Choice behavior in transition: Development of preference in a free-operant procedure

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...

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confidence: 96%

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confidence: 99%

Nonstable Concurrent Choice in Pigeons

Schofield

Davison

1997

“…An important exception is some recent work by Mazur and his colleagues (Mazur, 1992;Mazur & Ratti, 1991) looking at the devel-409 1994,62, NUMBER 3 (NOVEMBER) opment of new preference levels in a concurrent choice situation. They have found that equal differences between reinforcement probability schedules do not result in equally rapid adjustment of preference; rather, preference adjustment is primarily a function of the ratio of reinforcement probabilities.…”

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confidence: 99%

Ratio Versus Difference Comparators in Choice

Gibbon

Fairhurst

1994

Several theories in the learning literature describe decision rules for performance utilizing ratios and differences. The present paper analyzes rules for choice based on either delays to food, immediacies (the inverse of delays), or rates of food, combined factorially with a ratio or difference comparator. An experiment using the time-left procedure (Gibbon & Church, 1981) is reported with motivational differentials induced by unequal reinforcement durations. The preference results were compatible with a ratio-comparator decision rule, but not with decision rules based on differences. Differential reinforcement amounts were functionally equivalent to changes in delays to food. Under biased reinforcement, overall food rate was increased, but variance in preference was increased or decreased depending on which alternative was favored. This is a Weber law finding that is compatible with multiplicative, scalar sources of variance but incompatible with pacemaker rate changes proportional to food presentation rate.

“…Mazur and colleagues (Bailey & Mazur, 1990;Mazur, 1992Mazur, , 1995Mazur, , 1996Mazur, , 1997Mazur & Ratti, 1991) investigated the effects of a single within-session change in the reinforcer ratio available from two alternatives. Another approach used pseudorandom binary…”

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confidence: 99%

Choice in a Variable Environment: Effects of Unequal Reinforcer Distributions

Landon

Davison

Elliffe

2003

Six pigeons were trained in a procedure in which sessions included seven unsignaled components, each offering two pecking keys, and each providing a potentially different reinforcer ratio between the two keys. Across conditions, various combinations of reinforcer ratios and reinforcer-magnitude ratios were used to create unequal reinforcer distributions between the two alternatives when averaged across a session. The results extended previous research using the same basic procedure that had included only reinforcer distributions symmetrical around 1:1. Data analyses suggested that the variables controlling choice operated at a number of levels: First, individual reinforcers had local effects on choice; second, sequences of successive reinforcers obtained at the same alternative (continuations) had cumulative effects; and, third, when these sequences themselves occurred with greater frequency, their effects further cumulated. A reinforcer obtained at the other alternative following a sequence of continuations (a discontinuation) had a large effect and apparently reset choice to levels approximating the sessional reinforcer ratio.