Date of Award

1-2011

Degree Name

Doctor of Philosophy

Department

Psychology

First Advisor

Dr. Cynthia J. Pietras

Abstract

Research has shown that acute drug administration may affect impulsivity (i.e., choice for small, immediate rewards over large, delayed rewards) on laboratory delay-discounting tasks. Few studies have investigated how drug abstinence affects impulsivity. Investigating how drug abstinence affects impulsivity may be relevant to preventing relapse. Two previous studies have investigated the effects of short-term nicotine abstinence on impulsivity using delay-discounting tasks. The results were mixed, one study suggested that choices became more impulsive (i.e., delayed money was devalued) under nicotine deprivation. One goal of the present research was to further investigate how nicotine deprivation affects delay-discounting for money rewards. In delay-discounting procedures, the amounts and delays of the choice options differ. It is unclear if nicotine deprivation affects impulsivity by altering sensitivity to reward delay, amount, or both. A second goal was to analyze the effects of nicotine deprivation on sensitivities to reward amount and delay independently. Participants completed four tasks investigating (1) choice on a standard delaydiscounting task, (2) sensitivity to delay when reward amount was held constant, (3) sensitivity to delay when delay and amount varied, and (4) sensitivity to reward amount when delay was held constant. Choice in 15 adult cigarette-smokers was examined following a period of ad-lib smoking and 24-hr of nicotine abstinence. Ten adult nonsmokers were included as a comparison group. Nicotine deprivation significantly increased discounting rates (i.e., increased impulsivity) on the standard delay-discounting task. Nicotine deprivation also significantly decreased preference for the larger reward during the task investigating sensitivity to delay when delay and amount varied. The results from the delay-only and amount-only tasks were inconclusive, but the lack of effect on the delay-only task suggests that increased impulsivity during delay-discounting may be a result of decreases in sensitivity to reward amount. These results replicate earlier research showing that short-term nicotine abstinence increases impulsive choices for monetary rewards. This study is unique in that few studies with humans have investigated the mechanisms by which drugs affect impulsive choice on delay-discounting tasks.

Access Setting

Dissertation-Open Access

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