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| Changing Impulsivity: Manipulations That Affect Delay Discounting |
| Monday, May 30, 2016 |
| 10:00 AM–11:50 AM |
| Zurich AB, Swissotel |
| Area: EAB/BPN; Domain: Translational |
| Chair: Maggie Sweeney (Johns Hopkins University School of Medicine) |
| Discussant: Leonard Green (Washington University) |
| Abstract: Decades of research suggest that degree of delay discounting differs in clinically relevant populations relative to control populations. For example, individuals who smoke cigarettes, use illicit drugs, are obese, or fail to take preventative health measures tend to discount delayed rewards more relative to comparison groups. Recent evidence suggests that degree of discounting, previously been compared to a stable trait, is sensitive to experimental manipulation. This symposium presents data in which experimental manipulation affected delay discounting. Meredith Berry will present data suggesting visual exposure to natural environments decreases discounting, and that this effect may be related to lengthened time perception. Renee Renda will present data with rat subjects suggesting lasting reductions in discounting can be produced by delay exposure. Sarah Snider will present data in which episodic future thinking decreased discounting and intensity of demand for alcohol in alcohol dependent individuals. Matthew Johnson will present data suggesting acute doses of cocaine and alcohol increase discounting of condom-protected sex, but do not affect discounting of money. Leonard Green will integrate these presentations as discussant. Data in this symposium suggest degree of discounting has both trait and state characteristics. This knowledge is important for the development of interventions for impulsive decision making. |
| Keyword(s): behavioral pharmacology, delay discounting, episodic-future thinking, timing |
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| Making Time for Nature: Visual Exposure to Natural Environments Lengthens Time Perception and Reduces Impulsivity |
| MEREDITH STEELE BERRY (Johns Hopkins University School of Medicine), Meredith Repke (University of Montana), Kerry Jordan (Utah State University), Amy Odum (Utah State University) |
| Abstract: Impulsivity in delay discounting is associated with maladaptive behaviors such as overeating and drug and alcohol abuse. Identifying techniques to decrease impulsivity in delay discounting could help improve decision-making on a global scale. Visual exposure to natural environments is one recent approach shown to decrease impulsive decision-making in a delay discounting task, although the mechanism driving this result is currently unknown. The present experiment was thus designed to evaluate whether visual exposure to natural (mountains) relative to built (buildings) environments resulted in less impulsivity, but also whether this exposure influenced time perception. Participants viewed photographs of either natural scenes or built scenes before and during a delay discounting task in which they made choices about receiving immediate or delayed hypothetical monetary outcomes. Then measures of time perception were administered including how many minutes participants thought had passed during the session and a scale measurement of whether time "flew" or "dragged" during the session. Participants exposed to natural as opposed to built scenes were less impulsive and also reported longer subjective session times. These results are the first to suggest that decreased impulsivity from exposure to natural as opposed to built environments may be related to lengthened time perception. |
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| Experimentally Manipulating Delay Discounting in Rats: Durability and Generalization |
| RENEE RENDA (Utah State University), Jacy Draper (Utah State University), Brian Hess (Utah State University), Gregory J. Madden (Utah State University) |
| Abstract: Delay discounting characterizes the subjective devaluation of outcomes delayed in time. Robust, positive correlations exist between excessive delay discounting and many maladaptive behaviors (e.g., substance abuse, gambling). Several studies have demonstrated that delay discounting can be reduced and many hypothesize that this may result in more efficacious treatment outcomes. Experimentally manipulating delay discounting in nonhumans allows for the examination of variables that are not susceptible to human research (e.g., drug self-administration). Using a training regimen that involved early, extended experience with delayed reinforcement, Stein et al. (2013) found significant reductions in rats discounting delayed food rewards. A similar reduction was not observed in control rats (i.e., delay-naïve group) that had extended experience with immediate reinforcement. The present research sought to replicate and extend those findings. In our first study, we observed a significant, lasting reduction in delay discounting when reassessed at a 4-month follow-up (Panels A & B). In our second, ongoing experiment, we are examining whether this delay-exposure effect generalizes to other types of impulsive-choice assessments. Preliminary data with a small group of rats suggests that the data are trending in the predicted direction in the adjusting-delay procedure, but not in the variable-delay procedure (Panels C & D). |
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| Episodic Future Thinking: Expansion of the Temporal Window in Alcohol Dependents |
| SARAH EMILY SNIDER (Virginia Tech Carilion Research Institute), Stephen LaConte (Virginia Tech Carilion Research Institute), Warren K. Bickel (Virginia Tech Carilion Research Institute) |
| Abstract: Episodic future thinking (EPI) requires an individual to truly pre-experience a realistic future event. Given previous reports of reducing delay discounting following EPI in other populations, we examined the effects of engaging alcohol dependent individuals in episodic future (Active) or recent (Control) thinking to examine its effects on delay discounting and alcohol purchasing. Participants (n=50) were allocated into EPI or Control groups and asked to generate positive future or recent past events for each of five time-points. Participants then completed a delay-discounting task, during which event cues were displayed, and a hypothetical alcohol purchase task. EPI significantly increased valuation of future monetary rewards, while decreasing initial consumption (Q0) of alcoholic drinks indicative of lower demand intensity. Two additional findings suggest potential mechanisms. EPI more readily influenced alcohol dependents with low AUDIT scores, and self-reported cue valence differed between groups. Together, these results suggest a widening of alcohol dependents’ temporal window following engagement of EPI. While our data suggest that EPI may be moderated by certain susceptibility criteria, exercises such as episodic future thinking could be easily adaptable as a potential therapeutic tool for use in rehabilitation programs. |
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| Does Drug Administration Affect Delay Discounting in Humans? It Depends on What's Being Delayed |
| MATTHEW W. JOHNSON (Johns Hopkins University School of Medicine) |
| Abstract: Human studies have tended to show that alcohol and other drugs do not occasion changes in delay discounting. These studies have assessed discounting using money reward outcomes. However, substantial evidence indicates that individuals are not characterized by a single, universal discounting rate. Rather, delay discounting rate is dependent on the outcome being discounted, with discounting rate differing due to outcome magnitude, and outcome valence (reinforce or punisher). Moreover, an emerging literature has shown commodity-specific relations to clinical disorders, with the discounting rate of clinically relevant outcomes, as opposed to money, showing a stronger relation to pathological behavior. Systematically extending such observations, this presentation will review recent studies showing that administering drugs of abuse (e.g., alcohol, cocaine) causes no change in the discounting of money, but causes significant increases in the discounting of condom use within casual sex scenarios. This finding is consistent with substantial evidence showing episode-level associations between consumption of these drugs and sexual risk behavior. These findings suggest that universal conclusions regarding delay discounting as a behavioral process should not be based exclusively on tasks using money discounting. Moreover, these data indicate studies should assess discounting of outcomes that are closely tied to the clinical behavior of interest. |
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