Aphasic speech with and without SentenceShaper® : Two methods for assessing informativeness

Abstract

Background: SentenceShaper® (SSR) is a computer program that is for speech what a word‐processing program is for written text; it allows the user to record words and phrases, play them back, and manipulate them on‐screen to build sentences and narratives. A recent study demonstrated that when listeners rated the informativeness of functional narratives produced by chronic aphasic speakers with and without the program they gave higher informativeness ratings to the language produced with the aid of the program (Bartlett, Fink, Schwartz, & Linebarger, 2007). Bartlett et al. (2007) also compared unaided (spontaneous) narratives produced before and after the aided version of the narrative was obtained. In a subset of comparisons, the sample created after was judged to be more informative; they called this “topic‐specific carryover”. Aims: (1) To determine whether differences in informativeness that Bartlett et al.'s listeners perceived are also revealed by Correct Information Unit (CIU) analysis (Nicholas & Brookshire, 1993)—a well studied, objective method for measuring informativeness—and (2) to demonstrate the usefulness of CIU analysis for samples of this type. Methods & Procedures: A modified version of the CIU analysis was applied to the speech samples obtained by Bartlett et al. (2007). They had asked five individuals with chronic aphasia to create functional narratives on two topics, under three conditions: Unaided (“U”), Aided (“SSR”), & Post‐SSR Unaided (“Post‐U”). Here, these samples were analysed for differences in % CIUs across conditions. Linear associations between listener judgements and CIU measures were evaluated with bivariate correlations and multiple regression analysis. Outcomes & Results: (1) The aided effect was confirmed: samples produced with SentenceShaper had higher % CIUs, in most cases exceeding 90%. (2) There was little evidence of topic‐specific carryover. (3) CIU measures and listener ratings correlated strongly. Conclusions: That the percentage of CIUs was higher in SSR‐aided samples than in unaided samples confirms the central finding in Bartlett et al. (2007), based on subjective judgements, and thus extends the evidence that aided effects from SentenceShaper are demonstrable across a range of measures, stimuli and participants (cf. Linebarger, Schwartz, Romania, Kohn, & Stephens, 2000). The data also attest to the effectiveness of the CIU analysis for quantifying differences in the informativeness of aphasic speech with and without SentenceShaper; and they support prior studies that have shown that CIU measures correlate with the informativeness ratings of unfamiliar listeners.