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At least 271 records · Page 15Linked to original sources
PubMed1971

Concurrent schedules of response-independent reinforcement: duration of a reinforcing stimulus.

Presentations of grain to three pigeons were determined by two response-independent schedules. Interpresentation intervals varied with a mean interval of 1.5 min for each schedule. Both were concurrently operative, but grain was presented by one only when the chamber was illuminated with blue light and by the other only during amber illumination. A response on a white key, the only key in the chamber, alternated the stimulus conditions and the effective schedule. Grain presentation durations associated with the illumination conditions were varied from 1.5 to 4.5 sec. The proportion of the total session time spent in an illumination condition closely approximated the relative grain presentation duration provided in that illumination. For two of the birds, the proportion of the total number of grain presentations obtained in an illumination condition was an increasng function of the presentation duration in that illumination.

Journal Article↗
PubMed1962

A review of positive conditioned reinforcement.

This review critically analyzes experimental data relevant to the concept of conditioned reinforcement. The review has five sections. Section I is a discussion of the relationship between primary and conditioned reinforcement in terms of chains of stimuli and responses. Section II is a detailed analysis of the conditions in which the component stimuli in chained schedules of reinforcement will become conditioned reinforcers; this section also analyzes studies of token reinforcement, observing responses, switching responses, implicit chained schedules, and higher-order conditioning. Section III analyzes experiments in which potential conditioned reinforcers are used either to prolong responding or to generate responding during experimental extinction. This section discusses hypotheses that have been offered as alternatives to the concept of conditioned reinforcement and hypotheses concerning the necessary and sufficient conditions for establishing a conditioned reinforcer. Section IV discusses other variables that act when a conditioned reinforcer is being established or that act when an established conditioned reinforcer is used to develop or maintain behavior. Section V is a general discussion of conditioned reinforcement. The evidence indicates that the conditioned reinforcing effectiveness of a stimulus is directly related to the frequency of primary reinforcement occurring in its presence, but is independent of the response rate or response pattern occurring in its presence. Results from chained schedules comprised of several components indicate that a stimulus can be established as a conditioned reinforcer by pairing it with an already established conditioned reinforcer rather than a primary reinforcer; however, this type of higher-order conditioning has not been clearly demonstrated with respondent conditioning procedures. Although discriminative stimuli are usually conditioned reinforcers, the available evidence indicates that establishing a stimulus as a discriminative stimulus is not necessary or sufficient for establishing it as a conditioned reinforcer. Discriminative stimuli in chained schedules with several components are not always conditioned reinforcers; stimuli that are simply paired with reinforcers can become conditioned reinforcers. The hypotheses that have been offered as alternatives to the concept of conditioned reinforcement are too limited to integrate the data that exist. The concepts of conditioned reinforcement and chained schedule, however, can be used to integrate the data obtained with diverse techniques. Recent experiments have revealed several techniques for the development of effective conditioned reinforcers. These techniques provide a powerful tool for advancing understanding of conditioned reinforcement and for extending control over behavior.

Conditioning, Classical↗
PubMed2001

Reinforcer-ratio variation and its effects on rate of adaptation.

Six pigeons were trained in sessions that consisted of six or seven concurrent-schedule components, each of which could have a different reinforcer ratio arranged in it. The components were unsignaled and occurred in a random order separated by 10-s blackouts. The overall reinforcer rate arranged in each component was 2.22 reinforcers per minute. In Experiment 1, the range of reinforcer ratios in the seven components was varied from a condition in which the ratios were always 1:1, to a condition in which the ratios varied between concurrent variable-interval 27 s extinction (EXT) and concurrent extinction variable-interval 27 s (ratios of 1:EXT, 9:1, 3:1, 1:1, 1:3, 1:9, EXT:1). In Experiment 2, the range of reinforcer ratios was always 27:1 to 1:27, and the presence and absence of the intermediate reinforcer ratios used in Experiment 1 (9:1, 3:1, 1:1, 1:3, 1:9) were investigated. Log response-allocation ratios in components changed rapidly with increasing numbers of reinforcers in components, and Experiment 1 showed that sensitivity to reinforcement was usually higher when the range of reinforcer ratios was greater. When the range of reinforcer ratios was kept constant in Experiment 2, the presence or absence of less extreme reinforcer ratios had no clear effect on sensitivity. At a local level, individual reinforcers had predictable quantitative effects on response ratios: Successive same-alternative reinforcers in a component had rapidly diminishing effects in both experiments. Reinforcers obtained on the opposite alternative to one or more prior reinforcers always had large effects on preference, and these changes were greater when the range of reinforcer ratios was greater. The effects of such reinforcers in changing preference were enhanced, and produced clear preference reversals, when intermediate reinforcer ratios were absent in Experiment 2. Two processes, one local to reinforcers and one with a longer time course, may be necessary to account for these results.

Adaptation, Psychological↗