Propositional analysis of discourse produced by Chinese speakers with traumatic brain injury

Abstract

Background The limitations of standardized language batteries in detecting subtle language deficits among individuals with traumatic brain injury (TBI) have been discussed in the literature (e.g., Coelho et al., 1995; Marini et al., 2011; Murdoch & Theodoros, 2001). It has been suggested that non-standardized measures of discourse, such as propositional analysis, tended to be more sensitive to subtle communicative deficits in TBI patients and therefore should be included as a core component of assessment for this population (Coelho, 2007). The Propositional Complexity Index (PCI) has been reported to be a sensitive microlinguistic measure to highlight discourse impairments in TBI, as reflected by lower PCI scores than controls (Coelho et al., 2005; Marini et al., 2011). It is a ratio of proposition (defined as idea units composed of a judgment, or predicate, about one or more “objects”, or arguments; Kamhi & Johnston, 1992) to T-unit (defined as an independent clause plus any subordinate clauses associated with it; Hunt, 1970) within a discourse. The present study aimed to examine the disruption of semantic complexity in Chinese TBI discourse using PCI. The degree to which PCI ratings would indicate the severity of linguistic and cognitive impairments in native speakers of Chinese with TBI was also investigated. Methods Eighteen Mandarin-speaking and 11 Cantonese-speaking subjects who suffered from a single closed-head TBI with a post onset time of at least four months were recruited. Each of them provided language samples collected using the Chinese AphasiaBank protocol (see Kong et al., 2015) modified for TBI, including (a) personal narratives of own TBI story and an important event, (b) descriptive narratives of the “broken window” and “refused umbrella” sequential pictures, and (c) story narratives of “The tortoise and the hare” and “Cry wolf.” The subjects were also administered the Mandarin (MAB; Peking University Health Science Center, 1988) or Cantonese (CAB; Yiu, 1992) version of the Western Aphasia Battery, to reflect the severity of language impairment, as well as the Chinese adaptation of the Cognitive Linguistic Quick Test (CLQT; Helm-Estabrooks, 2001), to estimate their degree of cognitive deficits. PCI scores were calculated based on orthographic transcriptions of each subject’s samples. In particular, the nuclear (i.e., focal point of meanings usually with a main verb) and non-nuclear predicates as well as all related inherent arguments (e.g., adverbial, embedded, associated, or subordinated relationship with the nucleus) of a proposition within each sentence were identified. Results and Discussion Preliminary analysis based on nine Mandarin-speaking and five Cantonese-speaking subjects revealed a mean PCI of 2.46 and 1.85, respectively, which was comparable to earlier reports of English TBI speakers and inferior to ratings of healthy controls (Coelho, 2005). Positive correlations were also found between MAB/CAB scores and propositional efficiency as well as between PCI and CLQT scores. Data collection and analyses involving more TBI and control participants are in progress. Details regarding the modifications adopted in the present investigation to ensure adequate and appropriate highlight quantification of discourse propositions among Chinese speakers will be given. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions.