Jillian M. Rung

Sensitivity to Changing Contingencies in an Impulsivity Task

Using a video-game-based escalating interest task, participants repeatedly encountered a reward that gradually increased in value over a 10-second interval. Responding early in the interval netted less immediate reward than responding later in the interval. Each participant experienced four different reward contingencies for waiting. These contingencies were changed three times as the experiment proceeded. Behavior tracked these changing contingencies, but wait times reflected long-term carryover from the previously assigned contingencies. Both the tendency to respond slowly and the optimality of behavior were affected by the order of contingencies experienced. Demographic variables only weakly predicted behavior, and delay discounting rate in a hypothetical money choice task predicted choice only when the contingencies in the game were weaker.

Outcome Probability versus Magnitude: When Waiting Benefits One at the Cost of the Other

Using a continuous impulsivity and risk platform (CIRP) that was constructed using a video game engine, choice was assessed under conditions in which waiting produced a continuously increasing probability of an outcome with a continuously decreasing magnitude (Experiment 1) or a continuously increasing magnitude of an outcome with a continuously decreasing probability (Experiment 2). Performance in both experiments reflected a greater desire for a higher probability even though the corresponding wait times produced substantive decreases in overall performance. These tendencies are considered to principally reflect hyperbolic discounting of probability, power discounting of magnitude, and the mathematical consequences of different response rates. Behavior in the CIRP is compared and contrasted with that in the Balloon Analogue Risk Task (BART).

Learning to wait for more likely or just more: greater tolerance to delays of reward with increasingly longer delays

Little research has focused on training greater tolerance to delays of rewards in the context of delayed gratification. In delayed gratification, waiting for a delayed outcome necessitates the ability to resist defection for a continuously available smaller, immediate outcome. The present research explored the use of a fading procedure for producing greater waiting in a video-game based, delayed gratification task. Participants were assigned to conditions in which either the reward magnitude, or the probability of receiving a reward, was a function of time waited and the delay to the maximum reward was gradually increased throughout this training. Waiting increased for all participants but less for those waiting for a greater reward magnitude than a greater reward probability. All participants showed a tendency to wait in a final testing phase, but training with probabilistic outcomes produced a significantly greater likelihood of waiting during testing. The behavioral requirements of delay discounting versus delay gratification are discussed, as well as the benefits of training greater self-control in a variety of contexts.

Experimental reductions of delay discounting and impulsive choice: A systematic review and meta-analysis.

Many behaviors posing significant risks to public health are characterized by repeated decisions to forego better long-term outcomes in the face of immediate temptations. Steeply discounting the value of delayed outcomes often underlies a pattern of impulsive choice. Steep delay discounting is correlated with addictions (e.g., substance abuse, obesity) and behaviors such as seatbelt use and risky sexual activity. As evidence accumulates suggesting steep delay discounting plays a causal role in these maladaptive behaviors, researchers have begun testing methods for reducing discounting. In this first systematic and comprehensive review of this literature, the findings of 92 articles employing different methodologies to reduce discounting are evaluated narratively and meta-analytically. Although most of the methods reviewed produced significant reductions in discounting, they varied in effect sizes. Most methods were ideal for influencing one-off choices (e.g., framing and priming manipulations), although other successful manipulations, such as episodic future thinking, could be incorporated into existing therapies designed to produce longer-lasting changes in decision-making. The largest and longest-lasting effects were produced by learning-based manipulations, although translational research is needed to determine the generality and clinical utility of these methods. Methodological shortcomings in the existing literature and suggestions for ameliorating these issues are discussed. This review reveals a variety of methods with translational potential, which, through continued refinement, may prove effective in reducing impulsive choice and its associated maladaptive decisions that negatively impact quality of life.

Demand characteristics in episodic future thinking: Delay discounting and healthy eating.

Steep delay discounting, or rapid devaluation of future outcomes, is one mechanism that can account for the chronic selection of smaller-sooner over larger-later outcomes; that is, impulsive choice. Because steep delay discounting is correlated with maladaptive behavior, researchers have explored methods for reducing discounting. One empirically supported method is episodic future thinking (EFT), or vividly imagining one’s future before completing the discounting task. However, EFT procedures may include demand characteristics, which could account for some its beneficial effects. In two experiments, demand characteristics were evaluated by having participants read a description of the interactions between a fictional experimenter and a human subject in a typical EFT study. When subsequently asked to indicate what the fictional experimenter expected the human subject to do after the EFT exercise, participants correctly deduced the experimenter’s hypotheses: that EFT would reduce impulsive choice (Experiment 1A) and consumption of junk food (Experiment 1B). Future research should evaluate and control for the possibility that demand characteristics are at least partially responsible for the beneficial effects of EFT.

Continuous nicotine exposure does not affect resurgence of alcohol seeking in rats

Alcohol is the most commonly used drug in the United States and alcohol abuse can lead to alcohol use disorder. Alcohol use disorder is a persistent condition and relapse rates following successful remission are high. Many factors have been associated with relapse for alcohol use disorder, but identification of these factors has not been well translated into preventative utility. One potentially important factor, concurrent nicotine use, has not been well investigated as a causal factor in relapse for alcohol use disorder. Nicotine increases the value of other stimuli in the environment and may increase the value of alcohol. If nicotine increases the value of alcohol, then nicotine use during and after treatment may make relapse more probable. In the current study, we investigated the effect of continuous nicotine exposure (using osmotic minipumps to deliver nicotine or saline, depending on group, at a constant rate for 28 days) on resurgence of alcohol seeking in rats. Resurgence is a type of relapse preparation that consists of three phases: Baseline, Alternative Reinforcement, and Resurgence Testing. During Baseline, target responses produced a dipper of alcohol. During Alternative Reinforcement, target responses were extinguished and responses on a chain produced a chocolate pellet. During Resurgence Testing, responses on the chain were also extinguished and a return to responding on the target lever was indicative of resurgence. Multilevel modeling was used to analyze the effect of nicotine on resurgence. Both the nicotine and saline group showed resurgence of alcohol seeking, but there was no difference in the degree of resurgence across groups. Future directions could involve testing alternative drug delivery techniques.

