bluuebunny/crossref_metadata_2025 huggingface dataset:
THE USE OF RATS AS DISCRIMINATIVE STIMULI1
Authors: Husted John R. , McKenna Frank S.
Published: March 2006

A free operant procedure was used to determine whether or not one rat could discriminate: (1) between the presence and absence of a second rat, and (2) between two other rats of the same species and sex. The subjects were four male Wistar rats. The discriminatory response was a bar press and food was used as reinforcement during training. Although there were wide individual differences in rate of learning, all subjects learned to make both discriminations.
CARDIAC AND RESPIRATORY CONDITIONING, DIFFERENTIATION, AND EXTINCTION IN THE PIGEON1
Authors: Cohen David H. , Durkovic Russell G.
Published: March 2006

Paired light and foot shock in 12 pigeons rapidly developed acceleratory heart and respiratory conditioned responses. Sensitization and stimulus control birds did not condition. When a different colored stimulus light that was not reinforced was mixed in a random series with the reinforced light, rapid differentiation of both heart and respiratory responses occurred. In most cases neither heart nor respiratory conditioned responses could be extinguished by 100 nonreinforced presentations of the conditioned stimulus.
OPERANT CONDITIONING OF A SMALL‐SCALE MUSCLE RESPONSE1
Authors: Sasmor Robert M.
Published: March 2006

Six naive male subjects were reinforced for responses in the 20–30 microvolt range, and two each for those in 10–20 and 30–40 microvolt ranges. Records were taken of 15 min of “settling down,” 15 min of initial operant level responding, 30 min of conditioning, and 45 min of extinction, 30 min with light present and 15 min without. The results were: (1) small‐scale muscle potentials from the thenar eminence, in the 10–20, 20–30, and 30–40 microvolt ranges, were conditioned, using pointer movement as the reinforcement; (2) the response rate in adjacent ranges of greater and lesser amplitude also increased during such conditioning and decreased during the subsequent extinction; (3) during conditioning the frequency of response distribution shifted toward the reinforced range; (4) subjects were unaware of the reinforced response; (5) observing a noncontingent moving pointer increased the response rate in the 20–30 microvolt range, but did not lead to conditioning.
SECOND‐ORDER AVOIDANCE BEHAVIOR IN MONKEYS1
Authors: Findley J. D. , Schuster C. R. , Zimmerman J.
Published: March 2006

Two monkeys were trained on a three‐component multiple schedule using discrete trials. In one component (food), a response terminated a red stimulus and produced food and SΔ. In the second component (avoidance), a response terminated a green stimulus and avoided shock. In the third component (optional), a response terminated a blue stimulus and produced SΔ The consequence of not responding in the blue stimulus, however, was the production of either a food or an avoidance trial. Manipulation of these consequences showed that when food trials were available only a small percent of the time after optional trials, the subjects tended not to respond in the blue, even though this led to an increase in the total number of avoidance trials per day. If only avoidance trials followed as a consequence of not responding in the optional component, the animals terminated the blue stimulus and avoided the avoidance trials. Throughout the experiment both subjects maintained consistently low shock rates (about 10 per day) and these were not affected by the various manipulations. The data suggest that a stimulus associated with avoidance can be a conditioned aversive stimulus and will maintain a more remote avoidance response under certain conditions.
OPERANT CONDITIONING IN THE NEWLY HATCHED CHICKEN1
Authors: Marley E. , Morse W. H.
Published: March 2006

Techniques are described for conditioning key‐pecking reinforced with food and for recording cheeping in newly hatched chickens. A mirror in the test box is essential when conditioning isolated chickens up to five or more days old. Conditioning proceeds more rapidly when frequently pecked objects and materials that move when scratched are not present. Stimulus control over key‐pecking is present in the three‐day‐old chicken and multiple fixed‐ratio, fixed‐interval schedule control develops in succeeding days. In young chickens, pecking and cheeping are inversely related. The newly hatched chicken is useful for pharmacological studies and appears to offer other advantages for behavioral studies.
AN ELECTROMECHANICAL ANALYZER USING HISTOGRAM TECHNIQUES
Authors: Caggiano Vincent , Fallon Lee
Published: March 2006

In behavioral studies it is often necessary to classify events and store the number of events occurring in each classification. The classification requirements may be either functions of amplitude (i.e., intensity, force, peaks, etc.) or time (i.e., duration, interval, etc.). The following describes an analyzer capable of classifying events according to their duration, interval, or time of occurrence, and storing and displaying the number of such events in each classification.
INTERHEMISPHERIC TRANSFER OF LEVER PRESSING AS STIMULUS GENERALIZATION OF THE EFFECTS OF SPREADING DEPRESSION1
Authors: Schneider Allen M. , Ebbesen Ebbe
Published: March 2006

