bluuebunny/crossref_metadata_2025 huggingface dataset:
SOURCES OF STIMULUS CONTROL DURING MULTIPLE DISCRIMINATIONS1
Authors: Zeiler Michael D.
Published: March 2006

Pigeons learned to respond to the middle‐sized member of six or seven sets of three stimuli differing in size. The sets were used successively, each serving as the discrimination problem from 10 to 16 times. After attaining criterion with one set, the birds received the others as probes. The number of responses in probes was related to the similarity of the probes to the prevailing discrimination problem. The birds responded either to the probe stimulus to which responding had most recently been reinforced, or to the probe stimulus closest in size to the positive member (S+) of the prevailing discrimination problem. Responses to a middle‐sized probe‐set stimulus occurred when it was the probe‐set member most recently correlated with reinforcement, when it was one of two stimuli closest in size to S+, and when the stimulus closest in size to S+ was a negative member of the discrimination problem. All of the behavior could be explained in terms of control by the absolute sizes of the various stimuli.
CLOCK‐DELIVERED REINFORCERS IN CONJUNCTIVE AND INTERLOCKING SCHEDULES1
Authors: Powers Richard B.
Published: March 2006

The effects of different temporal requirements in conjunctive and interlocking schedules of reinforcement were examined. The compound schedules were arranged so that a reinforcer could be delivered by either a rat's response or a clock. As the temporal requirements increased in the interlocking schedules, the overall rate of responding increased, but the pattern of responding remained relatively unchanged. As the temporal requirement increased in the conjunctive schedules, the overall rate decreased and a pause‐and‐run pattern of responding emerged. When the response requirement was reduced to one in the conjunctive schedule for one animal, a low and extremely stable rate of responding developed.
THE EFFECT OF SMALL SEQUENTIAL CHANGES IN FIXED‐RATIO SIZE UPON THE POST‐REINFORCEMENT PAUSE1
Authors: Powell Robert W.
Published: March 2006

Duration of the post‐reinforcement pause was measured for three pigeons on fixed‐ratio schedules of reinforcement ranging from 10 to 160. Small sequential changes were made in the ratio values without disrupting stable performance. The post‐reinforcement pause increased consistently for all birds within three sessions as the ratio requirement increased. A frequency analysis of the individual pauses at selected fixed ratios revealed an increase in dispersion for all animals as the ratio size increased. Response rate tended to decrease for two of the birds and remained relatively stable for the third; but there were many reversals in these data.
AVOIDANCE RESPONDING IN PIGEONS1
Authors: Macphail Euan M.
Published: March 2006

Four pigeons were trained in a one‐way shuttle box avoidance situation. Three of the birds met the criterion of 90% avoidances; the fourth, although frequently avoiding successfully, was too erratic to meet the criterion. Avoidance responding in two of the birds was subsequently extinguished, showing that the response was true avoidance, and not escape from the buzzer warning stimulus. In Experiment 2, the three birds that had met criterion in Experiment 1 were trained in a two‐way avoidance task, and all three met the criterion of 90% avoidances. The shuttle box therefore provides a rapid and reliable method of obtaining avoidance performance in pigeons.
SOME EFFECTS OF RELATIVE REINFORCEMENT RATE AND CHANGEOVER DELAY IN RESPONSE‐INDEPENDENT CONCURRENT SCHEDULES OF REINFORCEMENT1
Authors: Brownstein Aaron J. , Pliskoff Stanley S.
Published: March 2006

Reinforcements were arranged independently of the pigeon's behavior by concurrent variable‐interval schedules. The reinforcements arranged by one of the schedules occurred when the chamber was illuminated with amber light, and the reinforcements arranged by the other schedule occurred when the chamber was illuminated with blue light. Both schedules functioned concurrently, but reinforcers were delivered by each only in the presence of the appropriate stimulus condition. A response on a white key, the only key in the chamber, alternated the stimulus condition and the effective schedule. The results of this procedure were similar to those obtained with concurrent response‐dependent variable‐interval schedules of reinforcement. The proportion of the total session time spent in the presence of a schedule component approximated the proportion of the total number of reinforcements in the component. Changeover rate was a decreasing function of the changeover delay and of the difference between the relative rates of reinforcement for each pair of concurrent schedules.
EFFECTS OF A PRE‐AVERSIVE STIMULUS UPON ODDITY PERFORMANCE IN MONKEYS1
Authors: Kruper Donald C.
Published: March 2006

Two monkeys (Macaca mulatta) were trained to perform an oddity discrimination using automatically projected patterned stimuli. After criteria for both response and discrimination stability were met, a tone followed by shock was superimposed upon the ongoing behavior. Each 60‐sec tone was terminated with the onset of a 0.3‐sec, 1 to 1.5‐ma electric shock. During the tone, baseline responding was partially suppressed but discrimination performance was little altered from the pre‐tone period. When shock was raised to 2 to 3 ma, responding was further suppressed, but discrimination performance was again essentially unaltered.
DIFFERENTIAL REINFORCEMENT AND STIMULUS CONTROL OF NOT RESPONDING1
Authors: Nevin John A.
Published: March 2006

