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Biomedical subjects

M D Zeiler

Publications and source records attributed to M D Zeiler.

At least 37 records · Page 2Linked to original sources
PubMed1976

Positive reinforcement and the elimination of reinforced responses.

Key pecking was maintained on a fixed-interval schedule while either a differential-reinforcement-of-not-responding or a fixed-time schedule was imposed simultaneously. The lower the time parameter of the not-responding schedule, the lower was the response rate. Similar effects occurred with the fixed-time schedule, if the pigeons had experience with reinforcement for not responding. Otherwise the effects were less orderly, to the extent that rate could reach maximum with the lowest-valued fixed-time schedule. The not-responding and the response-independent schedules had similar effects on rate in experienced pigeons only when the time parameter or nominal frequency of food presentation was considered. When considered in terms of obtained frequency of food presentation, reinforcement of not responding produced larger decrements in rate than did the fixed-time schedule.

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PubMed1976

Conjunctive schedules of response-dependent and response-independent reinforcement.

Pigeons received food when they emitted the number of responses specified by a fixed-ratio schedule, and the time specified by a fixed-time schedule had elapsed. The order of meeting the response and time requirements was irrelevant. In different conditions, stimuli signalled completion of one, both, or neither requirement. Ratio size interacted with stimulus condition to determine performance. When a stimulus signalled the end of the fixed-time period, under all ratios the birds tended to respond after the stimulus appeared. When stimuli followed both components, small ratios produced responding during the fixed-time period, and other ratios resulted in responses after the time period had elapsed. With either no stimulus changes, or with a stimulus correlated with completion of the ratio alone, responding first increased and then decreased as the ratio increased. Low and high ratios produced stable response frequencies and patterns in successive intervals. Intermediate ratios resulted in two types of performance. Intervals with long initial pauses and few responses during the fixed-time period were followed by intervals with short pauses and numerous responses and vice versa. The source of these dynamic effects was hypothesized to be number of responses per reinforcer in one condition and response-reinforcer contiguity in the other.

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PubMed1975

Stimulus properties of fixed-interval responses.

Responses in the first component of a chained schedule produced a change to the terminal component according to a fixed-interval schedule. The number of responses emitted in the fixed interval determined whether a variable-interval schedule of food presentation or extinction prevailed in the terminal component. In one condition, the variable-interval schedule was in effect only if the number of responses during the fixed interval was less than that specified; in another condition, the number of responses had to exceed that specified. The number of responses emitted in the fixed interval did not shift markedly in the direction required for food presentation. Instead, responding often tended to change in the opposite direction. Such an effect indicated that differential food presentation did not modify the reference behavior in accord with the requirement, but it was consistent with other data on fixed-interval schedule performance. Behavior in the terminal component, however, did reveal sensitivity to the relation between total responses emitted in the fixed interval and the availability of food. Response rate in the terminal component was a function of the proximity of the response number emitted in the fixed interval to that required for food presentation. Thus, response number served as a discriminative stimulus controlling subsequent performance.

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PubMed1974

Schedules of response-independent conditioned reinforcement.

Rates and patterns of responding of pigeons under response-independent and response-dependent schedules of brief-stimulus presentation were compared by superimposing 3-min brief-stimulus schedules on a 15-min fixed-interval schedule of food presentation. The brief-stimulus schedules were fixed time, fixed interval, variable time, and variable interval. When the brief stimulus was paired with food presentation, its effects depended upon the schedule and ongoing rates. Fixed- and variable-interval brief-stimulus schedules enhanced the low rates normally occurring early in the 15-min interval, whereas fixed- and variable-time schedules suppressed these rates. Although the overall rates later in the interval were not affected to any great extent, the fixed brief-stimulus schedules generated patterns of positively accelerated responding between stimulus presentations. These patterns appeared less frequently under the variable brief-stimulus schedules. Initially, when not paired with food delivery, presentations of the brief stimulus produced relatively little effect on either response rate or patterning. However, once the stimulus had accompanied food presentation, the original performance under the nonpaired condition was not recovered. The effects were more like those occurring when the stimulus was paired with food.

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PubMed1974

Patterning with fixed-time schedules of response-independent reinforcement.

