Objectives: The present study examined prototype learning in preschoolers with ASD and TD using a non-matching to sample task. We hypothesized that preschoolers with ASD would show decreased prototype category learning compared to preschoolers with TD. Further, we predicted that impaired prototype category learning would be related to autism symptoms, nonverbal reasoning, and language ability in preschoolers with ASD, but not preschoolers with TD.
Methods: In this ongoing study, six children with TD (mean age of 41 months) and five children with ASD (mean age of 57 months) matched on receptive language ability have completed the prototype learning task to date. Participants learned categories of novel animals whose features varied along several dimensions. Categorization skills were assessed using a non-matching to sample paradigm in which children were taught to chose the novel animal. Rewards were attached to the back of each card, such that choice of the novel animal resulted in a small toy or treat. Using this method, each child was familiarized to a category of animal (i.e., the MIP family). During test trials, children were shown two novel exemplars of the same animal family, one of which was the mathematical average of all previously seen animals (i.e., the prototype) and the other which was a non-averaged exemplar. A preference for the non-prototype animal was taken as evidence that children viewed the prototype as familiar rather than novel and suggested that children learned the animal category prototype.
Results: Performance was compared to chance (i.e., 50%). Children with ASD chose the novel animal 54% of the time which did not differ from chance, t(5)=.31, p=.77. Thus, there is no evidence that children with ASD showed prototype learning. However, children with TD chose the novel animal 75% of the time, suggesting that they viewed the prototype as familiar, t(4)=3.16, p=.03. Thus, children with TD showed strong evidence of prototype learning. Groups were significantly different from each other, t(9)=2.66, p=.06.
Conclusions: Preliminary results suggest significant group differences between preschoolers with ASD and TD on the prototype learning task. Children with TD showed a prototype learning rate that was significantly different from chance while children with ASD did not demonstrate prototype learning above chance levels. Taken together, these findings suggest that young children with ASD are not showing evidence of prototype learning even with simple task demands and a completely nonverbal task. Further research examining the relation between prototype formation, autism symptoms, and developmental level is ongoing.