The study of clearly identifiable patterns of atypical development can inform normal development in significant ways. Delayed or deviant development puts in high relief not only the sequence of development but also the individual components. This article presents the results of studies that compare adolescents with Williams syndrome, a rare metabolic neurodevelopmental disorder resulting in mental retardation, with cognitively matched adolescents with Down syndrome. We investigate the interaction between affect and language through storytelling. In contrast to the adolescents with Down syndrome, the Williams syndrome subjects tell coherent and complex narratives that make extensive use of affective prosody. Furthermore, stories from the Williams but not the Down subjects are infused with lexically encoded narrative evaluative devices that enrich the referential content of the stories. This contrast in expressivity between two matched atypical groups provides an unusual perspective on the underlying structure of the social cognitive domain.

What the Hands Reveal About the Brain provides dramatic evidence that language is not limited to hearing and speech, that there are primary linguistic systems passed down from one generation of deaf people to the next, which have been forged into antonomous languages and are not derived front spoken languages.

Many species can respond to the behavior of their conspecifics. Human children, and perhaps some nonhuman primates, also have the capacity to respond to the mental states of their conspecifics, i.e., they have a "theory of mind." On the basis of previous research on the theory-of-mind impairment in people with autism, together with animal models of intentionality, Brothers and Ring (1992) postulated a broad cognitive module whose function is to build representations of other individuals. We evaluate the details of this hypothesis through a series of experiments on language, face processing, and theory of mind carried out with subjects with Williams syndrome, a rare genetic neurodevelopmental disorder resulting in an uneven lin-guisticocognitive profile. The results are discussed in terms of how the comparison of different phenotypes (e.g., Williams syndrome, Down syndrome, autism, and hydrocephaly with associated myelomeningocele) can contribute both to understanding the neuropsychology of social cognition and to current thinking about the purported modularity of the brain.

A series of unordered recall tasks was administered to groups of congenitally deaf subjects for whom American Sign Language (ASL) is the principal means of communication. A suffix effect was observed when an ASL sign was suffixed to a list of ASL signs (Experiment 1), and when a line drawing of an ASL sign was suffixed to a list of line drawings of ASL signs (Experiment 3). The suffix effect was of diminished magnitude when a printed English word was suffixed to a list of printed words (Experiment 2). The findings of Experiments 1 and 3 argue conclusively against the suffix effect resulting solely from sensory store differences. Additionally, the results of Experiment 3 argue conclusively against explanation of the effect as arising solely from differences in the processing of "static" versus "changing-state" input.