Rats trained to lever‐press with spreading depression in one cerebral hemisphere showed weak responding when tested with depression shifted to the trained hemisphere. The rats were then divided into two groups: one group (normal) was permitted a single reinforced response with neither hemisphere depressed, the other group (depressed) was permitted a single reinforced response with the trained hemisphere depressed; both groups were then tested with the trained hemisphere depressed. Responding during this second test increased for both groups, but the magnitude of the increase tended to be greater for the depressed than for the normal group. Since memory transfer could not have occurred with the trained hemisphere depressed, the results were taken to indicate that the single reinforced response strengthened stimulus generalization between train‐test conditions.
AN ACCURATE REPEAT CYCLE TIMER1
Authors: Welford Norman T. , Gollin E. S.
Published: March 2006

This timer was designed to provide a compact and quiet unit to control the presentation of visual stimuli by means of a slide projector, but it is not limited to this use. It is a solid state device, ready for use as soon as switched on, and is made largely from commercial logic units. The output is in the form of contact closures: the ON relay and the OFF relay give short pulse closures at the beginning of their respective cycles. With circuit values as shown in Fig. 1, times, from 0.5 to 10 sec in increments of 0.5 sec with an accuracy of ±1%, are selected by separate switches on the ON and the OFF cycles. Single interval solid state timers have been described by Saslow and Markowitz (1964) and by Tapp and Clark (1964).
CLASSICAL CONDITIONING OF COURTING BEHAVIOR IN THE JAPANESE QUAIL, COTURNIX COTURNIX JAPONICA1
Authors: Farris Howard E.
Published: March 2006

Male Japanese quail were classically conditioned to display courting behavior at the sound of a buzzer, a previously neutral stimulus. The buzzer (conditioned stimulus) was paired with the presentation of a female quail (unconditioned stimulus) for a number of trials. The courting display, invariably elicited from the male by the presentation of the female, began to appear in part to the conditioned stimulus as early as the fifth pairing. All components of the display were elicited from all birds by the conditioned stimulus alone within 32 pairings of the conditioned and unconditioned stimuli.
EFFECTS OF REINFORCEMENT SCHEDULING ON SIMULTANEOUS DISCRIMINATION PERFORMANCE1
Authors: Nevin John A.
Published: March 2006

Pigeons were trained on a discrete‐trials, simultaneous discrimination procedure, with confusable stimuli such that asymptotic performance was about 85% correct. Trials were terminated if no response occurred within 2 sec of stimulus onset, so that probability of responding was free to vary. The schedule of reinforcement for correct responses was varied, with the following results: (1) there was no relation between frequency of reinforcement and accuracy of responding. (2) In extinction, the probability of responding fell to low levels, but accuracy remained roughly constant. (3) When reinforcement was available after a fixed number of trials or after a fixed number of correct responses, the probability of responding increased with successive trials after reinforcement, but accuracy was generally constant. (4) When every fifth correct response was reinforced, accuracy decreased immediately after reinforcement if the birds were required to respond on every trial.
FIXED‐INTERVAL BEHAVIOR MAINTAINED BY CONDITIONED REINFORCEMENT1
Authors: Lorge John de
Published: March 2006

The key‐pecking of a pigeon was reinforced with grain on an 18‐min second‐order schedule. During the 18 min, a key peck which completed a 3‐min fixed interval produced a stimulus of 0.5‐sec duration. The first 3‐min fixed interval completed after 18 min resulted in primary reinforcement. Behavior characteristic of fixed‐interval schedules was produced on both the 3‐min components and the 18‐min schedule. This performance was shown to be enhanced whenever the 0.5‐sec stimulus was also presented before the presentation of grain.
A SIMPLE HISTOLOGICAL TECHNIQUE FOR LOCALIZING ELECTRODE TRACKS AND LESIONS WITHIN THE BRAIN1
Authors: Hutchinson R. R. , Renfrew J. W.
Published: March 2006

Histological procedures are necessary in brain stimulation or lesion work to determine the neural area which has been stimulated or damaged. Preparation of brain tissue often involves embedding and staining techniques that require specialized training, and the expense of a technician and a large assortment of special apparatus and supplies. In addition, the results of such techniques are unavailable for at least several days. A photographic method, which requires little special skill and a minimal amount of apparatus, is described here. Results can be available within minutes after the subject is sacrificed. This method has been shown to be adequate for the gross determination of lesion boundaries and electrode or cannula tip loci in brains of rats, cats, and squirrel monkeys.
THE EFFECTIVENESS OF FADING IN PROGRAMMING A SIMULTANEOUS FORM DISCRIMINATION FOR RETARDED CHILDREN1
Authors: Sidman Murray , Stoddard Lawrence T.
Published: March 2006

A non‐verbal teaching program, combined with reinforcement and extinction (Program Group), was compared with reinforcement and extinction alone (Test Group) in teaching retarded children to discriminate circles from ellipses. In the Program Group, fading techniques were used to transfer stimulus control from “bright vs. dark” to “form vs. no‐form” and then to “circle vs. ellipse”. The Test Group had the task of learning the circle‐ellipse discrimination with no prior teaching program. With the program, seven of 10 children learned the circle‐ellipse discrimination. Without the program, one of nine learned. The eight Test‐Group children who failed to learn circle vs. ellipse were then given the opportunity to learn the form no‐form discrimination by reinforcement and extinction alone, without fading. Six of the eight learned, but only three of these six then learned circle vs. ellipse on a second test. All seven Program‐Group children who had learned form vs. no‐form also learned the circle‐ellipse discrimination by means of fading; each of the seven made fewer errors than any of the three who succeeded on the second test. Children who failed to learn circle vs. ellipse adopted response patterns incompatible with the development of appropriate stimulus control.
INTERACTION BETWEEN REFLEXIVE FIGHTING AND COOPERATIVE ESCAPE1
Authors: Ulrich Roger
Published: March 2006

