Year

2013

Degree Name

Doctor of Philosophy

Department

School of Psychology

Abstract

Problem gambling is characterised by maladaptive gambling patterns, resulting in severe psychological, interpersonal, and financial problems. Electronic gaming machines (EGMs, also called a ‘poker’ or ‘slot’ machines) are one of the most harmful gambling forms and are associated with higher risk, greater severity, and faster progression of problem gambling. The physiological arousal (perceived as excitement) caused by the experience of unpredictable positive reinforcement (wins) during EGM play has been posited to be a primary motivator for normal gambling activity, and dysfunctional incentive value processing has been implicated in the development of problem gambling behaviours. Specifically, hypersensitivity to reward in problem gamblers may selectively reinforce gains, but not discourage the effect of losses. Alternatively, problem gamblers may be hyposensitive to punishment, or hyposensitive to both reward and punishment, leading to compensatory thrill-seeking behaviours, such as gambling. Previous studies examining incentive processing in problem gambling have reported mixed results and the nature of deficit in this disorder remains unresolved. The primary aim of the current doctoral thesis was to investigate whether problem gamblers display abnormal psychophysiological responses to gambling outcomes. A variety of psychophysiological and psychometric measures were used to examine how naive gamblers, experienced regular gamblers, and problem gamblers process different magnitude wins, losses, near-wins, and losses disguised as wins. Ambulatory equipment was used to measure electrodermal and cardiac activity in order to examine the effect different gambling outcomes have on arousal levels in a sample of healthy controls (n = 23) while they played a computer gambling task, and in samples of problem (n = 15) and non-problem gamblers (n = 15) gambling their own money on an EGM in a licensed club. Cortical event-related potentials (ERPs) were recorded from healthy controls (n = 17) while they played a computer gambling task, and analysed using a principal components analysis, to examine the effects on key indices of reward and punishment processing, namely the P300 and the feedback-related negativity (FRN). These measures were also examined to determine whether they could successfully distinguish problem (n = 16) from non-problem gamblers (n = 20). Results from this series of studies indicate that outcomes of differing valence (good vs. bad) and magnitude (small vs. large) can be reliably captured and quantified using psychophysiological measures, and that responses to these outcomes can successfully differentiate problem gamblers from non-problem gamblers. A major finding is that, compared to healthy controls, problem gamblers were consistently less responsive to both reward and punishment stimuli, as evidenced by both cortical and autonomic responses. These findings suggest that dysfunction in reward-processing pathways of the brain may, at least partly, explain the aberrant behaviours associated with problem gambling. The thesis contributes significantly to the theoretical conceptualisation of the psychophysiology of gambling, helps clarification among the competing mechanisms suggested to underlie this disorder, and establishes a firm foundation to inform future research including the determination if a pattern of maladaptive incentive processing could serve as a reliable biological marker for problem gambling.

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