Impulsive choice and pre-exposure to delays: iv. effects of delay- and immediacy-exposure training relative to maturational changes in impulsivity: REDUCING IMPULSIVE CHOICE

Impulsive choice describes preference for smaller, sooner rewards over larger, later rewards. Excessive delay discounting (i.e., rapid devaluation of delayed rewards) underlies some impulsive choices, and is observed in many maladaptive behaviors (e.g., substance abuse, gambling). Interventions designed to reduce delay discounting may provide therapeutic gains. One such intervention provides rats with extended training with delayed reinforcers. When compared to a group given extended training with immediate reinforcers, delay-exposed rats make significantly fewer impulsive choices. To what extent is this difference due to delay-exposure training shifting preference toward self-control or immediacy-exposure training (the putative control group) shifting preference toward impulsivity? The current study compared the effects of delay- and immediacy-exposure training to a no-training control group and evaluated within-subject changes in impulsive choice across 51 male Wistar rats. Delay-exposed rats made significantly fewer impulsive choices than immediacy-exposed and control rats. Between-group differences in impulsive choice were not observed in the latter two groups. While delay-exposed rats showed large, significant pre- to posttraining reductions in impulsive choice, immediacy-exposed and control rats showed small reductions in impulsive choice. These results suggest that extended training with delayed reinforcers reduces impulsive choice, and that extended training with immediate reinforcers does not increase impulsive choice.

Differential Relations Between Delay Discounting and Distress Tolerance as a Function of Opportunity Cost and Alcohol Use

Delay discounting refers to one process by which an individual devalues delayed outcomes. Typical discounting tasks provide no information about events during delays to larger-later rewards. Imposing opportunity costs during the delay increases how steeply delayed rewards are discounted (P. S. Johnson, Herrmann, & Johnson, 2015). The present research evaluated whether distress tolerance (i.e., one’s ability to tolerate distressing emotions and events) is related to discounting rates when opportunity costs are low, high, or unspecified. In a sample of predominantly female college students, we partially replicated that delay discounting was related to distress tolerance when opportunity costs were unspecified (significant relations confined to particular facets of distress tolerance), but distress tolerance was not related to delay discounting when opportunity costs were specified as low or high. The nature of the relation between distress tolerance and discounting when opportunity costs were unspecified was clarified by a significant interaction between alcohol use and distress tolerance; distress tolerance was unrelated to delay discounting except among participants with problematic alcohol use. Further research is needed to characterize relations between alcohol use, distress tolerance, and delay discounting and inform prevention and treatment efforts in at-risk populations.

Reducing impulsive choice: V. The role of timing in delay-exposure training

Impulsive decision-making is common in addiction-related disorders, with some research suggesting it plays a causal role in their development. Therefore, reducing impulsive decision-making may prevent or reduce addiction-related behaviors. Recent research shows that prolonged experience with response-contingent delayed reward (delay exposure [DE] training) reduces impulsive choice in rats, but it is unclear what behavioral mechanisms underlie this effect. The present study evaluated whether improvements in interval timing mediate the effects of DE training on impulsive choice. Thirty-nine Long-Evans rats were randomly assigned to groups completing DE, immediacy-, or no-exposure training, followed by impulsive-choice and timing tasks (temporal bisection). Despite replicating the DE effect on impulsive choice, timing accuracy and precision were unaffected by DE training and unrelated to impulsive choice. The present findings did not replicate previous reports that timing precision and impulsive choice are related, which may be due to between-laboratory differences in impulsive choice tasks. Continued research to identify candidate behavioral mechanisms of DE training may assist in improving training efficacy and facilitating translational efforts.

Choosing the right delay-discounting task: Completion times and rates of nonsystematic data

A variety of delay discounting tasks are widely used in human studies designed to quantify the degree to which individuals discount the value of delayed rewards. It is currently unknown which task(s) yields the largest proportion of valid and systematic data using standard criteria (Johnson & Bickel, 2008). The goal of this study was to compare three delay-discounting tasks on task duration and amount of valid and systematic data produced. In Experiment 1, 180 college students completed one of three tasks online (fixed alternatives, titrating, or visual analogue scale [VAS]). Invalid and nonsystematic data, identified using standard criteria, were most prevalent with the VAS (47.3% of participants). The other tasks produced more (and similar amounts of) valid and systematic data, but required more time to complete than the VAS. Viewing systematic data as more important than completion times, Experiment 2 (n = 153 college students) sought to reduce the amount of invalid datasets in the fixed-alternatives task, and compare amounts of nonsystematic data with the titrating task. Completion times were superior in the titrating task, which produced modestly more systematic data than the fixed-alternatives task. Causes of invalid and nonsystematic data are discussed, as are methods for reducing data exclusion.