Dissertations, Theses, and Capstone Projects

Date of Degree

9-2015

Document Type

Dissertation

Degree Name

Ph.D.

Program

Speech-Language-Hearing Sciences

Advisor

Richard G. Schwartz

Subject Categories

Developmental Psychology | Linguistics

Keywords

autism; children; eye tracking; scalars

Abstract

This study examined scalar implicature to investigate semantic bases of pragmatic language impairment in children with autism spectrum disorders (ASD). Scalar implicatures are inferences made by listeners, whereby they strengthen the weaker meaning of a term that can be represented on a scale (Grice, 1975; Horn, 1992). Scalar terms include: some/all; or/and; numerals. These inferences depend on understanding a speaker's intent and having the cognitive skills necessary to process such information in real time. Informativeness is the value a listener places on having to derive an implicature and assumes that the listener perceives the speakers intentions. Cognitive effort includes the executive functions working memory, interference, and inhibition (Wilson & Sperber, 2004). Children with autism have difficulty with social language and appear to be insensitive to speaker's intentions, therefore, they may have difficulty understanding scalar implicatures (Happé, 1993). In addition, because it is also believed that inferences place great demands on cognitive resources, children with impaired executive functions, as may be the case in autism, may have difficulty comprehending these sentences (Ozonoff, South, & Provencal, 2005). Method Subjects viewed 1 or 4 pictures while hearing sentences under manipulations of cognitive effect (informativeness level) and cognitive effort (processing costs). Cognitive effect was controlled by experiment (2) and cognitive effort was manipulated by varying stimulus onset asynchrony (3). Three participant groups were tested: seven 7-9 year-old children with autism, ten 7-9 year-old children with typical language development (TD), and 14 adults with a history of typical language. Performance on three comprehension tasks were compared: a yes/no picture-sentence judgment task, a two-talker picture-sentence judgment task, and a 4AFC picture-sentence matching task using a table-top eye tracker (Tobii TX300). To assess the role of executive functions on scalar comprehension participants also completed a computerized non-verbal task function of attention, interference, and response inhibition. Results Children, regardless of clinical presentation, did not perform as well as adults. Within weak scalars (some, or) children had the greatest difficulty when the target was or. Within the strong scalar group, and was more difficult than all. Children with poorer performance on the executive functions task tended to be younger and also had the poorest accuracy on the scalar implicature tasks. There were no group differences between TD and ASD children in the executive functions task. The three different scalar tasks revealed task effects on inference making in children. TD children were able to accept more implied semantic sentences as correct in the two-talker task compared to the yes/no task. When the stimulus onset asynchrony was set so that the visual preceded the audio stimulus by 750 ms, TD children also performed better. Children with ASD did not demonstrate these differences. The eye tracking data also revealed slower processing of correct responses for children with ASD. Overall children with ASD accepted implied semantic interpretations of the weak scalars some and or. However, the process in which they did so was different from that of TD children and adults, with more individual variation within the ASD group. Acknowledgements This research was supported by two grants from the National Institutes of Health: a pre-doctoral fellowship, 5F31DC013002, to Karece Lopez and a multi-year award, 5R01DC011041, to Richard Schwartz.

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