ISSN:0022-5002    

DOI:10.1901/jeab.1992.57-1

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Pigeons were exposed to two different reinforcement schedules under different stimulus conditions in each of two daily sessions separated by 6 hr (Experiments 1 and 2) or in a single session (Experiment 3). Following this, either a fixed‐interval (Experiment 1) or a variable‐interval schedule (Experiments 2 and 3) was effected in both stimulus conditions. In the first two experiments, exposure to fixed‐ratio or differential‐reinforcement‐of‐low‐rate schedules led to response‐rate, but not pattern, differences in subsequent performance on fixed‐ or variable‐interval schedules that persisted for up to 60 sessions. The effects of reinforcement‐schedule history on fixed‐interval schedule performance generally were more persistent. In Experiment 3, a history of high and low response rates in different components of a multiple schedule resulted in subsequent response‐rate differences under identical variable‐interval schedules. Higher response rates initially occurred in the component previously correlated with high response rates. For 3 of 4 subjects, the differences persisted for 20 or more sessions. Previous demonstrations of behavioral history effects have been confined largely to between‐subject comparisons. By contrast, the present results demonstrate strong behavioral effects of schedule histories under stimulus contr

ISSN:0022-5002    

DOI:10.1901/jeab.1992.57-5

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Three pigeons were exposed sequentially across experimental phases to five different distances between the conditioned stimulus and the site of the unconditioned stimulus in a sign‐/goal‐tracking procedure. A computer‐controlled tracking system provided a continuous record of the bird's position by continuously monitoring the location of the bird's head in three‐dimensional space. It was found that birds sign‐tracked (i.e., approached the conditioned stimulus) when the conditioned stimulus was closest to the site of the unconditioned stimulus, goal‐tracked (i.e., approached the site of the unconditioned stimulus in the presence of the conditioned stimulus) when the conditioned stimulus was farthest from the site of the unconditioned stimulus, and engaged in both sign‐ and goal‐tracking (or something intermediate) at intermediate conditioned‐stimulus‐to‐unconditioned‐stimulus distances. When both sign‐ and goal‐tracking occurred, the former tended to occur in the first half and the latter in the second half of the interval in which the conditioned stimulus was present. The results suggest (a) whether sign‐ or goal‐tracking (or both) occurs is a function of the distance of the conditioned stimulus from the site of the unconditioned stimulus, (b) the fact that pigeons but not rats have been found to sign‐track consistently throughout the duration of the conditioned stimulus may be due to quantitatively rather than qualitatively different effects of conditioned‐stimulus‐to‐unconditioned‐stimulus distance across species (i.e., a “short” conditioned‐stimulus‐to‐unconditioned‐stimulus distance for a pigeon may be a “long” one for a rat), and (c) sign‐ and goal‐tracking may be competing behavioral tendencies that can (e.g., at intermediate conditioned‐stimulus‐to‐unconditioned‐stimulus distances) cancel each other out. The findings lend support to theories that specify an interaction between phylogenetic and reinforcement variables in determining whether si

ISSN:0022-5002    

DOI:10.1901/jeab.1992.57-17

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Pigeons responded on fixed‐ratio schedules ending in small or large reinforcers (grain presentations of different duration) interspersed within each session. In mixed‐schedule conditions, the response key was lit with a single color throughout the session, and pausing was directly related to the past reinforcer (longer pauses after large reinforcers than after small ones). In multiple‐schedule conditions, different colors accompanied the ratios ending in small and large reinforcers, and pausing was affected by the upcoming reinforcer as well as the past one. Pauses were shorter before large reinforcers than before small ones, but they continued to be longer after large reinforcers than after small ones. The influence of the past reinforcer was modulated by the magnitude of the upcoming reinforcer; in the presence of the stimulus before the small reinforcer, the effect of the past reinforcer was enhanced relative to its effect in the stimulus before the large reinforcer. These results show that pausing between ratios is jointly determined by two competing factors: past conditions of reinforcement and stimuli correlated with upcoming condi

ISSN:0022-5002    

DOI:10.1901/jeab.1992.57-33

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Pigeons pecked at one of two black forms, “+” or “+,” either of which could appear alone on a white computer monitor screen. In baseline series of sessions, each form appeared equally often, and two pecks at it produced food reinforcement on 10% of trials. Test series varied the relative probability or duration of reinforcement or frequency of appearance of the targets. Peck reaction times, measured from target onset to the first peck, were found to vary as a function of reinforcement probability but not as a function of relative target frequency or of reinforcement duration. Reaction times to the two targets remained approximately equal as long as the probability of reinforcement, per trial, was equal for the targets, even if the relative frequency of the targets differed by as much as 19 to 1. The results address issues raised in visual search experiments and indicate that attentional priming is unimportant when targets are easy to detect. The results also suggest that equalizing reinforcement probability per trial for all targets removes differential reinforcement as an important variable. That reaction time was sensitive to the probability but not the duration of reinforcement raises interesting questions about the processes reflected in reaction time compared with rate as a response

