Multiple Schedule Of Reinforcement Research Articles

DISCRIMINATIVE STIMULUS LOCATION AS A DETERMINANT OF POSITIVE AND NEGATIVE BEHAVIORAL CONTRAST IN THE PIGEON1

Four pigeons were exposed to a series of two-component multiple schedules of reinforcement that ordinarily yield positive and negative behavioral contrast. The stimuli that signalled the component schedules were sometimes located on the response key and sometimes off. Positive behavioral contrast was observed only when the stimuli were on the key. Negative contrast was observed independent of stimulus location. These data suggest that positive and negative contrast may be causally unrelated, and support an account of contrast in terms of the summation of key pecks that are separately controlled by response-reinforcer and stimulus-reinforcer dependencies.

Behavioral contrast in a second-order multiple schedule of reinforcement

Three pigeons were maintained on a two-component multiple schedule of reinforcement, each component of which was a two-component multiple schedule. Behavioral contrast was produced when (1) one of two VI 5-min components, (2) one of two VI 1-min components, or (3) one VI 5-min and one VI 1-min component were changed to extinction. The magnitude of the behavioral contrast was the same in all three cases. Some generalization of extinction and contrast was observed. The data are interpreted as favoring an account of behavioral contrast which is based on emotional processes.

THE RELATIONSHIP BETWEEN OBSERVING BEHAVIOR AND FOOD‐KEY RESPONSE RATES UNDER MIXED AND MULTIPLE SCHEDULES OF REINFORCEMENT1

Pigeons were trained under an observing response procedure in which pecks on one key (food key) were reinforced under a mixed fixed-interval 30-sec extinction schedule. A response on a second (observing) key replaced the mixed-schedule stimulus with either of two multiple-schedule stimuli (red and green keylights) for 5 sec. Observing response rates were positively correlated with food-key response rates in the presence of multiple-schedule stimuli and inversely related to food-key response rates in the presence of mixed-schedule stimuli. These results suggest that observing response output is controlled not only by the stimuli produced by observing responses but also by the stimuli in the presence of which observing responses occur. The possibility that observing responses alter the probability of reinforcement is advanced.

Protein deficiency and performance of pigeons on a multiple schedule of reinforcement.

AbstractPigeons reared from 2 pairs of healthy pigeons were fed on diets of either adequate (18%), medium (11%), or low (8%) protein for the first 30 days of life. The subjects were then placed on the 18% diet from 30 days of age until training and testing which was begun at 60 ± 3 days of age. Performance on a MULT FR30 FI60 was evaluated and the differences in the time necessary for the medium and low groups to stabilize were found to be statistically significant. Massed extinction trials to the FI were then begun followed by a schedule of MULT FR EXT. Differences between the adequate and inadequate protein groups were again found in both conditions. Other qualitative differences were found among the goups which suggested an analog of emotional lability and retardation.

Some interactions in a higher order multiple schedule of reinforcement

Two pigeons were trained on a multiple schedule, of which each component was a chain schedule. A high-rate contingency was added to one component of one chain. Negative behavioral contrast was observed. Tests for emotionality were negative. Reinforcement rates were constant and equal in both chains throughout the experiment.

Schedule-induced aggression against a slide-image target

Pigeons were trained to keypeck on a multiple schedule of reinforcement consisting of three 20-sec fixed interval components followed by one 200-sec fixed-interval component. In one phase of the study, a rear-projected slide image of a pigeon was present, while in another phase, a taxidermically prepared pigeon was present. Although more schedule-induced aggression occurred against the stuffed model than against the slide, the topography and temporal locus of attack against either target were comparable.

SCHEDULE‐INDUCED MIRROR RESPONDING IN THE PIGEON1

Two pigeons that were previously exposed to a multiple schedule of reinforcement in the presence of a stuffed and a live pigeon, and two of three naive pigeons, responded on a mirror during exposure to multiple fixed-ratio, fixed-ratio schedules of reinforcement for key pecking. Both the topography and temporal pattern of mirror responding were comparable to schedule-induced "attack" on live and stuffed targets. Rate of target responding was reduced when either the mirror was covered with paper or when the multiple schedule was removed. A reversal in the relationship between reinforcement schedules and discriminative stimuli demonstrated that mirror responding was controlled by the stimulus correlated with the higher fixed-ratio schedule. With one component of the multiple schedule held constant at fixed ratio 25 and the ratio requirement of the other component varying from 25 to 150, there was an inverted U-shaped relationship between rate of mirror responding and fixed-ratio schedule in the varied component. As in Flory's study (1969b) there was an inverted U-shaped relationship between target responding and inter-food intervals. The combined results of these studies suggest that the relationship between rate of target responding and reinforcement schedules is controlled primarily by the inter-food intervals resulting from the schedules.

Effects of yohimbine and mescaline on punished behavior in the rat.

