bluuebunny/crossref_metadata_2025 huggingface dataset:
THE COURSE OF ACQUISITION OF A LINE‐TILT DISCRIMINATION BY RHESUS MONKEYS1
Authors: Ray Barbara A.
Published: March 2006

Each of four groups of monkeys were trained on a different simultaneous discrimination procedure involving a vertical line as the correct choice. Each group, after acquiring the discrimination, was tested for generalization along the dimension of line tilt. Monkeys that learned to select the vertical line when the alternative choices were distinguished from the correct choice by two aspects (brightness and absence of line) showed almost complete tilt generalization (flat gradient). Monkeys that learned to select the line when the alternatives were distinguished only by the absence of the line showed poor tilt discrimination (generalization gradient slightly peaked at vertical). Monkeys developed a good tilt discrimination when nonvertical lines were gradually introduced by progressively darkening them on the previously blank alternatives. Monkeys developed a tilt discrimination with the lowest error rate when only horizontal alternatives were gradually introduced and then pairs of alternatives progressively closer to vertical were made available.
STIMULUS CONTROL OF TEMPORALLY SPACED RESPONDING IN SECOND‐ORDER SCHEDULES1
Authors: Thomas John R. , Stubbs Alan
Published: March 2006

Second‐order schedules consisting of sequences of component differential‐reinforcement‐of‐low‐rate schedules were used to investigate two different methods of introducing exteroceptive stimuli. When different exteroceptive stimuli were associated with each component (chained schedule), periods of pausing and lower response rates developed in the early components compared to the early components of the same sequence in the presence of a single exteroceptive stimulus (tandem schedule). When a brief stimulus change occurred at the completion of each component, response rates were higher in the early components compared to the tandem schedule. Changes in response rates in the early components were directly related to changes in reinforcement frequency in the terminal components produced by the two methods of presenting the exteroceptive stimuli.
LIMITATIONS ON ENVIRONMENTAL CONTROL OF MULTIPLE FIXED‐RATIO BEHAVIOR1
Authors: Keehn J. D. , Bratbak Richard B.
Published: March 2006

Eight white rats were trained to make fixed numbers of responses on each of two bars alternately in the presence of different exteroceptive stimuli. Three types of error were observed: alternating—bar switching before response requirements for reinforcement were met; perseverating—responding on the wrong bar after reinforcement; and overshooting—responding on a bar after reinforcement became available. Alternating and perseverating errors occurred mainly on the bar requiring the smaller ratio. When the ratios on the bars were changed, alternating errors were most common, but they diminished rapidly. Perseverating and overshooting errors did not diminish.
CONTROL OF SCHEDULE INDUCED POLYDIPSIA: TYPE, SIZE, AND SPACING OF MEALS1
Authors: Falk John L.
Published: March 2006

Rats were given daily 1‐min variable‐interval sessions for several types of food delivered in various amounts per reinforcement and the concurrent, schedule‐induced polydipsia was measured. Dry, solid food was neither a necessary nor sufficient condition for the development of polydipsia. Small portions of liquid Standard Monkey Diet produced polydipsia, but 45‐mg dextrose or sucrose pellets did not. Within the range studied, smaller portions of both solid and liquid foods produced more drinking than larger portions per reinforcement. Two‐min variable‐interval sessions produced a greater polydipsic response than 1‐min variable‐interval, even though the number of 45‐mg Noyes pellets allowed per session was held constant. Polydipsia was greatly attenuated on these schedules when the number of pellets remained constant, but were delivered two at a time. Within the ranges studied, the concurrent polydipsic response was increased by decreasing the rate of food acquisition, either by using smaller portions of food per reinforcement or by increasing the interreinforcement time.
TEMPORAL PATTERNS OF SEXUAL BEHAVIOR IN RABBITS AS DETERMINED BY AN AUTOMATIC RECORDING TECHNIQUE1
Authors: Rubin H. B. , Azrin N. H.
Published: March 2006

Sexual behavior between rabbits was automatically recorded by means of electrodes attached externally to the unrestrained animals. Current flowed only when the animals came into physical contact; the duration and amplitude of the current flow provided a means of automatic differentiation between sexual and other types of physical contact. Various temporal aspects of sexual behavior were revealed: (1) copulation was preceded by a series of thrusts that occurred at a constant frequency of 13 to 14 thrusts per sec; (2) the duration of a copulation was about 1.5 sec and could be as brief as 0.3 sec; (3) copulation was much more likely during the hours between dusk and dawn despite constant illumination; (4) copulations occurred in groups or “runs” characterized by many copulations within a few hours; (5) each run began with a high rate of copulation that often decreased over time; (6) between runs, several hours or days passed with little or no sexual activity; and (7) a run of copulations was noted at the end of every 16‐to 20‐day period (which corresponds to the known period of pseudopregnancy in rabbits) whether or not other runs occurred within this period.
CONDITIONED SUPPRESSION BY A STIMULUS ASSOCIATED WITH NALORPHINE IN MORPHINE‐DEPENDENT MONKEYS1
Authors: Goldberg Steven R. , Schuster Charles R.
Published: March 2006