Pigeons were trained to respond with equal variable‐interval reinforcement in the presence of a white key and also a white key with a vertical line. They were then trained not to respond to the vertical line by extinguishing the response or by reinforcing its non‐occurrence at various frequencies. During training, the rate of key‐pecking in the presence of the white key, maintained by a constant variable‐interval schedule of reinforcement, depended on the frequency of reinforcement in the presence of the line. When lines of different orientations were presented in a generalization test, birds trained with extinction responded more to other orientations than to the vertical line, whereas those trained with high frequencies of reinforcement for not responding tended to respond equally at all line orientations. Intermediate frequencies of reinforcement gave mixed results.
GENERALIZATION GRADIENTS OF INHIBITION AFTER DIFFERENT AMOUNTS OF TRAINING1
Authors: Farthing G. William , Hearst Eliot
Published: March 2006

Five groups of pigeons received seven sessions of variable‐interval reinforcement for pecking a blank white key, followed by either 1, 2, 4, 8, or 16 sessions of training on a successive discrimination in which the positive stimulus was the blank white key and the negative stimulus was a black vertical line on the white key. After training, a generalization test was administered along the line‐tilt continuum. Relative gradients of inhibition became steeper with increased amounts of training, and reliably nonhorizontal absolute gradients were obtained only from groups of subjects with at least four days of training. Therefore, inhibitory stimulus control improves with added training. Several problems with the concept of “inhibition” are examined and some implications of the results for theoretical analyses of operant discrimination learning are discussed.
SOME EFFECTS OF THE CONDITIONED SUPPRESSION PARADIGM ON OPERANT DISCRIMINATION PERFORMANCE1
Authors: Weiss Kenneth M.
Published: March 2006

Three experiments were conducted with rats to determine the effects of electric shock on responding during an operant discrimination. In two of these experiments, a conditioned suppression procedure was superimposed upon a stimulus signalling the availability of food reinforcement (SD). Response rates were greatly suppressed, not only in the warning signal periods which preceded each shock, but in the presence of SD, and the stimulus signalling the unavailability of reinforcement (SΔ) as well. A third experiment, in which a very mild shock was used without a warning signal, demonstrated an increased response rate in SD and SΔ, although this effect was rather unsystematic. In a similar study, Hearst (1965) found an increased rate in SΔ independent of any change in the SD rate. The present study failed to obtain Hearst's effect but illustrated a suppressive effect with a similar procedure.
DIFFERENTIAL CONDITIONAL EMOTIONAL AND CARDIOVASCULAR RESPONSES—A TRAINING TECHNIQUE FOR MONKEYS1
Authors: Nathan Marc A. , Smith Orville A.
Published: March 2006

A training technique has been developed which combines classical differential conditioning and conditional emotional response (CER) procedures. After monkeys were trained to lever‐press on a variable‐interval schedule, two stimulus lights were presented. One light (CS) was always followed, upon termination, by electrical shock; the other light (DS) was never followed by shock. The response to the CS was a decreased rate of lever‐pressing and increased heart rate and blood‐flow velocity. None of these responses occurred to the DS. This technique eliminates the possibility of pseudoconditioning and provides measurement of both somatic and autonomic responses in a CER situation.
THE EFFECT OF RESPONSE FORCE ON AVOIDANCE RATE1
Authors: Miller L. Keith
Published: March 2006

In a Sidman‐avoidance schedule of counter losses for two human subjects, the loss‐to‐loss and response‐to‐loss intervals were 20 sec. The avoidance response was a vocal response that was louder than a minimum vocal requirement. This requirement was set at 80 db, 95 db, or 110 db. In addition to vocal responses meeting the minimum requirement, all responses exceeding a threshold of 75 db or louder were recorded. The rate of both above‐threshold and avoidance responses decreased as the response‐force requirement increased. Thus, high response‐force requirements produced an effect on avoidance responding similar to its effect on positively reinforced responding.
FIXED‐RATIO SCHEDULE‐INDUCED AGGRESSION1
Authors: Gentry William D.
Published: March 2006

Pigeons' pecks were conditioned with food reinforcement. Subjects were exposed to sessions of no‐reinforcement and of fixed‐ratio reinforcement. The pigeons attacked a target animal during the fixed‐ratio reinforcement conditions. The attack occurred primarily during the post‐reinforcement pause and occurred after almost every instance of reinforcement. Little or no aggressive behavior was demonstrated during periods of no‐reinforcement except on the initial days of these conditions. The results indicated that a fixed‐ratio schedule of reinforcement has certain characteristics capable of producing aggression.
EFFECTS OF SHOCK INTENSITY AND DURATION ON THE FREQUENCY OF BITING ATTACK BY SQUIRREL MONKEYS1
Authors: Hutchinson R. R. , Azrin N. H. , Renfrew J. W.
Published: March 2006

Squirrel monkeys were periodically exposed to brief tail‐shocks in the presence of a rubber tube connected to a pneumatic switch. Biting attack upon this tube was found to be a decreasing function of time since shock delivery and a direct function of shock intensity and duration. These results parallel findings in investigations employing more “naturalistic” social situations, indicating that attack against the inanimate and animate environment is a direct function of the intensity of an aversive stimulus. The results also demonstrate that frequency of biting attack as a datum is sensitive to several experimental manipulations.
SECONDARY REINFORCEMENT AND NUMBER OF PRIMARY REINFORCEMENTS1
Authors: Fantino Edmund , Herrnstein R. J.
Published: March 2006