This investigation tested the hypothesis that conditioned aversive stimuli and drugs such as yohimbine and mescaline produce a common state in animals. Rats were trained to press a bar on a multiple schedule of reinforcement in which one component was variable interval 30 sec (food) and the other component was fixed ratio 10 (concurrent food and electric shock). Yohimbine did not have a selective depressant effect on response rate during the punished component. Indeed, punished rates were elevated or near normal when responding in the non-punished component was decreased to less than 50% of control values. In contrast, mescaline concurrently depressed rates on both components of the schedule. If yohimbine produces an anxiety-like state in animals which is akin to the state engendered by punishment procedures, the effects of punishment and yohimbine should be additive in terms of their depressant effects on lever-press responses. No such additivity was observed in this investigation. The present data do not support the assumption that punishment procedures and the administration of yohimbine produce a common state in the rat. No definitive conclusion could be drawn with respect to the actions of mescaline.

The effects of amount of training per reversal on successive reversals of a color discrimination.

Three groups of pigeons were trained on a red-green discrimination in which the stimuli were alternately presented in a multiple schedule of reinforcement. The discrimination was reversed 24 times. Groups were given 1, 2, or 4 hr of training on each discrimination. Increasing the length of training had two principal effects on reversal performance: it increased the rate of extinction of responding to one of the stimuli and increased the rate of reacquisition of responding to the other. The latter effect involved both an increase in reacquisition of responding to a positive stimulus within reversals and an increase in recovery of responding to the previous negative stimulus between reversals. Improvements in performance of each group over the series of reversals were qualitatively similar to the two effects of length of training on each discrimination, and were analogous to effects obtained in other studies involving overtraining and successive reversals of simultaneous discriminations.

OBSERVATIONAL LEARNING IN MONKEYS

Observer monkeys were housed next to demonstrator monkeys that were conditioned to respond on a multiple reinforcement schedule whose components were fixed-ratio 32, variable-interval 3-min, and extinction 5-min followed by an additional 30 sec of extinction during which every response started a new 30-sec interval. After observational periods from 113 to 210 hr long, during which observers could not perform the response and were given no extrinsic reinforcers, their first-response latencies to fixed ratio and variable interval were as short as the demonstrators; and their rates of responding were well above pre-observational baseline levels. About 8 hr later, a temporal pattern of responding appropriate to the multiple schedule emerged, including non-emission of responses during extinction. Controls lacking the chance to observe did not develop typically patterned responding after 60 hr in one case and, in two other cases, after 80 hr during which, on two occasions, every one of 50 responses was reinforced. In a second experiment, the stimulus lights associated with fixed ratio and variable interval were presented simultaneously. Subjects chose one of the schedules by responding to one of the levers beneath the lights. All subjects initially chose fixed ratio. Seeing the demonstrators switch to variable interval, due to increases in the fixed-ratio requirement, had no effect upon observers, which continued to choose fixed ratio.

A COMPARISON OF VARIABLE‐RATIO AND VARIABLE‐INTERVAL SCHEDULES OF REINFORCEMENT1

Four pigeons responded under a two-component multiple schedule of reinforcement. Responses were reinforced in one component under a variable-ratio schedule and in the other component under a variable-interval schedule. It was found that when rates of reinforcement were equal in the two components, the rate of response in the variable-ratio component was nearly twice that in the variable-interval component. Furthermore, for three of the four subjects, the function relating response rate to relative rate of reinforcement in the variable-ratio component had a slope 2.5 to 3 times the slope of the corresponding function for the variable-interval component.

Aggression during the fixed-ratio and extinction components of a multiple schedule of reinforcement.

Pigeons were trained to key peck for food on multiple reinforcement schedules including components of continuous and fixed-ratio reinforcement and extinction. At the end of the chamber opposite the response key was a restrained target pigeon. The target restraining equipment was designed to record automatically blows struck against the target. When the experimental pigeons were paired with restrained target pigeons they attacked the target. Attack occurred during extinction after both continuous and fixed-ratio reinforcement. Attack also occurred occasionally during fixed-ratio 25 and fixed-ratio 40 and frequently during fixed-ratio 60 and fixed-ratio 120. No attack occurred during fixed-ratio 15 and continuous reinforcement. After a history of stable responding without a target bird present, the introduction of a target bird resulted in severely strained key-peck responding characterized by long periods of neither key pecking nor aggressing.

The effects of punishment on food pellet discrimination

Rats were trained on a multiple schedule of reinforcement. The reinforcers were Noyes sucrose and standard food pellets. The onset of a shock of approximately.40 mA and 50 msec was paired, simultaneously and consistently, with one type of pellet. Removal of shock on alternate blocks of sessions resulted in contrast effects between rates following sucrose and standard pellets. The presence of shock suppressed postreinforcement rates of responding following the shock-paired pellet. Response rate decrements were less following the pellet type not paired with shock during the same session.