Three rhesus monkeys, physically dependent on morphine, were trained to press a lever for food on a fixed ratio of 10 responses. A tone, initially a neutral stimulus, was aperiodically presented every third or fourth session, 5 min before and after the intravenous injection of nalorphine, a morphine antagonist which produces an immediate withdrawal syndrome in morphine‐dependent monkeys. After several sessions, conditioned suppression of food‐lever response rate was observed. Conditioned bradycardia, emesis, and excessive salivation also occurred. In 40 to 45 sessions the conditioned suppression of food‐lever response rate and the conditioned autonomic changes were extinguished by presenting pairings of a tone and saline injection. The monkeys were then reconditioned by presenting the tone aperiodically, every third or fourth session, 5 min before and after the intravenous injection of nalorphine. Results were similar to the initial conditioning sessions. Two rhesus monkeys not dependent on morphine were stabilized on a food schedule similar to that used for the first three monkeys. These monkeys showed no change in food‐lever response rate during or after nalorphine injections.
TIME‐DEPENDENT CONTRAST EFFECTS IN A MULTIPLE SCHEDULE OF FOOD REINFORCEMENT1
Authors: Bernheim Joseph W. , Williams David R.
Published: March 2006

Four rats were rewarded for running in a wheel under two alternating conditions of food reinforcement. These periods of frequent and infrequent reinforcement, each accompanied by a particular stimulus, were presented a number of times in each daily session. Following shifts from high to low frequency of reinforcement, responding decreased suddenly and markedly, and then recovered within the next few minutes. The magnitude of this temporary depression was an increasing function of the duration of the immediately preceding component of high‐frequency reinforcement. A transient elevation in performance, which did not vary with the duration of the prior component, was noted in two subjects following shifts from low to high frequency of reinforcement. The elevation and depression effects did not appear simultaneously during the 48 experimental sessions. A possible relation between the difficulty of the discrimination and the extent of contrast effects is discussed.
A METHOD FOR INCREASING THE REINFORCEMENT MAGNITUDE OF INTRACRANIAL STIMULATION1
Authors: Pliskoff Stanley S. , Hawkins T. Daryl
Published: March 2006

Schedules of intermittent brain‐stimulation reinforcement have been shown to maintain performances when a reinforcement is defined as several response‐produced, brief trains of stimulation. The present experiments show that the number of response‐produced trains permitted per reinforcement is a variable analogous to amount or magnitude of reinforcement in the conventional food‐reinforcement experiment. Systematic effects were obtained when that variable was manipulated within a multiple schedule and also on variable‐interval schedules programmed concurrently.
SOME EFFECTS OF CORRELATION BETWEEN RESPONSE‐CONTINGENT SHOCK AND REINFORCEMENT1
Authors: Murray Marcia , Nevin John A.
Published: March 2006

Rats responded on a two‐component chain schedule in which a response‐contingent electric shock at the end of the first component was either positively correlated, negatively correlated, or uncorrelated with reinforcement availability in the second component. With 0.4‐ma shocks, rate in the first component depended on the shock‐reinforcement correlation: when shock and reinforcement availability were positively correlated, after extended exposure to the contingencies, rates exceeded those in the absence of shock; when shock and reinforcement availability were negatively correlated, responding was generally suppressed throughout. The discriminative control of shock over responding in the second component, in which reinforcement was available 50% of the time, also depended somewhat on correlation. However, rate change in the first component was not specifically related to discrimination in the second component. With 0.8‐ma shocks, responding was substantially suppressed in the first component at all three values of shock‐reinforcement correlations.
ATTENTION AND TEMPORAL DISCRIMINATION: FACTORS CONTROLLING RESPONDING UNDER A CYCLIC‐INTERVAL SCHEDULE1
Authors: Staddon J. E. R.
Published: March 2006

Pigeons were exposed to a cyclic schedule in which each cycle was composed of twelve 1‐min fixed intervals followed by four 3‐min fixed intervals; four such cycles comprised an experimental session. The pigeons responded at a much higher average rate during the 3‐min intervals than during the 1‐min intervals. Other effects were a depression of responding during the first short interval of each cycle and a shortening of postreinforcement pause during the second short interval. The main effect is attributable to a relatively fixed pattern of responding after reinforcement; this pattern consisted in a pause of approximately constant duration followed by responding at an approximately constant rate until the next reinforcement, resulting in much higher average response rates during the longer interreinforcement intervals. The other effects seem attributable to relatively slight differences between the pattern of responding characteristic of later long intervals and the pattern during later short intervals of each cycle. A major implication is that the pigeon is largely insensitive to the sequential properties of many interval‐reinforcement schedules. A description of interval‐schedule “frustration” phenomena in terms of the inhibitory effects of reinforcement is discussed in relation to these results.
PREFERENCE FOR MIXED‐ VERSUS FIXED‐RATIO SCHEDULES1
Authors: Fantino Edmund
Published: March 2006

Pigeons' pecks on one key produced a stimulus correlated with a mixed‐ratio schedule of food reinforcement. Pecks on a second key produced a stimulus correlated with a fixed‐ratio schedule. When the arithmetic mean of the mixed ratios equaled the fixed ratio, the former stimulus maintained a higher rate of pecking. When the fixed ratio was sufficiently smaller, preference shifted to it. The pigeons' relative preference for the schedules could be described by comparing the geometric mean of the reinforcement rates in the several mixed‐ratio components with the reinforcement rates in the fixed‐ratio components.
DISCRIMINATION LEARNING BY MACACA MULATTA WITH OPTION TO SWITCH BETWEEN S+ AND S‐1
Authors: Rees Rod , Schrier Allan M.
Published: March 2006