Pigeons' pecks on either of two concurrently available response keys produced secondary reinforcers according to independent one‐minute variable‐interval schedules. Different secondary reinforcers, in the presence of which the rates of primary reinforcement were equal, were associated with each key. The rate of pecking maintained by each secondary reinforcer varied directly, but nonproportionally, with the number of primary reinforcements given in the presence of the secondary reinforcer.
THE BISECTION OF A SPATIAL INTERVAL BY THE PIGEON
Authors: Walker John K. , Blough Donald S.
Published: March 2006

Pigeons pecked two response keys to move a white dot until it was equidistant from two other dots on a screen. Continuous records of dot position showed the effects of reinforcement and stimulus parameters upon the accuracy with which the dot was positioned. The method may prove useful for studying the perception of distance in non‐human organisms.
A QUANTITATIVE ANALYSIS OF THE RESPONDING MAINTAINED BY INTERVAL SCHEDULES OF REINFORCEMENT1
Authors: Catania A. Charles , Reynolds G. S.
Published: March 2006

Interval schedules of reinforcement maintained pigeons' key‐pecking in six experiments. Each schedule was specified in terms of mean interval, which determined the maximum rate of reinforcement possible, and distribution of intervals, which ranged from many‐valued (variable‐interval) to single‐valued (fixed‐interval). In Exp. 1, the relative durations of a sequence of intervals from an arithmetic progression were held constant while the mean interval was varied. Rate of responding was a monotonically increasing, negatively accelerated function of rate of reinforcement over a range from 8.4 to 300 reinforcements per hour. The rate of responding also increased as time passed within the individual intervals of a given schedule. In Exp. 2 and 3, several variable‐interval schedules made up of different sequences of intervals were examined. In each schedule, the rate of responding at a particular time within an interval was shown to depend at least in part on the local rate of reinforcement at that time, derived from a measure of the probability of reinforcement at that time and the proximity of potential reinforcements at other times. The functional relationship between rate of responding and rate of reinforcement at different times within the intervals of a single schedule was similar to that obtained across different schedules in Exp. 1. Experiments 4, 5, and 6 examined fixed‐interval and two‐valued (mixed fixed‐interval fixed‐interval) schedules, and demonstrated that reinforcement at one time in an interval had substantial effects on responding maintained at other times. It was concluded that the rate of responding maintained by a given interval schedule depends not on the overall rate of reinforcement provided but rather on the summation of different local effects of reinforcement at different times within intervals.
RESPONDING IN THE CAT MAINTAINED UNDER RESPONSE‐INDEPENDENT ELECTRIC SHOCK AND RESPONSE‐PRODUCED ELECTRIC SHOCK1,2
Authors: Byrd Larry D.
Published: March 2006

Key‐pressing responses in the cat were maintained under conditions in which brief electric shock was first postponed by responses (avoidance), then periodically presented independently of responses, and finally produced by responses on a fixed‐interval schedule of 15 min (FI 15‐min). A steady rate of responding occurred under shock avoidance and under response‐independent shock; positively accelerated responding was engendered by the FI 15‐min schedule. A second experiment studied responding under second‐order schedules composed of three FI 5‐min components. Responding was suppressed when a stimulus was presented briefly at completion of each FI 5‐min component and a shock followed the brief stimulus at completion of the third component. Responding was maintained when each of the first two components was completed either with or without presentation of a brief stimulus and a shock alone was presented at completion of the third FI 5‐min component.
THE PRESENCE OF A TEMPORAL DISCRIMINATION IN THE CONDITIONED EMOTIONAL RESPONSE WITH HUMANS1,2
Authors: Sachs David A. , May Jack G.
Published: March 2006

Six college students participated in matching‐to‐sample tasks. Conditioned emotional response (CER) training consisted of pairing a tone with a “painful” level of shock. Three of the subjects demonstrated response suppression, one subject showed facilitation, and two showed no change. Analysis of response rate during the tone interval indicated that, for those subjects who showed response suppression, the decrease in response rate was greatest immediately before onset of the unconditioned stimulus. This temporal discrimination was similar to that obtained with infrahumans.
PUNISHMENT OF SHOCK‐INDUCED AGGRESSION1
Authors: Ulrich Roger , Wolfe Marshall , Dulaney Sylvia
Published: March 2006

Squirrel monkeys were restrained in a chair equipped with a tail‐shock apparatus and a pneumatic bite hose located in front of the subject's face. An aggressive response was recorded when the monkey bit the hose. Initial sessions in which no shocks were delivered produced some biting. When biting during these sessions stabilized at a near‐zero level, regularly scheduled shocks were delivered to the monkey's tail, causing a consistently higher rate of biting. After several sessions under these conditions, a punishment phase was introduced in which the previous shock conditions were maintained, and every bite was followed immediately by another, more intense shock. Biting under these conditions was suppressed to a near‐zero level. When the punishment contingency was removed, biting increased. With one subject, two additional bite‐contingent stimuli were examined: (1) a milder shock that, when made contingent upon hose biting, also suppressed that response, and (2) a contingent tone that had no obvious suppressing or facilitating effect. Individual differences among subjects were extreme, but the effect of bite‐contingent shock was consistent. Observations of the subjects during the punishment sessions indicated the existence of certain side effects that resulted from the use of punishment to suppress shock‐induced aggression.
SOME EFFECTS OF PUNISHMENT ON PAIN‐ELICITED AGGRESSION1
Authors: Baenninger Ronald , Grossman Jan C.
Published: March 2006

