Date of Award


Degree Name

Doctor of Philosophy



First Advisor

Dixon, Mark


Problem gambling is a growing social concern that results in debt, lost jobs, broken families, and at times, suicide. Slot machines are the most popular and most addictive form of gambling, generating nearly 70% of annual profits for the commercial casino industry in North America. Behavioral researchers have identified variables that establish and maintain problem gambling on slot machines, and the data reveal characteristics that influence preference for specific games, and subsequently, time spent engaged with specific machines. A degree of variability has been reported in the outcomes observed across participants and studies; such variability may be influenced by generic features of the games used by researchers utilizing a “one machine suits all” approach to slot research, i.e., within most studies a single machine is used for all participants rather than chosen according to participant preference for the machine or features therein. The following set of studies aimed to investigate variables related to slot machine selection, gambler preference for structural characteristics, and the reinforcing effectiveness of the machine on gambling behavior. The first of three experiments evaluated participant preference for functional and structural characteristics of popular three-, four- and five-reel electronic Vegas-style slot machines according to (a) a Likert rating scale of attitudes toward the machines, (b) forced ranking of most-preferred machines, and (c) a paired-stimulus preference assessment. Experiment II utilized a series of multiple schedules randomized across participants to examine differences in the rate of play when participants gambled on their most- and least-preferred machines. In Experiment III, the reinforcing effectiveness of the machines was evaluated. Participants engaged in an arbitrary task to gain access to their highest- and least-preferred machines as indicated in Experiment I. Response effort during the work task was evaluated under a progressive ratio schedule of reinforcement to determine the degree to which the individual would work to gain access to the machine. Participant break points were compared across the two conditions. Results of Experiment I yielded significant differences in the degree to which participants rated the machines: three-reel machines and those displaying a win were rated significantly higher in the attitude assessment when compared to four- or five-reel machines, and when compared to those with a loss, respectively. During the forced ranking procedure, participants again selected three-reel machines significantly more frequently in their “top five” favorite machines than four- or five-reel options. Last, when subjected to the paired stimulus preference assessment, participants selected three-reel machines on a significantly higher percentage of trials than five-reel alternatives. Results of Experiment II demonstrated that rate of play on high-preference machines is on average, faster than rate of play on lower-preference machines, and results from Experiment III yielded on average, higher break points in participant responding when offered the opportunity to gamble on high-preference slot machines following a response requirement than when offered a low-preference option; however, the average rate of response on the work task that led to machine access was lower during high-preference conditions than low-preference conditions. Implications of these findings for the gambling literature and for the effective prevention and treatment of disordered slot machine gambling are discussed.




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