Language Discourse Profiles in the Broad Autism Phenotype

Background: Impaired language discourse (i.e., connected speech such as conversation or narrative) is a hallmark of autism.  Studies have documented similar but milder discourse features in relatives of individuals with autism (e.g. Landa et al., 1991; 1992), which have been referred to as one component of the broad autism phenotype (BAP). Prior studies using global rating scales have documented patterns of abrupt topic changes, topic preoccupation, over-talkativeness, detailed and confusing accounts, and insufficient background information (Landa et al., 1991; 1992; Ruser et al., 2007; Piven et al., 1997). While richly descriptive, it is unclear what discourse mechanisms might underlie these profiles. In attempt to address this question, this study employed a fine-grained discourse coding system to conversational samples obtained from parents of individuals with autism and parents of typically developing individuals. The coding scheme applied has been used in prior studies of high-functioning individuals with autism (Losh & Capps, 2003; Capps, Losh, & Thurber, 2000), and thus may afford direct comparisons of discourse profiles in autism and the BAP

Objectives: Analyses aimed to document the extent to which the discourse features of the BAP may be qualitatively similar to those documented in high functioning autism. We also aimed to identify specific discourse mechanisms that could underlie the global pragmatic language difficulties noted in prior work by examining associations between our microanalytic discourse coding system and global ratings of pragmatic language violations using measures employed in prior work.

Methods: Conversational samples were collected from 11 autism parents and 11 control parents using a semi-structured interview. Conversations were transcribed verbatim and coded for discourse elements by coders blind to group status. Coding focused on the use of evaluative devices, which are used to imbue narratives with a psychological perspective and integrate episodic elements within an overarching theme (e.g., Labov & Waletzky, 1967). The use of evaluation has been shown to be impaired in high functioning autism. Pragmatic language was also coded from video by independent coders using the Pragmatic Rating Scale (PRS) (Landa, et al, 1992) which has been used in prior work to document global pragmatic language violations in the BAP.

Results: No significant group differences were found in the length of conversations or in the frequency of evaluation. However, differences were detected in the use of specific types of evaluation that have been shown to be impaired in autism – autism parents differed from controls in their use of mental state language [t(1, 20)=2.314, p=.031] and hedges [t(1, 20)=-2.194, p=.04].  Parents’ use of these evaluative devices was also correlated with more severe pragmatic language impairments as measured by the PRS (p < .05).

Conclusions: Results highlight particular discourse mechanisms (i.e., the use of evaluation) as potentially underpinning the pragmatic language features associated with the BAP and autism. Because the use of evaluation has also been shown to be impaired in autism, these findings may point toward this discourse device as a marker for genetic liability to autism.