Painful mechanical tail‐pinch elicited aggressive responses in paired rats; response‐contingent electric shock to either forepaws or hindpaws suppressed fighting and stereotyped aggressive postures, including those in which dominance was expressed. There was no evidence that aggression was facilitated by shock that was contingent on pain‐elicited aggressive responses. Aggressive responding recovered when shock was discontinued.
THE EFFECT OF RATE OF DELIVERY OF RESPONSE‐INDEPENDENT SHOCKS UPON AVOIDANCE RESPONDING1
Authors: Jones Robert T.
Published: March 2006

Two hooded rats were trained to bar‐press to avoid electric shock on a continuous avoidance schedule with response‐shock and shock‐shock intervals equal. The rate of delivery of response‐independent shocks superimposed on this schedule was varied. The response‐independent shocks led to generally higher response rates but, with responses during shock omitted, the rates decreased as the response‐independent shock rate was increased. The actual shock rate received by the subjects was linearly related to the maximum potential shock rate. There was an increasing, negatively accelerated function between percentage avoidance and response rate, but there was no consistent relation between the number of shocks avoided and response rate. Response rate decreased as the potential shock rate increased, but responding was maintained even when as few as 15% of the shocks could be avoided.
DENSITY AND DELAY OF PUNISHMENT OF FREE‐OPERANT AVOIDANCE1
Authors: Baron Alan , Kaufman Arnold , Fazzini Dan
Published: March 2006

In two experiments, the free‐operant shock‐avoidance behavior of rats was punished by electric shock. Two aspects of the schedule of response‐produced shock were varied: the frequency of punishment over time (punishment density) and the temporal interval between the punished response and the punishment (punishment delay). The general finding was that response‐produced shock suppressed avoidance responding under most of the density‐delay combinations studied, and suppression increased as a function of increases in density and decreases in delay. Rate increases of small magnitude also were observed, usually as an initial reaction to the lesser densities and longer delays. Response suppression, while decreasing the number of punishment shocks received, also increased the number of avoidance shocks, so that the total number of shocks received usually was greater than the minimal number possible. The results were discussed from the standpoint of similarities between the effects of punishing positively and negatively reinforced behavior. The finding that subjects did not minimize the total number of shocks suggested that when avoidance behavior is punished, responding is controlled more by the local consequences of responding than by overall shock frequencies during the course of the session.
CONDITIONING HISTORY AND THE CONTROL OF HUMAN AVOIDANCE AND ESCAPE RESPONDING1
Authors: Weiner Harold
Published: March 2006

Inter‐subject differences in response rates under free‐operant avoidance and escape schedules are commonly obtained from humans. Data are presented which demonstrate that such differences can be controlled experimentally by giving subjects different conditioning histories. Subjects given a fixed‐ratio history avoided and/or escaped from “point‐loss periods” at higher rates than subjects given a differential‐reinforcement‐of‐low‐rates history. History related differences in response rates were maintained during 40 hr of escape responding. For low‐rates history subjects, response rates under escape contingencies decreased as the rate of point‐loss periods decreased.
THE EFFECTS OF ESCAPE CONDITIONING AND SHOCK INTENSITY ON RESPONDING DURING INESCAPABLE SHOCK
Authors: Domjan Michael P. , Rowell John W.
Published: March 2006

Eight albino rats, conditioned to press a lever to escape shock, continued to lever press during short inescapable shocks presented subsequently. The rate of this behavior was found to be higher for higher shock intensities regardless of the order in which shock values were presented. Relative to the immediately preceding escape rate, responding during inescapable shock was higher following conditioning at higher fixed‐ratio escape requirements. Four subjects not conditioned to escape shock pressed the lever very infrequently during inescapable shock and showed little change with changes in shock intensity. The escape conditioning effects suggest that responding during inescapable shock is superstitious escape behavior. The effects of shock intensity on this behavior appear to be similar to reported effects of shock intensity on escape behavior.
PERSISTENT SHOCK‐ELICITED RESPONDING ENGENDERED BY A NEGATIVE‐REINFORCEMENT PROCEDURE1
Authors: Powell Robert W. , Peck Stephen
Published: March 2006

