bluuebunny/crossref_metadata_2025 huggingface dataset:
CHOICE, TIME ALLOCATION, AND RESPONSE RATE DURING STIMULUS GENERALIZATION1
Authors: Mandell Charlotte , Nevin John A.
Published: March 2006

Six pigeons were trained to discriminate between two noise intensities using a procedure that assessed choice, time allocation, and response rate simultaneously and independently. Responses on the left or right key (R1 or R2) were respectively correct in the presence of two different intensities, S1 and S2. After a correct response, reinforcement became available for pecks on the center key. Reinforcement density for R1|S1 relative to R2|S2 was varied across experimental conditions. Generalization tests followed extensive training at each condition. As a function of stimulus intensity, proportions of initial choices of R2, of time spent in R2‐initiated components, and of center‐key responses emitted in R2‐initiated components all yielded sigmoidal gradients of similar slope, which shifted slightly in location when relative reinforcement density changed. Changeovers were maximal where initial choice proportions approximated 0.5. Gradients relating the absolute number of center‐key responses to stimulus intensity were also roughly sigmoidal, but were more sensitive to changes in reinforcement density. Gradients of momentary response rate also depended on reinforcement density. During training, large but transitory shifts in choice responding occurred when reinforcement density changed, while differences in momentary response rate developed slowly, suggesting separate control of choice and response rate by the contingencies of reinforcement.
ESCAPE, AVOIDANCE, PUNISHMENT: WHERE DO WE STAND?
Authors: Dinsmoor James A.
Published: March 2006

This paper reviews progress since the author's previous writings in three areas. In escape training, the preparatory‐response explanation of bar holding still appears to be valid. In avoidance, the newer safety‐signal version of two‐factor theory has much to recommend it and readily incorporates Anger's conditioned aversive temporal stimuli formulation. Shock‐density reduction is rejected as a substitute for two‐factor theory. Finally, criticisms of the avoidance interpretation of punishment are answered and recent empirical data are cited in its support.
CONDITIONED REINFORCEMENT AND CHOICE
Authors: Nevin J. A. , Mandell C.
Published: March 2006

In a series of three experiments, rats were exposed to successive schedule components arranged on two levers, in which lever pressing produced a light, and nose‐key pressing produced water in 50% of the light periods. When one auditory signal was presented only during those light periods correlated with water on one lever, and a different signal was presented only during those light periods correlated with nonreinforcement on the other lever, the former lever was preferred in choice trials, and higher rates of responding were maintained on the former lever in nonchoice (forced) trials. Thus, the rats preferred a schedule component that included a conditioned reinforcer over one that did not, with the schedules of primary reinforcement and the information value of the signals equated. Preferences were maintained when one or the other of the auditory signals was deleted, but were not established in naive subjects when training began with either the positive or negative signal only. Discriminative control of nose‐key pressing by the auditory signals was highly variable across subjects and was not correlated with choice.
REPEATED ACQUISITION OF CONDITIONAL DISCRIMINATIONS1
Authors: Moerschbaecher Joseph M. , Boren John J. , Schrot John
Published: March 2006

A new technique was developed to study the repeated acquisition of conditional discriminations. Using a discrete trial procedure, pigeons were required to learn during each session a different two‐member chain of conditional discriminations. Key color and geometric forms were used as stimuli. After the pigeons had reached a steady state of relearning (40 to 60 sessions), the technique was used to investigate variables that have previously been shown to affect the repeated acquisition of response sequences. Various (0 to 90 seconds) durations of timeout for errors were investigated in Experiment I. The stimulus change associated with a timeout, rather than its duration, was found to be the critical variable in acquisition of the discrimination. Extended training on a single chain was found to reduce total errors across sessions in Experiment II. Extended training (three sessions) did not, however, change the pattern of within‐session error reduction. In some cases, extended training facilitated acquisition of a partially reversed discrimination. In Experiment III, color rather than chain position was found to control behavior, for three of the four birds, as the second stimulus dimension in the conditional situation. The results of these experiments replicate and extend previous findings concerning some of the variables that affect the repeated acquisition of response sequences.
CONTRAST EFFECTS IN MULTIPLE FIXED‐INTERVAL REINFORCEMENT SCHEDULES
Authors: Innis Nancy K.
Published: March 2006

Pigeons were exposed to a multiple fixed‐interval one‐minute fixed‐interval three‐minute schedule of reinforcement following training on either a multiple fixed‐interval one‐minute fixed‐interval one‐minute schedule or a multiple fixed‐interval three‐minute fixed‐interval three‐minute schedule. For all birds, large negative local contrast effects developed during the first of four three‐minute intervals in a component; response rate was depressed and postreinforcement pause lengthened in this interval. Positive local contrast effects were evident during the first of 12 one‐minute intervals in a component for five of six birds; at asymptote, the pause was very short and response rate slightly elevated during this interval. Overall positive contrast was generally transient and varied considerably across subjects, while overall negative contrast effects, if they occurred, appeared only after a large number of sessions.
A COMPARISON OF FORWARD AND BACKWARD PROCEDURES FOR THE ACQUISITION OF RESPONSE CHAINS IN HUMANS
Authors: Weiss Kenneth M.
Published: March 2006

Ten university students each learned four separate six‐link response chains, two forward and two backward. All 10 subjects made fewer errors in the forward procedure. It was concluded that the forward procedure is superior because each link of the response chain is acquired by direct reinforcement.
RESPONDING UNDER SCHEDULES COMBINING RESPONSE‐DEPENDENT AND RESPONSE‐INDEPENDENT SHOCK DELIVERY
Authors: Bacotti Alfred V.
Published: March 2006

Lever pressing of three squirrel monkeys with experience under continuous avoidance schedules was maintained by response‐produced shock under a 5‐minute variable‐interval schedule. Responding decreased when half of the scheduled shocks were delivered independently of lever pressing and decreased further when all shocks were independent of lever pressing. Responding was lowest when all shocks were eliminated. When the proportion of response‐dependent shocks increased, responding increased. This relation occurred even though the frequency and temporal distribution of shock delivery remained the same. Responding of two monkeys increased in a graded fashion as the frequency of shock was increased by arranging variable‐time 5‐minute, 2‐minute, and 1‐minute schedules jointly with the variable‐interval 5‐minute schedule. Thus, increasing the proportion of response‐independent shocks decreased responding when the overall frequency of shocks stayed the same, but increased responding when the overall frequency of shock delivery increased.
EFFECTS OF VARYING THE DURATION OF GRAIN PRESENTATION ON AUTOMAINTENANCE1
Authors: Balsam Peter D. , Brownstein Aaron J. , Shull Richard L.
Published: March 2006

In a series of three experiments the effects of variation in grain duration on automaintenance were evaluated. In the first experiment, key illumination was followed by grain only when pigeons did not peck the key. Each subject was exposed to 2‐, 4‐, and 8‐second feeder durations in blocks of 10 sessions. Subjects pecked on a high percentage of trials at all feeder durations. The mean peck latency was shorter in the 8‐second condition than in the two other conditions in five of six subjects. The conditional probability of pecking given successive keylight‐grain pairings did not increase as the number of pairings increased. The second experiment was identical to the first, except that key pecking had no scheduled consequence. Under these conditions, all three subjects showed substantial responding. The recorded measures showed no systematic relationship to feeder duration in this study. In the third experiment, two different stimuli were followed by feeder presentations of either identical (2‐ or 8‐second) or different (2‐ and 8‐second) durations within each session. Subjects tended to respond sooner and with a higher overall rate in the presence of the stimulus associated with the longer feeder duration only when different feeder durations were presented within the same session. This result was confirmed by direct observation of the pigeons. The results of these experiments suggest that the effects of varying grain duration may be small, compared to the effects of varying other variables. The results also suggest that the location as well as the frequency of pecking may be an important measure in the analysis of factors controlling the pigeon's key peck.
THE EFFECTS OF DIFFERENT COMPONENT RESPONSE REQUIREMENTS IN MULTIPLE AND CONCURRENT SCHEDULES
Authors: Davison Mike , Ferguson Alan
Published: March 2006

Six pigeons were trained on multiple and concurrent schedules. The reinforcement rates were varied systematically (a) when lever pressing was required in one component and key pecking in the successive component; (b) when lever pressing was required in both multiple components; (c) when key pecking was required in both multiple components; and (d) when key pecking was required on one schedule and lever pressing was required on the concurrently‐available schedule. Only the absolute level of responding was changed by different response requirements. Analyzed by the generalized matching law, performance under different response requirements resulted in a bias toward key pecking, and the measured response bias was the same in multiple and concurrent schedule arrangements. The bias in time measures obtained from concurrent schedule performance was reliably smaller than the obtained response biases. The sensitivity to reinforcement‐rate changes was ordered: concurrent key‐lever; multiple key‐key; multiple lever‐key; and, the least sensitive, multiple lever‐lever. The results confirm that requirements of different topographical responses can be handled by the generalized matching law mainly in the bias parameter, but problems for this type of analysis may be caused by the changing sensitivity to reinforcement in multiple schedule performance as response requirements are changed.
EFFECTS OF COMPONENT LENGTH AND OF THE TRANSITIONS AMONG COMPONENTS IN MULTIPLE SCHEDULES1
Authors: Hinson John M. , Malone John C. , McNally Kathleen A. , Rowe David W.
Published: March 2006

