Mark R. Dixon

Bio: Mark R. Dixon is an academic researcher from University of Illinois at Chicago. The author has contributed to research in topics: Autism & Acceptance and commitment therapy. The author has an hindex of 34, co-authored 219 publications receiving 3964 citations. Previous affiliations of Mark R. Dixon include University of Nevada, Reno & Southern Illinois University Carbondale.

Delay discounting by pathological gamblers.

Abstract: Discounting of delayed rewards by pathological gamblers was compared to discounting of delayed rewards by matched control nongambling participants All participants completed a hypothetical choice task in which they made repeated choices between dollars 1,000 available after a delay and an equal or lesser amount of money available immediately The delay to the large amount of money was varied from 1 week to 10 years across conditions Indifference points between immediate money and delayed money were identified at each delay condition by varying the amount of immediate money across choice trials For the majority of participants, indifference points decreased monotonically across delays Overall, gamblers discounted the delayed rewards more steeply than did control participants

Contextual control of delay discounting by pathological gamblers.

Abstract: The present study demonstrated the relative impact of gambling and nongambling contexts on the degree of delay discounting by pathological gamblers. We used a delay-discounting task with 20 pathological gamblers in and out of the natural context in which they regularly gambled. For 16 of the 20 participants, it appeared that the difference of context altered the subjective value of delayed rewards, thereby producing relative changes in delay-discounting rates that were generally consistent with a hyperbolic model of intertemporal choice. The current data suggest that empirically derived k values from delay-discounting tasks are context sensitive and are not constant across various settings for the individual. Implications for future transitional research on addictive disorders generally, and gambling specifically, are discussed.

Neurobehavioral evidence for the “near‐miss” effect in pathological gamblers

Abstract: The purpose of this translational study was twofold: (1) to contrast behavioral and brain activity between pathological and nonpathological gamblers, and (2) to examine differences as a function of the outcome of the spin of a slot machine, focusing predominately on the “Near-Miss”—when two reels stop on the same symbol, and that symbol is just above or below the payoff line on the third reel. Twenty-two participants (11 nonpathological; 11 pathological) completed the study by rating the closeness of various outcomes of slot machine displays (wins, losses, and near-misses) to a win. No behavioral differences were observed between groups of participants, however, differences in brain activity were found in the left midbrain, near the substantia nigra and ventral tegmental area (SN / VTA). Near-miss outcomes uniquely activated brain regions associated with wins for the pathological gamblers and regions associated with losses for the nonpathological gamblers. Thus, near-miss outcomes on slot machines may contain both functional and neurological properties of wins for pathological gamblers. Such a translational approach to the study of gambling behavior may be considered an example that gives life to B. F. Skinner's conceptualization of the physiologist of the future.

Near-miss effects on response latencies and win estimations of slot machine players

Abstract: The present study examined the degree to which slot machine near-miss trials, or trials that displayed 2 of 3 winning symbols on the payoff line, affected response times and win estimations of 12 recreational slot machine players. Participants played a commercial slot machine in a casino-like laboratory for course extra-credit points. Videotaped sessions were later coded to assess trial types and participant response latencies and win estimations for each participant. Results show that all 12 participants emitted verbalizations suggesting near-miss trials were of a higher approximation to a win than non-near-miss losing trials. Of the 12 participants 8 also demonstrated higher response latencies following losing trials than following winning trials. Variations across participants’ response latencies were attributed to the presence of and response to near miss trials. The implications of the near-miss on game preference, resistance to extinction, and the development of a behavioral treatment for pathological gamblers are discussed.

Using a Self-Control Training Procedure To Increase Appropriate Behavior.

Abstract: The present study evaluated a technique for teaching self-control and increasing desirable behaviors among adults with developmental disabilities. Results showed that when participants were initially given the choice between an immediate smaller reinforcer and a larger delayed reinforcer, all participants repeatedly chose the smaller reinforcer. Concurrent fixed-duration/progressive-duration reinforcement schedules then were introduced in which initially both the smaller and larger reinforcers were available immediately. Thereafter, progressively increasing delays were introduced for the schedule associated with the larger reinforcer only. When initial short-duration requirements for access to the larger reinforcer were gradually increased, participants repeatedly selected the larger reinforcer, thereby demonstrating increased self-control.

Delayed reward discounting and addictive behavior: a meta-analysis

Abstract: Rationale Delayed reward discounting (DRD) is a behavioral economic index of impulsivity and numerous studies have examined DRD in relation to addictive behavior. To synthesize the findings across the literature, the current review is a meta-analysis of studies comparing DRD between criterion groups exhibiting addictive behavior and control groups.

A review of delay-discounting research with humans: relations to drug use and gambling.

Abstract: Delay discounting represents the extent to which consequences, or outcomes, decrease in effectiveness to control behavior as a function of there being a delay to their occurrence. Higher rates of delay discounting are often operationalized as an index of impulsivity, and as such impulsive discounting may hold considerable potential for understanding fundamental behavioral processes associated with a range of problematic behaviors - including drug use and pathological gambling. This paper first provides a review of several assessment methods used in delay-discounting research with humans. Following, the delay-discounting literature related to drug use and gambling is reviewed. Consistencies across this literature are identified; and future research directions are discussed, which include (a) improving methods of assessment for delay discounting and (b) moving drug-use research progressively to causal interpretations, with high rates of delay discounting either predisposing to drug use or resulting from drug use itself.