A procedure in which responses reduced intermittently presented electric shocks to one quarter of their originally scheduled intensity, effectively engendered and maintained lever pressing in hooded rats. This contingency also markedly increased the response rates of rats initially trained under an unsignaled avoidance procedure. The responding of all animals extinguished rapidly when shock was withdrawn. Subsequently, it was discovered that high response rates could be maintained solely through presentation of shocks that were not affected by responses. Variations in the interval between shocks and changes in shock intensity over a wide range did not attenuate responding. Terminal performance was characterized by a consistent pattern of shock‐elicited responses. Responses were also elicited by a tone following repeated tone‐shock pairings. Finally, responding that was maintained by response‐independent shocks was quickly suppressed by response‐contingent shocks of the same intensity.
RESPONSE RATE AS A FUNCTION OF AMOUNT OF REINFORCEMENT FOR A SIGNALLED CONCURRENT RESPONSE1
Authors: Rachlin Howard , Baum William M.
Published: March 2006

Pigeons were exposed to two equal, concurrent variable‐interval schedules of reinforcement on two response keys. One key was continuously illuminated. Pecking on that key produced reinforcements of constant duration. The other key was normally dark, except that availability of reinforcement was signalled by illuminating the key. The duration of access to a grain reinforcer was varied on the key that signalled reinforcement. Rate of response on the first key, the one that did not signal reinforcement, was found to vary inversely with duration of signalled reinforcement on the other key. The latency between the signal and the peck that produced signalled reinforcement remained about constant. These results show that responding on one key in concurrent variable‐interval schedules depends on the reinforcement delivered by both schedules and is independent of responding on the other key.
CONDITIONAL DISCRIMINATION LEARNING IN THE PIGEON1
Authors: Born David G. , Snow Mark E. , Herbert Emily W.
Published: March 2006

Four pigeons received conditional discrimination training in which reinforcement contingencies were related to specific combinations of color and form, but were unrelated to either color or form considered separately. During discrete‐trial training, each response in the presence of two of four color‐form displays produced reinforcement and terminated the trial; responding to the other two displays was never reinforced, and each such response prolonged the particular trial on which it occurred. Subsequently, the subjects received multiple‐schedule training in which responding to either of the displays previously associated with reinforcement was now reinforced on a variable‐interval schedule, and extinction was the schedule again correlated with the other two displays. After differential responding to the stimuli was clearly evident, intensity of the combination displays was changed in subsequent training sessions. Complex stimulus control was generally maintained across variation in intensity, although there were temporary disruptions in performance associated with onset of some of the intensity changes. Finally, a component‐stimulus test revealed considerably more responding to the forms than to the colors.
EXTINCTION OF A HETEROGENEOUS CHAIN AFTER SEVERAL REINFORCEMENT SCHEDULES1
Authors: D'Andrea Thomas
Published: March 2006

Rats were conditioned to emit the following two‐member chain of responses on two different operanda always available: responses on a vertical bar produced a discriminative stimulus for food‐reinforced responding on a horizontal bar. Responses on the vertical bar produced a discriminative stimulus on a variable‐interval 1‐min schedule, and the horizontal bar produced food on a variable ratio of 10 responses. Control conditions were included in which vertical bar responses were also food‐reinforced simultaneous with the onset of the discriminative stimulus for the horizontal bar response and a tandem schedule which had the same response requirements but without different exteroceptive stimuli associated with the separate components of the response chain. The latter condition greatly retarded acquisition of the response chain compared to the other schedules studied here and compared to reports in the literature on homogeneous (single operandum) response chains. Intermittent reinforcement of the chain led to greater resistance to extinction of both members and the chain remained intact longer in the sense that stimulus control was maintained.
CONTINUOUS PUNISHMENT OF FREE‐OPERANT AVOIDANCE IN THE RAT1
Authors: Powell Robert W. , Morris Grant
Published: March 2006

Three groups of albino rats were trained under a free‐operant avoidance (Sidman) procedure with equal shock‐shock and response‐shock intervals. After stable performance was achieved, the animals were concurrently exposed to a brief electric shock after each response. The procedures were as follows: Punishment Schedule I: punishment shock was introduced at an intensity approximately one quarter that of avoidance shock; increments of nearly this same size were made as stable performance was achieved at succeeding punishment shock intensities. Punishment Schedule II: punishment shock was introduced at approximately one‐half the intensity of avoidance shock; after stable performance, punishment shock was increased to the same intensity as avoidance shock. Punishment Schedule III: punishment shock was introduced and maintained at the same intensity as avoidance shock. Punishment was continued for all groups until one of two suppression criteria was attained. All animals made fewer responses and received more avoidance shocks as a function of increasing punishment shock. Half of the animals under Punishment Schedule I required punishment shock higher than avoidance shock to meet their assigned suppression criterion. A comparison of all procedures showed that suppression was greater when punishment shock was initially at high intensity.
PERIODIC SHOCK WITH ADDED CLOCK1
Authors: Hendry Derek P. , Yarczower Matthew , Switalski Richard C.
Published: March 2006

Rats were shocked every 6 min while responding was maintained on a variable‐interval schedule of reinforcement. With some rats, shocks were interspersed with a sequence of three different stimulus conditions (S3→S2→S1), or clock cues, each lasting 2 min. For other rats, a single stimulus condition prevailed between shocks at the beginning of the experiment and clock cues were introduced later. Response rate decreased from S3 to S1. Response rate in S3, S2, and S1 was inversely related to shock intensity. When clock cues were added, response rate increased in all 2‐min intershock periods. During clock cues, an index of curvature, indicating the degree of negative acceleration of response rate, was greatest for S1 and least for S3, and was directly related to shock intensity. The response‐facilitating effect of shock and its relation to a possible discriminative function of shock and to behavioral contrast is discussed.
STUDIES ON RESPONDING UNDER FIXED‐INTERVAL SCHEDULES OF REINFORCEMENT: THE EFFECTS ON THE PATTERN OF RESPONDING OF CHANGES IN REQUIREMENTS AT REINFORCEMENT1
Authors: Dews P. B.
Published: March 2006