The Effects of Punishment on Food Pellet Discrimination

Rats were trained on a multiple schedule of reinforcement. The reinforcers were Noyes sucrose and standard food pellets. The onset of a shock of approximately.40 mA and 50 msec was paired, simultaneously and consistently, with one type of pellet. Removal of shock on alternate blocks of sessions resulted in contrast effects between rates following sucrose and standard pellets. The presence of shock suppressed postreinforcement rates of responding following the shock-paired pellet. Response rate decrements were less following the pellet type not paired with shock during the same session.

Induction, contrast, and resistance to extinction.

The resistance of responding to extinction after variable-interval reinforcement in one of two components of a multiple schedule of reinforcement was (1) greater, when responding in the second component was reinforced on a variable-interval schedule than when responding there was extinguished, (2) not reduced, by a more rapid decrease in the rate of responding than occurs in ordinary extinction in the second component, and, (3) increased, by the occurrence of positive behavioral contrast before the beginning of extinction.

Conditioned suppression or facilitation as a function of the behavioral baseline.

Rats were exposed to a multiple schedule of reinforcement. During one component, a bar-press was followed by reinforcement only if it occurred between 15 and 20 sec after the previous response. This differential-reinforcement-of-low-rate (DRL) schedule produced a typical slow rate of responding. During the other component, reinforcement followed the first response to be emitted during limited periods of time which occurred at fixed intervals. These fixed-interval schedules with a limited hold produced higher response rates, described as ;interval' or ;ratio-like' behavior. Responding during the DRL component increased in frequency during a tone which ended with an unavoidable shock of low intensity, but decreased during the tone when the shock intensity was raised. The ;interval' and ;ratio-like' responding decreased in frequency during the tone at all shock intensities. Initial acceleration of the DRL responding appeared to be due to adventitious punishment of collateral behavior which was observed between the bar-presses. The more severe conditioned suppression during the fixed-interval components might be the result of the lower probability of reinforcement after any single response.

Selective action of pentobarbital on a multiple schedule of reinforcement.

MANY demonstrations of the sensitivity of behaviour to drugs in a variety of situations have established the importance of environmental factors in determining drug behaviour interactions1. More specifically, patterns of responding that are differentially sensitive to drugs can be obtained by arranging different schedules of reinforcement2 or by manipulating the parameters of a particular contingency3.

Operant electrodermal conditioning under multiple schedules of reinforcement.

ABSTRACTAn operant discrimination procedure was used to determine whether human subjects show shifts in palmar skin potential response rate under varying schedules of reinforcement. In Experiment I, a monetary reinforcer was either given or subtracted on a short fixed ratio schedule during alternating 5‐min periods. In Experiment II, the schedules alternated between 10‐min periods in which either a variable ninnber of responses or long interresponse times were reinforced. Each experiment consisted of seven subjects tested over several sessions. The results indicated differences in response rates consonant with changes in the scheduling of reinforcement. Concurrent recordings of respiration, heart rate, and skin potential level showed that the reinforcement effects were generally specific to the skin potential response variable.

Stimulus discrimination through intracranial reinforcement.

5 satiated rats and a guinea pig with chronically implanted electrodes were operantly conditioned to respond on a lever to receive intracranial self-stimulation (I.C.S.) under a multiple schedule of reinforcement. Response rates, under the control of visual or auditory discriminative stimuli, were appropriately high or low according to the requirements of the schedule. Alternating changes of the discriminative stimuli resulted in immediate shifting of response rates by Ss. Electrode placements were in the mammillary body area and the posterior hypothalamus. The findings indicate that I.C.S. reinforcement can be used to study discrimination acquisition in lower organisms.

DISCRIMINATIVE AND REINFORCING PROPERTIES OF TWO TYPES OF FOOD PELLETS1

In Experiment I some discriminative functions of food pellets were studied by developing a multiple schedule of reinforcement (mult FR 30 FI 3) in which the delivery of a standard laboratory food pellet as a reinforcer set the occasion for reinforcement on every 30th response (FR 30), and the delivery of a sucrose food pellet as a reinforcer set the occasion for reinforcement after a 3-min interval (FI 3). Discriminative stimulus control by the type of pellet was also demonstrated by reversing the operant discrimination and having the standard pellet control the FI 3 and the sucrose pellet control the FR 30. In Experiment II a mult FR 30 FR 30 with two bars was developed; a standard food pellet was followed by an FR 30 on Bar 1 and extinction (ext) on Bar 2, while a sucrose pellet was followed by an FR 30 on Bar 2 and ext on Bar 1. A control rat was placed, for comparison, on a mixed (mix) FR 30 FR 30 schedule with two bars, but neither bar correlated with the type of food pellet. In Experiments I and II the similarity between pellet controlled multiple schedules and multiple primed schedules was discussed, as was the comparability of transitions and effectiveness of control between pellet controlled multiple schedules and multiple schedules providing continuous exteroceptive stimuli.