Translational approaches to studying reward-based purposive behaviours

Doran, Kate S (2016) Translational approaches to studying reward-based purposive behaviours. Doctoral thesis (PhD), University of Sussex.

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Within classical economics, an agent is deemed “rational” if their preferences are both consistent and maximize utility of positive, subjective experience. Violations from this norm may occur as a result of utility devaluation (proceeding from risk or delay) or when an imbalance occurs between ‘liking’ and ‘wanting’.

The current studies investigate how changes in reward-contingencies, delay before reward receipt, and reinforcer devaluation contribute to such utility-based decision-making in human and rodent models. I examined the effects of devaluation through pre-exposure and outcome-contingency on the development and maintenance of sign- and goal-tracking responses in rats (chapter three) and humans (chapter four). Chapter four presents a novel, translational, eye-tracking procedure and correlates of such behaviour, including trait-impulsivity and discounting performance.

In chapter five I presented probability- and temporal discounting using a mouse model, exploring the consequences of satiety-based devaluation, and changes in outcome-contingencies- and delays. In Chapter six I presented the same factors in a human sample using a novel laboratory-based procedure and sought to explore the impact of trait and state impulsivity and correlates of rapid discounting.

Finally, in chapter seven I considered the relationship between trait impulsivity, alcohol use, smoking and discounting behaviour using a more conventional online questionnaire. The results represent some of the first to present probability discounting using a mouse model and characterisation of reliable sign- and goal-tracking performance in humans. The results of the latter studies broadly support previous findings in rats showing that lowered reward contingency diminishes goal-oriented, but enhances sign-oriented, responding. Chapter six establishes a human equivalent to rodent discounting paradigms through implicit learning that will allow future controlled studies in humans. Finally, chapter seven presents evidence for an association between delay discounting and trait impulsivity.

The results of these studies support the assertion that irrational decision-making arises, in part, from changes in reward utility as a function of delay, probability, devaluation and individual differences. Furthermore the translational-homologous models presented allow for future biopsychological research into mechanisms underlying such behaviours.

Item Type: Thesis (Doctoral)
Schools and Departments: School of Psychology > Psychology
Subjects: B Philosophy. Psychology. Religion > BF Psychology > BF0199 Behaviourism. Neobehaviourism. Behavioural psychology
Depositing User: Library Cataloguing
Date Deposited: 07 Dec 2016 10:22
Last Modified: 07 Dec 2016 10:22

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