摘要:

Pigeons worked on concurrent variable‐interval, variable‐interval schedules with the alternatives signaled by slides either containing trees or not. The schedules were designed to hold both overall and relative rates of reinforcement within narrowly constrained limits, and slides were quasi‐randomly ordered each day. Responding to the two alternatives was well described by the generalized matching equation with substantial undermatching. Using an adaptation of the matching law, we estimated that the subjects were correctly classifying 82% to 95% of exemplars. The matching performance transferred to new exemplars of trees and nontrees with only slight generalization decrement. The pigeons appeared to be discriminating among exemplars even when the alternatives provided equal rates of reinforcement and the average relative performances were close t

ISSN:0022-5002    

DOI:10.1901/jeab.1987.47-5

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Pigeons' rates of responding and food reinforcement under simple random‐ratio schedules were compared with those obtained under comparable ratio schedules in which free food deliveries were added, but the duration of each food delivery was halved. These ratio‐with‐free‐food schedules were constructed so that, were the pigeon to maintain the same rate of responding as it had under the simple ratio schedule, total food obtained (earned plus free) would remain unchanged. However, any reduction in responding would reduce total food consumption below that under the simple ratio schedule. These “compensated wage decreases” led to decreases in responding and decreases in food consumption, as predicted by an economic model of labor supply. Moreover, the reductions in responding increased as the ratio value increased (i.e., as wage rates decreased). Pigeons, therefore, substituted leisure for consumption. The relationship between these procedures and negative‐income‐tax pr

ISSN:0022-5002    

DOI:10.1901/jeab.1987.47-17

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Four pigeons were trained on multiple variable‐interval schedules in which components alternated after a fixed number of responses had been emitted. In Part 1, each component change occurred after 20 responses; in Part 2, the number was 40; and in Part 3, the number of responses before change was 10. Component reinforcer rates were varied over five experimental conditions in each of Parts 1 to 3. Component response rates decreased as the specified number of responses per component was increased. However, the relation between component response‐rate ratios and component reinforcer‐rate ratios was independent of the specified number of responses per component, and was similar to that found when components alternate after fixed time periods. In the fourth part of the experiment, the results from Parts 1 to 3 were systematically replicated by keeping the component reinforcer rates constant, but different, while the number of responses that produced component alternation was varied from 5 to 60 responses. The results showed that multiple‐schedule performance under component‐response‐number constraint is similar to that under conventional component‐duration constraint. They further suggest that multiple‐schedule response rates are controlled by component reinforcer rates and not by principles of maximizing overall reinforcer rates or meliorating component r

ISSN:0022-5002    

DOI:10.1901/jeab.1987.47-29

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

The contingency between responding and stimulus change on a chain variable‐interval 33‐s, variable‐interval 33‐s, variable‐interval 33‐s schedule was weakened by interposing 3‐s delays between either the first and second or the second and third links. No stimulus change signaled the delay interval and responses could occur during it, so the obtained delays were often shorter than the scheduled delay. When the delay occurred after the initial link, initial‐link response rates decreased by an average of 77% with no systematic change in response rates in the second or third links. Response rates in the second link decreased an average of 59% when the delay followed that link, again with little effect on response rates in the first or third links. Because the effect of delaying stimulus change was comparable to the effect of delaying primary reinforcement in a simple variable‐interval schedule, and the effect of the unsignaled delay was specific to the link in which the delay occurred, the results provide strong evidence for the concept of conditio

ISSN:0022-5002    

DOI:10.1901/jeab.1987.47-41

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Pigeons' choices between alternatives that provided different percentages of reinforcement in mixed schedules were studied using the concurrent‐chains procedure. In Experiment 1, the alternatives were terminal‐link schedules that were equal in delay and magnitude of reinforcement, but that provided different percentages of reinforcement, with one schedule providing reinforcement twice as reliably as the other. All pigeons preferred the more reliable schedule, and their level of preference was not systematically affected by variation in the absolute percentage values, or in the magnitude of reinforcement. In Experiment 2, preference for a schedule providing 100% reinforcement over one providing 33% reinforcement increased systematically with increases in the duration of the terminal links. In contrast, preference decreased systematically with increases in the duration of the initial links. Experiment 3 examined choice with equal percentages of reinforcement but unequal delays to reinforcement. Preference for the shorter delay to reinforcement was not systematically affected by variation in the absolute percentage of reinforcement. The overall pattern of results supported predictions based on an extension of the delay‐reduction hypothesis to choice procedures involving mixed schedules of percentage reinforc

