ISSN:0022-5002    

DOI:10.1901/jeab.1988.49-1

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

ISSN:0022-5002    

DOI:10.1901/jeab.1988.49-3

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

A concurrent‐chains procedure was used to examine pigeons' preferences between segmented and unsegmented terminal‐link schedules of reinforcement. During the initial link, a pair of independent, concurrent variable‐interval 60‐s schedules was in effect. In the terminal link, reinforcement was provided by a chain fixed‐interval fixed‐interval schedule on one key and by a simple fixed‐interval schedule with an equal interreinforcement interval in the other. The relative duration between the first and second components (segmentation ratio) in the terminal‐link chained schedule was systematically varied while the terminal‐link duration was kept constant at either 15 s or 30 s in two sets of conditions. With few exceptions, the simple schedule was preferred to the chained schedule. Furthermore, this preference was inversely related to the size of the segmentation ratio in the segmented schedule. When the segmentation ratio was smaller than 1:1, preference was more extreme for a 30‐s condition than for a 15‐s condition. However, preference decreased more rapidly in conditions with the longer terminal‐link duration when the ratio increased. Taken together, these results were consistent with previous findings concerning the effect of the terminal‐link duration on choice between segmented and unsegmented schedules. In addition, the data suggested that segmentation ratio in a segmented schedule constitutes another potent factor influencing preference for

ISSN:0022-5002    

DOI:10.1901/jeab.1988.49-9

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Six pigeons were trained to respond on two keys, each of which provided reinforcers on an arithmetic variable‐interval schedule. These concurrent schedules ran nonindependently with a 2‐s changeover delay. Six sets of conditions were conducted. Within each set of conditions the ratio of reinforcers available on the two alternatives was varied, but the arranged overall reinforcer rate remained constant. Each set of conditions used a different overall reinforcer rate, ranging from 0.22 reinforcers per minute to 10 reinforcers per minute. The generalized matching law fit the data from each set of conditions, but sensitivity to reinforcer frequency (a) decreased as the overall reinforcer rate decreased for both time allocation and response allocation based analyses of the data. Overall response rates did not vary with changes in relative reinforcer rate, but decreased with decreases in overall reinforcer rate. Changeover rates varied as a function of both relative and overall reinforcer rates. However, as explanations based on changeover rate seem unable to deal with the changes in generalized matching sensitivity, discrimination accounts of choice may offer a more promising interpretat

ISSN:0022-5002    

DOI:10.1901/jeab.1988.49-21

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

In a series of conditions, pigeons chose between 1.5 s and 3 s of access to grain, each preceded by some delay. The delay that preceded the small reinforcer was constant throughout a condition. The delay that preceded the large reinforcer was increased or decreased a number of times each session in order to estimate an “indifference point,” a delay at which the subject chose each alternative about equally often. The experiment was designed to determine whether variations in any of four features of this adjusting‐delay procedure would systematically alter the estimated indifference points. The four features were the total trial duration, the number of center‐key responses necessary to begin a trial, the number of choice trials that preceded each change in the adjusting delay, and step size—the size of each increment and decrement in the delay. Manipulation of the first three features had no systematic effects on the indifference points. As step size was increased from 0.5 s to 6 s, within‐session variability of the adjusting delay steadily increased, and the 6‐s step size produced larger indifference‐point estimates for some subjects. The results suggest that, within certain limits, these procedural features can be altered without affecting the indifference‐point estimates, but that the use of a large step size can distort the estimates. Some theoretical implications of the relative constancy of indifference points across these procedural variati

ISSN:0022-5002    

DOI:10.1901/jeab.1988.49-37

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

The responding maintained by a reinforcer depends on the relation of the reinforcer not merely to the response that produces it but also to other preceding responses. Early responses in a sequence that ends in a reinforcing consequence make smaller contributions to later response rates than more recent ones, by virtue of the longer delays that separate them from the reinforcer. This study shows that the relation between a response and a later reinforcer contributes to responding only if no other reinforcers intervene; in other words, each reinforcer blocks responses that precede it from the effects of later reinforcers. Pigeons' pecks were maintained by fixed‐interval (FI) schedules of food reinforcement. When FI 60‐s (short) and FI 75‐s (long) schedules began simultaneously within constant 150‐s cycles, long FIs did not affect short‐FI performances, but short FIs eliminated the first 60 s of long‐FI performances. Removing either short‐FI reinforcers or short‐FI stimuli showed that short‐FI reinforcers and not short‐FI stimuli blocked the first 60 s of the long‐FI performance from the retroactive effects of the long‐FI reinforcer. With FI 15‐s and FI 75‐s schedules, the short‐FI reinforcer was followed by reduced long‐FI responding, but a schedule that prevented discrimination based on time since a reinforcer eliminated this proactive effect of the short‐FI reinforcer. In other words, the retroactive effects were reinforcer effects whereas the proactive effects were discriminative effects. Quantitative descriptions of variable‐interval performances, in which reinforcer effects may operate in the absence of temporal discriminative effects,