Pigeons received equal variable‐interval reinforcement during presentations of two line‐orientation stimuli while five other orientations appeared in extinction. Component duration was 30 seconds for all orientations and the sequence was arranged so that each orientation preceded itself and each other orientation equally often. The duration of one component (0°) was shortened to 10 seconds and the other (90°) was lengthened to 50 seconds. All animals showed large increases in response rate in the shortened component and this increase was recoverable after an interpolated condition in which all components were again 30 seconds in duration. This effect was replicated in a second experiment in which component duration was changed from 150 seconds to 50 seconds and 250 seconds. An examination of local contrast effects during the first experiment showed that the shortened component produced local contrast during subsequent presentations of the lengthened component, just as would a component associated with more frequent reinforcement. When the presentation sequence was changed so that the lengthened component was always followed by the shortened component, response rates generally increased during the lengthened component. When the sequence was arranged so that the shortened component always preceded the longer component, response rate decreased in the former. These effects, as well as the increases in response rate following change in component length, seem not to be the product of local contrast effects among components.
THE RELATION BETWEEN THE GENERALIZED MATCHING LAW AND SIGNAL‐DETECTION THEORY
Authors: Davison M. C. , Tustin R. D.
Published: March 2006

The generalized matching law can be applied to a signal‐detection matrix to give two equations. The first relates responding in the presence of the stimulus to the reinforcements for the responses, and the second relates responding in the absence of the stimulus to the reinforcements for the responses. Evidence for stimulus discrimination is given by biases that are opposite in sign in the two equations. As the logarithmic ratio and z proportion transformations are similar, the combination of the absolute values of the two logarithmic biases gives a measure equivalent to the signal‐detection measures d′ and η. The two equations can also be combined to eliminate the biases caused by the signalling stimuli and to produce a generalized matching‐law statement relating overall performance to the obtained reinforcements.
CLUSTERING IN THE OUTPUT OF BEHAVIOR1
Authors: Zeiler Michael D. , Davis E. R.
Published: March 2006

Pigeons exposed to fixed‐interval schedules of 3, 5, 15, 40, and 120 minutes all maintained considerable variability in daily response rates for as many as 104 sessions. However, variations did not occur at random. Instead, rate in a session appeared dependent on those occurring previously. The series displayed a wave‐like form arising because a group of high rates was followed by a group of low rates and vice versa. These sequential relations produced a curve having irregular periodicity, sometimes superimposed on a declining or rising linear trend. Whether grouping of response rates stemmed from experimental or extra‐experimental sources was not determined. If the phenomenon was either totally or partially produced by the schedule itself, it suggests that response rate is determined by a combination of positive and negative feedback. Control by factors extrinisic to the experiment itself implies that response rate may be influenced by some rhythmic physiological process.
LOCAL RESPONSE‐RATE CONSTANCY ON CONCURRENT VARIABLE‐INTERVAL SCHEDULES OF REINFORCEMENT
Authors: Pliskoff Stanley S. , Cicerone Robert , Nelson Thomas D.
Published: March 2006

Concurrent variable‐interval schedules were arranged with a main key that alternated in color and schedule assignment, along with a changeover key on which a small fixed ratio was required to changeover. Acceptable matching was observed with pigeons in two replications, but there was a tendency toward overmatching. Local response rates were found to differ for unequal schedules of a concurrent pair: local response rate was greater for the variable‐interval schedule with the smaller average interreinforcement interval, but qualifications based on an interresponse‐time analysis were discussed. In a second experiment, two 3‐minute variable‐interval schedules were arranged concurrently, and the experimental variable was the changeover procedure: either a changeover delay was incurred by each changeover or a small fixed ratio on a changeover key was required to complete a changeover. Changeover delays of 2 and 5 seconds were compared with a fixed‐ratio changeover of five responses. The response output on the main key (associated with the variable‐interval schedules) was greater when a changeover delay was arranged than when a fixed ratio was required to changeover. A detailed analysis of stripchart records showed that a 2‐second delay generated an increased response rate for 3 seconds after a changeover, while the fixed‐ratio requirement generated an increased rate during the first second only, followed by a depressed response rate for 2 seconds.
RELATIONSHIP BETWEEN RESPONSE RATE AND REINFORCEMENT FREQUENCY IN VARIABLE‐INTERVAL SCHEDULES: THE EFFECT OF THE CONCENTRATION OF SUCROSE REINFORCEMENT
Authors: Bradshaw C. M. , Szabadi E. , Bevan P.
Published: March 2006

Four rats were exposed to variable‐interval schedules specifying a range of different reinforcement frequencies, using sucrose of two different concentrations and distilled water as the reinforcer. With sucrose, the rates of responding of all four rats were increasing negatively accelerated functions of reinforcement frequency, the data conforming closely to Herrnstein's equation; this was also true of the data from three of the four rats when distilled water was used as the reinforcer. The values of both constants in Herrnstein's equation were related to the sucrose concentration: the asymptotic response rate decreased, and the reinforcement frequency corresponding to the half‐maximal response rate increased, with decreasing sucrose concentration.
MATCHING, CONTRAST, AND EQUALIZING IN THE CONCURRENT LEVER‐PRESS RESPONDING OF RATS1
Authors: Norman Wayne D. , McSweeney F. K.
Published: March 2006

