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| Discriminating and Attending |
| Sunday, May 28, 2006 |
| 3:00 PM–4:20 PM |
| Hong Kong |
| Area: EAB; Domain: Basic Research |
| Chair: Amy Odum (Utah State University) |
| Abstract: This symposium brings together recent research on discriminating and attending. Woods and colleagues will present data on the effects of quinpirole on cocaine-maintained responding and responding for cocaine-related stimuli. Shahan and Podlesnik will report on the effects of added free food on the persistence of observing. Vaidya and colleagues will show the effects of observing response requirements on the duration of the delay in a titrating delayed matching-to-sample procedure. Nevin and colleagues will present data on reinforcement contrast effects in response rate and accuracy of conditional discrimination. |
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| Effects of the Dopamine D2/D3 Agonist Quinpirole on Responding Maintained by Cocaine and Cocaine-Associated Stimuli in Rhesus Monkeys. |
| JAMES H. WOODS (University of Michigan), Chad M. Galuska (University of Michigan), Gail Winger (University of Michigan) |
| Abstract: We investigated the effects of the dopamine D2/D3 agonist quinpirole on cocaine self-administration and responding maintained by cocaine-associated stimuli. Three rhesus monkeys produced cocaine (0.01 mg/kg/inj) on a multiple random-interval (RI) extinction (EXT) schedule. In some sessions, saline was substituted for cocaine. Pretreatments of quinpirole (0.0032-0.32 mg/kg) administered (i.v.) 30 min prior to sessions dose dependently decreased cocaine responding. Quinpirole also increased saline responding, but did not affect discrimination of the RI and EXT components. Subsequently, we investigated the effects of quinpirole on observing. Responses on one lever produced cocaine according to a mixed RI EXT schedule, and responses on two other levers intermittently produced stimuli correlated with the ongoing schedule component for 30 s (observing). Quinpirole dose dependently decreased both responding maintained by cocaine and observing responding without affecting discrimination of the two schedule components. In both experiments, reductions in response rates were observed at doses of quinpirole that were not selective for the dopamine D3 receptor; this rate suppression may reflect dopamine D2 receptor activity. Overall, the results provide little support for the contention that dopamine D3 selective compounds modulate the conditioned reinforcing functions of cocaine-associated stimuli. The finding that quinpirole increases saline self-administration, however, warrants further research. |
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| Effects of Added Free-Food Presentations Uncorrelated with S+ on Observing Rates and Resistance to Change. |
| TIMOTHY A. SHAHAN (Utah State University), Christopher A Podlesnik (Utah State University) |
| Abstract: Observing responses may be considered analogous to attending to stimuli to be discriminated. Added response-independent reinforcers decrease baseline response rates but increase the persistence of responding maintained by primary reinforcement. We examined whether adding response-independent reinforcement to one component of a two-component multiple schedule of observing-response procedures would increase the persistence of observing. In both components, periods of a variable-interval (VI) 60-s schedule and extinction alternated on a center key with nondifferential stimuli (mixed schedule). Observing responses on a left key provided 15-s access to a stimulus correlated with the VI schedule. In the rich component, response-independent food was presented regardless of the schedule in effect (i.e., VI or extinction). Baseline observing, S+, and mixed food-key rates were either similar or lower in the rich component. There were no systematic differences in resistance to change during S+ periods, but resistance to change of observing and S+ mixed food-key responding was more persistent in the rich component. These results show that, despite producing likely decreases in the value of S+, added response-independent food increases the persistence of observing. These results suggest that, as with food-maintained behavior, the persistence of attending is governed by the overall rate of reinforcement in the context. |
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| The Role of Extended Exposure to Sample Stimuli in a Titrating-delay-matching-to-sample Procedure with Pigeons. |
| MANISH VAIDYA (University of North Texas), Joshua A. Levine (University of North Texas), Brian D. Kangas (University of North Texas) |
| Abstract: Extending exposure to a sample stimulus facilitates the acquisition of conditional discriminations. Despite this knowledge and the consistent use of extended observing of the sample stimulus to facilitate conditional discrimination learning, there is little within subject parametric data available on the role of extended observing responses in the organization of conditional discrimination performances. This examined the role of extended observing on conditional discrimination by arranging a titrating-delay matching-to-sample procedure. Pigeons were exposed to a matching-to-sample procedure in which the delay between the offset of sample stimuli and the onset of comparison stimuli was continually adjusted as a function of the birds’ ongoing accuracy of performance. Specifically, two correct responses increased the delay between sample offset and comparison onset by 1 s whereas one incorrect response decreased the delay between sample offset and comparison onset by 1 s. Across conditions, the number of observing responses required to initiate the delay was increased systematically. Results showed that extended observing response requirements served to increase the adjusted delay value. These data suggest that extending the amount of exposure to sample stimuli attenuates the oft-reported delay-related decreases in accuracy. Implications for accounts involving attention and short-term remembering will be discussed. |
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| Contrast Effects on Accuracy and Response Rate in Delayed Matching to Sample. |
| JOHN A. NEVIN (University of New Hampshire), Timothy A. Shahan (Utah State University), Amy Odum (Utah State University) |
| Abstract: Four pigeons were trained in multiple schedules where key pecking produced delayed matching-to-sample (DMTS) trials on a variable-interval (VI) schedule. Reinforcer probability for correct matches was constant at .3 in one component and the conditions of reinforcement were varied in the second component. In Experiment 1, the varied component arranged DMTS trials with reinforcer probabilities of .9 or .1 across conditions. Both VI response rate and DMTS accuracy were directly related to reinforcer probability in the varied component, but in the constant component, contrast effects on VI response rate were unreliable and there was no evidence of contrast in accuracy of matching. In Experiment 2, the varied component was either VI with immediate food reinforcement or extinction. Reliable contrast effects were obtained in both VI response rate and DMTS accuracy in the constant component. These results join previous findings in demonstrating equivalent effects of reinforcement on free-operant responding and accuracy of discrimination. |
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