ISSN:0022-5002    

DOI:10.1901/jeab.1988.49-49

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

In Experiment 1 rats were trained to press a lever on a variable‐ratio schedule of food presentation and were then exposed to progressively increasing magnitudes of food reinforcement. Response running rates (rates exclusive of the postreinforcement pause) were found to increase as a function of increasing reinforcement magnitudes. The effect of reinforcement magnitude on response rates inclusive of the postreinforcement pause, however, was less pronounced. Increases in the magnitude of reinforcement were also found to increase the length of the postreinforcement pause. Rats in Experiment 2 were trained to respond on a chained differential‐reinforcement‐of‐low‐rate variable‐ratio schedule, and were exposed to increasing magnitudes of reinforcement as in Experiment 1. Response running rates increased in the variable‐ratio component but decreased in the other component of the schedule. The results are discussed with reference to incentive accounts of reinforcement and the action of reinforcement on the response units generated by the operative

ISSN:0022-5002    

DOI:10.1901/jeab.1988.49-75

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

After training under short or long fixed‐interval schedules, humans responded under a modified fixed‐interval schedule in which magnitude of reinforcement (X or 2X) was minimally correlated with response frequency. Response frequencies that equaled or exceeded a minimum response criterion were followed by the larger reinforcer at the end of the interval; otherwise, the smaller reinforcer was delivered. The modified schedule alternated with the baseline schedule across conditions. In a control condition, the reinforcer magnitudes produced by control subjects were yoked to those of experimental subjects. Experimental subjects, but not control subjects, showed increased responding. In addition to the baseline and modified fixed‐interval schedules used in Experiment 1, subjects in Experiment 2 also responded under a second modified fixed‐interval contingency in which increases in reinforcer magnitude were more highly correlated with response frequency. Experimental subjects, but not control subjects, showed increased responding under both procedures. Direct comparison of these two procedures showed that the high‐correlation procedure produced greater increases in responding than did the low‐correlatio

ISSN:0022-5002    

DOI:10.1901/jeab.1988.49-87

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Two eight‐member equivalence classes of visual stimuli were established during three phases of a training program. In Phase 1, two training arrangements were compared. In one, 3 subjects were taught on different trials to select from a single pair of comparison stimuli (A1, A2) in response to eight sample stimuli that were trained in pairs (B1, B2; C1, C2; D1, D2; E1, E2). In the second arrangement, subjects were taught to select from four pairs of comparisons (B1, B2; C1, C2; D3, D2; E2, E2) in response to two samples (A1) A2). Training with the single pair of comparison stimuli resulted in the development of equivalence relations (B1C1, B2C2, D1B1, D2B2, B1E1, B2E2, C1D1, C2D2, C1E1, C2E2, D1E1, D2E2, and their reciprocals) between the sample stimuli without direct training of these relations. In the other training arrangement, these relations among the comparison stimuli developed in the performance of 1 subject only. In Phase 2, three new pairs of stimuli (F1, F2; G1, G2; H1, H2) were substituted for three of the original pairs (B1, B2; C1, C2; D1, D2) and the training arrangements for the groups were reversed. Following training, the performances that showed equivalence relations on the probes in the first phase also showed equivalence relations in the second phase. If such relations did not develop in the first phase, they did not do so in the second phase. In Phase 3, relations between stimuli across the two previous phases (e.g., B1F1, B2F2, B1G1, B2H2, C1F1, etc.) were investigated. The 4 subjects whose performances showed the development of these relations were taught to select one stimulus from each class (E1and E2) in response to a verbal label (I1and I2) and then were tested to see if the verbal label controlled responding to the remaining members of the class (e.g., I1A1, I2A2, I1B1, I2B2, etc.). For 3 subjects, this generalized control occurred; for the 4th, generalization occurred only after verbal training with a second pair of visual stimuli (F1and F2). In retests several months later, these auditory‐visual relations were found to be intact or, if not, were recovered without direct train

ISSN:0022-5002    

DOI:10.1901/jeab.1988.49-95

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

In three experiments, pigeons' responses were reinforced on two keys in each component of a series of multiple‐schedule conditions. In each series, concurrent variable‐interval schedules were constant in one component and were varied over conditions in the other component. In the first experiment both components arranged the same, constant total number of reinforcers, in the second the two components arranged constant but different totals, and in the third experiment the total was varied in one component and remained constant in the other. Relative reinforcer rate during the varied component was manipulated over conditions in all three experiments. In all these experiments, response and time allocation in the constant component were invariant when reinforcer ratios varied in the other component, demonstrating independence of behavior allocation in a multiple‐schedule component from the relative reinforcer rate for the same alternatives in another component. In the two experiments which maintained constant reinforcer totals in components, sensitivity to reinforcement in the multiple schedules was the same as that in the concurrent schedules arranged during the varied component, with multiple‐schedule bias in the experiment in which the totals were

ISSN:0022-5002    

DOI:10.1901/jeab.1988.49-117

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY