Comparison of the Production of Formulaic Language by Adults with Traumatic Brain Injury ( TBI ) and Healthy Controls

B ackground and aims: Views on language processing have evolved from being solely focussed on newly created, novel sentences, to recognising the substantial role that “prefabricated” formulaic expressions have in conversational dialogue. Neuro-linguistic studies have concluded that a dual process model of language processing exists, whereby novel and formulaic expressions are processed by distinct cerebral structures. The aim of this study was to systematically evaluate the proportion of formulaic language used by adults with severe TBI and to compare this usage with that of healthy matched control participants. Method: Participants were 15 adults with TBI and 15 gender, age and education matched controls. Language samples were analysed using established formulaic language analysis techniques. Proportions of total formulaic language produced and proportions across seven formulaic language subcategories were calculated and compared. Results: Participants with TBI and control participants were observed to use similar total proportions of formulaic language and no significant difference was detected (U = 109.50, p = 0.901). Participants with TBI showed some difference in their use of formulaic language compared to controls in two subcategories. The difference in the proportions of formulaic distortion errors produced by the two groups reached statistical significance (U = 75.00, p = 0.017) and the difference in the proportions of expletives produced approached significance (U = 90.00, p = 0.073). Conclusions: These findings are not consistent with the neural substrates that are proposed to underlie formulaic language production in the dual process model. In line with this model, individuals with TBI would be expected to have a deficit in their overall production of formulaic language. However, this was not observed, as the TBI and control participants in this study produced the same proportions of formulaic language.