In pigeons responding under a 180‐sec fixed‐interval schedule of reinforcement, the frequency distribution of the duration of the final interresponse time before the reinforcer was compared with the distribution of the preceding two interresponse times. The results confirmed qualitatively and quantitatively the expected preferential reinforcement of longer interreinforcement times under fixed‐interval reinforcement. Requirements at reinforcement were then changed to eliminate the preferential reinforcement of longer interresponse times. Local patterns and mean rate of responding could change, without the characteristic fixed‐interval pattern of increasing responding through the interval (scalloping) being much affected. It is concluded that this characteristic pattern of fixed‐interval responding does not depend crucially on effects of the reinforcer at the moment of reinforcement, but rather to effects extending over much longer periods of time than just the last interresponse time.
THE BISECTION OF A BRIGHTNESS INTERVAL BY PIGEONS
Authors: Boakes R. A.
Published: March 2006

Pigeons were trained on a discrete trials, successive discrimination procedure, in which the stimuli were two luminance values on the center key. Behavior was maintained by 25% reinforcement of correct responses on two side‐keys. During occasional test trials the luminance of the center key was maintained at one of a number of values, intermediate to those of the two training stimuli, and a function relating the relative frequency of responses on the two side keys to stimulus intensity was obtained. The intersection of this function with the 50% line provided an estimate of the bisection point. Since no bisection point occurred below the geometric mean of the interval, the results were not consistent with a logarithmic scale of brightness but fitted the general mean theorem with an exponent of 0.24. With continued testing, the performance of individual subjects oscillated in an irregular manner about the mean bisection point. The relative stability of the test behavior and the absence of context effects indicated that the method was suitable as a general procedure for measuring stimulus distances.
TILTED LINES AS COMPLEX STIMULI1
Authors: Touchette Paul E.
Published: March 2006

Severely retarded boys were taught to respond differentially to lines tilted at 45° and 135°. While all subjects could perform the discrimination, the aspect of the stimulus that controlled responding was shown to differ among subjects.
CONCURRENT SCHEDULES OF PRIMARY AND CONDITIONED REINFORCEMENT IN RATS1
Authors: Zimmerman Donald W.
Published: March 2006

Rats responded on a fixed‐interval schedule during which a 3‐sec stimulus preceded each water reinforcement. The stimulus was then scheduled concurrently for responses on the same lever according to either a variable interval or a variable ratio. Although water reinforcement. continued on a fixed‐interval schedule, the pattern of responding became typical of a variable‐interval or variable‐ratio schedule. When the 3‐sec stimulus was presented on a variable‐interval or variable‐ratio schedule, but was omitted on the fixed‐interval schedule, the response rate decreased. When the stimulus occurred after the same time periods as those of the variable‐interval schedule, but at least 7‐sec after the last response, the rate decreased. The rate became higher when the fixed‐interval schedule was discontinued and each presentation of the 3‐sec stimulus was followed by water on a variable‐interval schedule. When both water and the 3‐sec stimulus were discontinued for a period of time, resulting in extinction of the lever response, and the 3‐sec stimulus alone then presented on a variable‐interval or variable‐ratio schedule after lever responses, rate increased and then gradually decreased.
AUTO‐SHAPING IN BOBWHITE QUAIL1
Authors: Gardner William M.
Published: March 2006

Bobwhite quail were given extended auto‐shaping, a procedure in which response‐key illumination or color change is paired with response‐independent food presentations. Continuation of the auto‐shaping procedure yielded increased responding across sessions, although responses were never instrumental in producing food. The quail were shifted directly from the auto‐shaping procedure to a variable‐interval 60‐sec schedule of reinforcement. All three birds were approaching stable response rates by the fifth session on the variable‐interval schedule.
EFFECTS OF TIMEOUT ON SPACED RESPONDING IN PIGEONS
Authors: Kramer Thomas J. , Rilling Mark
Published: March 2006

Three pigeons were trained under a differential‐reinforcement‐of‐low‐rate schedule of 20 sec, and then exposed to a schedule under which responses terminating interresponse times less than 20 sec produced timeout and responses terminating interresponse times greater than 20 sec produced reinforcement. Response‐produced timeouts selectively decreased the probability of short interresponse times and thereby produced a higher frequency of reinforcement. The suppressive effect of timeout was independent of timeout duration, with timeouts of 5, 10, or 20 sec. Similar effects were found when the minimum interresponse time that could be terminated by response‐produced reinforcement was increased to 30 sec. The suppressive effects of timeout on responding maintained by these schedules were similar to previous reports in which responding was punished with electric shock.
COMPOUNDING OF PRE‐AVERSIVE STIMULI1
Authors: Miller Laurence
Published: March 2006