ISSN:0022-5002    

DOI:10.1901/jeab.1987.47-57

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

The bar pressing of rats was reinforced on a multiple fixed‐interval schedule. The schedule intervals were 1 and 5 min long, and the sequence was such that intervals of either duration were equally likely to be followed by intervals of the same or of the other duration. Rates were higher during 1‐min and after 5‐min intervals. Best fit equations for cumulative responses during the 5‐min intervals produced very similar exponents regardless of preceding duration. It was concluded that preceding duration may have affected the subjects' performances through direct effects on temporal discrim

ISSN:0022-5002    

DOI:10.1901/jeab.1987.47-73

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Six rats were trained with food deliveries contingent upon their pressing a lever and holding it down for either fixed or variable cumulative durations. Fixed‐hold requirements ranged from 15 s to 90 s over experimental conditions; variable‐hold requirements ranged from 15 s to 120 s. At most long and intermediate values, variable‐hold requirements maintained more lever holding than fixed requirements. At the longest hold requirements studied, more lever holding was maintained by variable requirements than by fixed requirements of equivalent mean length for each rat. Postreinforcement‐pause duration increased with lever‐holding time for both fixed‐ and variable‐hold requirements. At comparable lever‐holding times per reinforcer, longer pauses typically were produced by fixed requirements than by variable requirements. Data from this study on the maintenance of responding, temporal response patterns, and postreinforcement pausing are comparable to those obtained with intermittent reinforcement of discrete responses. These findings suggest that the response—reinforcer relation specified by a reinforcement schedule is a fundamental determinant of responding, whether responding consists of discrete units or of co

ISSN:0022-5002    

DOI:10.1901/jeab.1987.47-81

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Rats were trained on concurrent schedules in which pressing one lever postponed shock and pressing the other occasionally produced a 2‐min timeout during which the shock‐postponement schedule was suspended and its correlated stimuli were removed. Throughout, the shock‐postponement schedule maintained proficient levels of avoidance. Nevertheless, in Experiment 1 responding on the timeout lever was established rapidly, was maintained at stable levels on variable‐interval schedules, was extinguished by withholding timeout, was reestablished when timeout was reintroduced, and was brought under discriminative control with a multiple variable‐interval extinction schedule of timeout. These results are in contrast with Verhave's (1962) conclusion that timeout is an ineffective reinforcer when presented to rats on intermittent schedules. In Experiment 2 the consequence of responding on the timeout lever was altered so that the shock‐postponement schedule remained in effect even though the stimulus conditions associated with timeout were produced for 2 min. Responding extinguished, indicating that suspension of the shock‐postponement schedule, not stimulus change, was the source of reinforcement. By establishing the reinforcing efficacy of timeout with standard variable‐interval schedules, these experiments illustrate a procedure for studying negative reinforcement in the same way as positiv

ISSN:0022-5002    

DOI:10.1901/jeab.1987.47-97

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Rats were trained on concurrent schedules in which pressing one lever postponed shock and pressing the other occasionally (variable‐interval schedule) produced a 2‐min timeout during which the shock‐postponement schedule was suspended and its correlated stimuli were removed. These procedures provided a baseline for studying the effects of drugs on behavior maintained by different sources of negative reinforcement (shock avoidance and timeout from avoidance). Experiment 1 studied a benzodiazepine agonist, chlordiazepoxide, and antagonist, CGS 8216. Chlordiazepoxide (2.5–30 mg/kg) had little effect on avoidance responding except at higher doses, when it reduced responding. By comparison, responding on the timeout lever was increased in 5 of 6 rats. These effects were reversed by CGS 8216 (2.5–5 mg/kg) in the 2 rats tested, but CGS 8216 had no effect by itself. Experiment 2 studied an opiate agonist, morphine, and antagonist, naltrexone, with 3 rats. Morphine's (2.5–20 mg/kg) effects were opposite those of chlordiazepoxide: At doses that either increased or had no effect on avoidance responding, morphine depressed timeout responding. Naltrexone (5 mg/kg) reversed these actions but had no effec

ISSN:0022-5002    

DOI:10.1901/jeab.1987.47-115

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

We develop a simple model of switching between the initial links of a concurrent‐chain procedure. Behavior is determined by four parameters μ1, μ2,q1, andq2. The first two are the basic rates of switching from Schedule 1 and Schedule 2, respectively. The second two are the probabilities of leaving Schedule 1 and Schedule 2 after the corresponding terminal link has been completed. We show that for fixed values of these four parameters, the relative allocation on the initial links may change as a result of changes in initial‐link schedules. The effect can be quite large if the switching rates are low. An implication is that relative allocation is not necessarily a good measure of beh

ISSN:0022-5002    

DOI:10.1901/jeab.1987.47-127

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY