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| International Symposium - Operant Behavior Variation |
| Tuesday, May 30, 2006 |
| 9:00 AM–10:20 AM |
| Montreal |
| Area: EAB; Domain: Basic Research |
| Chair: Josele Abreu-Rodrigues (Universidade de Brasilia) |
| Discussant: Allen Neuringer (Reed College) |
| Abstract: Several studies have suggested that behavioral variability itself can be selected by contingencies of reinforcement. That is, specifying that a given response sequence must differ from those emitted recently results in greater variation in the sequences than occurs in the absence of such a requirement. In demonstrating that behavior variation (and repetition) is affected by reinforcement history and delayed reinforcers, and that variation and repetition may exert discriminative control upon other behavior, the present symposium contribute to the general idea of variation (and repetition) as dimensions of the operant. |
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| Discrimination of Vary and Repeat Contingencies of Reinforcement. |
| ALESSANDRA SOUZA (Universidade de Brasília), Josele Abreu-Rodrigues (Universidade de Brasília) |
| Abstract: This study investigated the discriminative properties of vary and repeat contingencies. Pigeons were exposed to a matching-to-sample procedure in which there was a mix vary-repeat schedule in effect on the sample keys. In the vary component, four-responses sequences with a frequency less or equal to 10% (threshold) were legible for reinforcement. In the repeat component, the emission of only two sequences (among the 16 possible sequences) was followed by reinforcement. After 1 minute of sample exposure, the first reinforcer presentation was followed by two comparison stimuli. If the vary component had been in effect, pecking the white key was reinforced; but if the repeat component had been in effect, pecking the green key was reinforced. After stable choice behavior was reached, the threshold was manipulated across conditions such that the vary contingency became progressively lenient. Reinforcement rates were close in both components. During baseline conditions, the percentage of correct responses was above 70% in most sessions, with a mean value of 75% for both components. Manipulations of the threshold were followed by a decrease in choice accuracy. The results suggest that vary and repeat contingencies may exert discriminative control upon matching behavior. |
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| Operant Variability When Reinforcement is Delayed. |
| KATIE WAGNER (Reed College), Allen Neuringer (Reed College) |
| Abstract: This study examined what happens when delayed reinforcers were contingent upon operant response variability. Three groups of rats were rewarded for varying their response sequences, with one group rewarded for High variability, another for Middle, and the third for Low levels. Consistent with many reports in the literature, responding slowed significantly in all groups as delays were lengthened. Consistent with other reports, large differences in variability were maintained across the three groups despite the delays. Reinforced variability appears to be relatively immune to disruption by such things as delays, response slowing, prefeeding, and non-contingent reinforcement. Furthermore, the small effects on variability depended on baseline levels: as delays lengthened, variability increased in the Low group, was statistically unchanged in the Middle group, and decreased in the High group, an interaction similar to that reported previously when reinforcement frequencies were lowered. Thus, variable operant responding is controlled by reinforcement contingencies, but sometimes differently than more commonly studied repetitive responding. |
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| Effects of Independent Reinforcers and Extinction upon the Acquisition of Varying and Repeating Behaviors. |
| JOSELE ABREU-RODRIGUES (Universidade de Brasilia), Alessandra Souza (Universidade de Brasilia) |
| Abstract: This study evaluated the effects of a history with independent reinforcers as well as with extinction upon the acquisition of both varying and repeating performances. College students were distributed in eight groups. Each group was exposed to a specific combination of the following conditions: vary contingency (V), repeat contingency (R), extinction (E), and independent reinforcers (I). There were four VARY groups (VEV, EVE, VIV and IVI), and four REPEAT groups (RER, ERE, RIR, and IRI) which differed with respect to the order of conditions. The task was to emit sequences of three responses distributed in three keys on the computer keyboard. In the VARY contingency, sequences with a frequency less or equal to 2% were reinforced; in the REPEAT contingency, just one sequence was followed by reinforcement. During extinction, sequences were not followed by reinforcers; and with independent reinforcers, 50% of the sequences were reinforced according to a pre-determined order. The results showed that: 1) a history of extinction and independent reinforcers affected more substantially acquisition of repeating than of varied behavior; 2) repeating behavior was less resistant to extinction and independent reinforcers than varied behavior. |
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