Five rats pressed levers for food reinforcers delivered by several concurrent variable‐interval variable‐interval schedules. The rate of reinforcement available for responding on one component schedule was held constant at 60 reinforcers per hour. The rate of reinforcement available for responding on the other schedule varied from 30 to 240 reinforcers per hour. The behavior of the rats resembled the behavior of pigeons pecking keys for food reinforcers. The ratio of the overall rates of responding emitted under, and the ratio of the time spent responding under, the two components of each concurrent schedule were approximately equal to the ratio of the overall rates of reinforcement obtained from the components. The overall rate of responding emitted under, and the time spent responding under, the variable component schedule varied directly with the overall rate of reinforcement from that schedule. The overall rate of responding emitted under, and the time spent responding under, the constant component schedule varied inversely with the overall rate of reinforcement obtained from the variable component. The local rates of responding emitted under, and the local rates of reinforcement obtained from, the two components did not differ consistently across subjects. But they were not exactly equal either.
THE ECONOMICS OF DAILY CONSUMPTION CONTROLLING FOOD‐ AND WATER‐REINFORCED RESPONDING1
Authors: Hursh Steven R.
Published: March 2006

In the first experiment, two rhesus monkeys earned their entire ration of food and water during daily sessions with no provisions to ensure constant daily intakes. Two variable‐interval schedules of food presentations were concurrent with one variable‐interval schedule of water presentations; the maximum rate of food presentations arranged by one food schedule was varied. As the rate of food presentations was increased, the absolute level of responding on the two food schedules combined decreased, while responding on the water schedule increased. The preference for the variable food schedule compared to the other food schedule approximately matched the proportion of reinforcers obtained from it. The preference for the variable food schedule compared to the water schedule did not match, but greatly decreased, as the proportion of reinforcers from the food schedule increased. When Experiment I was replicated, with provisions to ensure constant daily intakes of food and water (Experiment II), the absolute response rates under the two food schedules combined and under the water schedule no longer changed with increases in the rate of food during the sessions. On the other hand, choice between the two food schedules remained proportional to the distribution of obtained food pellets. These results were interpreted as indicating that behavior to obtain nonsubstitutable commodities, such as food and water, is strongly controlled by the economic conditions of daily consumption, while choice between substitutable commodities is independent of these factors.
ADDITIVE SUMMATION FOLLOWING INTRADIMENSIONAL DISCRIMINATION TRAINING
Authors: Hamm Robert J. , Mattson James C.
Published: March 2006

Rats were exposed to intradimensional composite stimuli presented on the response lever that varied in both light intensity and flicker rate. For all subjects, pressing the lever was reinforced when it was illuminated at a high intensity and flickered at a low rate (I + f) or when it was illuminated at a low intensity and flickered at a high rate (i + F). For half the subjects, lever responding was not reinforced when it was illuminated at a low intensity and flickering at a low rate (i + f). For the remaining subjects, lever presses were not reinforced when the lever was illuminated at a high intensity and flickered at a high rate (I + F). When the composite stimulus composed of the light intensity and flicker rates that had been associated only with reinforced responding was displayed (1 + F for half the subjects and i + f for the remaining subjects), it controlled the highest response rate of all stimuli (additive summation). The results demonstrated that similar attentional processes control intra‐ and interdimensional composite‐stimulus discriminations in a manner consistent with Weiss' (1972) analysis of summation.
RESPONSE RATE AND CHANGEOVER PERFORMANCE ON CONCURRENT VARIABLE‐INTERVAL SCHEDULES1
Authors: Hunter I. W. , Davison M. C.
Published: March 2006

Six pigeons were exposed to variable‐interval schedules arranged on one, two, three, and four response keys. The reinforcement rate was also varied across conditions. Numbers of responses, the time spent responding, the number of reinforcements, and the number of changeovers between keys were recorded. Response rates on each key were an increasing function of reinforcement rate on that key and a decreasing function of the reinforcement rate on other keys. Response and time‐allocation ratios under‐matched ratios of obtained reinforcements. Three sets of equations were developed to express changeover rate as a function of response rate, time allocation, and reinforcement rate respectively. These functions were then applied to a broad range of experiments in the literature in order to test their generality. Further expressions were developed to account for changeover rates reported in experiments where changeover delays were varied.
EFFECTS ON CHOICE OF REINFORCEMENT DELAY AND CONDITIONED REINFORCEMENT1
Authors: Williams Ben A. , Fantino Edmund
Published: March 2006

Pigeons chose between fixed‐interval schedules of different durations presented in the terminal links of concurrent‐chains schedules. The pair of schedules was always in the ratio of 2:1, but the absolute duration of the fixed intervals varied. In one set of conditions, the different terminal‐link schedules were associated with different keylight stimuli (cued conditions). In a second set of conditions, the different terminal‐link schedules were associated with the same stimulus (uncued conditions). Results from the cued conditions replicated previous findings that preference for the shorter fixed‐interval schedule increased with fixed‐interval duration. Preferences in the uncued conditions were lower than in the corresponding cued conditions but also increased with fixed‐interval length. In addition, the degree of control under the uncued conditions was correlated with the extent to which the schedule during the terminal link was discriminated immediately upon entry into the terminal link. The pattern of results in both conditions was inconsistent with the notion that choice behavior matches relative immediacy of reinforcement. Reanalysis of previous evidence for matching (Chung and Herrnstein, 1967) showed that matching in fact did not occur, as the preferences of their subjects for the shorter of two delays also increased with the absolute size of the delays.
FADING AND ERRORLESS TRANSFER IN SUCCESSIVE DISCRIMINATIONS1
Authors: Fields Lanny
Published: March 2006

