Browsing by Author "Koffarnus, Mikhail N."

Now showing 1 - 7 of 7
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    Choice Bundling Increases Valuation of Delayed Losses More Than Gains in Cigarette Smokers
    Stein, Jeffrey S.; Brown, Jeremiah M.; Tegge, Allison N.; Freitas-Lemos, Roberta; Koffarnus, Mikhail N.; Bickel, Warren K.; Madden, Gregory J. (Frontiers, 2022-01-13)
    Choice bundling, in which a single choice produces a series of repeating consequences over time, increases valuation of delayed monetary and non-monetary gains. Interventions derived from this manipulation may be an effective method for mitigating the elevated delay discounting rates observed in cigarette smokers. No prior work, however, has investigated whether the effects of choice bundling generalize to reward losses. In the present study, an online panel of cigarette smokers (N = 302), recruited using survey firms Ipsos and InnovateMR, completed assessments for either monetary gains or losses (randomly assigned). In Step 1, participants completed a delay-discounting task to establish Effective Delay 50 (ED50), or the delay required for an outcome to lose half of its value. In Step 2, participants completed three conditions of an adjusting-amount task, choosing between a smaller, sooner (SS) adjusting amount and a larger, later (LL) fixed amount. The bundle size (i.e., number of consequences) was manipulated across conditions, where a single choice produced either 1 (control), 3, or 9 consequences over time (ascending/descending order counterbalanced). The delay to the first LL amount in each condition, as well as the intervals between all additional SS and LL amounts (where applicable), were set to individual participants' ED50 values from Step 1 to control for differences in discounting of gains and losses. Results from Step 1 showed significantly higher ED50 values (i.e., less discounting) for losses compared to gains (p < 0.001). Results from Step 2 showed that choice bundling significantly increased valuation of both LL gains and losses (p < 0.001), although effects were significantly greater for losses (p < 0.01). Sensitivity analyses replicated these conclusions. Future research should examine the potential clinical utility of choice bundling, such as development of motivational interventions that emphasize both the bundled health gains associated with smoking cessation and the health losses associated with continued smoking.
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    Choosing Money over Drugs: The Neural Underpinnings of Difficult Choice in Chronic Cocaine Users
    Wesley, Michael J.; Lohrenz, Terry; Koffarnus, Mikhail N.; McClure, Samuel M.; De La Garza, Richard II; Salas, Ramiro; Thompson-Lake, Daisy G. Y.; Newton, Thomas F.; Bickel, Warren K.; Montague, P. Read (Hindawi, 2014-08-14)
    Addiction is considered a disorder that drives individuals to choose drugs at the expense of healthier alternatives. However, chronic cocaine users (CCUs)who meet addiction criteria retain the ability to choose money in the presence of the opportunity to choose cocaine. The neural mechanisms that differentiate CCUs from non-cocaine using controls (Controls) while executing these preferred choices remain unknown. Thus, therapeutic strategies aimed at shifting preferences towards healthier alternatives remain somewhat uninformed. This study used BOLD neuroimaging to examine brain activity as fifty CCUs and Controls performed single- and cross-commodity intertemporal choice tasks for money and/or cocaine. Behavioral analyses revealed preferences for each commodity type. Imaging analyses revealed the brain activity that differentiated CCUs from Controls while choosing money over cocaine. We observed thatCCUs devalued future commodities more than Controls. Choices for money as opposed to cocaine correlated with greater activity in dorsal striatum of CCUs, compared to Controls. In addition, choices for future money as opposed to immediate cocaine engaged the left dorsolateral prefrontal cortex (DLPFC) of CCUs more than Controls. These data suggest that the ability of CCUs to execute choices away from cocaine relies on activity in the dorsal striatum and left DLPFC.
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    Delayed reward discounting and grit in men and women with and without obesity
    Thomas, J. Graham; Seiden, Andrew; Koffarnus, Mikhail N.; Bickel, Warren K.; Wing, Rena R. (Wiley, 2015-08-15)
    Objective The objective of this study was to examine how sensitivity to short-term reward and longterm goal perseverance are related to body mass index (BMI; kgm²) in a large sample of men and women with and without obesity. Methods A total of 450 participants (56.2% male; 73.1% non-Hispanic White) with mean ± standard deviation age of 30.7 ± 10.4 years and BMI of 29.3 ± 8.2 completed online versions of the Delayed Reward Discounting task to measure sensitivity to short-term reward and the Grit Scale to measure long-term goal perseverance. Results In regression analysis, higher sensitivity to short-term reward (i.e. a preference for receiving smaller rewards after a shorter delay; b = 0.49, p = 0.016) and lower long-term goal perseverance (b = 1.26, p = 0.042) were independently associated with higher BMIs. Individuals with a favourable score on one measure were not ‘protected’ from the risk associated with an unfavourable score on the other measure. Conclusions An overvaluation of short-term reward (e.g. the taste of palatable food and the comfort of engaging in sedentary activities) and undervaluation of long-term health goals (e.g. achieving a healthy weight and avoiding obesity-related comorbidities) may contribute to excess weight. Additional research incorporating prospective experimental designs is needed to determine whether decision-making strategies can be targeted to improve weight management.
