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| Recent Topics on the Disruptive Effects of Negative Incentive Shifts |
| Monday, May 25, 2009 |
| 2:30 PM–3:50 PM |
| North 227 BC |
| Area: EAB; Domain: Experimental Analysis |
| Chair: Tammy Wade-Galuska (University of South Carolina-Salkehatchie) |
| Discussant: Dean C. Williams (University of Kansas) |
| Abstract: Negative incentive shifts, or shifts from favorable to unfavorable reinforcement conditions, result in counterproductive disruptions in behavior. It has been suggested that such disruptions, which often take the form extended pausing following reinforcement, actually is a form of escape behavior. When given an explicit option to turn off the schedule during this transition, for example, pigeons have been shown to do so fairly reliably. Along these lines, the first study in this symposium investigates the disruptive effects of negative incentive shifts in two strains of rats, one of which (Fischer 344) has been shown to be more sensitive to other aversive stimuli (shock). The second study investigates whether or not negative incentive shifts in reinforcement context make pigeons mistake-prone. This study arranged a delayed-matching-to-sample task to determine if negative incentive shifts would engender inaccuracy in identity-matching in addition to extended pausing as measured by the latency to peck the sample stimulus. Finally, in applied settings, one way to attenuate the disruptive effects of transitions between activities is to maintain a very rigid schedule and provide advance notice of imminent transitions. The last study explores whether increasing the predictability of negative incentive shifts will lessen their disruptive effects in rats. |
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| Pre-Ratio Pausing Following Rich-to-Lean Transitions on Multiple Schedules in Fischer 344 and Lewis rats |
| ADAM T. BREWER (University of Kansas), Patrick S. Johnson (University of Kansas), Jeff S. Stein (University of Kansas), Monica T. Francisco (University of Kansas), Dean C. Williams (University of Kansas), Gregory J. Madden (University of Kansas) |
| Abstract: Pausing is maladaptive on fixed-ratio (FR) schedules because it decreases the rate of reinforcement. Perone and Courtney (1992) demonstrated that pigeons pause longer at transitions from a rich (large reinforcer magnitude) to a lean (small reinforcer magnitude) component in a multiple FR-FR schedule. Perone (2003) showed that pigeons were more likely to escape at rich-lean transitions suggesting that these transitions are aversive. Moreover, pausing may function as form of escape when no explicit-escape contingency is provided. To further assess the aversiveness account, pausing was compared between inbred rat strains differing in responsiveness to aversive stimulation. Fischer 344 (F344) rats are more sensitive to aversive stimulation than Lewis rats in shock-avoidance (Katzev & Mills, 1974) and conditioned-taste aversion tasks (Lancellotti et al., 2001). If rich-lean transitions are aversive, then F344 rats should pause longer than Lewis rats. Both strains were exposed to a multiple FR-FR schedule with FR values that ranged from 1 to 100. In rich components, ratio completion resulted in a large amount of food (7 pellets), while lean components resulted in a small amount of food (1 pellet). Our results support the aversiveness account because F344 rats paused longer at rich-to-lean transitions than Lewis rats. |
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| Effects of Signaled and Unsignaled Shifts in Reinforcer Magnitude on Delayed Matching-to-Sample Performance in Pigeons |
| YUSUKE HAYASHI (West Virginia University), Chata A. Dickson (West Virginia University), Michael Perone (West Virginia University) |
| Abstract: We investigated the effects of signaled and unsignaled shifts in reinforcer magnitude in a delayed identity matching-to-sample procedure with retention intervals ranging from 0 to 16 s. Four pigeons were trained on two conditional discriminations with red and green as sample and comparison stimuli. Under the multiple-schedule condition, the brightness of the houselight was correlated with the magnitude of the upcoming food reinforcer for a correct choice, whereas under the mixed-schedule condition, the brightness of the houselight was undifferentiated. A fixed-ratio schedule specified the number of trials that had to be completed correctly to earn a food reinforcer. We will describe the joint effects of past reinforcer magnitude and stimuli correlated with upcoming magnitude on sample latency (pausing) as well as on the accuracy on the delayed matching-to-sample task. The generality of earlier reports on disruptive effects of discriminative shifts in reinforcer magnitude (e.g., Perone & Courtney, 1992) will be discussed. |
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| The Disruptive Effects of Negative Incentive Shifts: Does Predictability Matter? |
| CHAD M. GALUSKA (College of Charleston), Tracy Taylor (College of Charleston) |
| Abstract: Negative incentive shifts involve transitions from favorable-to-unfavorable conditions of reinforcement and engender behavioral disruptions in animals and humans. The purpose of this paper is to explore a seemingly inconsistent finding between the animal and human literature. In animal models, signaling the occurrence of a negative incentive shift results in disrupted behavior in the form of extended pausing. A small experimental data set in humans, however, suggests that highly structured and signaled transitions between activities actually reduce behavioral problems. One difference in methodology is that existing animal models do not actually provide advance notice of imminent negative incentive shifts. In several experiments, we provided advance notice of negative incentive shifts involving reinforcer magnitude in a rat model. We also explored differences in the behavioral disruption engendered by predictable versus unpredictable sequences of large and small reinforcers. Our results suggest that, in rats, predictability plays but a minor role in attenuating the behavioral disruption engendered by negative incentive shifts. |
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