Date of Completion

5-8-2015

Embargo Period

5-6-2016

Keywords

discourse, traumatic brain injury, discourse production, discourse comprehension, working memory, inference, discourse model, story grammar, story completeness

Major Advisor

Carl Coelho

Associate Advisor

Emily Myers

Associate Advisor

Tammie Spaulding

Field of Study

Speech, Language, and Hearing Sciences

Degree

Doctor of Philosophy

Open Access

Open Access

Abstract

Purpose: The goal of the current research study was to advance our knowledge of cognitive-communicative disorders following traumatic brain injury (TBI) by identifying the cognitive and communicative processes underlying narrative discourse ability. The study 1) examined the role of working memory (WM) and inferencing in narrative discourse, 2) tested key assumptions posited by the Structure Building Framework (SBF; Gernsbacher, 1990), a cognitive model of normative discourse comprehension and 3) attempted to disambiguate the relationship between discourse comprehension and discourse production.

Methods: Forty-four native English speakers participated, comprising 21 individuals with TBI, all with closed-head injuries, and 23 non-brain-injured (NBI) comparison individuals. Participants completed six core study tasks yielding seven measures of interest: verbal and nonverbal working memory updating (WMU-V, WMU-NV), predictive inference, the Discourse Comprehension Test (DCT; Brookshire & Nicholas, 1993), a picture story comprehension task (PSC) and story retelling (story grammar and story completeness). Three regression analyses were performed. In the first and second set of models, WM and inferencing were predictors for discourse comprehension and production outcomes, respectively. In the third set of models, discourse comprehension measures were predictors production outcomes.

Results: WMU-V and WMU-NV were found to be highly collinear. Thus, only WMU-V was used as the WM measure in the regression models. WM and inferencing accounted for one-third of the variance in DCT but the model for PSC was nonsignificant. WM and inferencing were not significant predictors for either story grammar or story completeness. DCT and PSC did not significantly predict story grammar. However, the discourse comprehension measures accounted for 60% of the variance in story completeness with DCT as the significant predictor.

Discussion: Findings were interpreted as supporting SBF assumptions of domain-generality of cognitive processes and mechanisms involved in discourse and partially supporting assumptions that the same cognitive substrates are marshalled for comprehension and production processes. WM was more strongly associated with comprehension processes. Yet, comprehensions measures were highly predictive of narrative content, a production measure, suggestive of shared mental representations and share cognitive substrates outside of WM. In recent accounts, declarative memory has been shown to be critical for short-term recall, highlighting its potential for subserving both discourse comprehension and production systems and merits consideration for future investigations of the cognitive-communicative underpinnings of discourse ability.

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