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| Drugs and Choice: Behavioral Mechanisms |
| Saturday, May 26, 2007 |
| 3:30 PM–4:50 PM |
| Ford C |
| Area: BPH |
| Chair: Matt Locey (University of Florida) |
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| An Adjusting Delay Procedure to Separate Nicotine Effects on Amount and Delay Sensitivity. |
| Domain: Applied Research |
| MATT LOCEY (University of Florida), Jesse Dallery (University of Florida) |
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| Abstract: Three experiments examined how nicotine affects impulsive choice. In Experiment 1, nicotine dose-dependently increased impulsive choice. In Experiment 2 nicotine had no effect on delay-based risky choice with equal reinforcer amounts, suggesting that nicotine decreased amount sensitivity rather than increased temporal discounting in Experiment 1. In Experiment 3, we used a delay-based risky choice procedure with different amounts on each option. Nicotine increased risky choice to the same extent that nicotine increased impulsive choice in Experiment 1. Overall, the results suggest that nicotine increases impulsive choice by a decrease in amount sensitivity rather than an increase in temporal discounting. |
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| How Nicotine Affects Delay and Amount Sensitivity in a Concurrent Chains Procedure. |
| Domain: Applied Research |
| MATT LOCEY (University of Florida), Jesse Dallery (University of Florida) |
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| Abstract: Two groups of rats responded on concurrent chains with equal-interval initial links. Terminal links differed in either reinforcer amount (group A) or reinforcer delay (group B). Pre-session nicotine injections produced dose-dependent decreases in preference for larger amounts in group A, but had no effect on preference for shorter delays in group B. These results are consistent with recent findings that indicate nicotine increases impulsive choice by decreasing amount sensitivity rather than by increasing delay sensitivity. |
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| Rapid Acquisition in Concurrent Schedules: Effects of d-Amphetamine on Sensitivity to Reinforcement Amount. |
| Domain: Applied Research |
| DAVID R. MAGUIRE (University of North Carolina, Wilmington), Andrew M. Rodewald (University of North Carolina, Wilmington), Christine E. Hughes (University of North Carolina, Wilmington), Raymond C. Pitts (University of North Carolina, Wilmington) |
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| Abstract: Recent research indicates that psychomotor stimulants enhance choice of larger, more delayed over smaller, immediately delivered reinforcers under “self-control” procedures. Such effects suggest at least two possible behavioral mechanisms of drug action: a drug-induced change in sensitivity to reinforcement delay and/or drug-induced change in sensitivity to reinforcement amount. Because self-control procedures contain a delay-amount confound (i.e., the larger reinforcer is usually presented following the larger delay), disentangling the two processes can be difficult (see Pitts and Febbo, 2004). The purpose of the present research was to examine the effects of psychomotor stimulant d-amphetamine on sensitivity to reinforcement amount under concurrent schedules using a rapid-acquisition procedure. Four pigeons were trained on concurrent variable-interval 30-s schedules. Relative reinforcement amounts arranged across the 2 alternatives were varied from session to session according to a pseudorandom binary sequence (cf. Hunter and Davison, 1985); the ratios were either 1/7 or 7/1. Reinforcer amount was manipulated by varying the number of 1.2-s hopper presentations. Reinforcers delivered following responses on either alternative were delivered immediately. d-Amphetamine had no systematic effect on either sensitivity to reinforcer amount or on bias. |
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