Follow-Up on the Story Goodness Index for Characterizing Discourse Deficits Following Traumatic Brain Injury

Purpose: The Story Goodness Index (SGI) is a hybrid analysis of narrative discourse combining 2 macrostructural measures: story grammar and story completeness. Initially proposed by Le and colleagues (Le, Coelho, Mozeiko, & Grafman, 2011), the SGI is intended to characterize the discourse performance of individuals with cognitive-communication disorders. In this study, the SGI was utilized to examine the discourse of 2 groups, one with closed head injuries and another with non-brain injured (NBI) peers. The intent of this study was to ascertain whether the SGI could differentiate the discourse performance of the 2 groups, as was previously reported for individuals with penetrating traumatic brain injury and an NBI comparison group (Le, Coelho, Mozeiko, Krueger, & Grafman, 2012). Because of the retrospective nature of this study, the wordless visual narrative used to elicit discourse was different from the narrative used by Le and colleagues (2012). Method: A retrospective analysis of discourse was performed on 55 individuals with a history of closed head injury and 47 NBI socioeconomically matched peers. During the initial assessment, participants were engaged in a narrative retell task. Each participant was shown a wordless picture story and then asked to retell the story to the examiner. Story narratives were reanalyzed for story grammar (organization) and completeness (critical content). Results: A significant group difference was noted for the story grammar measure, but not for story completeness. Although the SGI plots depicted the heterogeneity in discourse performance of the 2 groups, a chi-square test of independence revealed no significant association between group membership and SGI quadrant. Conclusions: Findings from this study were inconsistent with those of Le and colleagues. The studies did not use identical SGI protocols; specifically, different picture stimuli were used to elicit the story retells. Therefore, this study cannot be considered a replication. The story used by Le and colleagues was judged to be more complex, requiring more inference for story interpretation. Future studies should interpret findings within the context of the story stimuli presented.