A successive discrimination between red positive and green negative stimuli was established with pigeon subjects. Then, lines with different angular orientations were superimposed on one of the colors to form compound stimuli. Finally, either the colored element of the positive compound, the colored element of the negative compound, or both colored elements together, were gradually attenuated. Before each attenuation, the line elements were presented alone against dark backgrounds as probes to assess the degree to which they had acquired control of responding. When the positive color was attenuated alone or in conjunction with the negative color, angular orientation acquired control of responding in an errorless fashion. Lines, however, did not acquire control when only the negative component was attenuated. These results were interpreted in terms of changes in the predictability of reinforcement by color and line elements during stimulus attenuation. Finally, attenuation of the negative stimulus influenced the number of “dimensions” of the new line stimuli that acquired control of responding. When the positive stimulus was attenuated with the negative, only one dimension of the lines acquired control. When the positive stimulus was attenuated without the negative, however, more than one dimension of the lines acquired control of responding. These results were interpreted in terms of how errorless performance can be maintained while an organism attends to different dimensions of the new stimuli.
VISUAL DOMINANCE IN THE PIGEON
Authors: Randich A. , Klein R. M. , LoLordo V. M.
Published: March 2006

In Experiment 1, three pigeons were trained to obtain grain by depressing one foot treadle in the presence of a 746‐Hertz tone stimulus and by depressing a second foot treadle in the presence of a red light stimulus. Intertrial stimuli included white light and the absence of tone. The latencies to respond on auditory element trials were as fast, or faster, than on visual element trials, but pigeons always responded on the visual treadle when presented with a compound stimulus composed of the auditory and visual elements. In Experiment 2, pigeons were trained on the auditory‐visual discrimination task using as trial stimuli increases in the intensity of auditory or visual intertrial stimuli. Again, pigeons showed visual dominance on subsequent compound stimulus test trials. In Experiment 3, on compound test trials, the onset of the visual stimulus was delayed relative to the onset of the auditory stimulus. Visual treadle responses generally occurred with delay intervals of less than 500 milliseconds, and auditory treadle responses generally occurred with delay intervals of greater than 500 milliseconds. The results are discussed in terms of Posner, Nissen, and Klein's (1976) theory of visual dominance in humans.
SCHEDULE‐INDUCED DRINKING AS FUNCTIONS OF INTERPELLET INTERVAL AND DRAUGHT SIZE IN THE JAVA MACAQUE1
Authors: Allen Joseph D. , Kenshalo Dan R.
Published: March 2006

Three Java monkeys received food pellets that were assigned by both ascending and descending series of fixed‐time schedules whose values varied between 8 and 256 seconds. The draught size dispensed by a concurrently available water‐delivery tube was systematically varied between 1.0 and 0.3 milliliter per lick at various fixed‐time values during the second and third series determinations. Session water intake was bitonically related to the interpellet interval and was determined by the interaction of (1) the probability of initiating a drinking bout, which fell off at the highest interpellet intervals and, (2) the size of the bout, which increased directly with increases in interpellet interval. Variations in draught size had little effect on total session intakes, but reduced bout size at draught sizes of 0.5 milliliter and below. Thus, a volume‐regulation process of schedule‐induced drinking operated generally at the session‐intake level, but was limited to higher draught sizes at the bout level.
UNSIGNALLED DELAY OF REINFORCEMENT IN VARIABLE‐INTERVAL SCHEDULES
Authors: Sizemore O. J. , Lattal Kennon A.
Published: March 2006

Three pigeons responded on several tandem variable‐interval fixed‐time schedules in which the value of the fixed‐time component was varied to assess the effects of different unsignalled delays of reinforcement. Actual (obtained) delays between the last key peck in an interval and reinforcement were consistently shorter than the nominal (programmed) delay. When nominal delays were relatively short, response rates were higher during the delay condition than during the corresponding nondelay condition. At longer nominal delay intervals, response rates decreased monotonically with increasing delays. The results were consistent with those obtained from delay‐of‐reinforcement procedures that impose either a stimulus change (signal) or a no‐response requirement during the delay interval.
SAME/DIFFERENT CONCEPT LEARNING IN THE PIGEON: THE EFFECT OF NEGATIVE INSTANCES AND PRIOR ADAPTATION TO TRANSFER STIMULI
Authors: Zentall Thomas R. , Hogan E.
Published: March 2006

