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| Delay Discounting |
| Tuesday, June 1, 2010 |
| 10:30 AM–11:50 AM |
| Republic C (Grand Hyatt) |
| Area: EAB |
| Chair: Matthew W. Johnson (Johns Hopkins University School of Medicine) |
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| Revisiting the Hypothetical Versus Real Rewards Issue in Discounting Research: A Procedural Extension |
| Domain: Experimental Analysis |
| STEVEN R. LAWYER (Idaho State University) |
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| Abstract: Delay and probability discounting procedures provide behavioral measures of impulsive choice and have increased understanding of the behavioral processes that underlie a number of socially-relevant outcomes (e.g. substance abuse). Research to date (Johnson & Bickel, 2002; Madden, et al., 2003) suggests that hypothetical discounting choices generate data that are similar to those for (potentially) real outcomes, but these studies used relatively few participants, focused only on delay discounting, and did not measure the frequency of nonsystematic response patterns (Johnson & Bickel, 2008) that could result from using hypothetical outcomes. In the present study, community-recruited participants (n = 75) completed discounting tasks for hypothetical and potentially real (they received three randomly selected outcomes) outcomes. Preliminary analyses for 35 participants suggest that discounting patterns for hypothetical and potentially real outcomes are similar, though there is a trend (p < .01) toward steeper discounting rates for potentially real outcomes. Hypothetical and potentially real outcomes generated similar rates of nonsystematic response patterns, but delay discounting procedures are more likely to generate nonsystematic response patterns than are probability discounting procedures (p < .05). These findings have important implications regarding the use of discounting procedures in laboratory behavioral research. |
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| The Effect of Caffeine Abstinence on Monetary and Caffeine Delay Discounting |
| Domain: Experimental Analysis |
| Stephen Provost (Southern Cross University), Allison Kingston (Southern Cross University), LEWIS A. BIZO (The University of Waikato) |
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| Abstract: Delay discounting refers to an individual’s preference for smaller immediate reinforcement rather than larger delayed reinforcement, and has been shown to be influenced by deprivation state in smokers and opiate users. The effect of caffeine withdrawal has not yet been examined in a delay discounting procedure, however, despite its status as the most widely used stimulant drug. Caffeine consumers (n = 24) completed a monetary and a caffeine delay discounting task following normal caffeine consumption on one occasion, and following 12h caffeine abstinence on another occasion, counterbalanced across participants. In line with the results of such studies relating to other drugs, delayed monetary and caffeine rewards were discounted at a significantly higher rate when participants had abstained from caffeine consumption. Discounting rates of non-abstinent caffeine consumers was indistinguishable from that of eight participants who did not consume caffeine products. The implications of this result for an understanding of impulsive behaviour and drug-taking, as well as its ramifications for decision-making behaviour in the real world, will be discussed. |
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| An Efficient Operant Choice Procedure for Assessing Delay Discounting in Humans |
| Domain: Experimental Analysis |
| MATTHEW W. JOHNSON (Johns Hopkins University School of Medicine) |
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| Abstract: Delay discounting refers to the observation that a consequence’s control over behavior declines as a function of delay until the consequence. Many studies now suggest that delay discounting may be a fundamental behavioral process in drug dependence and other behavioral disorders. Human delay discounting studies have usually relied on hypothetical choices or questionnaires. Some human tasks have attempted to measure delay discounting using operant procedures with contingent consequences provided during the task, as in nonhuman delay discounting studies. However, these tasks have had limitations such as long duration (limiting use in experimental contexts such as drug administration), indeterminate (non-operationally defined) data, or the potential confounding of delayed reinforcement with probabilistic reinforcement. An ongoing study in cocaine dependent volunteers (current N=8) is assessing a novel operant delay discounting procedure that provides real-time monetary reinforcement, and requires approximately 12 minutes to complete. Preliminary analyses have shown generally systematic effects of delay, and that a hyperbolic function provides a significantly better fit to the data than an exponential function, consistent with previous delay discounting findings. Data (based on a larger N) will be presented, including a within-subject comparison of the novel task with previously used delay discounting tasks that are also being administered. |
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