摘要:

A signal appeared for a certain time period. After the period elapsed, pigeons had to begin and complete a sequence of 15 responses in a time window ranging from the signal duration to 50% longer. Sessions involved as many as 10 different signal durations occurring in a random sequence. The times produced by pigeons often were in the same ranges as those that have been found with adult human subjects. The average times were described equally well as linear or power functions of signal duration. However, instead of the overestimation of durations usually found when animals have timed the duration of antecedent stimuli, the linear functions suggested that the pigeons underestimated the durations of their own behavior. The birds showing the strongest control when the conditions involved eight or 10 different duration requirements revealed the constant coefficients of variation that support Weber's law and scalar timing theory. Scalar timing in temporal differentiation appears to depend on non‐ambiguous information about the duration required for reinforcement and on a high degree of sensitivity to the duration requiremen

ISSN:0022-5002    

DOI:10.1901/jeab.1989.52-81

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

ISSN:0022-5002    

DOI:10.1901/jeab.1989.52-96

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Concurrent‐chains schedules of reinforcement were arranged for humans and pigeons. Responses of humans were reinforced with tokens exchangeable for money, and key pecks of 4 birds were reinforced with food. Variable‐interval 30‐s and 40‐s schedules operated in the terminal links of the chains. Condition 1 exposed subjects to variable‐interval 90‐s and variable‐interval 30‐s initial links, respectively. Conditions 2 and 3 arranged equal initial‐link schedules of 40 s or 120 s. Experimental conditions tested the descriptive adequacy of five equations: reinforcement density, delay reduction, modified delay reduction, matching and maximization. Results based on choice proportions and switch rates during the initial links showed that pigeons behaved in accord with delay‐reduction models, whereas humans maximized overall rate of reinforcement. As discussed by Logue and associates in self‐control research, different types of reinforcement may affect sensitivity to delay differentially. Pigeons' responses were reinforced with food, a reinforcer that is consumable upon presentation. Humans' responses were reinforced with money, a reinforcer exchanged for consumable reinforcers after it was earned. Reinforcers that are immediately consumed may generate high sensitivity to delay and behavior described as delay reduction. Reinforcers with longer times to consumption may generate low sensitivity to delay and behavior that max

ISSN:0022-5002    

DOI:10.1901/jeab.1989.52-97

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

For 4 rhesus monkeys, mouth‐contact responses with either of two brass spouts were reinforced according to fixed‐ratio schedules by 0.65‐mL liquid deliveries during daily 3‐hr sessions. Three experiments were conducted. In each experiment, independent fixed‐ratio schedules were concurrently in effect at the two spouts. Following completion of each fixed ratio on a spout, a specified number of liquid deliveries were available from that spout under a continuous‐reinforcement schedule. The number of such deliveries available at each spout was manipulated independently. In Experiment 1, a 1‐mg/mL pentobarbital solution was simultaneously available with water (the drug vehicle) under concurrent fixed‐ratio schedules of 32 responses for 3 subjects and 64 responses for the remaining subject. The number (N) of liquid deliveries that were available after completion of each fixed ratio was varied in the following order: 8, 4, 2, 1, and 8 (retest). For each subject at each condition, drug maintained more responding than water. The number of drug deliveries obtained per session was directly related to the amount of drug available per fixed ratio (i.e., to N), whereas the number of fixed ratios completed per session generally was inversely related to the value of N. In Experiment 2, fixed‐ratio size was the same for each subject as in Experiment 1, but deliveries of a 1‐mg/mL pentobarbital solution were available at both spouts. The number of drug deliveries available under one fixed‐ratio schedule (Ns, the “standard” reinforcer amount) was held at eight, and the number of drug deliveries available under the second schedule (Nc, the “comparison” reinforcer amount) was changed across blocks of six sessions of stable responding in the following order: 1, 2, 4, 8, 4, 2, and 1. The identical series of comparison reinforcer amounts (Nc) was then tested twice more, but with the standard reinforcer (Ns) held first at four and then at two deliveries. Across the three choice series, reinforcing effects were directly related to reinforcer magnitude. In Experiment 3, deliveries of a 1‐mg/mL pentobarbital solution again were available at both spouts. However, the two reinforcer amounts were held constant atN= 8 deliveries under one schedule andN= 4 deliveries under the second schedule, and fixed‐ratio size was systematically varied. Across the range of fixed‐ratio sizes from low to high, the degree to which behavior was better maintained by the larger of the two drug quantities was an inverted U‐shaped function of fixed‐ratio size. The findings of Experiment 3 are discussed in the context of recent studies that have shown that the relative proportions of behavior maintained by concurrently available reinforcers depend on the absolute values of the concurrent reinforcement condi

