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| Fixed-ratios, Delay-to-reinforcement & Signals: Methodological Issues and Extension |
| Monday, May 25, 2009 |
| 3:30 PM–4:50 PM |
| North 225 |
| Area: EAB/BPH; Domain: Experimental Analysis |
| Chair: David P. Jarmolowicz (West Virginia University) |
| Abstract: The effects of delay-to-reinforcement have been examined on a variety of schedules of reinforcement such as variable interval schedules (e.g., Lattal, 1984), differential reinforcement of low rate schedules (e.g., Lattal & Ziegler, 1982) and on fixed-ratio (FR) schedules (e.g., Kendall & Newby, 1978). Since Lattal and Gleeson (1990) published their seminal article on acquisition with delay-to reinforcement, delay to reinforcement on FR1 schedules has received considerable attention. For example, experiments have examined the effects of delay duration (e.g., Sutphin, Byrne, & Poling, 1998), signals (e.g., Lattal, 1984), and the use of these schedules to examine the effects of various drugs (e.g., LeSage, Byrne & Poling, 1996) and strain differences (animal models of various disorders; e.g., Anderson & Elcoro, 2006). The work presented in the present symposium builds upon previous work using delay-to-reinforcement on FR1 schedules by examining the effects of end-of-delay stimuli on acquisition with delay to reinforcement and by evaluating acquisition with delayed reinforcement with Spontaneously Hypertensive Rat (a purported model of ADHD). Procedural issues in the use of acquisition with delay-to-reinforcement are then reviewed; and work extending from FR1 to a range of FR schedules is presented. |
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| Further Failure to Demonstrate Blocking of Response Acquisition with Delayed Reinforcement with End-of-Delay Stimuli |
| ANDREW T. FOX (Central Michigan University), Mark P. Reilly (Central Michigan University) |
| Abstract: Previous research has shown that stimuli at the end of long response-reinforcer delays can attenuate acquisition of lever-pressing in rats. The explanation for this result is that the intervening stimulus “blocks” (in a Pavlovian sense) the response-reinforcer association. Several attempts to replicate this finding in our lab have failed. Two such experiments are reported here. In the first, a houselight was explicitly paired with food reinforcement before acquisition sessions under a 30-s non-resetting delay condition were conducted. This arrangement was more explicitly analogous to a Pavlovian blocking preparation. Blocking did not occur; all subjects in all conditions acquired lever pressing. In the second, one of the major differences (manner of food restriction) between our experiments and the previous ones was explored. Two types of food restriction (2-hour access versus 85% free-feeding weight) were imposed on the subjects during response acquisition sessions with end-of-delay stimuli. Five of six subjects gained weight when given 2-hour access to chow and only one subject acquired lever pressing. When the same rats were subsequently restricted to 85% of their free-feeding weights, all acquired lever pressing, precluding unequivocal interpretation of the failure to acquire lever-pressing in the 2-hour access phase in terms of Pavlovian blocking. |
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| Response Acquisition with Signaled Delayed Reinforcement in a Rodent Model of Attention-Deficit/Hyperactivity Disorder |
| DENNIS HAND (Central Michigan University), Andrew T. Fox (Central Michigan University), Mark P. Reilly (Central Michigan University) |
| Abstract: Impulsivity has been characterized as a hypersensitivity to delayed reinforcement, and this characteristic has been proposed to contribute to the learning deficits reported in children diagnosed with Attention-Deficit/Hyperactivity Disorder (ADHD). The Spontaneously Hypertensive Rat (SHR), a purported model of ADHD, has been shown to exhibit this hypersensitivity to reinforcer delay. Previous research by Hand, Fox and Reilly (2006) showed that response acquisition was retarded in SHRs relative to control rats when unsignaled delays of 15 s separated responses from food delivery. To further explore the variables that underlie this sensitivity to delayed reinforcement, the present study exposed SHR and Wistar-Kyoto rats to signaled, response-reinforcer delays of 15 s (chain FR 1, DRO 15 s). The present study tested the idea that signaled delays should facilitate response acquisition in SHRs thus resulting in no strain differences: The signal should function as an immediate conditioned reinforcer and thus reduce the overall effect of the delay. As predicted, response acquisition was similar between strains. Although SHRs averaged slightly more responses and DRO resets, the number of pellets earned was identical. Thus, signaling response-reinforcer delays eliminated previously demonstrated differences in response acquisition deficits between SHRs and Wistar-Kyoto rats under 15-s resetting delays of reinforcement. |
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| Drug Effects on Response Acquisition with Delayed Reinforcement: Procedural and Definitional Issues |
| ALAN D. POLING (Western Michigan University), Thomas P. Byrne (MCLA) |
| Abstract: Several studies from our laboratory and elsewhere have examined the effects of a number of drugs on response acquisition under conditions where neither shaping nor autoshaping were arranged and putative reinforcers were delayed by different intervals. This presentation will summarize work in this area, with particular emphasis placed on methodological issues. Although procedures involving response acquisition with delayed reinforcement have some appealing features for studying drug effects on learning, their use is fraught with difficulty. |
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| Fixed-Ratio Schedules: Effects of Delay-to-Reinforcement |
| DAVID P. JARMOLOWICZ (West Virginia University), Kennon A. Lattal (West Virginia University) |
| Abstract: A number of studies have examined the effects of signaled and unsignaled delays-to-reinforcement on behavior on FR1 schedules (e.g., Critchfield & Lattal, 1993; Sutphin, Byrne, & Poling, 1998); however, notably less is known about the effects of reinforcement delays on other FR schedules (e.g. Kendall & Newby, 1978). The current experiments examined some effects of a range of signaled and unsignaled delays to reinforcement on behavior maintained by FR schedules. In Experiment 1, behavior maintained on a FR50 schedule was rapidly exposed to a range of delays-to reinforcement (i.e., 1-s to 320-s). In Experiment 2 behavior maintained on a range of FR schedules (i.e., FR10 to FR400) was exposed to delays of various durations. In general, negative relations between rate and delay and positive relations between delay and post reinforcement pause were observed. |
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