Contamination sensitivity in autism, Down syndrome, and typical development

Although typically developing children are attuned early to others’ communicative signals, one of the very first noticeable impairments in children with autism is in attending to voices and speech. Yet it is through conversations with others that children are made aware that apparently edible substances may in reality be contaminated. In two experiments, we examined contamination sensitivity in children with autism, typically developing children, and a group of children with Down syndrome. In Experiment 1, many children with autism who ranged in age from 4 to 10 years were prepared to drink liquids that had been contaminated by insects. There was evidence for a developmental delay as contamination sensitivity in autism was associated with increasing age. In Experiment 2, children with autism were prepared to drink liquids that had been contaminated by human hair or had insects in close proximity. By contrast, in both experiments, both typically developing children and children with Down syndrome demonstrated strong contamination sensitivity. We discuss the results in terms of constraints on the early learning of the edible–inedible distinction.