Can adolescents with Williams syndrome tell the difference between lies and jokes?

A group of adolescents with Williams syndrome (WS) was compared to matched groups of adolescents with Prader-Willi syndrome and nonspecific mental retardation on a task that tested the ability to distinguish different forms of nonliteral language. Participants listened to stories that ended in either a lie or an ironic joke. They were asked to decide the form of the nonliteral utterance and justify their responses. Almost none of the participants in any of the groups were able to correctly classify the ironic jokes, instead judging them to be lies because they did not correspond to reality. Their errors were similar to those made by younger normally developing children, but contrasted with those made by brain-damaged adults. These data are taken as further evidence that neurodevelopmental disorders are quite different from acquired brain disorders and require different neuropsychological models. The findings from this study also have important implications for considering the difficulties that adolescents with WS and other disorders will have in everyday social situations, especially among peers.