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    Quantifying the Effects of a Constricted Temporal Window in Reinforcer Pathology
    Mellis, Alexandra Michelle (Virginia Tech, 2019-03-18)
    Health behaviors, positive and negative, can support or reduce risk for multiple chronic diseases, such as substance use disorder and obesity. These diseases are marked by overconsuming commodities that offer predictable short-term benefits, and neglecting other behaviors with variable long-term benefits (e.g., fast food is enjoyable in the moment; exercise may have delayed benefits, but moment-to-moment may not be as reinforcing as fast food). An individual's valuation of these fast food or exercise may depend on how far out into the future these benefits are considered, their temporal window. The first study shows that the temporal window is constricted among high-risk substance users than people who do not have substance problems, especially when considering higher-value choices. The second study shows that the temporal window can change depending on the environment. Specifically, engaging with stories of job loss can constrict the temporal window. The third study shows that engaging with job loss can specifically constrict the temporal window and increase the value of fast food among obese individuals. The final study shows that a similar hardship scenario, natural disasters, can constrict the temporal window, increase demand for alcohol and cigarettes, and decrease the valuation of more temporally extended reinforcers (e.g., employment, savings, and seatbelt wearing) among smoking drinkers. Together, these studies support a model, reinforcer pathology; wherein the temporal window, which can differ both between individuals and environments, drives valuation of reinforcers that impact health.
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    Remote Alcohol Monitoring to Facilitate Incentive-Based Treatment for Alcohol Use Disorder: A Randomized Trial
    Koffarnus, Mikhail N.; Bickel, Warren K.; Kablinger, Anita S. (2018-12)
    B ackground: The delivery of monetary incentives contingent on verified abstinence is an effective treatment for alcohol use disorder. However, technological barriers to accurate, frequent biochemical verification of alcohol abstinence have limited the dissemination of this technique. Methods: In the present randomized parallel trial, we employed a breathalyzer that allows remote, user-verified collection of a breath alcohol sample, text messaging, and reloadable debit cards for remote delivery of incentives to evaluate a contingency management treatment for alcohol use disorder that can be delivered with no in-person contact. Treatment-seeking participants with alcohol use disorder (n = 40) were recruited from the community and randomized to either a contingent or a noncontingent group (n = 20 each). The contingent group received nearly immediate monetary incentives each day they remotely provided negative breathalyzer samples. The noncontingent group received matched monetary payments each day they successfully provided samples independent of alcohol content. Groups were not masked as awareness of group contingencies was an essential intervention component. Results: The primary outcome of the intent-to-treat analyses (analyzed n = 40) was percent days abstinent as measured by the remote breathalyzer samples. Abstinence rates in the contingent group were 85%, which was significantly higher than the 38% recorded in the noncontingent group, corresponding to an odds ratio of 9.4 (95% CI = 4.0 to 22.2). Breathalyzer collection adherence rates were over 95%, and participant ratings of acceptability were also high. Conclusions: These results support the efficacy, acceptability, and feasibility of this remotely deliverable abstinence reinforcement incentive intervention for the initiation and near-term maintenance of abstinence from alcohol in adults with alcohol use disorder. Due to low provider and participant burden, this procedure has the potential for broad dissemination.
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    Stuck in Time: Negative Income Shock Constricts the Temporal Window of Valuation Spanning the Future and the Past
    Bickel, Warren K.; Wilson, A. George; Chen, Chen; Koffarnus, Mikhail N.; Franck, Christopher T. (PLOS, 2016-09-15)
    Insufficient resources are associated with negative consequences including decreased valuation of future reinforcers. To determine if these effects result from scarcity, we examined the consequences of acute, abrupt changes in resource availability on delay discounting—the subjective devaluation of rewards as delay to receipt increases. In the current study, 599 individuals recruited from Amazon Mechanical Turk read a narrative of a sudden change (positive, neutral, or negative) to one’s hypothetical future income and completed a delay discounting task examining future and past monetary gains and losses. The effects of the explicit zero procedure, a framing manipulation, was also examined. Negative income shock significantly increased discounting rates for gains and loses occurring both in the future and the past. Positive income windfalls significantly decreased discounting to a lesser extent. The framing procedure significantly reduced discounting under all conditions. Negative income shocks may result in short-term choices.
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    A tribute to Howard Rachlin and his two-parameter discounting model: Reliable and flexible model fitting
    Franck, Christopher T.; Traxler, Haily K.; Kaplan, Brent A.; Koffarnus, Mikhail N.; Rzeszutek, Mark J. (Wiley, 2023-01)
    Delay discounting reflects the rate at which a reward loses its subjective value as a function of delay to that reward. Many models have been proposed to measure delay discounting, and many comparisons have been made among these models. We highlight the two-parameter delay discounting model popularized by Howard Rachlin by demonstrating two key practical features of the Rachlin model. The first feature is flexibility; the Rachlin model fits empirical discounting data closely. Second, when compared with other available two-parameter discounting models, the Rachlin model has the advantage that unique best estimates for parameters are easy to obtain across a wide variety of potential discounting patterns. We focus this work on this second feature in the context of maximum likelihood, showing the relative ease with which the Rachlin model can be utilized compared with the extreme care that must be used with other models for discounting data, focusing on two illustrative cases that pass checks for data validity. Both of these features are demonstrated via a reanalysis of discounting data the authors have previously used for model selection purposes.