Formulaic language performance in left- and right-hemisphere damaged patients: structured testing

Background: Formulaic expressions—conversational speech formulas, idioms, pause fillers, conventional phrases, proverbs, expletives, and so on—constitute on average about 25% proportionally of everyday communication. While some clinical and experimental studies have implicated a right hemisphere involvement, controversy remains surrounding cerebral processing with respect to comprehension and production of formulaic expressions. Aims: The purpose of this study was to further investigate hemispheric specialisation for production and comprehension of formulaic and matched literal expressions by examining performance of individuals with unilateral brain damage compared with matched healthy controls (HCs) utilising structured tasks involving repetition, elicited speech, and comprehension. Methods & Procedures: Individuals with unilateral brain damage (right hemisphere damage (RHD) or left hemisphere damage (LHD)) due to cerebrovascular accident and matched HC participants completed five different tasks (Repetition, Multiple Choice Sentence Completion, Free-form Sentence Completion, Picture-matching Completion, and Written Multiple Choice) involving formulaic and literal expressions. Outcomes & Results: The LHD and RHD groups showed significant differences between two types of sentences (formulaic versus literal expressions) in the free-form sentence completion and picture-matching tasks, respectively, but not in the repetition or multiple choice (spoken or written) tasks. Conclusions: The findings lend support to the dual process model of formulaic and literal expressions, implying a right hemisphere involvement in processing of formulaic expressions when elicitation tasks are utilised. Because repetition and multiple choice tasks did not reflect differential processing, the results also indicate that task may differentially manifest speech characteristics of brain-damaged individuals.