When two discriminative stimuli, each capable of maintaining a response, are combined, their compound will maintain a frequency of response greater than the frequencies maintained by the individual stimuli. This has been called additive summation. The present experiments extended the investigation of this phenomenon to a converse situation in which two pre‐aversive stimuli were combined. Each pre‐aversive stimulus was capable of reducing the frequency of an ongoing response. The combination of these stimuli reduced the relative frequency of response below that resulting from either stimulus. Furthermore, the compounding of two highly suppressive stimuli produced more suppression than the compounding of two less‐suppressive stimuli. Evidence was also presented to suggest that the compound continued to reduce responding even when the single stimuli were no longer effective. A fourth experiment demonstrated that summation of response tendencies could not be accounted for in terms of stimulus intensity or sensory interaction.
CONTROLLING HUMAN FIXED‐INTERVAL PERFORMANCE1
Authors: Weiner Harold
Published: March 2006

Both high and relatively constant rates of responding without post‐reinforcement pauses and lower rates with pauses after reinforcement are produced by human subjects under fixed‐interval (FI) schedules. Such FI rates and patterns may be controlled when subjects are provided with different histories of conditioning and different conditions of response cost (reinforcement penalties per response). Subjects with a conditioning history under ratio schedules typically produce high and relatively constant rates of responding under FI schedules; this responding does not change systematically with changes in FI value. In contrast, subjects with a history under schedules which produce little or no responding between reforcements [such as differential‐reinforcement‐of‐low‐rate (DRL) schedules] tend to pause after reinforcement and respond at low rates under FI schedules, whether or not they also have ratio conditioning histories; cost increases the likelihood of this type of performance. For DRL‐history subjects, post‐reinforcement pauses increase and response rates decrease as FI values increase.
THE CONCURRENT REINFORCEMENT OF TWO INTERRESPONSE TIMES: THE RELATIVE FREQUENCY OF AN INTERRESPONSE TIME EQUALS ITS RELATIVE HARMONIC LENGTH1
Authors: Shimp Charles P.
Published: March 2006

The relative lengths of two concurrently reinforced interresponse times were varied in an experiment in which three pigeons obtained food by pecking on a single key. Visual discriminative stimuli accompanied the two time intervals in which reinforcements were scheduled according to a one‐minute variable‐interval. The steady‐state relative frequency of an interresponse time approximately equalled the complement of its relative length, that is, its relative harmonic length. Thus, lengths of interresponse times and delays of reinforcement have the same effect on the relative frequencies of interresponse times and choices in one‐key and two‐key concurrent variable‐interval schedules, respectively. A second experiment generalized further the functional equivalence between the effects of these one‐key and two‐key concurrent schedules by revealing that the usual matching‐to‐relative‐immediacy in two‐key concurrent schedules is undisturbed if reinforcement depends upon the occurrence of a response at the end of the delay interval, as it does in the one‐key schedules. The results of both experiments are consistent with a quantitative theory of concurrent operant behavior.
DISRUPTION OF A TEMPORAL DISCRIMINATION UNDER RESPONSE‐INDEPENDENT SHOCK1
Authors: Snapper A. G. , Ramsay D. A. , Schoenfeld W. N.
Published: March 2006

The responding of rats was reinforced on one key after a 1‐sec auditory stimulus and on a second key after a 5‐sec stimulus. With errors punished by a short timeout, all subjects achieved a high level of accuracy. A chain of responses during the stimuli mediated the performance so that when the auditory signals were omitted accuracy decreased only slightly. Response‐independent aversive stimulation superimposed upon this procedure both suppressed the total amount of behavior and reduced the accuracy of the discriminative performance, the intensity of the stimulus determining the error rate. The increase in errors under these conditions may have depended in part upon differential suppression of members of the response chain, but such suppression was not necessary, since error rate increased even in its absence. Furthermore, the locus of response disruption within the chain was not consistent from day to day either for any individual animal or across animals.
CONTROL OF RESPONDING BY THE ELEMENTS OF A COMPOUND DISCRIMINATIVE STIMULUS AND BY THE ELEMENTS AS INDIVIDUAL DISCRIMINATIVE STIMULI1
Authors: Birkimer John C.
Published: March 2006

In the first of two studies, the responding of four albino rats was differentially reinforced in the presence of noise and light together and then tested in the presence of the noise and the light separately during extinction. The light exercised substantially more control of responding than did the noise. In the second study the responding of a similar group of four rats was differentially reinforced in the presence of the noise and the light separately. Control of responding by the light developed more rapidly than control by the noise. Results suggest that levels of control by stimuli after differential reinforcement with respect to the stimuli together can be predicted by the rates of development of control during differential reinforcement with respect to the stimuli separately.
GENERALIZATION DURING ACQUISITION, EXTINCTION, AND TRANSFER OF MATCHING WITH AN ADJUSTABLE COMPARISON1
Authors: Cohen Leila R.
Published: March 2006

