Exploring theory of mind after severe traumatic brain injury

Previous studies have reported a dissociation between social behavioral impairments after severe traumatic brain injury (TBI) and relatively preserved performances in traditional tasks that investigate cognitive abilities. Theory of mind (ToM) refers to the ability to make inferences about other's mental states and use them to understand and predict others' behavior. We tested a group of 15 patients with severe TBI and 15 matched controls on a series of four verbal and non-verbal ToM tasks: the faux pas test, the first-order and second-order false belief task, the character intention task and the Reading the Mind in the Eyes Test. Participants with severe TBI were also compared to controls on non-ToM inference tasks of indirect speech act from the Montreal Evaluation of Communication (M.E.C.) Protocol and empathy (Davis Interpersonal Reactivity Index - I.R.I.) and tests for executive functions. Subjects with TBI performed worse than control subjects on all ToM tasks, except the first-order false belief task. The findings converge with previous evidence for ToM deficit in TBI and dissociation between ToM and executive functions. We show that ToM deficit is probably distinct from other aspects of social cognition like empathy and pragmatic communication skills. (C) 2009 Elsevier Srl. All rights reserved.