correlated within participants, indicating that several mechanisms, associated with anterior cingulate cortex, are atypical in autism. Together, these three measures provide group classification with above 80% accuracy, showing promise for their utility as a neurocognitive biomarker of autism. Significance statementA characteristic of autism is cognitive "slowness" in updating expectations in new contexts. Our study shows that this cognitive difference is related to a reduced use of feedback, linked to atypical activity in a brain area involved in error detection and behavioral adjustment. Using EEG, we found that autistic individuals have weaker feedback-related signals and do not adjust their behavior as effectively as non-autistic individuals. Together, these neurocognitive signals could serve as a biomarker for autism. This is the first time such brain responses have been measured in a perceptual task requiring continuous adjustments. Understanding these brain mechanisms can inform strategies to enhance learning and adaptability in autism, providing new insights into the neural basis of behavioral flexibility.