Three rhesus monkeys were trained to press either of two response keys. A response on the reinforcement key during presentation of the reinforced stimulus produced a sucrose pellet followed by an intertrial interval, but during presentation of the unreinforced stimulus produced only the intertrial interval. A response on the switching key changed the discriminative stimulus from reinforced to unreinforced or from unreinforced to reinforced. The reinforced stimulus was presented automatically on half the trials, but could be produced only by a switching response on the other half. Switching tended to occur in three distinct stages during acquisition of discriminative behavior. The first stage was identified as “nondiscriminative switching”; the second as “nonswitching”; and the third as “discriminative switching”.
SOCIAL FACILITATION OF RESPONSES DURING A STIMULUS PAIRED WITH ELECTRIC SHOCK1
Authors: Hake D. F. , Laws D. R.
Published: March 2006

Key‐pecking responses of a pigeon were maintained by a variable‐interval schedule of food reinforcement. The responses were suppressed during the occasional presentation of a warning stimulus paired with electric shock. The presence of a second pigeon emitting the same response for food reinforcement reduced the suppression that otherwise occurred during the warning stimulus when the second pigeon was absent. These results reveal that the social facilitation phenomenon can be used to restore behavior that is suppressed by a conditioned aversive stimulus.
THE DEVELOPMENT OF IMITATION BY REINFORCING BEHAVIORAL SIMILARITY TO A MODEL1
Authors: Baer Donald M. , Peterson Robert F. , Sherman James A.
Published: March 2006

This research demonstrated some of the conditions under which retarded children can be taught to imitate the actions of adults. Before the experiment, the subjects were without spontaneous imitative behavior, either vocal or motor. Each subject was taught, with food as reinforcement, a series of responses identical to responses demonstrated by an experimenter; i.e., each response was reinforced only if it was identical to a prior demonstration by an experimenter. Initially, intensive shaping was required to establish matching responses by the subjects. In the course of acquiring a variety of such responses, the subjects' probability of immediate imitation of each new demonstration, before direct training, greatly increased. Later in the study, certain new imitations, even though perfect, were never reinforced; yet as long as some imitative responses were reinforced, all remained at high strength. This imitativeness was then used to establish initial verbal repertoires in two subjects.
A COMPARISON OF THE PUNISHING EFFECTS OF RESPONSE‐PRODUCED SHOCK AND RESPONSE‐PRODUCED TIME OUT1
Authors: McMillan D. E.
Published: March 2006

Electric shock and time out were compared as punishers in the squirrel monkey. At the parameters investigated, both suppressed responding to about the same degree. Scheduling punishment intermittently or administering pentobarbital reduced the effectiveness of both punishers. The effects of the punishers were different in that responding suppressed by shock recovered more within a session than responding suppressed by time out. Responding was suppressed after some shock‐punishment components, but less often after time‐out‐punishment components. The similarities of the two punishers were more striking than the differences.
IS BAR‐HOLDING WITH NEGATIVE REINFORCEMENT PREPARATORY OR PERSEVERATIVE?
Authors: Keehn J. D.
Published: March 2006

Three of four white rats learned to press first one bar and then another to escape or avoid electric shocks. Cumulative bar‐holding‐time records showed that holding occurred frequently on the second bar but hardly ever on the first, indicating that bar‐holding is more “perserverative” than “preparatory”. The response chain, first‐bar press second‐bar press, was more easily established by a forward than by a backward chaining procedure.
PROJECTOR SLIDE CHANGING AND FOCUSING AS OPERANT REINFORCERS
Authors: Benton Richard G. , Mefferd Roy B.
Published: March 2006

Uninstructed subjects choose to view, in sharp focus where possible, projected visual images in preference to various simpler auditory and visual stimuli (e.g., buzzers of flashing lights). The rate of responding on the lever rapidly increased above the operant level (projector inoperative) even though the stimuli were nonsense syllables. When focusing also was made contingent on responses, the subjects promptly started sharpening the focus of legible but blurred nonsense syllables. When the visual material was colored landscape scenes, the rates of slide‐changing generally decreased, because of increased viewing time relative to the nonsense syllables, at the same time that the latencies of focusing decreased. Both the sharpness of focus and the total time spent with the image in sharp focus increased greatly with the colored slides, establishing that the subjects were under control of the stimulus events. Extinction of both responses occurred very rapidly when the controls became inoperative.
BEHAVIORAL CONTROL BY AN IMPRINTED STIMULUS: LONG‐TERM EFFECTS1
Authors: Hoffman Howard S. , Kozma Frederick
Published: March 2006