Subjects separated by a Plexiglas partition were trained to follow a cooperative escape procedure which produced behavior like the escape responding of individual subjects. Removal of the partition produced fighting and less efficient escape. Efficient escape behavior was restored and fighting disappeared when the partition was replaced. Neither increased space nor a moving toy affected escape behavior. The results indicate that switching animals from an isolated to a social situation produced a change in the effect of shock upon escape which was related to shock‐induced fighting.
EFFECTS OF CONDITIONED REINFORCEMENT FREQUENCY IN AN INTERMITTENT FREE‐FEEDING SITUATION1,2
Authors: Zimmerman Joseph , Hanford Peter V. , Brown Wyman
Published: March 2006

Key‐pecking intermittently produced a set of brief exteroceptive stimulus changes under two‐component multiple schedules of conditioned reinforcement. Throughout the study, free access to grain was concurrently provided on an intermittent basis via a variable‐interval tape. Free food presentations scheduled by the tape were delivered if no peck had been emitted for 6 sec, and the brief stimulus changes produced by responding under the multiple schedules were those which accompanied food presentation. The second component of each multiple schedule was always associated with a 1‐min, variable‐interval schedule of conditioned reinforcement. The schedule associated with the first component was systematically varied and conditioned reinforcement was either absent (extinction) or programmed on a 1‐, 3‐, 6‐, or 12‐min variable‐interval schedule. Under these conditions, rate of responding in the manipulated component decreased monotonically with a decrease in the frequency of conditioned reinforcement. In addition, contrast effects were often obtained in the constant, second component. These results are similar to those obtained with similar multiple schedules of primary reinforcement.
A PEAK SHIFT ON A LINE‐TILT CONTINUUM1
Authors: Bloomfield T. M.
Published: March 2006

Pigeons were trained to discriminate the presence or absence of a vertical line, and their performance on a subsequent generalization test was compared with that of other pigeons trained to discriminate a vertical from a 45° line. On the generalization gradient after discrimination training, the presence/absence discrimination group showed a peak at 0° (vertical) while the peak for the 0°/45° discrimination group shifted from 0° in a direction away from the 45° line. The results, discussed in connection with a recent suggestion about the role of color in the peak‐shift effect, are interpreted as supporting the generality of the phenomenon.
MODIFICATION OF A RESPONSE BIAS THROUGH DIFFERENTIAL AMOUNT OF REINFORCEMENT1
Authors: Galloway Charles
Published: March 2006

A procedure is described for assessing response bias to either the form or color dimension of a compound standard stimulus. Responding was assessed under conditions of equal reinforcement (three tokens) for responding to either the form or color dimension. Under these conditions, the four male subjects (aged 7 to 11 yr) differentially responded to the form dimension. After a bias was assessed, the number of tokens delivered contingent upon form responses was reduced. After a reversal in differential responding, the equal‐reinforcement condition was reintroduced. Two of the subjects returned to their initial response bias when equal reinforcement for either dimensional response was reintroduced, and two maintained the reversal established during the differential‐reinforcement phase. For the latter two subjects, differential reinforcement was again imposed, in favor of form. This partial replication reinstated their original pattern of response bias.
CONDITIONING OF THE AGGRESSIVE BEHAVIOR OF PIGEONS BY A FIXED‐INTERVAL SCHEDULE OF REINFORCEMENT1
Authors: Azrin N. H. , Hutchinson R. R.
Published: March 2006

Operant reinforcement of aggression was studied in food‐deprived pigeons by delivering food for attacks against a target pigeon. The food was delivered according to a fixed‐interval schedule and attack behavior was recorded automatically. Attack could be conditioned and extinguished, and the proportion of time spent in attack was a direct function of the frequency of reinforcement of the attack. The fixed‐interval schedule produced an increasing rate of attack during the interval between food reinforcements. This positive curvature was an inverse function of the duration of the interval. The findings revealed that the duration and temporal patterning of the complex social behavior of attack can be influenced in a substantial and predictable manner by the schedule and frequency of operant reinforcement.
QUASI‐REINFORCEMENT: CONTROL OF RESPONDING BY A PERCENTAGE‐REINFORCEMENT SCHEDULE1
Authors: Neuringer Allen J. , Chung Shin‐Ho
Published: March 2006

When a variable‐interval schedule of reinforcement was segmented into small fixed‐interval components, with reinforcements following some components and brief blackouts following the others, rate of responding doubled and a positively accelerated pattern within each component was obtained. Presented according to this percentage reinforcement paradigm, the blackouts approximated the functions of a food reinforcer. These effects occurred only when the behavior sequence required to produce reinforcement was identical to that required to produce blackout. The quasi‐reinforcing effects of these blackout stimuli suggest that a neutral stimulus need not occasion or accompany a primary reinforcer to acquire reinforcing properties.
DISCRIMINATED PUNISHMENT: AVOIDABLE AND UNAVOIDABLE SHOCK
Authors: Gibbon John
Published: March 2006

