Language Development in Autism

Abnormal language development used to define autism, but no longer does. Indeed, language development no longer even figures into contemporary diagnostic criteria, although early delays in language often lead to parents’ concerns. In this chapter, we review recent empirical research on language development in autism. To paint a contemporary picture, we restrict our review to studies published in the 21 century. We conclude that language development in autism is often delayed, but not deviant; that a delay in language development is not unique to autism; and that language development in autism is remarkably heterogeneous. The diagnostic criteria for autism in the American Psychiatric Association’s most recent Diagnostic and Statistical Manual (2013) are mute with regard to language development. Instead, the most recent diagnostic criteria mention only aspects of socio-cultural communication, such as eye contact, facial expressions, or hand gestures. Language itself – the perception and production of speech or writing – is not referenced; neither is language development. In contrast, over thirty years ago, when autism first appeared in the Diagnostic and Statistical Manual (1980), “gross deficits in language development” were considered so dispositive of the autistic phenotype that this diagnostic criterion was not only required but was one of only a handful of criteria (Gernsbacher et al., 2005a, b). Seven years later, the focus moved away from how language developed to how language was produced. “Marked abnormalities in the production of speech, including volume, pitch, stress, rate, rhythm, and intonation” and “marked abnormalities in the form or content of speech, including stereotyped and repetitive use of speech” appeared as diagnostic criteria. But these two criteria were among more than a dozen other criteria, and they need not be met to warrant a diagnosis (APA, 1987). Another seven years passed, and language development recurred in the diagnostic criteria (“delay in, or total lack of, the development of spoken language”), but again as only one of numerous criteria, for which only a subset needed to be met (APA,1994; 2000). Thus, abnormal language development at one time defined autism, then became an optional means for making a diagnosis, but now no longer figures into contemporary diagnostic criteria. In this chapter, we review recent empirical research on language development in autism. To paint a contemporary picture, we restrict our review to studies published in the 21 century. We conclude that language development in autism is often delayed, but not deviant; that a delay in language development is not unique to autism; and that language development in autism is remarkably heterogeneous and vari-