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Biomedical subjects

M C Davison

Publications and source records attributed to M C Davison.

27 records · Page 2Linked to original sources
PubMed1972

Performance in concurrent interval schedules.

Four pigeons were trained under concurrent variable-interval variable-interval and fixed-interval variable-interval schedules in a two-key situation. Both response allocation and time allocation to the two schedules were measured when various reinforcement rates were arranged on each key. All animals showed an approximately constant proportional preference for the variable-interval schedule over the fixed-interval schedule. These results support Schneider's (1969) analysis of fixed-interval schedule performance.

Journal Article↗
PubMed1972

Performance in multiple fixed-interval schedules.

The performances of five pigeons were studied under a variety of multiple fixed-interval schedules in which both component duration and reinforcement rate were varied. The three series of experimental conditions were: (a) when the ratio of component durations equalled the reciprocal of the ratio of component reinforcement rates; (b) when the component durations were equal; and (c) when the ratio of component durations equalled the ratio of component reinforcement rates. Relative response rates were related to relative reinforcement rates in the same manner as in multiple variable-interval schedules, but no effect of component duration was found.

Journal Article↗
PubMed1971

Preference for qualitatively different reinforcers.

Three pigeons were studied under two-key concurrent variable-interval schedules with food as the reinforcer on one key and ectostriatal brain stimulation as the reinforcer on the other. Brain-stimulation parameters were kept constant while the rate of food reinforcement availability was varied. The results showed that qualitatively different reinforcers could be handled in the same theoretical framework that applies when choice is between different rates, immediacies, and amounts of a single reinforcer.

Journal Article↗
PubMed1970

A choice technique to assess the effects of selective punishment on fixed-ratio performance.

The emission of a fixed number of responses by rats was followed by food reinforcement. This fixed number could be accumulated in any way from two continuously available but mutually incompatible response classes, bar pressing, and not bar pressing for a fixed time period. A preference for one response class was arranged by specifying different maximum reinforcement rates for the two classes. Under selective punishment conditions, the preferred response occasionally led to both food and electric shock, while the non-preferred response led only to food. Selective punishment effects were measured through changes in the preference to the two responses in the sequence. The actions of shock intensity, deprivation, the specification of the non-preferred response, and three drugs were investigated. The results were broadly similar to the work reported by Dardano and Sauerbrunn (1964), who found localized increases in interresponse times before punished responses in fixed-ratio schedules. Performance under this procedure was found to be stable and sensitive to each of the experimental variables examined.

Journal Article↗
PubMed1969

Preference for mixed-interval versus fixed-interval schedules.

Pigeons were trained on a two-link concurrent chain schedule in which responses on two keys were reinforced according to independent variable-interval schedules by the production of a change in key color. Further responses on the key on which the stimulus change had been produced gave a single food reinforcement and a return to concurrent variable-interval conditions. On one key the terminal link was a two-valued mixed-interval schedule, while on the other, the terminal link was a fixed-interval schedule. When the mixed-interval values were kept constant and the fixed-interval values varied, relative response rates in the initial concurrent links matched relative reinforcement rates in the terminal links when these were computed from cubic transformations of the reciprocals of the intervals comprising the terminal link schedules.

Journal Article↗
PubMed1969

Successive interresponse times in fixed-ratio and second-order fixed-ratio performance.

Three rats were trained on a schedule in which every sixth response produced a timeout of 5 sec minimum duration, and food was delivered at the onset of timeout. Successive interresponse times were measured under these conditions, and also when behavior was maintained by second-order fixed-ratio and fixed-interval schedules. Under the second-order schedules, each six-response fixed-ratio component was followed by a timeout, and occasionally food was delivered at the onset of a timeout. In the fixed-ratio schedule, the successive interresponse times showed a decrease followed by an increase before food delivery, but this systematic variation in interresponse times was not found when the performance was under second-order reinforcement. Under both second-order schedules the latencies of successive components, and the successive interresponse times within each component, showed a decrease as food delivery was approached.

Journal Article↗
PubMed1968

Response cost and the control of verbal behavior under free-operant avoidance schedules.

Human subjects were tested in a free-operant avoidance procedure. Shock could be avoided by the emission of a verbal response of adequate intensity and duration. These schedules were found to control the emission of verbal operants in the same way they control motor operants. Some subjects showed conventional control by this schedule with or without response-produced feedback. Other subjects verbalized at a high rate under both these conditions until the addition of response cost brought this behavior under conventional schedule control.

Avoidance Learning↗