Corpus-Based Transitivity Biases in Individuals with Aphasia.

Background: This study investigated whether individuals with aphasia (IWA) retain verb biases in expressive language. Verb biases refer to the likelihood that a given verb will occur in different sentence structures. We focused on the likelihood of verbs occurring in transitive and intransitive structures.

Aims: The main goal of this study was to determine whether IWA and controls show similar verb biases or whether IWA show a preference for transitive or intransitive structures that supersedes individual verb biases. We also investigated whether IWA show a preference for intransitively or transitively biased verbs, whether verb biases differ as a function of aphasia type, and how verb bias affects errors in IWA's speech production.

Methods: The current study analyzed 236 transcribed interviews of IWA from AphasiaBank. All uses of 54 verbs were coded based on the sentence structure and the presence of errors. We report data from 11 transitively biased and 11 intransitively biased verbs.

Outcomes and Results: IWA's transitivity biases were indistinguishable from controls' biases. In addition, IWA produced more intransitively biased verbs than transitively biased verbs overall. In ungrammatical productions, IWA's error rates were higher in sentence structures that conflicted with verb bias and highest when an intransitively biased verb was attempted in a transitive structure.

Main Conclusions: These findings indicate that IWA are sensitive to verb bias and verb complexity within expressive language. The effects are consistent with previous literature concerning IWA's sensitivity to verb bias in receptive language tasks and to verb complexity in verb retrieval tasks.