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. (PsycINFO Database Record
Episodic future thinking (EFT), or imagining experiencing one's future, reduces discounting of future rewards, but the mechanisms of this effect are unclear. We examined the role of cues to engage in EFT, possible demand characteristics inherent to those cues (prompting awareness of the hypothesized effects of EFT), and changes in temporal horizon (how far one thinks into the future) in these reductions in delay discounting. In Experiment 1, cues prompting participants to engage in EFT during the discounting task were presented or withheld: EFT decreased discounting only when cues were present. In a time-perspective task in which cues were not presented, EFT did not broaden temporal horizon; however, episodic recent thinking (the putative control activity) shortened temporal horizons. In Experiment 2, cues were manipulated in a way designed to make them either more theoretically relevant (prompting episodic thought) or more prone to demand characteristics (prompting attention to the correspondence in delays between EFT and discounting tasks). Only theoretically relevant cues reduced delay discounting. These results do not support the hypothesis that EFT reduces delay discounting because of demand characteristics. Instead, they suggest limitations on the generalizability of EFT effects in uncued contexts and suggest that mechanisms other than temporal horizon may be responsible for its effects.
In delay discounting, temporally remote outcomes have less value. Cigarette smoking is associated with steeper discounting of money and consumable outcomes. It is presently unclear whether smokers discount health outcomes more than non-smokers. We sought to establish the generality of steep discounting for different types of health outcomes in cigarette smokers. Seventy participants (38 smokers and 32 non-smokers) completed four hypothetical outcome delay-discounting tasks: a gain of $500, a loss of $500, a temporary boost in health, and temporary cure from a debilitating disease. Participants reported the duration of each health outcome that would be equivalent to $500; these durations were then used in the respective discounting tasks. Delays ranged from 1 week to 25 years. Smokers’ indifference points for monetary gains, boosts in health, and temporary cures were lower than indifference points from non-smokers. Indifference points of one outcome were correlated with indifference points of other outcomes. Smokers demonstrate steeper discounting across a range of delayed outcomes. How a person discounts one outcome predicts how they will discount other outcomes. These two findings support our assertion that delay discounting is in part a trait.
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. (PsycINFO Database Record
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.
Delay discounting describes the tendency to devalue delayed consequences or future prospects. The degree to which an individual discounts delayed events appears trait-like in that it is stable over time and across functionally similar situations. Steeply discounting delayed rewards is correlated with most substanceuse disorders, the severity of these disorders, rates of relapse to drug use, and a host of other maladaptive decisions affecting human health. Longitudinal data suggest steep delay discounting and high levels of impulsive choice are predictive of subsequent drug taking, which suggests (though does not establish) that reducing delay discounting could have a preventive health-promoting effect. Experimental manipulations that produce momentary or long-lasting reductions in delay discounting or impulsive choice are reviewed, and behavioral mechanisms that may underlie these effects are discussed. Shortcomings of each manipulation technique are discussed and areas for future research are identified. Although much work remains, it is clear that impulsive decision making can be reduced, despite its otherwise trait-like qualities. Such findings invite technique refinement, translational research, and hope.
Most delay discounting studies use tasks that arrange delay progressions in which the spacing between consecutive delays becomes progressively larger. To date, little research has examined delay discounting using other progressions. The present study assessed whether the form or steepness of discounting varied across different delay progressions. Human participants completed three discounting tasks with delay progressions that varied in the time between consecutive delays: a standard (increasing duration between delays), linear (equal duration between delays), and an inverse progression (decreasing duration between delays). Steepness of discounting was generally reduced, and remained so, following experience with the inverse progression. Effects of the delay progression on the best fitting equation were order-dependent. Overall the hyperbola model provided better fits, but the exponential model performed better with data from the inverse progression. Regardless, differences in which model fit best were often small. The finding that the best fitting model was dependent, in some cases, on the delay progression suggests that a single quantitative model of discounting may not be applicable to describe discounting across all procedural contexts. Ultimately, changes in steepness of discounting following experience with the inverse progression appeared similar to anchoring effects, whose mechanism will require further study to delineate.
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