Three groups of pigeons were given conditional discrimination training in which the number of standard stimuli was varied across groups. In the presence of each standard, a pigeon adjusted the comparison stimulus on a second key until the two keys matched. A report of this match (response on the first key) was reinforced. Transfer of the matching performance was investigated by adding new standards to the ones already available. All pigeons were exposed to two extinction sessions after 155 sessions of training. Rapidity of acquisition was inversely related to the number of standards presented. Generalization gradients derived from the several comparison stimuli showed that all pigeons reached a high level of accuracy in the presence of at least one standard, and some pigeons did so in the presence of as many as four of the six standards. There was no evidence of a systematic effect of extinction upon overall accuracy, or the individual generalization gradients. When a new standard was added, a given pigeon's performance (in terms of responding to the comparisons) was similar to performance in the presence of one of the old standards. However, the pigeons did not show evidence of confusion among the comparisons.
AUTO‐MAINTENANCE IN THE PIGEON: SUSTAINED PECKING DESPITE CONTINGENT NON‐REINFORCEMENT2
Authors: Williams David R. , Williams Harriet
Published: March 2006

If a response key is regularly illuminated for several seconds before food is presented, pigeons will peck it after a moderate number of pairings; this “auto‐shaping” procedure of Brown and Jenkins (1968) was explored further in the present series of four experiments. The first showed that pecking was maintained even when pecks turned off the key and prevented reinforcement (auto‐maintenance); the second controlled for possible effects of generalization and stimulus change. Two other experiments explored procedures that manipulated the tendency to peck the negatively correlated key by introducing alternative response keys which had no scheduled consequences. The results indicate that pecking can be established and maintained by certain stimulus‐reinforcer relationships, independent of explicit or adventitious contingencies between response and reinforcer.
AUTOSHAPING OF KEY PECKING IN PIGEONS WITH NEGATIVE REINFORCEMENT2
Authors: Rachlin Howard
Published: March 2006

Pigeons exposed to gradually increasing intensities of pulsing electric shock pecked a key and thereby reduced the intensity of shock to zero for 2 min. Acquisition of key pecking was brought about through an autoshaping process in which periodic brief keylight presentations immediately preceded automatic reduction of the shock. On the occasions of such automatic reduction of shock preceding the first measured key peck, little or no orientation to the key was observed. Observations of pigeons with autoshaping of positive reinforcement also revealed little evidence of orientation toward the key.
SELECTIVE ATTENTION: THE EFFECTS OF COMBINING STIMULI WHICH CONTROL INCOMPATIBLE BEHAVIOR1
Authors: Ray Barbara A.
Published: March 2006

Four rhesus monkeys learned both a color and tilt discrimination. The stimuli were combined to produce incompatible behavior. The behavior controlled by one set of stimuli was reinforced until “errors” virtually disappeared. The stimuli were tested separately again. Sixteen replications of the entire procedure indicated that the stimuli producing “errors” were ignored.
STIMULUS CONTROL AND THE RESPONSE‐REINFORCEMENT CONTINGENCY1
Authors: Yarczower Matthew , Gollub Lewis R. , Dickson James F.
Published: March 2006

Pigeons were trained under a schedule in which reinforcement was made available at varying periods of time after a prior reinforcement. The first key peck after a reinforcer was available began a timer and a second key peck, which exceeded a specified minimal time interval, produced the reinforcer. It was shown that a contingency which contains a minimal inter‐response time does not necessarily weaken stimulus control by an exteroceptive stimulus.
STIMULUS CONTROL IN THE GOLDFISH AFTER MASSED EXTINCTION1
Authors: Yarczower Matthew , Switalski Richard
Published: March 2006

Compared with the data of goldfish trained only with stimuli correlated with reinforcement, interspersed reinforcement‐stimulus and extinction‐stimulus trials resulted in sharper stimulus control and a marked reduction in the percentage of key‐presses emitted in the presence of stimuli located near the extinction stimulus on the test dimension. If non‐reinforced trials were not interspersed with reinforced trials, there was no sharpening of stimulus control and less reduction in key presses in the presence of stimuli near the extinction stimulus on the test dimension.
THE EFFECT OF HIGH AMBIENT TEMPERATURE ON TIMING BEHAVIOR IN RATS
Authors: Barofsky Ivan
Published: March 2006

The present experiments demonstrated a reliable within‐session increase in rectal temperature (Tre) at 25° C during stable differential‐reinforcement‐of‐low‐rate (DRL) performance. The thermal response was found to be independent of the DRL value and reinforced DRL performance, but dependent on the state of the animal's deprivation. Exposure to a 35°‐C environment increased the post‐session Tre significantly above the 25°‐C post‐session Tre for seven of eight subjects. Response and reinforcement rate at 35° C was found to be independent of DRL value, although it decreased as DRL value increased at 25° C. A discriminative stimulus used to mark the end of the interval increased the reinforcement rate at 25° C but provided no advantage at 35° C. Measurement of the pattern of responding during DRL performance revealed increases in the proportion of long interresponse times at 35° C. Reinforcement rate was found to decrease progressively at 35° C, reaching a minimum within 40 to 50 min of the 90‐min session. Visual observation of overt behaviors during DRL performance at 35° C revealed a reduction in the frequency of overt behavior, characteristic of 25°‐C performance, and a time‐dependent increase in the probability of an alternative set of behaviors.