Warning stimuli for two punishment conditions were alternated with periods of appetitive responding by rats. In either warning stimulus, the first response produced a brief shock, terminated the stimulus, and started an interval during which the baseline appetitive schedule was in effect. Not responding resulted in stimuli of random duration, which terminated with a shock under one condition and without a shock under the other. Each subject was exposed to several shock intensities, with trials for the two conditions programmed during alternate portions of the session. In general, response frequency in the warning signal for either condition decreased with increasing intensity; however, at a given intensity, responding was more frequent in the stimulus invariably terminating with shock than in the stimulus terminating without shock when no response was made. The frequency difference was greatest at intensities intermediate between those producing minimal and maximal suppression.
METHYLPHENIDATE AND STIMULUS CONTROL OF AVOIDANCE BEHAVIOR1
Authors: Stretch Roger , Skinner Nicholas
Published: March 2006

The introduction of a warning signal that preceded a scheduled shock modified the temporal distribution of free‐operant avoidance responses. With response‐shock and shock‐shock intervals held constant, response rates increased only slightly when the response‐signal interval was reduced. The result is consistent with Sidman's (1955) findings under different conditions, but at variance with Ulrich, Holz, and Azrin's (1964) findings under similar conditions. Methylphenidate in graded doses increased response rates, modifying frequency distributions of inter‐response times. Drug treatment may have disrupted a “temporal discrimination” formed within the signal‐shock interval. More simply, methylphenidate influenced response rates by increasing short response latencies after signal onset; this effect was more prominent than the drug's tendency to increase the frequency of pre‐signal responses. When signal‐onset preceded shock by 2 sec, individual differences in performance were marked; methylphenidate suppressed responding in one rat as a function of increasing dose levels to a greater degree than in a second animal, but both subjects received more shocks than under control conditions.
STRATEGIES OF SCHEDULE PREFERENCE IN CHIMPANZEES1
Authors: Hodos William , Trumbule Gerald H.
Published: March 2006

Two chimpanzees were required to choose between a fixed‐ratio schedule and a progressive‐ratio schedule which increased in response requirement by 20 responses each time it was chosen. Each choice of the fixed ratio reset the progressive ratio to its minimum value. The fixed‐ratio requirement was varied from 40 to 1000 responses. The subjects' preferences for the progressive‐ratio schedule varied as a function of the magnitude of the fixed‐ratio requirement. An analysis of the preference data indicated that the animals tended to minimize reinforcement cost rather than match the progressive‐ratio requirement to the fixed‐ratio requirement. In a second experiment, selection of the fixed ratio did not reset the progressive‐ratio requirement to its minimum value. In this case, the animals matched the progressive‐ratio requirement to the fixed‐ratio requirement. A model based on reinforcement cost is presented which permits accurate prediction of preferences between fixed and progressively increasing ratio schedules.
FREE‐OPERANT COMPOUNDING OF VARIABLE‐INTERVAL AND LOW‐RATE DISCRIMINATIVE STIMULI1
Authors: Weiss Stanley J.
Published: March 2006

Four rats were trained on a schedule containing stimuli associated with variable‐interval 30‐sec and differential‐reinforcement‐of‐low‐rate 20‐sec schedules of reinforcement. Subsequently, a stimulus compounding test was administered that included individual presentations of two intensities of each stimulus plus compounds of these stimuli. In training, extremely high rates were emitted to the variable‐interval stimulus, and very low rates to the differential‐reinforcement‐of‐low‐rate stimulus. Compounding the two training stimuli always produced an overall response rate intermediate between the rates controlled by the two stimuli separately presented. Essentially the same relationship held with different stimulus intensities. These results resolve the confounding of response and reinforcement variables present in previous conditioning studies reporting response averaging. They are discussed in terms of the incompatibility of the response chains associated with the individual stimuli compounded.
ADRENOCORTICAL INFLUENCES ON FREE‐OPERANT AVOIDANCE BEHAVIOR1
Authors: Wertheim George A. , Conner Robert L. , Levine Seymour
Published: March 2006

Rats were conditioned to avoid shock on a free‐operant avoidance schedule in which no exteroceptive stimulus signaled impending shock. Injections of adrenocorticotropic hormone (ACTH) or dexamethasone raised blood levels of glucocorticoids. These increases were accompanied by changes in avoidance performance: there was a higher frequency of long‐duration interresponse times, a greater stability among them, and fewer short interresponse times, total responses, and shocks.
STIMULUS CONTROL WITH FIXED‐RATIO REINFORCEMENT1
Authors: Zeiler Michael D.
Published: March 2006

