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The Picoeconomics of Addiction
Published in Hanna Pickard, Serge H. Ahmed, The Routledge Handbook of Philosophy and Science of Addiction, 2019
In addition to the tangle of personal rules just described, hyperbolic discounting predicts a simple mechanism for apparent habit. Devalued addictive reward does not lose its power evenly over a consumption episode; initial phases stay rewarding, at least relative to the alternatives still available, but no longer last as long. Given its reduced average value the consumption may look like robotic repetition, while hyperbolic overvaluation of the near future keeps it the dominant choice. A recurring urge followed by disappointment has the time pattern of an itch, but the path of least resistance is still to scratch the itch—light another cigarette, eat another snack—rather than tax a depleted willpower fighting recurrent urges. The activity is still based on reward (see Ainslie, 2017a).
Delay Discounting, Glycemic Regulation and Health Behaviors in Adults with Prediabetes
Published in Behavioral Medicine, 2021
Leonard H. Epstein, Rocco A. Paluch, Jeffrey S. Stein, Teresa Quattrin, Lucy D. Mastrandrea, Kyle A. Bree, Yan Yan Sze, Mark H. Greenawald, Mathew J. Biondolillo, Warren K. Bickel
where V is discounted value, A is reward amount, D is delay, and k is a free parameter that indexes rate of discounting. Higher values of k indicate more rapid devaluation of the delayed reward and greater impulsivity. Patterns of responding in the adjusting amount task were checked to see if systematic responding was observed using two rules: 1) If the subsequent indifference point was 20% less than the preceding indifference point of the larger, later reward. 2) If the last indifference point was not less than the first indifference point by at least a magnitude equal to 10% of the larger later reward.22 Nonsystematic participants were excluded from analyses for each respective discounting measure, resulting in 79 participants with valid $100 discounting, and all 81 participants showed valid responding for the $1000 discounting task. Figure 1 presents the hyperbolic discounting curve for both the $100 and $1000 delayed rewards.
Evaluating effects of episodic future thinking on valuation of delayed reward in cocaine use disorder: a pilot study
Published in The American Journal of Drug and Alcohol Abuse, 2021
Sarah E. Forster, Stuart R. Steinhauer, Andrea Ortiz, Steven D. Forman
With respect to discounting behavior, “switch points” were determined for each condition by averaging the maximum delayed value resulting in immediate amount selection and the minimum delayed value resulting in delayed amount selection. A hyperbolic discounting model was then applied using R (https://www.R-project.org/), wherein the subjective value of delayed reward (V) is a function of the reward amount (A), delay (D), and discounting rate (k) of the form: V = A/(1+ kD) (see 57). For each participant and condition (EFT, Standard), the parameter k that minimized least square errors across all switch points was determined (see Figure 2 for example discounting functions). Root-mean-square error (RMSE) was subsequently computed for each model, with lower values reflecting better model fit. Paired t-tests were conducted to compare discounting rates and RMSE derived from models applied to EFT versus standard discounting conditions. Due to the skewed distribution of discounting rates, the natural log of k was used for all statistical comparisons.
Development and Validation of a Future Self-Continuity Questionnaire: A Preliminary Report
Published in Journal of Personality Assessment, 2020
Temporal Discounting Task. We used a task developed by Hardisty and Weber (2009) where participants are asked their preferences for receiving lottery winnings. They are given a series of binary choices where they choose between receiving $120 now or varying amounts of money ($113, $120, $137, $154, $171, $189, $206, $223, and $240) a year from now. Based on when they started selecting the larger sum for a year from now, we calculated a discounting rate (k) for each subject using the hyperbolic-discounting formula (see Hardisty & Weber [2009] for details). Increasing values of k, indicating participants did not switch to the future benefiting option until the sums were larger than the present option, imply increased temporal discounting.