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| International Paper Session - Temporal and Probability Discounting |
| Sunday, May 25, 2008 |
| 10:30 AM–11:50 AM |
| Barbershop |
| Area: EAB |
| Chair: Andrew T. Fox (Central Michigan University) |
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| Reward Contrast in Delay and Probability Discounting. |
| Domain: Basic Research |
| ZHIJIE DAI (University of Canterbury), Randolph C. Grace (University of Canterbury), Simon Kemp (University of Canterbury) |
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| Abstract: The present research asked whether contrast effects - which are commonly obtained in psychophysical research - influence delay and probability discounting in choices. Participants responded to a series of hypothetical questions involving amounts of money available immediately or after a delay, or available for sure or with uncertainty in a computer-based task (Grace & McLean, 2005). In Experiment 1, for different groups, discounting questions involving a test amount ($500) were preceded by blocks of questions in which a smaller ($50) or larger ($5,000) amount was used. All participants answered questions in both delay and probability discounting scenarios. In Experiment 2, participants were divided into delay-discounting and probability-discounting groups. Questions for both smaller ($50) and larger ($5,000) amounts were completed by all participants. In each group, questions for test amounts - $475 or $525, were completed after the smaller or larger amounts. Participants also completed questionnaires BIS-11 (Patton, Stanford & Barratt, 1995) and SOGS (Lesieur & Blume, 1987). In both experiments, we found evidence of contrast effects for both delay and probability discounting. Specifically, discounting rates for test amounts varied in a manner consistent with the hypothesis that the subjective magnitude depended inversely on the amount used in the prior block of questions. |
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| Delay and Probability Discounting for Hypothetical Food and Money. |
| Domain: Basic Research |
| WILLIAM J.P. REILLY (Idaho State University), Erin B. Rasmussen (Idaho State University) |
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| Abstract: We used the delay and probability discounting paradigms to determine if discounting for hypothetical food could be quantified via the delay and probability discounting functions, and how hypothetical food compared to more established rewards, such as money. Eighty participants completed a computer-based task that presented a series of hypothetical choices between dollar amounts that varied in terms of delay (in days), and value (e.g., “Would you rather have 1 dollar now or 4 dollars in 10 days?”). Choices were presented also as varied probabilities to the dollar amounts (e.g., Would you rather be guaranteed 3 dollars or have a 25% chance of receiving 10 dollars?”) Participants were also asked to imagine a 1” cube as a standardized bite of their favorite food, and given the delay and probability discounting tasks, except the independent variables were standardized bites of food and time (minutes). Indifference points for each subject were fit to the delay discounting and probability discounting exponential and hyperbolic equations. Results suggest that the majority of participants’ data fit the money and food discounting equations. Moreover, food was discounted more steeply than money. These results suggest that individuals will discount more for hypothetical food than they will hypothetical money. |
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| The Role of Temporal Discounting in the Analysis of Social Interaction. |
| Domain: Basic Research |
| SHAWN R. CHARLTON (University of Central Arkansas), Joyce Brownlee (University of Central Arkansas) |
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| Abstract: Extensive literature documents the loss of reinforcing value as an outcome becomes more temporally delayed. However, the majority of this research has focused on the affect of delay on non-social outcomes such as money, food, and other tangible commodities. Real world behavior, however, frequently involves another less-tangible outcome, social interaction. In this paper, we review an emerging body of research exploring the affect of temporal discounting on the reinforcing value of social interactions. Discussion will be given both to how temporal delay affects the evaluation of social interactions as well as how social interactions are affected by changes in temporal discounting. |
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| Delayed Discounting in the Mouse: A Parametric Analysis. |
| Domain: Basic Research |
| CRISTINA VARGAS-IRWIN (Virginia Commonwealth University), Jaime Robles (Virginia Commonwealth University) |
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| Abstract: Advances in forward genetics have made the laboratory mouse the animal model of choice in many pharmacological and behavioral genetic settings, yet the operant literature using mice as subjects continues to be relatively sparse. We described the challenges involved in operant work with the laboratory and present data on the acquisition of operant responding and delay discounting procedures in mice, and compare the discount functions with those reported in the literature for other mammalian species. |
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