Pigeons were trained on a three‐stimulus simultaneous discrimination with reinforcements given on fixed‐ratio schedules ranging from one response per reinforcement to 205 responses per reinforcement. Responses to any of the three stimuli advanced the ratio, but, when it was completed, a reinforcement followed a response to one designated stimulus. Throughout the ratio, the birds responded mainly to the designated stimulus. The relatively few responses to the other stimuli usually occurred immediately after postreinforcement pauses. The distribution of responses to the various stimuli was not affected by omitting reinforcements.
EFFECTS OF TIMEOUT ON A DISCRIMINATION BETWEEN FIXED‐RATIO SCHEDULES1
Authors: Rilling Mark
Published: March 2006

A discrimination was established between two fixed‐ratio schedules of reinforcement. In one, fixed ratio 25, the reinforcer was delivered on the twenty‐fifth response; on the other, fixed ratio 50, the fiftieth response was reinforced. In the first component of a chain, either fixed ratio 25 or fixed ratio 50 was randomly programmed on the center key of a three‐key pigeon box. Reinforcement of a single peck on the side key was contingent upon discriminating which schedule had just been completed on the center key. During test trials, a timeout was introduced after the first response on fixed ratio 25 and after either the first or twenty sixth response on fixed ratio 50. When the timeout followed the first response on fixed ratio 25 and fixed ratio 50, the accuracy of the discrimination was unaffected. When the timeout followed the first response on fixed ratio 25 and the twenty sixth response on fixed ratio 50, the accuracy of the discrimination decreased rapidly to chance as a function of the duration of the timeout. The loss of discrimination was primarily due to errors after fixed ratio 50 was completed. The timeout appears to weaken the control over the choice response by the response‐produced stimuli which preceded the timeout. The results are consistent with the interpretation that the discrimination between fixed ratio 25 and fixed ratio 50 is maintained by chaining of response‐produced stimuli within the ratio cycle.
EXTINCTION OF SIDMAN AVOIDANCE BEHAVIOR1
Authors: Shnidman Susan R.
Published: March 2006

Extinction of Sidman avoidance behavior by eliminating the noxious stimulus was studied in Sprague‐Dawley rats with bar‐pressing as the response. Each of three subjects was trained and extinguished on each of the following schedules in a different order: nondiscriminated, response‐shock interval = 20 sec, shock‐shock interval = 5 sec; nondiscriminated, response‐shock interval = 40 sec, shock‐shock interval = 5 sec; discriminated, response‐white noise interval = 15 sec, noise‐shock interval = 5 sec, shock‐shock interval = 5 sec. Less than one 4‐hr session was required for extinction for all procedures. When a warning stimulus was present, resistance to extinction increased. Subjects did not, however, respond to avoid the signal. Only small differences in extinction were found after training on different schedules with no warning signal.
SOME DETERMINERS OF ATTENTION1
Authors: Johnson Daniel F. , Cumming William W.
Published: March 2006

Three experiments, using a total of 13 pigeons, examined the stimulus control acquired by the separate components of a compound visual stimulus transilluminating the pecking key. Experiment I measured the control acquired by components of compound discriminative stimuli used in discrimination training. Experiment II sought to demonstrate the effect of pretraining a single stimulus discrimination on control acquired by each component in a compound stimulus discrimination. It also investigated the effect of training the compound stimulus discrimination before the single stimulus discrimination. Experiment III sought a continuous stimulus control function when pretraining stimulus intensities were varied. The results suggest that the extent to which a bird “pays attention” to a stimulus, defined in terms of the degree of stimulus control acquired by that stimulus, is determined by how well it previously learned to discriminate that stimulus from other stimuli.
FURTHER EVIDENCE OF A SENSORY‐TONIC INTERACTION IN PIGEONS1
Authors: Thomas David R. , Lyons Joseph
Published: March 2006

The five pigeons in Group 1 were given successive intradimensional discrimination training in which responses to a line of 49° were reinforced on a variable‐interval schedule and responses to a line of 33° were not reinforced. Subsequent generalization testing with other line orientations revealed a peak shift from the positive stimulus in the direction away from the negative stimulus in all subjects. The four pigeons in Group 2 received successive discrimination training with the 49° value on the key during both stimuli. During the negative stimulus, however, the floor was tilted 16° counterclockwise. When tested (with the floor flat) these subjects showed peak shifts similar to those observed with Group 1. A third group of three pigeons, given successive interdimensional discrimination training with the 49° line as the positive stimulus and the absence of the line as the negative, showed no peak shift in a subsequent generalization test. It was concluded that tilting the floor on which the pigeon stood systematically distorted the bird's visual perception of the orientation of the line in a manner consistent with the results of other studies in this laboratory.
FACILITATION AND SUPPRESSION OF HUMAN LOSS‐AVOIDANCE BY SIGNALED, UNAVOIDABLE LOSS1
Authors: Baron Alan , Kaufman Arnold
Published: March 2006