ISSN:0022-5002    

DOI:10.1901/jeab.1989.52-111

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

In a residential research ward the reinforcing and subjective effects of caffeine were studied under double‐blind conditions in volunteer subjects with histories of heavy coffee drinking. In Experiment 1, 6 subjects had 13 opportunities each day to self‐administer either a caffeine (100 mg) or a placebo capsule for periods of 14 to 61 days. All subjects developed a clear preference for caffeine, with intake of caffeine becoming relatively stable after preference had been attained. Preference for caffeine was demonstrated whether or not preference testing was preceded by a period of 10 to 37 days of caffeine abstinence, suggesting that a recent history of heavy caffeine intake (tolerance/dependence) was not a necessary condition for caffeine to function as a reinforcer. In Experiment 2, 6 subjects had 10 opportunities each day to self‐administer a cup of coffee or (on different days) a capsule, dependent upon completing a work requirement that progressively increased and then decreased over days. Each day, one of four conditions was studied: caffeinated coffee (100 mg/cup), decaffeinated coffee, caffeine capsules (100 mg/capsule), or placebo capsules. Caffeinated coffee maintained the most self‐administration, significantly higher than decaffeinated coffee and placebo capsules but not different from caffeine capsules. Both decaffeinated coffee and caffeine capsules were significantly higher than placebo capsules but not different from each other. In both experiments, subject ratings of “liking” of coffee or capsules covaried with the self‐administration measures. These experiments provide the clearest demonstrations to date of the reinforcing effects of caffeine in capsules

ISSN:0022-5002    

DOI:10.1901/jeab.1989.52-127

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Effects of methadone on pigeons' key pecking were examined under four conditions selected to analyze the control of behavior under alternative fixed‐ratio fixed‐interval schedules. In Condition 1, pigeons pecked under one of three different alternative schedules (alternative fixed‐ratio 50 fixed‐interval 90 s, alternative fixed‐ratio 75 fixed‐interval 90 s and alternative fixed‐ratio 200 fixed‐interval 90 s) each week. In Condition 2, fixed‐ratio 50 or fixed‐ratio 75 schedules were in effect during baseline sessions, and alternative fixed‐ratio 50 fixed‐interval 90‐s or alternative fixed‐ratio 75 fixed‐interval 90‐s schedules were in effect during sessions in which methadone was administered. In Condition 3, effects of methadone on key pecking maintained under fixed‐ratio 50 and fixed‐ratio 75 schedules were examined, whereas in Condition 4 the effects of methadone on key pecking under a fixed‐interval 90‐s schedule as well as fixed‐ratio 50 and fixed‐ratio 75 schedules were investigated. Control by the fixed‐interval contingency was assessed by computing the proportion of total session reinforcers delivered under the fixed‐interval schedule. Methadone administration (0.5–4.0 mg/kg) shifted the predominant source of schedule control under the alternative schedule from the fixed‐ratio schedule to the fixed‐interval contingency. This shift was dependent on methadone dose and fixed‐ratio size. Control by the fixed‐interval contingency was greatest following extensive exposure to the interval component embedded within the alternative schedule (Condition 1), but was apparent to a lesser degree with even very limited exposure to the alternative fixed‐ratio fixed‐interval schedule (Condition 2). Interreinforcement intervals comparable to those under a fixed‐interval schedule were not observed under the fixed‐ratio schedules presented alone (Condition 3). Repeated exposure to the fixed‐interval contingency outside the context of the alternative fixed‐ratio fixed‐interval schedule did not engender performance changes under a fixed‐ratio schedule which would mimic those of increased fixed‐interval contingency control (Condition 4). These data suggest that drug administration can be used to unmask the influence of contingencies that are latent under baseline condit

