Microlinguistic deficits in the narrative discourse of adults with traumatic brain injury

Background: Recent studies of microlinguistic impairments in the narrative discourse of adults with traumatic brain injury (TBI) have applied syntactic analyses, with some noting no deficits and others specific problems with sentence formulation. An alternative approach to examining the microlinguistic dysfunction in the discourse of individuals with TBI is through the use of propositional analysis. The advantage of propositional analysis is that it enables one to assess semantic complexity of utterances apart from sentence structure and grammaticality.

Aims: The present study applied propositional analysis to the story narratives of participants with TBI and participants with no brain injury (NBI). Specifically, the mean number of propositions within a sentence was tallied, in other words the participants' ability to insert multiple ideas into single surface sentences. It was hypothesized that the participants with TBI would produce fewer propositions per sentence because of organizational problems than the participants with NBI, regardless of level of education.

Methods and procedures: Two story narratives (retelling and generation) previously elicited from the two participant groups (TBI (n = 53) and NBI (n = 42)) were analysed. For each language sample, the number of propositions was tallied and divided by the number of T-units. The resulting number, the propositional complexity index (PCI), was the average number of predicates per sentence.

Outcomes and results: Results indicated that the group with TBI produced significantly fewer propositions per T-unit.

Conclusions: The present findings are in harmony with the notion that the participants with TBI studied presented with impairments of both micro- and macrolinguistic processes involved with the organization of semantic information in discourse. Clinical implications are discussed.