Pigeons were trained on a matching‐to‐sample or oddity‐from‐sample task with shapes (circle and plus). Half of each group was exposed to “negative instance” trials i.e., for matching birds, neither comparison key matched the sample, and for oddity birds both comparison keys matched the sample. When all birds were transferred to a new task involving colors (red and green), nonshifted birds (transferred from matching to matching, or oddity to oddity) performed significantly better than shifted birds (transferred from matching to oddity, or oddity to matching), but only if they had experienced negative instances of the training concept. When all birds were exposed to negative instances of the transfer task and then transferred to a new color task (yellow and blue), dramatic transfer effects were observed. The effect of pre‐exposure to the yellow and blue colors, in order to reduce transfer‐stimulus novelty, had a minor effect on transfer.
THE EFFECT OF FOREPERIOD DURATION ON REACTION TIME AND ITS RELATION TO INTERVAL SCHEDULES OF REINFORCEMENT
Authors: Keller John V. , Schoot Frank van der
Published: March 2006

Two groups of pigeons were exposed to a simple reaction‐time procedure in which mean foreperiod duration was 5, 10, or 20 seconds. For one group, the foreperiods had an arithmetic, or rectangular, distribution; for the second group, they had a constant‐probability, or Bernoulli, distribution. Under both distributions, mean response latency was an increasing, negatively accelerated function of mean foreperiod duration. On a given trial, response latency was a function of its associated foreperiod duration: latency was a decreasing function of foreperiod duration in the arithmetic distribution, and an increasing function of foreperiod duration in the constant‐probability distribution. Examination of the distribution of latencies revealed a harmonic structure reminiscent of distributions of interresponse times under variable‐interval schedules of reinforcement. Taken together, the results confirm and extend previous findings with human subjects, and also suggest numerous similarities to behavior maintained by variable‐interval schedules.
THE NATURE OF STANDARD CONTROL IN CHILDREN'S MATCHING‐TO‐SAMPLE1
Authors: Dixon Michael H. , Dixon Lois S.
Published: March 2006

In Experiment I, six preschool‐aged children were given matching‐to‐sample training with two figures in which they were required to choose one of two comparison stimuli that was identical in shape to the standard stimulus. Following this training, they were given intermittent test trials in which a novel stimulus figure was substituted for the previously correct comparison stimulus. Five of the six subjects consistently chose the substituted stimulus during test trials. Experiment II replicated the findings of Experiment I with three other preschool‐aged children. Experiment II also provided controls for the possibility that the subjects of Experiment I were selecting the substituted stimulus because of its novelty. The investigators concluded that eight of the nine subjects were exhibiting the type of control described by Berryman, Cumming, Cohen, and Johnson (1965) as S‐delta responding.
REINFORCEMENT AND SUBSTITUTION IN HUMANS: A MULTIPLE RESPONSE ANALYSIS1
Authors: Bernstein Daniel J. , Ebbesen Ebbe B.
Published: March 2006

Three adult human subjects engaged in activities such as reading, sewing, artwork, and candlemaking while living alone in a laboratory apartment 24 hours per day for several weeks. After a baseline period in which the activities were fully available, access to a particular activity (contingent response) was made dependent on engaging in another less‐preferred activity (instrumental response). The contingencies produced substantial increases in instrumental responding, and responding decreased toward baseline levels when the dependency was removed. Under the contingent conditions, time earned for the concurrent activity was always less than the baseline level. To determine the contribution of this reduction to the instrumental increase, access to the contingent activity was restricted in the absence of any dependency. The results indicated that increases among responses that filled the newly available time could be selective, e.g., artwork increased when reading was restricted but candlemaking did not. It was concluded that the reductions in the contingent response that accompany contingencies usually do not exclusively determine instrumental increases, but selective increases can contribute to the increase in time devoted to the instrumental response.
RESPONDING MAINTAINED UNDER FIXED‐INTERVAL AND FIXED‐TIME SCHEDULES OF ELECTRIC SHOCK PRESENTATION1
Authors: Malagodi E. F. , Gardner Michael L. , Palermo Greg
Published: March 2006

Following initial histories under a schedule of electric shock postponement, lever pressing in squirrel monkeys was maintained under fixed‐interval and fixed‐time schedules of electric shock presentation. No difference in either rate or pattern of responding was obtained when these schedules were presented as components of a multiple schedule. When they were presented singly for long periods of time, the fixed‐interval schedule consistently maintained a higher response rate than the fixed‐time schedule. The pattern of responding under both schedules was similar, typically consisting of a pause at the beginning of each interval followed by either a steady or a positively accelerating rate of responding. The results suggest that the response‐shock dependency is of critical importance in the maintenance of high rates of responding under schedules of electric shock presentation, and support the general view that such responding may be conceptualized as operant behavior under control of many of the same variables that control responding under comparable schedules of food or water reinforcement.
AVOIDANCE BASED ON SHOCK INTENSITY REDUCTION WITH NO CHANGE IN SHOCK PROBABILITY
Authors: Bersh Philip J. , Alloy Lauren B.
Published: March 2006

Rats were trained on a free‐operant avoidance procedure in which shock intensity was controlled by interresponse time. Shocks were random at a density of about 10 shocks per minute. Shock probability was response independent. As long as interresponse times remained less than the limit in effect, any shocks received were at the lower of two intensities (0.75 mA). Whenever interresponse times exceeded the limit, any shocks received were at the higher intensity (1.6 mA). The initial limit of 15 seconds was decreased in 3‐second steps to either 6 or 3 seconds. All animals lever pressed to avoid higher intensity shock. As the interresponse time limit was reduced, the response rate during the lower intensity shock and the proportion of brief interresponse times increased. Substantial warmup effects were evident, particularly at the shorter interresponse‐time limits. Shock intensity reduction without change in shock probability was effective in the acquisition and maintenance of avoidance responding, as well as in differentiation of interresponse times. This research suggests limitations on the generality of a safety signal interpretation of avoidance conditioning.
CONCURRENT RANDOM‐INTERVAL SCHEDULES AND THE MATCHING LAW1
Authors: Rodewald H. Keith
Published: March 2006

In Experiment I, a group of eight pigeons performed on concurrent random‐interval schedules constructed by holding probability equal and varying cycle time to produce ratios of reinforcer densities of 1:1, 3:1, and 5:1 for key pecking. Schedules for a second group of seven were constructed with equal cycle times and unequal probabilities. Both groups deviated from simple matching, but the two forms of the schedules appeared to produce no consistent patterns of deviation. The data were found to be consistent with those obtained in concurrent variable‐interval situations. The parameters of the matching equation in the form of Y = k Xa were estimated; the value of k was unity and a was 0.84. In Experiment II, six pigeons were exposed to two conc RI RI schedules in which one component increasingly approximated an FI schedule. The value of k was not 1.0. Concurrent RI RI schedules were shown to represent a continuum from conc FI VI to conc VI VI schedules. The use of the exponential equation in testing “matching laws” suggests that a < 1 will continue to be observed, and this will set limits on the form of new laws and the assumed or rational values of the component variables in these laws.
THE RELATIVE LAW OF EFFECT: EFFECTS OF SHOCK INTENSITY ON RESPONSE STRENGTH IN MULTIPLE SCHEDULES1
Authors: Bouzas Arturo
Published: March 2006

Key pecking of four birds was reinforced with food according to a two‐component multiple variable‐interval 1‐minute variable‐interval 4‐minute schedule. In addition, key pecking was punished by a brief shock according to a variable‐interval 30‐second schedule during both components of the multiple schedule. The intensity of the shock was varied. For all birds, punishment had a stronger suppressive effect on the responding maintained by the leaner food schedule, and the ratio of responding during the two components of the multiple schedule became closer to the ratio of reinforcement as shock intensity was increased, as the relative law of effect predicts. At the higher shock intensity, there was some evidence that the ratio of responses overmatched the ratio of reinforcements.
INTERACTIONS IN MULTIPLE SCHEDULES: NEGATIVE INDUCTION WITH SQUIRREL MONKEYS1
Authors: Spealman Roger D.
Published: March 2006

In Experiment I, lever pressing by squirrel monkeys was maintained under a sequence of variable‐interval, multiple variable‐interval variable‐interval, and multiple variable‐interval extinction schedules of food presentation. Negative induction (decreased responding in the unchanged component) occurred when one component of the multiple variable‐interval variable‐interval schedule was changed to extinction. Negative induction was transient over sessions; responding in the unchanged component usually recovered to a rate similar to that under the multiple variable‐interval variable‐interval schedule. Negative induction was not accompanied by consistent changes in the patterns of local responding within the unchanged component, and did not depend on whether component schedules were associated with localized (lever lights) or diffuse visual stimuli (houselights), or on whether the unchanged component was a 60‐ or 180‐sec variable‐interval schedule. In Experiment II, responding was maintained under a sequence of variable‐interval and multiple variable‐interval timeout schedules of food presentation. Negative induction occurred when responding declined gradually in the timeout component but not when responding declined abruptly. The nature of interactions in multiple schedules may depend on the species; negative induction was observed with squirrel monkeys under conditions similar to those that produce positive contrast with pigeons.
POSITIVE CONDITIONED SUPPRESSION: AN EXPLANATION IN TERMS OF MULTIPLE AND CONCURRENT SCHEDULES1
Authors: Stubbs D. A. , Hughes J. E. , Cohen S. L.
Published: March 2006

Rats performed under a baseline variable‐interval schedule of food presentation. A response‐independent food schedule was then superimposed on the baseline schedule for different periods of time across different conditions. The response‐independent schedule operated for the whole session in some conditions, intermittently for sixty second periods in some, and intermittently for ten‐second periods in others. Under these latter two sets of conditions, the response‐independent food schedule was stimulus correlated and alternated with the baseline schedule according to a multiple schedule. Response‐independent food presentations always suppressed responding. The degree of suppression tended to increase the longer the period of response‐independent food. Control conditions, in which the superimposed schedule was response‐dependent, rather than response‐independent, did not produce response suppression. The results fit an analysis of positive conditioned suppression phenomena in the context of multiple and concurrent schedule effects.
DISCRIMINATED RESPONSE AND INCENTIVE PROCESSES IN OPERANT CONDITIONING: A TWO‐FACTOR MODEL OF STIMULUS CONTROL1
Authors: Weiss Stanley J.
Published: March 2006

Understanding stimulus control generated in instrumental learning requires the direct investigation of discriminated response and reinforcer (incentive) processes acquired exclusively through the response‐reinforcer contingencies operating on complex (multicomponent) baselines. Two series of stimulus‐compounding studies accomplished this direct investigation. In one series, the independent variable was the relative reinforcement between schedule components; in the second series, it was relative response rate between components. Stimulus‐compounding tests revealed that response and incentive processes enhanced each other when in agreement, counteracted each other when in opposition, and produced intermediate results when only one factor was operating. This pattern of results led to the conclusion that these factors were algebraically combining and to the development of a response/incentive matrix reflecting these dynamics. This two‐factor analysis was extended to the peak‐shift effect in stimulus generalization experiments and to the generation of inhibitory control. Two decades of stimulus compounding and peak‐shift research were organized within this two‐factor framework, extending this traditional approach to learning to active research areas heretofore not systematically considered in these terms.
TRANSFER OF MATCHING PERFORMANCE IN PIGEONS
Authors: Holmes Paul W.
Published: March 2006

Three pigeons were given extensive training on three‐key simultaneous matching problems using geometric‐form and hue stimuli. After acquisition of matching, the birds were tested with pairs of stimuli involving one or both novel members. Matching during the test stimuli occurred less often than during the later stages of the acquisition phase, but more often than would occur if no transfer had taken place. Greater positive transfer was observed for problems that involved one, rather than two, novel stimuli. In the second phase of the experiment, previously trained birds were shifted to problems that required symbolic matching, i.e., the pigeons had to associate a particular center‐key stimulus with a particular side‐key stimulus. On each trial, one of two simuli was presented on the center key, and two other stimuli, different from those used on the center key, were displayed on the side keys. When the problem shift was introduced, correct responding was impaired, but remained considerably above chance level and quickly recovered in following sessions. The results were interpreted as favoring a stimulus‐response‐chaining account of matching behavior.
PENTOBARBITAL AND d‐AMPHETAMINE EFFECTS ON CONCURRENT PERFORMANCES
Authors: Bacotti Alfred V.
Published: March 2006

The effects of pentobarbital and d‐amphetamine were studied in pigeons responding under several concurrent fixed‐ratio variable‐interval and concurrent fixed‐ratio fixed‐interval schedules of food presentation. Drug effects were compared with different fixed ratios, fixed and variable intervals, changeover delays, and with the schedules operating singly. Doses of d‐amphetamine that increased or did not affect responding under the interval schedules decreased responding under the fixed‐ratio schedule, whereas doses of pentobarbital that increased responding under the fixed‐ratio schedule decreased or eliminated responding under the interval schedules. These effects depended both on the schedule of food delivery and the parameters of schedules arranged concurrently. Pentobarbital increased responding under the fixed‐ratio schedule with 4‐minute and 10‐minute interval schedules arranged concurrently, but not with 1.5‐minute schedules. d‐Amphetamine decreased concurrent ratio and interval responding with the 1.5‐minute interval schedules, but either increased or did not affect responding with the longer intervals. Changes in the parameter of one schedule altered responding controlled by that schedule and also other concurrent performances. As a consequence, the effects of drugs on each behavior were altered.
A PELLET FEEDER FOR THE BIRDS
Authors: Millard W. J.
Published: March 2006

An alternative means of delivering food to pigeons in operant conditioning research is described. The feeder allows greater control of the amount of food delivered and reduces the amount of time necessary for the pigeon to collect the food. It is possible to extend the length of experimental sessions due to the reduction of food intake. Data obtained using the pellet feeder indicated that the control of responding is comparable to that observed with the standard grain‐magazine feeder.
CONTROL BY STIMULUS FEATURES DURING FADING1
Authors: Doran Judith , Holland James G.
Published: March 2006

Sixteen children were given four successive circle‐size discrimination problems with luminance as the fading stimulus. Children who were first presented with a difficult size discrimination failed to acquire this discrimination. Those who first received an easy discrimination learned the difficult discrimination. At the end of each 10‐trial block, two probe stimuli were presented to monitor any shift in control from luminance to size. One probe was the same size as the positive stimulus but of different luminance; the other was the same luminance but of different size. If, in the course of fading, size and luminance both controlled responding, fading was successful. If luminance alone controlled responding until the end of fading, the size discrimination was not established. Dual control, and thus successful fading, resulted when the target stimuli were very discriminable, or when the target stimuli were subtly different provided that previous fading series had first established less subtle discriminations.