Newly hatched ducklings were exposed to imprinting procedures and subsequently trained to peck a key by presenting the imprinting stimulus as the reinforcing (response‐contingent) event. Individual ducklings then lived in the apparatus under an arrangement in which each peck produced a 15‐sec stimulus presentation. For all ducklings, key‐pecks tended to occur in bursts, and as the duckling matured, burst length decreased and the interval between bursts increased. However, even when subjects were 60 days old, some responses still occurred.
CHANGEOVER DELAY AND CONCURRENT SCHEDULES: SOME EFFECTS ON RELATIVE PERFORMANCE MEASURES1
Authors: Shull Richard L. , Pliskoff Stanley S.
Published: March 2006

The pigeon and the rat partition total response output between both schedules of a concurrent variable‐interval pair. The quantitative nature of a partition seems critically dependent on the relative rates with which the two schedules provide reinforcements for responding, in addition to the changeover delay. The manner in which the changeover delay controls the partition was studied by varying the duration of the changeover delay from 0 to 20 sec with each of two pairs of concurrent variable‐interval schedules, viz., Conc VI 1.5‐min VI 1.5‐min and Conc VI 1‐min VI 3‐min. Rats served as the subjects and brain stimulation was employed as the reinforcer. When the schedules were Conc VI 1.5‐min VI 1.5‐min, relative response rate approximated 0.50 at all values of the changeover delay. When the schedules were Conc VI 1‐min VI 3‐min, relative response rate, computed with respect to the VI 1‐min schedule, increased when the duration of the changeover delay increased. Changeover rate decreased when the duration of the changeover delay increased. The decrease was the same for both VI schedules of the Conc VI 1.5‐min VI 1.5‐min pair but was more rapid for the VI 3‐min schedule of the Conc VI 1‐min VI 3‐min pair.
ANTECEDENT REINFORCEMENT CONTINGENCIES IN THE STIMULUS CONTROL OF AN AUDITORY DISCRIMINATION1
Authors: Pierrel Rosemary , Blue Scot
Published: March 2006

In order to assess possible confounding of discriminative stimulus effects with those produced by the reinforcing stimulus, three groups of four rats each were trained for 45 hr on a variable‐interval 1‐min reinforcement program. Two groups were run on a multiple variable‐interval extinction schedule in which the reinforcement stimulus (SD) and the nonreinforcement stimulus (SΔ) were two intensities of a 4‐kHz (cps) tone separated by 40 or 10 db. The third group was run on a mixed schedule with a single intensity constantly present. The mixed‐schedule animals showed no discrimination of the reinforcement program. Under the multiple schedule, the highest SΔ rates were obtained after SD intervals, regardless of the reinforcement availability in the SD interval. These local rate variations in SΔ were small in proportion to those produced by the SD versus SΔ intensities.
A NEW PRINCIPLE OF PELLET FEEDER DESIGN1
Authors: Cox Nigel , Adair Eleanor R.
Published: March 2006

Most current commercial devices dispense dry food pellets by moving the pellets horizontally toward a discharge point. Individual pellets, captured by perforations in a horizontal metal disk, are discharged one by one by stepwise rotation of the disk within the pellet reservoir. In our laboratory, where the average pellet discharge rate is some 20,000 pellets per week, feeders of this type produced occasional problems. Some were electronic; others involved failure always to capture a pellet in each perforation, particularly when the pellet supply was low. But the most common problem was an accumulation of pellet chips and dust under and around the perforated disk, which ultimately jammed the mechanism. Despite weekly cleaning and maintenance, troubles arose at least twice a month, prompting a search for a simpler pellet‐feeder design which would be more reliable and require less maintenance. The present pellet feeder employs a vertical rather than horizontal design principle. It has been used extensively in operant conditioning applications for more than a year. More than 200,000 pellets have been reliably discharged from a single feeder without a breakdown. No maintenance, other than a weekly cleaning of the discharge tube, has been required.
DRUG EFFECTS IN SQUIRREL MONKEYS TRAINED ON A MULTIPLE SCHEDULE WITH A PUNISHMENT CONTINGENCY
Authors: Hanson H. M. , Witoslawski J. J. , Campbell E. H.
Published: March 2006

The behavior of four monkeys trained on a multiple schedule was differentially sensitive to selected pharmacological agents. The three components of the multiple schedule were: (1) a variable‐interval schedule in which responses were reinforced on the average of once per minute; (2) a concurrent schedule in which every tenth response was reinforced and every fifteenth response, on the average, was shocked; and, (3) a neutral stimulus in the presence of which responses were neither reinforced nor shocked. Pentobarbital, chlordiazepoxide, and meprobamate increased responding during each of the components. Scopolamine and d‐amphetamine decreased variable‐interval performance, had minimal effects on performance during the concurrent‐schedule component, and increased responding in the presence of the neutral stimulus. Chlorpromazine decreased variable‐interval responding and had slight effects on the responding during the other two components.
AN INEXPENSIVE ELECTRO‐FISTULAR SWIVEL FOR NEGATIVE FEEDBACK CONTROL OF SELF‐STIMULATION1
Authors: Panksepp Jaak , Trowill Jay A. , Trehub Arnold
Published: March 2006

A swivel was developed for concurrent intraorganismic fluid injection and intracranial electrical stimulation of the unrestrained rat. Effects of various intragastric injections on bar‐pressing maintained by electrical stimulation of the hypothalamus were studied. In some subjects, intragastric injections of either water or milk decreased the rate of responding. This decrease resulted from pauses in responding rather than from decreases in the local rates of responding. The decrement in responding occurred at a lower gastric volume during milk injection than during water injection. In other subjects, however, neither water, milk, nor 32% sucrose injections affected the rate of self‐stimulation.
CHOICE AND DELAY OF REINFORCEMENT1
Authors: Chung Shin‐Ho , Herrnstein R. J.
Published: March 2006

Pigeons were trained to peck either of two response keys for food reinforcement on equated aperiodic schedules. The distribution of responding at the two keys was studied as reinforcement was delayed for various durations. The relative frequency of responding at each key was shown to match the relative immediacy of reinforcement, immediacy defined as the reciprocal of the delay of reinforcement.
THE EFFECT OF SHOCK INTENSITY ON CONCURRENT AND SINGLE‐KEY RESPONDING IN CONCURRENT‐CHAIN SCHEDULES1
Authors: Rachlin Howard
Published: March 2006

Pigeons were trained to respond in a two‐link, concurrent‐chain schedule. Pecks on each key during the concurrent initial links occasionally produced a 5‐min terminal link, during which only that key was operative. Food reinforcement and various intensities of shock were scheduled during the terminal links. When shock was contingent on response, the effect of shock was greater on terminal‐link responding than on initial‐link responding. When shock was independent of response, the effect was reversed, with larger changes in initial‐link responding than terminal‐link responding. In general, shock was found to affect behavior most drastically when behavior could, in turn, affect the rate of shock.
THE EFFECTS OF PUNISHMENT INTENSITY ON SQUIRREL MONKEYS1
Authors: Hake D. F. , Azrin N. H. , Oxford Rebecca
Published: March 2006

Responses of squirrel monkeys were maintained by a variable‐interval schedule of food reinforcement. Concurrently, punishment consisting of a brief electric shock followed each response. As has been found for pigeons and rats, punishment did not produce extreme, all‐or‐none reactions. By gradually increasing the punishment intensity it was possible to produce response rates intermediate to no suppression and complete suppression. Similarly, the moment‐to‐moment response rate was free of extreme fluctuations. A “warm‐up” effect occurred in which the punished responses were especially suppressed during the initial part of a session. The pre‐punishment performance was negatively accelerated within a session, and punishment reduced the degree of negative acceleration. When punishment was discontinued, responding recovered immediately except when suppression had been complete or prolonged. When the punishment intensity was decreased gradually, more suppression resulted at a given intensity than when intensity was increased gradually. This suggests a “behavioral inertia” effect wherein behavior at a new punishment intensity is biased toward the behavior at the previous value. A corollary generalization is that the larger the change in intensity, the less the behavior at the new value will be biased toward the behavior at the previous value.
AUTO‐SHAPING OF THE PIGEON'S KEY‐PECK1
Authors: Brown Paul L. , Jenkins Herbert M.
Published: March 2006

Reliable acquistion of the pigeon's key‐peck response resulted from repeated unconditional (response‐independent) presentations of food after the response key was illuminated momentarily. Comparison groups showed that acquisition was dependent upon light—food pairings, in that order.
PAUSE RELATIONSHIPS IN MULTIPLE AND CHAINED FIXED‐RATIO SCHEDULES1
Authors: Crossman E. K.
Published: March 2006

On a multiple fixed‐ratio 10 fixed‐ratio 100 schedule, pigeons pause for relatively long periods of time before the fixed‐ratio 100 schedule. Only a short pause occurs before the fixed‐ratio 10 schedule. A chain fixed‐ratio 10 fixed‐ratio 100 schedule produces the reverse pattern, i.e., a short pause before the fixed‐ratio 100 schedule and a long pause before the fixed‐ratio 10 schedule. Procedurally, the only difference between the two schedules is that the fixed‐ratio 10 component is always terminated by some unconditioned reinforcer in the multiple schedule but never in the chained schedule. In the present experiment, the percentage of fixed‐ratio 10 components which included reinforcement was gradually decreased for birds on the multiple schedule and gradually increased for birds on the chained schedule. It was found that percentage reinforcement within the fixed‐ratio 10 component was inversely related to the duration of the pause before the fixed‐ratio 10 component and directly related to the duration of the pause before the fixed‐ratio 100 component. Thus, the relative rate of reinforcement paired with a particular stimulus was seen to be an important factor in determining response latency to that stimulus.
PUNISHED AND UNPUNISHED RESPONDING IN MULTIPLE VARIABLE‐INTERVAL SCHEDULES1
Authors: Tullis Carole , Walters Gary
Published: March 2006

The performance of rats trained on multiple variable‐interval schedules was examined before, during, and after punishment. The same linear function related relative response rates to relative density of reinforcement both in the presence and absence of punishment. Equal relative suppression was seen in both the high and low reinforcement density components. The intercept value of the function was zero. Each component of the schedule was programmed on a separate lever: thus during any component, there was an opportunity for responses on the nonoperative lever (errors). The proportions of these errors declined to a near‐zero value during punishment and did not regain their prepunishment values after punishment was removed, suggesting that some discrimination learning occurred during punishment. Recovery of response rate during punishment was seen only where a greater‐than‐zero probability of reinforcement was associated with the response.
EFFECTS OF REQUIRED RATES OF RESPONDING UPON CHOICE1
Authors: Fantino Edmund
Published: March 2006

Pigeons' responses in the presence of two concurrently available (initial‐link) stimuli produced one of two different (terminal‐link) stimuli according to identical but independent variable‐interval schedules. Responses in the presence of each terminal‐link stimulus produced equal frequencies of food reinforcement, but in the presence of one of the stimuli, food depended upon the emission of a response rate either higher or lower than a specified value (differential reinforcement of rates). The measure of preference, the dependent variable, was the distribution of responses in the presence of the concurrently available stimuli of the initial links. Each pigeon, the responding of which was appropriately controlled by the response‐rate requirements in the two terminal‐link stimuli, consistently preferred the stimulus not associated with a response‐rate requirement.
RESPONSE COST AND THE CONTROL OF VERBAL BEHAVIOR UNDER FREE‐OPERANT AVOIDANCE SCHEDULES1
Authors: Davison M. C. , Kirkwood B. J.
Published: March 2006

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.
SUCCESSIVE REVERSALS OF A CLASSICALLY CONDITIONED HEART‐RATE DISCRIMINATION1
Authors: Tighe Thomas J. , Graves David M. , Riley Charles A.
Published: March 2006

Rats were trained to criterion in successive reversals of a classically conditioned heart‐rate discrimination. Criterion was attained more rapidly in the later reversals in the series than in the early reversals and the inter‐problem learning curve was of the same general form as that found with successive instrumental discrimination reversal in the same species.
THE DISCRIMINATION OF STIMULUS DURATION BY PIGEONS1
Authors: Stubbs Alan
Published: March 2006

Pigeons were trained to discriminate the duration of a stimulus. One response in a psychophysical choice situation was reinforced, given the immediately prior presentation of a stimulus duration in one class of durations called short durations, and the other response was reinforced given the immediately prior presentation of a stimulus duration in a second class called long durations. Durations of equal logarithmic difference from the cutoff, whether in the short or long class, yielded equal accuracy. Accuracy was a function not only of the properties of the stimuli to be discriminated, but also of the experimental contingencies used. Accuracy was greater in variable‐ratio than in fixed‐ratio schedules of reinforcement of the discriminative responses, and was lower at the beginning than later in individual fixed ratios. Proportion of short or long responses (response bias) was affected by sequential dependencies among long and short durations and was effectively controlled through the use of asymmetric reinforcement and fixed‐ratio contingencies.
THE DISTRIBUTION OF INTERRESPONSE TIMES IN THE PIGEON DURING VARIABLE‐INTERVAL REINFORCEMENT1
Authors: Blough Patricia M. , Blough Donald S.
Published: March 2006

Three pigeons' pecks were reinforced on 1‐ and 2‐min variable‐interval schedules, and frequency distributions of their interresponse times (IRTs) were recorded. The conditional probability that a response would fall into any IRT category was estimated by the interresponse‐times‐per‐opportunity transformation (IRTs/op). The resulting functions were notable chiefly for the relatively low probability of IRTs in the 0.2‐ to 0.3‐sec range; in other respects they varied within and between subjects. The overall level of the curves generally rose over the course of 32 experimental hours, but their shapes changed unsystematically. The shape of the IRT distribution was much the same for VI 1‐min and VI 2‐min. The variability of these distributions supports the notion that the VI schedule only loosely controls response rate, permitting wide latitude to adventitious effects. There was no systematic evidence that curves changed over sessions to conform to the distribution of reinforcements by IRT.
ON THE MEASUREMENT OF REINFORCEMENT FREQUENCY IN THE STUDY OF PREFERENCE1
Authors: Killeen Peter
Published: March 2006

In a two‐link, concurrent‐chain schedule, pigeons' pecks on each key during the initial link occasionally produced a terminal link, during which only that key was operative. Responses in the terminal link were reinforced with food on either fixed‐interval or variable‐interval schedules. In one experiment, relative amount of responding in the initial link equaled the relative harmonic rate of reinforcement in the terminal links. In a second experiment, the selection of interreinforcement intervals in variable‐interval schedules in the terminal links was such that rates of reinforcement based on the harmonic or on the arithmetic means of the interreinforcement intervals predicted opposite preferences in the initial links. The observed preference was consistent with that predicted by the harmonic rather than by the arithmetic rates of reinforcement.
DISCRIMINATION OF BRIGHTNESS DIFFERENCES BY RATS WITH FOOD OR BRAIN‐STIMULATION REINFORCEMENT1
Authors: Terman Michael , Kling J. W.
Published: March 2006

Rats were trained to respond to the brighter of two keys. Four animals were trained with food pellets and four with electrical brain stimulation. Each discrimination sequence was initiated when the animal broke a light beam at the rear of the chamber, turning on the key lights and starting a 30‐sec reinforcement period. An initial response on the brighter key was immediately reinforced, and further responses on the brighter key were then intermittently reinforced. Any time the dimmer key was pressed, a 30‐sec timeout was introduced. During timeout, no response had any programmed consequence. When the reinforcement period or the timeout ended, a new discrimination sequence could be initiated. Daily 1‐hr training sessions were conducted, and after seven or eight sessions, all animals were at or near errorless performance levels. The luminance of the brighter key was then systematically reduced, in seven steps, with two 30‐min test sessions at each step. Orderly psychometric functions were generated for individual animals. Initial acquisition, once position preferences were broken, was equally rapid for food and for brain‐stimulation animals, and the two reinforcement procedures yielded comparable levels of brightness discriminability.
AN OBSERVATION ON STIMULUS CONTROL IN A TILT DISCRIMINATION BY CHILDREN1
Authors: Stoddard Lawrence T.
Published: March 2006

Most children who learned to discriminate opposing 45° line tilts on a relational basis—oddity —did not learn the specific direction of the positive tilt. Most children who did not use oddity did discriminate the specific tilt.
FIXED AND VARIABLE SCHEDULES OF RESPONSE‐INDEPENDENT REINFORCEMENT1
Authors: Zeiler Michael D.
Published: March 2006

After response‐dependent reinforcement established key‐pecking as the predominant response, pigeons received schedules in which reinforcements occurred without reference to responding. These response‐independent schedules involved either a reinforcement every 5 min, or reinforcements at irregular intervals that averaged 5 min. The response‐independent schedules generated characteristic patterns of responding. The fixed schedule produced positively accelerated responding between reinforcements, and the variable schedule produced either steady rates, erratic, or negatively accelerated patterns. The pat/terns developed independent of the distribution of responses existing when the schedule was first imposed. The rate of responding varied for the three birds, but, for all, response‐independent schedules decreased the rates below the level maintained by response‐dependent reinforcement. Although the rate of responding was affected primarily by the events contiguous with reinforcement, the pattern of responding appeared to be determined mainly by the presentation of reinforcements in relation to time.
FADING PROCEDURES AND CONDITIONAL DISCRIMINATION IN CHILDREN1
Authors: Gollin Eugene S. , Savoy Pamela
Published: March 2006

A discrimination reversal task followed by a conditional discrimination problem was administered to children (age range 36 to 107 months). A fading procedure was used during the discrimination reversal training of some subjects and other subjects were trained by a traditional procedure. More subjects trained by the fading procedure performed without errors during training and more subjects in the traditional group solved the conditional discrimination problem.
INDUCTION, CONTRAST, AND RESISTANCE TO EXTINCTION1
Authors: Reynolds G. S.
Published: March 2006

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.
SUMMATION OF RESPONSE RATES TO DISCRIMINATIVE STIMULI ASSOCIATED WITH QUALITATIVELY DIFFERENT REINFORCERS1
Authors: Lawson Reed , Mattis Peter R. , Pear Joseph J.
Published: March 2006

In Experiment I, a four‐ply multiple schedule was used to study the effects on rate of responding in rats of food, water, and food and/or water reinforcement under different deprivation conditions. Food and water were associated separately with different stimuli, the combination of which was associated with food and water together, or with food or water randomly. Rates in the presence of the combined stimuli were consistently intermediate to the rates generated by the separate stimuli, a result seemingly incompatible with a “summation” hypothesis. Experiment II was a simplified systematic replication of Experiment I, verifying the major findings.
STIMULUS CONTROL IN THE EXPERIMENTAL STUDY OF COOPERATION1
Authors: Schmitt David R. , Marwell Gerald
Published: March 2006

The cooperative responses of pairs of human subjects were reinforced under several stimulus conditions in two settings designed to require a “social” response, i.e., where at least one of the two persons is responding to the behavior of the other. The first task, designed by Lindsley and Cohen, required individual responses within 0.5 sec of one another for reinforcement. The second (modified) task required a delay of 3 sec between individual responses. To determine dependence of cooperation on social stimuli, rates of cooperative behavior on these tasks were compared in the presence and absence of a stimulus indicating to each subject the other's response and a stimulus which indicated the duration of the timeout after reinforcement. The results indicated that only in the modified task was a high rate of cooperation always contingent upon the presence of the social stimuli.
FIXED‐RATIO PUNISHMENT BY TIMEOUT OF CONCURRENT VARIABLE‐INTERVAL BEHAVIOR1
Authors: Thomas John R.
Published: March 2006

Pigeons' responding was maintained by two concurrently available variable‐interval reinforcement schedules. A fixed‐ratio punishment schedule of timeout periods from the concurrent reinforcement schedules was arranged for responding during one of the variable‐interval schedules. The greater the probability of a timeout after a response on the punished variable‐interval schedule (the smaller the fixed ratio that produced timeout), the greater the decline in the relative punished response rates. Relative reinforcement rates remained invariant when relative response rates declined. Both behavioral contrast and induction effects were observed on the unpunished variable‐interval schedule as a function of timeout punishment of the other schedule.
ESCAPE FROM AN EFFORTFUL SITUATION1
Authors: Miller L. Keith
Published: March 2006

This experiment investigated the tendency to escape from a situation requiring effortful responding. Five human subjects responded in a situation where the response mechanism required 20‐lb force to operate; responses were reinforced according to a variable‐interval schedule. A subject escaped from this situation by emitting a vocal response which produced a 60‐sec “easy period”. During the easy period the reinforcement contingency was switched to a response mechanism requiring 1 lb to operate. It was found that: (1) Escape responding could be conditioned and maintained by producing the easy period; the easy period did not maintain escape responding when the force requirement in the normal situation was equated with it. (2) The rate of escape responding was a function of the magnitude of the force normally required. (3) When easy periods were scheduled after fixed ratios, pausing from the end of the previous easy period to the first escape response was noted. It was concluded that a situation requiring high‐force responding is a negative reinforcer. The pattern of fixed‐ratio responding suggests that this reinforcer produces typical schedule control in human subjects.
BITING ATTACK BY RATS IN RESPONSE TO AVERSIVE SHOCK1
Authors: Azrin N. H. , Rubin H. B. , Hutchinson R. R.
Published: March 2006

Paired rats are known to behave aggressively when given painful electric shocks. The present study developed a procedure whereby individual rats given shocks might bite an inanimate target object. Unavoidable shock was delivered to the rat while it was restrained in a position close to, and facing a target object. Biting of the target was recorded automatically. Shock caused the rat to bite metal, wood, or rubber targets. Biting was most frequent immediately after shock and decreased as a direct function of time since the shock. Almost every shock produced biting and the behavior continued as long as the shocks were delivered. Biting ceased within and between sessions when shocks were discontinued. These results show how the pain‐aggression relation can be studied objectively with rats.
THE REPEATED ACQUISITION OF BEHAVIORAL CHAINS1
Authors: Boren John J. , Devine Dennis D.
Published: March 2006

Monkeys were trained with food reinforcement in a chamber containing four groups of three levers. For each session the monkey's task was to learn a new four‐response chain by pressing the correct lever in each group. A stable pattern of learning resulted, and the number of errors reached a steady state from session to session. The technique was then used to determine how various durations of timeouts, following errors, affected the acquisition of new chains. With no timeout, the monkeys made a great many errors, due in large part to superstitious responses within the reinforced chain. Timeout durations ranging from 1 sec to 4 min reduced the number of errors substantially. A second experiment investigated the effects upon acquisition errors of presenting a single light (an “instruction” stimulus) over the correct lever. When this light did not influence the monkeys' responses to the three alternatives, the chains were learned as without it. When the light did control responding, the monkey pressed the appropriate sequence of levers but did not learn the sequence. Thus, when the light was removed, the monkey performed as if learning that sequence for the first time.
SEPARATING THE EFFECTS OF INTERREINFORCEMENT TIME AND NUMBER OF INTERREINFORCEMENT RESPONSES1
Authors: Neuringer Allen J. , Schneider Bruce A.
Published: March 2006

The relative importance of interreinforcement time and interreinforcement responses was evaluated by varying each independently. To do this, a blackout was presented after each non‐reinforced response under both fixed‐ratio and fixed‐interval schedules of reinforcement. Manipulating the blackout duration under the fixed‐ratio schedule caused interreinforcement time to vary without affecting the number of interreinforcement responses. Pigeons' post‐reinforcement and post‐blackout response latencies were found to increase linearly with interreinforcement time. Under the fixed‐interval schedule, the same blackout manipulations changed the number of interreinforcement responses without affecting interreinforcement time. Post‐reinforcement and post‐blackout response latencies under this condition were approximately constant. These results suggest that responding is controlled by interreinforcement time and is not influenced by the number of responses emitted between reinforcements.
SPACED RESPONDING AND CHOICE: A PRELIMINARY ANALYSIS1
Authors: Staddon J. E. R.
Published: March 2006

Pigeons were exposed to reinforcement both for short (2 < IRT < 3 sec) and long (10 < IRT < 11 sec) interresponse times. They developed bimodal interresponse‐time distributions, which were decomposable into two independent component distributions under the control of the short and long contingencies respectively. The birds' allocation of responses between these two distributions was determined by a simple power‐law relationship between reinforcement ratios, and response ratios derived from the component distributions. Comparison between this situation and concurrent choice situations raises the possibility that the power‐law relation between ratios may be a more general law pf choice than the matching of relative frequencies (probabilities).
DISCRIMINATION LEARNING, THE PEAK SHIFT, AND BEHAVIORAL CONTRAST1
Authors: Terrace H. S.
Published: March 2006

A discrimination between two successively alternating stimuli was trained under conditions that maintained equal frequencies of reinforcement in the presence of each of the discriminative stimuli (S1 and S2) but that also reduced the rate of responding to S2. These conditions included a multiple variable‐interval differential‐reinforcement‐of‐low‐rate schedule and a multiple variable‐interval variable‐interval schedule in which responses to S2 were punished. Whenever the rate of responding to S2 was reduced, rate of responding to S1 (behavioral contrast) increased, and the peak of a subsequently obtained generalization gradient did not occur at the expected location (between S1 and S2) but was displaced away from S2, below S1. Discrimination training in which the frequencies of reinforcement earned in S1 and S2 were not equal (variable‐interval 1‐min variable‐interval 5‐min training) produced contrast and the peak shift only if the rate of responding to S2 had been reduced, as after non‐differential reinforcement in which variable‐interval 1‐min schedules were correlated with SI and with S2. It was concluded that a sufficient condition for the occurrence of behavioral contrast and the peak shift was reduction of the rate of responding to one of two alternating discriminative stimuli and that a peak shift will occur only if contrast had occurred during discrimination training.