A 15‐sec stimulus followed by unavoidable monetary loss was presented to human subjects who were avoiding loss on a free‐operant schedule. As has been observed in studies where shock is the aversive event, initial reactions to the pre‐loss stimulus were transient increases in overall and stimulus rates. Unlike shock studies, continued training produced decreased rates, in the presence of the 15‐sec stimulus, which were maintained in two of three subjects. Subsequent observations indicated that lowered rates were a function of the subject's rate of avoidance responding, the duration of the stimulus, and the scheduling of avoidable losses. Increasing the duration of the stimulus eliminated lowered rates in the presence of the stimulus and subsequent exposures to conditions which previously produced lowered rates did not result in recovery of the phenomenon. Introduction of the pre‐loss stimulus on an extinction baseline (avoidable losses were omitted), however, reinstituted lowered rates. It is proposed that the pre‐loss stimulus assumed discriminative control over low rates because responding in the presence of the stimulus was ineffective in avoiding the unavoidable loss. Recovery from lowered rates is attributed to the occurrence of avoidable losses during the stimulus period, and maintenance of lowered rates on the extinction schedule to the omission of such avoidable losses.
PERFORMANCE OF TWO SPECIES OF QUAIL ON BASIC REINFORCEMENT SCHEDULES1
Authors: Cloar F. Thomas , Melvin Kenneth B.
Published: March 2006

Two bobwhite quail (Colinus virginianus) and two Japanese quail (Coturnix coturnix japonica) were trained to peck a response key to obtain food. In general, performance on fixed ratio 20 and variable‐ and fixed‐interval 60‐sec schedules was comparable to the response patterns of other species under these schedules.
A SIMPLE TECHNIQUE FOR DELIVERING LIQUIDS DIRECTLY TO THE MOUTH OF AN UNRESTRAINED RAT1
Authors: Gross Douglas M. , Trapold Milton A. , Hyde Thomas S.
Published: March 2006

A simple surgical procedure is described that makes it possible to deliver liquids directly into the mouth of a freely mobile rat. Data presented show that an 8% sucrose solution delivered by this technique is an effective reinforcer in a variety of simple and discriminative schedules of reinforcement.
AN EXPERIMENTAL SPACE COMBINING INDIVIDUAL AND SOCIAL PERFORMANCES1
Authors: Ferster C. B. , Hammer C. , Randolph J.
Published: March 2006

This report describes several primate environments in which two or more animals shared a common social area. Automatic programming was used to permit concurrent individual sessions. Some of the behavioral phenomena observed in these environments, including reinforcing properties of social interactions, are discussed.
THE PEAK SHIFT IN STIMULUS GENERALIZATION: EQUIVALENT EFFECTS OF ERRORS AND NONCONTINGENT SHOCK1
Authors: Grusec Theodore
Published: March 2006

Terrace suggested that the peak shift in stimulus generalization occurs because the training stimulus not correlated with reinforcement has become aversive. This hypothesis is plausible in the light of instances where the peak shift is obtained compared with those where it fails to appear. The present experiment attempted to test implications of this hypothesis. Two groups of pigeons learned the same two‐stimulus discrimination between colors by different training methods in a free‐operant situation. When the discrimination was trained with many errors, a large peak shift was obtained in a subsequent generalization test of wavelength; after discrimination training with few errors, a negligible shift was observed. Half of each group then received noncontingent aversive shock during presentations of the stimulus not correlated with reinforcement in continued discrimination training. After this treatment, the errorless‐shock subgroup showed a large peak shift and the error‐shock subgroup tended to show a larger shift than before. Nonshocked control groups showed little change in the peak shift. It was concluded that pairing aversive shock with a stimulus not correlated with reinforcement is sufficient to produce or enhance a peak shift. In their effect on the peak shift, aversive shock and large amounts of nonreinforced responding appear to be equivalent.
THE RELATION BETWEEN RESPONSE RATES AND REINFORCEMENT RATES IN A MULTIPLE SCHEDULE1
Authors: Pliskoff Stanley S. , Shull Richard L. , Gollub Lewis R.
Published: March 2006

In a multiple schedule, exteroceptive stimuli change when the reinforcement schedule is changed. Each performance in a multiple schedule may be considered concurrent with other behavior. Accordingly, two variable‐interval schedules of reinforcement were arranged in a multiple schedule, and a third, common variable‐interval schedule was programmed concurrently with each of the first two. A quantitative statement was derived that relates as a ratio the response rates for the first two (multiple) variable‐interval schedules. The value of the ratio depends on the rates of reinforcement provided by those schedules and the reinforcement rate provided by the common variable‐interval schedule. The following implications of the expression were evaluated in an experiment with pigeons: (a) if the reinforcement rates for the multiple variable‐interval schedules are equal, then the ratio of response rates is unity at all reinforcement rates of the common schedule; (b) if the reinforcement rates for the multiple schedules are unequal, then the ratio of response rates increases as the reinforcement rate provided by the common schedule increases; (c) the limit of the ratio is equal to the ratio of the reinforcement rates. Satisfactory confirmation was obtained for the first two implications, but the third was left in doubt.
USE OF PROGRESSIVE FIXED‐RATIO PROCEDURES IN THE ASSESSMENT OF INTRACRANIAL REINFORCEMENT1
Authors: Keesey Richard E. , Goldstein Michael D.
Published: March 2006

