Nonstable Concurrent Choice in Pigeons

Abstract

Six pigeons were trained on concurrent variable-interval schedules in which the arranged reinforcer ratios changed from session to session according to a 31-step pseudorandom binary sequence. This procedure allows a quantitative analysis of the degree to which performance in an experimental session is affected by conditions in previous sessions. Two experiments were carried out. In each, the size of the reinforcer ratios arranged between the two concurrent schedules was varied between 31-step conditions. In Experiment 1, the concurrent schedules were arranged independently, and in Experiment 2 they were arranged nonindependently. An extended form of the generalized matching law described the relative contribution of past and present events to present-session behavior. Total performance in sessions was mostly determined by the reinforcer ratio in that session and partially by reinforcers that had been obtained in previous sessions. However, the initial exposure to the random sequence produced a lower sensitivity to current-session reinforcers but no difference in overall sensitivity to reinforcement. There was no evidence that the size of the reinforcer ratios available on the concurrent schedules affected either overall sensitivity to reinforcement or the sensitivity to reinforcement in the current session. There was also no evidence of any different performance between independent and nonindependent scheduling. Because of these invariances, this experiment validates the use of the pseudorandom sequence for the fast determination of sensitivity to reinforcement.Key words: concurrent schedules, choice, acquisition, generalized matching, key peck, pigeonsIn general, research on concurrent choice has concentrated on steady-state relations between the relative allocation of behavior and independent variables that are associated with reinforcement or aspects of responding. The development of quantitative models describing stable-state choice has been successful, and is exemplified by the generalized matching law (see Davison & McCarthy, 1988, for a review), which provides a description of the relation between behavior-output ratios and reinforcer-input ratios when two variableinterval (VI) schedules are concurrently available. This relation can be written asEquation 1 is the commonly used logarithmic form of the generalized matching law. TheWe thank the Foundation for Research, Science, and Technology for support of this research. We also thank Mick Sibley and Paula Johnson, who tended the subjects, and the undergraduate and graduate students who helped to run this experiment.Reprints may be obtained from either Grant Schofield, Central Queensland University, Rockhampton, QLD 4702, Australia, or Michael Davison, Department of Psychology, Auckland University, Private Bag 92019, Auckland, New Zealand (E-mail: g.schofield@cqu.edu.au or m.davison@auckland.ac.nz).parameter a is termed sensitivity to reinforcement, and measures the sensitivity with which the independent variable controls the allocation of responding. Log c...

Basolateral amygdala lesions and sensitivity to reinforcer magnitude in concurrent chains schedules

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Serial discrimination reversal learning in pigeons as a function of intertrial interval and delay of reinforcement

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RAPID ACQUISITION OF PREFERENCE IN CONCURRENT CHAINS: EFFECTS OF d‐AMPHETAMINE ON SENSITIVITY TO REINFORCEMENT DELAY

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