ISSN:0022-5002    

DOI:10.1901/jeab.1989.52-141

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

The present investigation developed and tested a new percentile reinforcement schedule suited to study pattern variability, whose main feature was the relative dissociation it provided between the variability requirement defining criterional responses and overall probability of reinforcement. In a discrete‐trials procedure, pigeons produced patterns of four pecks on two response keys. If the pattern emitted on the current trial differed from theNpreceding patterns, reinforcement was delivered with probabilityu. The schedule continuously adjusted the criterionNsuch that the probability of a criterional response, estimated from the subject's recent behavior, was always constant. In these circumstances, the criterion corresponded to an invariant percentile in the distribution of recent responses.Using a between‐subjects design, Experiment 1 manipulated the variability requirement—the percentile—while keeping overall reinforcement probability constant. The degree of variability varied directly with the requirement. In addition, an inverse relationship existed between the requirement and within‐group variance. Experiment 2 manipulated probability of reinforcement while maintaining the variability requirement constant. No consistent relationship was found between variability and reinforcement probability. A tentative hypothesis was advanced ascribing the operant conditioning of behavioral variability to a process ofprobability‐dependen

ISSN:0022-5002    

DOI:10.1901/jeab.1989.52-155

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Four rats were exposed to an A‐B‐A‐B series of 30 sessions each of variable‐ratio 20 (A) and fixed‐interval 30‐s (B) schedules. Four other rats received 120 sessions of fixed‐interval 30 s. The rats with a history of variable‐ratio responding subsequently showed primarily high or low response‐rate patterns on the fixed‐interval schedule without evidence of classical scalloping (i.e., increased rates of responding throughout the interreinforcement interval), except infrequently in 1 rat. The rats exposed to only the fixed‐interval 30‐s schedule displayed the expected sequence of scalloping giving way to lower rate break‐run or simply low‐rate responding over time. This experiment shows that when naive rats are exposed to even a simple history of reinforcement (in this case, a variable‐ratio 20), their subsequent fixed‐interval performance is very different from comparable performance in naive rats, and might be said to be more similar to the responding of adult humans. The argument is made that care should be taken in comparing the fixed‐interval performance of humans and nonhumans because humans have a complex history of reinforcement, whereas laborat

ISSN:0022-5002    

DOI:10.1901/jeab.1989.52-167

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Two kinds of mediating behavior were compared with respect to their effectiveness in variable‐delay matching‐to‐sample and oddity‐matching tasks. Each of four 5‐year‐old children was trained to emit either differential or common mediating responses. The differential mediating response consisted of pressing a specific computer key corresponding to either of two possible sample stimuli (a red or a green square). The common mediating response consisted of pressing one of the two response keys regardless of the sample. The differential‐response subjects did not show the typical, delay‐related decrease in matching‐to‐sample performance that characterized the behavior of common‐response subjects. An oddity‐matching task was then introduced, and subjects were instructed to use the mediating keys however they preferred, including not at all. Differential‐response subjects continued to respond on the originally trained mediating keys in response to sample presentation and later reversed their choice responding, thus accommodating the oddity‐matching requirements. Common‐response subjects continued to emit the previously trained mediating response and experienced limited success in oddity matching. Results were interpreted in terms of stimulus control, instructional cont

ISSN:0022-5002    

DOI:10.1901/jeab.1989.52-181

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

ISSN:0022-5002    

DOI:10.1901/jeab.1989.52-193

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY