Normal but Different: Autistic Adolescents Who Score Within Normal Ranges on Standardized Language Tests Produce Frequent Linguistic Irregularities in Spontaneous Discourse.

Background and aims: A substantial minority of autistic individuals score within typical ranges on standard language tests, suggesting that autism does not necessarily affect language acquisition. This idea is reflected in current diagnostic criteria for autism, wherein language impairment is no longer included. However, some work has suggested that probing autistic speakers' language carefully may reveal subtle differences between autistic and nonautistic people's language that cannot be captured by standardized language testing. The current study aims to test this idea, by determining whether a group of autistic and nonautistic individuals who score similarly on a standardized test show differences in the number of unconventional and erroneous language features they produce in a spontaneous language sample. Methods: Thirty-eight older children and adolescents (19 autistic; 19 nonautistic), between the ages of 10 and 18, were recruited. Both participant groups scored within normal ranges on standardized language and IQ tests. Participants engaged in a "double interview" with an experimenter, during which they were first asked questions by the experimenter about themselves, and then they switched roles, so that it was the participant's turn to ask the experimenter questions. Participants' language during the interview was transcribed and analyzed for linguistic irregularities, including both semantic anomalies and morphosyntactic errors. Results: Group membership accounted for significant variance in irregularity frequency; autistic participants produced more linguistic irregularities than nonautistic participants. Scores on a standardized language test did not improve model fit. Secondary analyses involving irregularity type (semantic vs. morphosyntactic) showed that group differences were primarily driven by relatively high numbers of semantic unconventionalities produced by the autistic group. While the autistic group made more morphosyntactic errors than the nonautistic group, differences in these numbers were only marginally significant. Conclusions and implications: These findings suggest that a commonly used standardized language test does not adequately predict the number and perhaps type of language irregularities produced by some older autistic children and adolescents during spontaneous discourse. Results also suggest that differences in language use, especially semantic differences, may characterize autistic language, even the language produced by people who score within normal ranges on standardized language tests. It is debatable whether differences reflect underlying language impairments and/or a linguistic style adopted/preferred by autistic speakers. In this paper, we discuss both possibilities and offer suggestions to future research for teasing these possibilities apart.