Pigeons were first exposed to a schedule providing food when the time between successive key pecks (the interresponse time) exceeded a specified duration. When food then was presented at regular intervals independent of responding (fixed-time schedule), responses typically occurred at a steady rate in the periods between successive food presentations. Once the birds had been exposed to a fixed-ratio schedule, however, response rate under fixed-time schedules was positively accelerated. Variations in the sequence of conditions given different subjects indicated that the changes in patterning were due to the fixed-ratio schedule, rather than to the number of transitions from a response-dependent to the response-independent fixed-time schedule, to changed parameter values, or to prolonged experience with the fixed-time schedule. The effects of fixed-time schedules on patterning depended upon experimental history.

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PubMed1974

Time limits for completing fixed ratios. III. Stimulus variables.

Pigeons received food only if they took longer than a specified time to begin and complete a fixed ratio. In Experiment 1, ratios with shorter durations had no stimulus consequence; in Experiment 2, these ratios ended with a stimulus change. In both studies, the mean time to complete the ratio exceeded requirements of less than 30 sec, approximately matched requirements of 30 sec, and fell progressively short of matching thereafter. Variability increased together with the means. The various effects resembled those of temporal differentiation experiments involving single responses. Although both number of ratios and time separating successive food presentations increased along with ratio duration, control experiments showed that differential reinforcement of duration, rather than either form or reinforcer intermittency, accounted for the performance. Experiment 2 also studied the effects of adding a stimulus that signalled when the required time had elapsed. The stimulus produced durations that matched even the most stringent requirements. This precision was not maintained when the stimulus was removed. Temporal differentiation schedules seem to have similar effects regardless of the response class and temporal property involved.

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PubMed1972

Fixed-interval behavior: effects of percentage reinforcement.

The percentage of fixed intervals terminating with food presentation was varied parametrically. Intervals that did not end with food were terminated by a stimulus uncorrelated with food presentation (a timeout stimulus). In Experiment I, the pigeons' response rates were an inverted U-shaped function of the percentage of food presentations: decreasing the percentage from 100% to 90%, 70%, or 50% produced an increase in response rates; lower percentages decreased the rates. The patterns of responding in the 100% condition differed from those of the other conditions. In Experiment II, the chamber was darkened after food presentations and timeouts. Response rate was directly related to the percentage of food presentations: decreasing the percentage decreased the response rate. Characteristic fixed-interval patterns of responding were maintained as long as there were occasional food presentations; pausing followed by positively-accelerated responding occurred in percentage conditions ranging from 7% to 100%. The ability to maintain fixed-interval performance with percentage reinforcement suggested that the behavioral sequences occurring in each interval may operate as unitary responses.

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PubMed1972

Time limits for completing fixed ratios. II. Stimulus specificity.

Pigeons were exposed to two stimuli that were each correlated with the same fixed-ratio schedule. During one stimulus, the ratio had to be completed in more than a specified time for food to be presented. During the other, the ratio had to be completed in less than a specified time. Failures to meet the time criterion produced a timeout and reset the ratio. Treating the entire behavioral sequence generated by a fixed-ratio schedule as a unitary response and scheduling differential reinforcement with respect to the duration of the sequence produced effects comparable to those observed previously with individual responses. The times taken to complete the ratios conformed to the time criteria under both stimulus conditions. Similar effects have been observed with differential reinforcement of the duration of individual responses and in experiments specifying running speed criteria under discrete trial conditions.

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PubMed1972

Reinforcement of spaced responding in a simultaneous discrimination.

Pigeons were exposed to three stimuli simultaneously with responses reinforced according to differential-reinforcement-of-low-rate schedules. Responses to one stimulus (the positive stimulus) that were spaced appropriately resulted in food presentation. The variables manipulated were the time parameter of the schedule (5, 10, 20, 30 sec) and the consequences of responding to the other two stimuli (the negative stimuli). The percentage of the total responses that occurred to each stimulus was independent of the schedule value but was dependent on the consequences of responding to the negative stimuli. If responses to both reset the schedule timer, responding was confined largely to the positive stimulus. If responses to neither had scheduled effects, the birds were more likely to respond to those stimuli. Responding to one negative stimulus could be selectively attenuated by having responses to that stimulus alone reset the timer. With the schedule time value held constant, the absolute rate of responding to the positive stimulus was either stable or decreased with maintained exposure; it did not change as a function of increases or decreases in responding to the negative stimuli. Rather than interacting and affecting each other, responses to the three stimuli were controlled independently by their relation to reinforcement. There was no evidence that responses to the negative stimuli mediated the spacing of responses to the positive stimulus.