Six rats with electrodes chronically implanted in septal or hypothalamic sites were tested for intracranial reinforcement on a progressive fixed‐ratio schedule. Two variations of this schedule were also examined and compared. Functions relating the highest level of stable fixed‐ratio responding to a wide range of stimulus currents were, unlike those derived from continuous reinforcement rates, monotonic at all stimulation sites tested. One of the procedures described, in particular, is quite sensitive to intracranial reinforcement parameters, provides a reliable technique for within‐session assays of these parameters, and successfully avoids many problems commonly encountered with administration of central stimulation on a continuous reinforcement schedule.
A DEMONSTRATION OF AUTO‐SHAPING WITH MONKEYS
Authors: Sidman Murray , Fletcher F. Garth
Published: March 2006

The Brown‐Jenkins auto‐shaping procedure for pigeons was found applicable to monkeys. Repeated pairings of lighted keys with reinforcement generated key‐pressing behavior. The animals rapidly learned a simultaneous light‐dark discrimination. The topographies of key‐pressing and magazine behavior differed; the food tray was not illuminated.
OPERANT CONDITIONING OF EYE MOVEMENT IN THE MONKEY (Macaca nemestrina)1
Authors: Berger Ralph J.
Published: March 2006

With the horizontal electrooculographic potential as the operant, four monkeys (Macaca nemestrina) were conditioned to move their eyes at high and low rates by initial use of fixed‐ratio schedules of reinforcement, followed by a changeover to multiple schedules of fixed‐ratio reinforcement and discriminated differential reinforcement of low rate. These differences in rate of eye movement were not observed in a control animal given the same patterns of discriminative stimuli and deliveries of the reinforcing agent independent of its eye movements.
SOME EFFECTS OF DISCRIMINATIVE TRAINING WITH EQUATED FREQUENCY OF REINFORCEMENT1
Authors: Yarczower Matthew , Gollub Lewis R. , Dickson James F.
Published: March 2006

Pigeons were exposed to a multiple schedule which provided equally frequent reinforcement in the presence of two stimuli but which produced markedly different rates of key‐pecking. Generalization gradients were displaced away from the stimulus associated with the lower rate of key‐pecking. Another group of pigeons had similar training, except that a low rate of key‐pecking was established in a stimulus with a much higher frequency of food reinforcement. In this case, the generalization gradients were not affected by the training on the schedule producing a low response rate.
CUE‐PRODUCING BEHAVIOR IN THE CAPUCHIN MONKEY DURING REVERSAL, EXTINCTION, ACQUISITION, AND OVERTRAINING1
Authors: D'Amato M. R. , Etkin Michael , Fazzaro James
Published: March 2006

In a two‐choice discrimination situation, a cue‐producing response produced the discriminanda for 0.05 sec. The cue‐producing responses beyond those normally necessary to identify the discriminanda thus provided only redundant information. Two of the four Capuchin monkeys studied showed a large increase in cue‐producing responses during reversal learning and extinction, and they reversed much faster than the two whose cue‐producing responses showed little increase. During acquisition of a difficult discrimination, the cue‐producing responses of the first two subjects reached a high level and during overtraining gradually reduced to their initial low level. The results were related to Wyckoff's theory of observing behavior and to the notions of uncertainty, reduction, and lack of information as extensions of the concepts of reinforcement and motivation.
ACQUISITION AND MAINTENANCE OF MATCHING WITHOUT A REQUIRED OBSERVING RESPONSE1
Authors: Eckerman David A. , Lanson Robert N. , Cumming William W.
Published: March 2006

Two experiments demonstrated that matching‐to‐sample performance was improved when an explicit observing response was required to the sample stimulus. The first experiment demonstrated that fewer training sessions were required to establish matching with than matching without such a response. The second experiment demonstrated the dependence of established matching accuracy upon this observing response and the development in two of three subjects of a new overt observing response even when none was required by the experimenter.
STIMULUS FUNCTION IN SIMULTANEOUS DISCRIMINATION1
Authors: Biederman Gerald B.
Published: March 2006

In discrimination learning, the negativity of the stimulus correlated with nonreinforcement (S–) declines after 100 training trials while the stimulus correlated with reinforcement (S+) is paradoxically more positive with lesser amounts of discrimination training. Training subjects on two simultaneous discrimination tasks revealed a within‐subjects overlearning reversal effect, where a more‐frequently presented discrimination problem was better learned in reversal than was a discrimination problem presented less frequently during training.
A COMPARISON OF ESCAPE AND AVOIDANCE CONDITIONING IN WILD AND DOMESTICATED RATS1
Authors: Powell Robert W. , Morris Grant
Published: March 2006

In the first of two experiments, three cotton rats (Sigmodon hispidus) and three albino rats were exposed to instrumental escape, unsignaled avoidance, and signaled avoidance, in that order. All subjects learned the escape procedure quickly, with the albino rats having generally shorter latencies, higher response rates, and requiring fewer sessions to reach the criterion. When the avoidance contingency was introduced, the cotton rats continued to respond almost entirely in the presence of the shock, whereas the albino rats responded in its absence, thus displaying effective avoidance behavior. Introduction of a pre‐aversive stimulus did not improve the performance of the cotton rats. In the second experiment, five cotton rats and four albino rats were exposed to a free‐operant (Sidman) avoidance procedure with a shock‐shock interval of 3 sec and a response‐shock interval of 20 sec. The cotton rats initiated responding at lower shock intensities than the albino rats, but their asymptotic avoidance responding was far less effective.
RESPONSE RATE, REINFORCEMENT FREQUENCY, AND CONDITIONED SUPPRESSION1
Authors: Blackman Derek
Published: March 2006

