BACKGROUND: Pragmatic communication difficulties encompass many distinct behaviours, including the use of vague and/or insufficient language, a common characteristic following traumatic brain injury (TBI) that negatively impacts psychosocial outcomes. Existing assessments evaluate pragmatic communication broadly, often with only one or two items capturing each behaviour, thus limiting sensitivity and precision to variations within each behaviour. Given that greater nuance is needed to detect subtle pragmatic communication differences and investigate underlying cognitive mechanisms, a more refined measure is critical to improve psychosocial outcomes. The Vague scale was developed to address those needs. AIM: To provide preliminary evidence supporting the novel Vague language use (Vague) scale's reliability, validity and clinical utility. METHODS AND PROCEDURES: The Vague scale rates each discourse sample utterance for vague language use on a 3-point scale; the measure's Vague score represents the mean of utterance-level ratings. Using the Vague scale, two raters naïve to diagnosis evaluated Cinderella narratives of 46 adults with severe TBI and 46 controls with no brain injury, providing reliability, construct validity and classification accuracy evidence. Vague scores were also compared to other clinical measures to gather criterion-related validity evidence. OUTCOMES AND RESULTS: Interrater agreement across all transcripts was moderate. Construct validity was supported by expected group differences and criterion validation, including significant relationships with increased violations of Grice's maxim of quantity and measures of lexical variation; significant relationships with psychosocial outcomes, supporting clinical utility; and nonsignificant relationships with measures of syntax and overall pragmatic communication. Classification accuracy expectedly did not support using Vague scores in isolation for diagnosis, due to unacceptable sensitivity (0.696). CONCLUSIONS AND IMPLICATIONS: Evidence supported the Vague scores' psychometric properties. Thus, the Vague scale shows promise as a measure of one distinct pragmatic communication behaviour: vague language use. Future research should apply the Vague scale to determine its sensitivity in individuals with subtle social communication challenges (e.g., mild TBI), explore its utility with more naturalistic discourse samples as part of a pragmatic communication battery, longitudinally examine changes in Vague scores, and investigate cognitive mechanisms underlying this specific pragmatic communication behaviour. WHAT THIS PAPER ADDS: What is already known on this subject Use of vague language is common following traumatic brain injury (TBI) and may contribute to negative psychosocial outcomes related to employment and relationships. However, existing measures of vague language lack sensitivity and precision, limiting their utility for identifying subtle performance variations or determining the cognitive mechanisms underlying this specific pragmatic communication behaviour. What this study adds to existing knowledge The current study gathered promising reliability, validity and clinical utility evidence to support using the novel Vague language use (Vague) scale, which was developed to address these limitations. Based on complex (Cinderella) stories of adults with and without TBI, Vague scores demonstrated moderate interrater agreement and promising construct validity based on expected group differences and criterion validation, including moderate associations with related constructs and weak associations with unrelated constructs. Because pragmatic communication profiles post-TBI can vary, classification accuracy expectedly indicated that Vague scores should not be used alone to identify communication differences post-TBI. What are the clinical implications of this work? Vague scores show promise for documenting clients' use of vague language and planning intervention to address associated discourse-level challenges. Future research should investigate applying the Vague scale to naturalistic discourse samples (1) as part of a battery that sensitively and precisely identifies pragmatic communication differences and (2) as a tool for investigating cognitive mechanisms underlying vague language use, with the goal of improving interventions that support pragmatic communication and enhance psychosocial outcomes.