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PubMed1971

The choices and preferences of nursery school children.

After a period of equal reinforcement for choices of any job revealed which of 10 jobs each of 24 preschool children preferred and did not prefer, token payment became dependent on particular choices. Some children received tokens only for choosing previously non-preferred jobs, others for choosing previously preferred jobs. When tokens depended on choosing the nonpreferred jobs, those came to be preferred. When tokens depended on choosing the preferred jobs, the preferences were strengthened. The effects were replicated both within and between subjects, except in the case of one boy who consistently avoided token pay.

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PubMed1971

Eliminating behavior with reinforcement.

Responding produced food according to a fixed-ratio schedule while the prevailing key-color alternated between red and blue. Stimulus durations were varied until a period was found that maintained equal rates of responding in the presence of both colors. Then, food presentation was discontinued in the presence of one stimulus and made dependent on not responding in the presence of the other. Food presentation dependent on not responding reduced the rate of responding faster than did extinction. Spontaneous recovery occurred only during the stimulus correlated with extinction.

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PubMed1970

Time limits for completing fixed ratios.

Two experiments investigated how the addition of time limits affected fixed-ratio behavior. In Exp. 1, pigeons obtained food only if they completed the ratio within a specified time after the end of the preceding ratio. In Exp. 2, they obtained food only if they took longer than a specified time. Failures to meet the time criteria produced brief timeouts. The times taken depended on the requirements in both experiments. In Exp. 1, progressively briefer time criteria resulted in faster ratios, and in Exp. 2, longer time criteria increased the time taken in each ratio. The pigeon's sensitivity to the temporal variable, a property of the entire period extending from the first opportunity to respond to the end of the ratio, indicated that performance involved a behavioral unit encompassing both the post-reinforcement pause and the responses comprising the ratio.

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PubMed1970

Fixed-interval stimulus control.

Pigeons were exposed to three stimuli simultaneously, with responses to one of them, the positive stimulus, followed by food presented according to a fixed-interval schedule (FI 2-min, FI 4-min, FI 8-min, or FI 16-min). Over 90% of the total responses emitted were to the positive stimulus within a few sessions. When the birds were then studied under each of four fixed intervals, responding continued to be confined primarily to the same stimulus independent of interval size. In subsequent conditions, the three stimuli changed positions after each quarter of the interval. If the position changes did not require a response, response rate and the percentage of responses occurring to the positive stimulus decreased. If the changes did depend on a response, the complete interval appeared to be divided into four smaller intervals with a pause and then positively accelerated responding following each position change. Position changes produced by a response to any stimulus decreased control by the positive stimulus, and changes produced only by a response to it increased the percentage of responses made to that stimulus. All of the data suggested that the stimulus conditions contiguous with reinforcement controlled behavior.

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PubMed1969

Repeated measurements of reinforcement effects on gradients of stimulus control.

Two experiments studied the effects of reinforcement schedules on generalization gradients. In Exp. 1, after pigeons' responding to a vertical line was reinforced, the pigeons were tested with 10 lines differing in orientation. Reconditioning and the redetermination of generalization gradients were repeated from 8 to 11 times with the schedule of reinforcement varied in the reconditioning phase. Stable gradients could not be observed because the successive reconditionings and tests steepened the gradients and reduced responding. Experiment 2 over-came these effects by first training the birds to respond to all of the stimuli. Then, brief periods of reinforced responding to the stimulus correlated with reinforcement alternated with the presentation of the 10 lines in extinction. The development of stimulus control was studied eight times with each bird, twice with each of four schedules of reinforcement. Gradients were similar each time a schedule was imposed; the degree of control by the stimulus correlated with reinforcement varied with particular schedules. Behavioral contrast occurred when periods of reinforcement and extinction alternated and was more durable with fixed-interval, variable-interval, and variable-ratio schedules than with fixed-ratio or differential-reinforcement-of-low-rate schedules.

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