In the first of two experiments, periods of noise were terminated with unavoidable shock to 36 rats. The rats' continuously reinforced responding was later completely suppressed during the noise when it was introduced without shock. The rats were then assigned to nine experimental groups. Each group was exposed to different paced variable‐interval schedules of reinforcement, which independently controlled response rate and reinforcement frequency. Periods of the noise were periodically superimposed on these schedules, and loss of response suppression was studied. Differences between the groups were assessed statistically. The second experiment used a steady‐state design. Six rats were exposed to paced schedules which generated two alternating response rates but gave constant reinforcement frequencies, and six rats to schedules which maintained the same response rates throughout, but in which the reinforcement frequency was alternately high and low. Response suppression was studied during a pre‐shock stimulus superimposed on each rat's two behavioral baselines. Both experiments suggest that (1) conditioned suppression is affected by rate of operant responding, high rates being most suppressed, and (2) the frequency of reinforcements obtained also has an effect, most suppression occurring when frequency is low.
MULTIPLE SCHEDULES: EFFECTS OF THE DISTRIBUTION OF REINFORCEMENTS BETWEEN COMPONENTS ON THE DISTRIBUTION OF RESPONSES BETWEEN COMPONENTS1
Authors: Lander D. G. , Irwin R. J.
Published: March 2006

Two pigeons were trained to peck a key under several multiple variable‐interval variable‐interval schedules of reinforcement; different numbers of reinforcements were scheduled in two components of equal duration which were correlated with red and green illumination of the response key respectively. The results showed: (1) that the total number of responses in a session was proportional to the one‐sixth power of the total number of reinforcements delivered in that session; and (2) that the ratio of responses between the two components was equal to the one‐third power of the ratio of reinforcements between them. This latter exponent may be regarded as reflecting the sensitivity of the distribution of responses between the components to the distribution of reinforcements. It was suggested that the effects of a number of complex schedules of reinforcement could be summarized by different values of this exponent.
MAGNITUDE AND FREQUENCY OF REINFORCEMENT AND FREQUENCIES OF INTERRESPONSE TIMES1
Authors: Shimp Charles P.
Published: March 2006

The relative magnitude and relative frequency of reinforcement for two concurrent interresponse times (1.5 to 2.5 sec and 3.5 to 4.5 sec) were simultaneously varied in an experiment in which pigeons obtained grain by pecking on a single key. Visual discriminative stimuli accompanied the two time intervals in which reinforcements were arranged by a one‐minute variable‐interval schedule. The resulting interresponse times of each of three pigeons fell into two groups; “short” (1.0 to 2.5 sec) and “long” (3.0 to 4.5 sec). Steady‐state relative frequencies of these interresponse times were orderly functions of both reinforcement variables. The combined effects of both independent variables were well summarized by a linear function of one variable, relative access to food. Unlike corresponding two‐key concurrent variable‐interval schedules, the present schedule did not produce an equality between the relative frequency of an operant and either the relative magnitude or the relative frequency of reinforcement of that operant. A tentative account is provided for this difference between one‐key and two‐key functions.
CONDITIONED SUPPRESSION OR FACILITATION AS A FUNCTION OF THE BEHAVIORAL BASELINE1
Authors: Blackman Derek
Published: March 2006

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.
SEQUENTIAL CONTRAST EFFECTS WITH HUMAN SUBJECTS1
Authors: O'Brien Floyd
Published: March 2006

Institutionalized retardates were exposed to a multiple variable‐interval: extinction schedule of reinforcement in which 5‐min periods of variable‐interval reinforcement and 5‐min periods of extinction were presented in a random order. This schedule was found to generate sequential contrast effects: response rates during variable‐interval reinforcement were higher when a variable‐interval period followed an extinction period than when it followed another variable‐interval period. The rate of responding within a variable‐interval period also was affected by the number of extinction periods preceding a variable‐interval period. As the number of successive extinction periods that preceded a variable‐interval period increased, the rate of responding during that variable‐interval period increased. The sequential contrast effects were transient, being most evident during the early sessions and generally disappearing by the tenth session.
ON SOME CAUSES OF BEHAVIORAL CONTRAST1
Authors: Reynolds G. S. , Limpo Alan J.
Published: March 2006

Responding at low rates was differentially reinforced in each of two components of a multiple schedule. In order to study the relative contributions to behavioral contrast in one component of the rates of responding, and of reinforcement in a second component, a series of visual stimuli correlated with the duration of each interresponse time was added to one component. The added stimuli resulted in a decreased rate of responding and hence an increased rate of reinforcement in that component. Despite the increase in the rate of reinforcement, the rate of responding without added stimuli in the other component increased (contrast), even though the increase resulted in less frequent reinforcement.