Altered category learning and reduced generalization in autistic adults

Individuals with autism spectrum condition (ASC) are suggested to experience difficulties with categorization and generalization. However, empirical studies have mainly focused on one process at a time, and neglected underlying neural mechanisms. Here, we investigated categorization and generalization at a behavioral and neural level in 38 autistic and 38 neurotypical (NT) adults. By presenting shapes sampled from an artificial multidimensional stimulus space, we investigated (1) behavioral and neural underpinnings of category learning and (2) behavioral generalization of trained categorization to both an extended version of the stimulus space and a novel stimulus space. Our previous findings showed that individuals with autism were slower in category learning. In this study, we demonstrate that this slower learning in autism was not related to differences in applied categorization strategy. In contrast, electroencephalography recordings during training did reveal a reduced amplitude of the N1 component in the right occipital temporal cortex after stimulus presentation in autistic participants, which suggests atypical categorical proficiency. In addition, we observed delayed and higher activation in the frontal regions after receiving (negative) feedback in the autistic group, potentially suggesting more explicit feedback processing or a higher salience of prediction errors in autism. Finally, autistic and NT individuals were able to generalize their learned categorization after training. However, when generalizing to a novel set of shapes, autistic individuals were significantly less accurate. Reduced generalization significantly correlated with increased intolerance to uncertainty scores. This multi-level approach reveals behavioral and neural differences in learning and generalization that could be related to clinical symptoms in autism.