Mechanisms and consequences of impaired decision making in social contexts following severe traumatic brain injury

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Copyright: Kelly, Michelle
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Abstract
Decision making forms an important part of our everyday lives and is commonly impaired after a severe traumatic brain injury (TBI). Past research examining decision making after TBI has relied on a non-social card playing game, the Iowa Gambling Task (Bechara, Damasio, Damasio, & Andersson, 1994), however, there is little evidence that this task is indicative of real-world social decision making capabilities. This thesis presents the development of an alternative, social decision making task. Study 1 contrasted social decision making (SDMT) with non-social decision making (IGT), revealing a dissociation between them. Performance on the SDMT was not associated with age, gender, intelligence or probability learning. Next, it was demonstrated that the SDMT is sensitive to severe TBI [Study 2 (a)], and that group differences are not simply the result of retracted learning in those with TBI [Study 2 (b)]. Study 3 revealed that impairments in social decision making, as indexed by the novel task, are related to disorders of drive, reversal learning, and theory of mind (trend). This attests to the construct validity of the SDMT, and suggests that the ability to process relevant social cues, and use this information to guide future behaviour, is essential for successful social decision making. In order to further examine whether adults with TBI were sensitive to social feedback, a different ball-tossing paradigm (Cyberball: Williams, Cheung, & Choi, 2000) was employed to create the experience of social exclusion. Studies 4-6 demonstrated that adults with TBI experience the negative psychological effects of ostracism, albeit less than control participants (Study 5), and experience a different physiological response to controls (Study 6 - trend). Abnormal physiological responses to this experience may have implications for whether individuals with TBI engage in pro-social or antisocial behaviours in response to social isolation (Studies 4 and 6). Overall, this investigation provides evidence for the utility of a novel task for assessing decision making in social contexts following TBI. Examining the determinants of poor social decision making, as well as the role of physiological markers in responding to social cues, provides a significant contribution to the literature on social cognition. The importance of these findings is magnified by the incidence of mental illness in adults with TBI, and the understanding of the role of social isolation in this process.
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Author(s)
Kelly, Michelle
Supervisor(s)
McDonald, Skye
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Publication Year
2012
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Thesis
Degree Type
PhD Doctorate
UNSW Faculty
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