ISSN:0022-5002    

DOI:10.1901/jeab.1992.57-47

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Six pigeons were trained to discriminate between two intensities of white light in a symbolic matching‐to‐sample procedure. These stimuli were then used to signal which schedule was available on the main key in a switching‐key concurrent schedule. The concurrent schedules led to a symbolic matching‐to‐sample phase in which the subject identified the concurrent schedule to which it last responded before a reinforcer could be obtained. The concurrent schedules were varied across conditions. Discriminability, measured during the symbolic matching‐to‐sample performance, was high throughout and did not differ across the two procedures. Performance in the concurrent schedules was like that typically obtained using these schedules. Delays were then arranged between completion of the concurrent schedules and presentations of the symbolic matching‐to‐sample phase. A series of conditions with an intervening delay of 10 s showed that both concurrent‐schedule performance and symbolic matching‐to‐sample performance were affected by the delay in a similar way; that is, choice responding was

ISSN:0022-5002    

DOI:10.1901/jeab.1992.57-51

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Pigeons chose between two schedules of food presentation, a fixed‐interval schedule and a progressive‐interval schedule that began at 0 s and increased by 20 s with each food delivery provided by that schedule. Choosing one schedule disabled the alternate schedule and stimuli until the requirements of the chosen schedule were satisfied, at which point both schedules were again made available. Fixed‐interval duration remained constant within individual sessions but varied across conditions. Under reset conditions, completing the fixed‐interval schedule not only produced food but also reset the progressive interval to its minimum. Blocks of sessions under the reset procedure were interspersed with sessions under a no‐reset procedure, in which the progressive schedule value increased independent of fixed‐interval choices. Median points of switching from the progressive to the fixed schedule varied systematically with fixed‐interval value, and were consistently lower during reset than during no‐reset conditions. Under the latter, each subject's choices of the progressive‐interval schedule persisted beyond the point at which its requirements equaled those of the fixed‐interval schedule at all but the highest fixed‐interval value. Under the reset procedure, switching occurred at or prior to that equality point. These results qualitatively confirm molar analyses of schedule preference and some versions of optimality theory, but they are more adequately characterized by a model of schedule preference based on the cumulated values of multiple reinforcers, weighted in inverse proportion to the delay between the choice and each

ISSN:0022-5002    

DOI:10.1901/jeab.1992.57-67

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

It has been hypothesized that the magnitude‐of‐reinforcement effect may differ in closed and open experimental economies. We determined the relationship between magnitude of reinforcement and response rate in three feeding conditions: a closed economy in which total intake was unrestricted, a closed economy in which total intake was restricted so as to maintain body weight at 85% of free‐feeding weight, and a traditional open economy in which subjects received food outside the experimental session. In the closed economies, regardless of body weight, the rats responded faster for smaller pellets and when the fixed ratio for pellets was higher. In the open economy, there was no reliable effect of pellet size or pellet cost on response rate. It is concluded that although there are circumstances in which response rate is an immediate function of the parameters of reinforcement, rate is not necessarily a measure of response strength. Response rate may instead, or additionally, contribute to a strategy of reducing the costs associated with resource utiliz

ISSN:0022-5002    

DOI:10.1901/jeab.1992.57-81

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

A caffeine versus placebo discrimination procedure was used to determine the lowest caffeine dose that could produce discrimination and self‐reported mood effects in normal volunteers. During daily sessions under double‐blind conditions, caffeine‐abstinent subjects orally ingested a capsule containing 178 mg caffeine or placebo. Before beginning discrimination training, the compounds were identified to subjects by letter codes. Fifteen, 30, and 45 min after capsule ingestion, subjects guessed the capsule's letter code. Correct guesses at 45 min earned money. After each session, subjects received a supplementary capsule containing caffeine or placebo to ensure that, within each phase of the study, subjects received the same daily dose of caffeine equal to the training dose. Five of the 15 subjects acquired the caffeine versus placebo discrimination within the first 20 sessions (≥75% correct); 6 other subjects acquired the discrimination with additional training. Nine subjects who acquired the discrimination were subsequently trained at progressively lower caffeine doses. In general, the lowest dose to produce discrimination (≥75% correct) was also the lowest dose to produce self‐reported mood effects: 4 subjects showed discrimination and self‐reported mood effects at 100 mg caffeine, 2 at 56 mg, 1 at 32 mg, and 1 at 18 mg. One of these subjects also showed self‐reported mood effects at 10 mg. The present study documents discriminative stimulus and self‐reported mood effects of caffeine at doses below those previously shown to affect any behavior in

ISSN:0022-5002    

DOI:10.1901/jeab.1992.57-91

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Two experiments demonstrated the efficacy of sample stimulus‐control shaping programs for teaching arbitrary matching to 4 subjects who did not acquire the performances via standard methods (i.e., differential reinforcement and, in two cases, comparison intensity fading). All 4 had previously demonstrated identity matching with two‐dimensional forms. Identity matching performances were then transformed into arbitrary matching by gradually changing the sample stimuli until they no longer resembled the comparison stimuli. Where applicable, these methods may have advantages over others that have been used after the failure of standard techniq

ISSN:0022-5002    

DOI:10.1901/jeab.1992.57-109

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY