bluuebunny/crossref_metadata_2025 huggingface dataset:
STUDIES ON RESPONDING UNDER FIXED‐INTERVAL SCHEDULES OF REINFORCEMENT: II. THE SCALLOPED PATTERN OF THE CUMULATIVE RECORD
Authors: Dews P. B.
Published: March 2006

Responding under fixed‐interval schedules usually generates either scalloped or break‐and‐run cumulative records. Earlier, it was generally accepted that the characteristic pattern was the scallop, but in recent years there has been an increasing emphasis on the break‐and‐run pattern. The break‐and‐run pattern has been shown quantitatively to provide a good fit of certain fixed‐interval patterns. In the present work, responding during fixed‐interval 1000‐second components of a multiple fixed‐interval 1000‐second fixed‐ratio 50 responses schedule was examined in two rhesus monkeys. Even after responding had started in an interval, there was a high tendency for responding to accelerate over subsequent 100‐second segments of the interval. In segments with responding, the rate increased from one segment to the next in 303 of 389 segments in one monkey and in 310 of 419 segments in the other. The size of the increase was substantial, the rate in the fifth segment after responding started being an average of 4.5 times higher than the rate in the first segment after responding started. Hence, the usual pattern of responding in individual intervals was of sustained and substantial acceleration, vindicating numerically the conclusion derived from inspection of the scalloped patterns of the cumulative records.
INHIBITING FUNCTION OF REINFORCEMENT: MAGNITUDE EFFECTS ON VARIABLE‐INTERVAL SCHEDULES1
Authors: Harzem Peter , Lowe C. Fergus , Priddle‐Higson Peter J.
Published: March 2006

In two experiments, the performance of rats under constant‐probability and arithmetic variable‐interval schedules respectively was compared when the concentration of a liquid reinforcer was varied within sessions; in other sessions, half of the reinforcers were randomly omitted. When the discriminative function of the reinforcer as a signal for a decrease in the probability of reinforcement was attenuated (the constant‐probability schedule) the postreinforcement pause duration was nevertheless an increasing function of reinforcer magnitude. This relationship was also present, but more marked, when the temporal discriminative function of the reinforcer was enhanced (the arithmetic schedule). These results suggested that reinforcement has an unconditioned suppressive effect on the reinforced response distinct from any discriminative function it may acquire. The reinforcement‐omission effect, where response rate accelerates following omission, was observed when the reinforcer functioned as an effective temporal discriminative stimulus, but not when such temporal control was absent.
CONTRAST AND AUTOSHAPING IN MULTIPLE SCHEDULES VARYING REINFORCER RATE AND DURATION
Authors: Hamilton Bruce E. , Silberberg Alan
Published: March 2006

Thirteen master pigeons were exposed to multiple schedules in which reinforcement frequency (Experiment I) or duration (Experiment II) was varied. In Phases 1 and 3 of Experiment I, the values of the first and second components' random‐interval schedules were 33 and 99 seconds, respectively. In Phase 2, these values were 99 seconds for both components. In Experiment II, a random‐interval 33‐second schedule was associated with each component. During Phases 1 and 3, the first and second components had hopper durations of 7.5 and 2.5 seconds respectively. During Phase 2, both components' hopper durations were 2.5 seconds. In each experiment, positive contrast obtained for about half the master subjects. The rest showed a rate increase in both components (positive induction). Each master subject's key colors and reinforcers were synchronously presented on a response‐independent basis to a yoked control. Richer component key‐pecking occurred during each experiment's Phases 1 and 3 among half these subjects. However, none responded during the contrast condition (unchanged component of each experiment's Phase 2). From this it is inferred that autoshaping did not contribute to the contrast and induction findings among master birds. Little evidence of local contrast (highest rate at beginning of richer component) was found in any subject. These data show that (a) contrast can occur independently from autoshaping, (b) contrast assays during equal‐valued components may produce induction, (c) local contrast in multiple schedules often does not occur, and (d) differential hopper durations can produce autoshaping and contrast.
TEMPORAL FACTORS INFLUENCING THE PIGEON'S SUCCESSIVE MATCHING‐TO‐SAMPLE PERFORMANCE: SAMPLE DURATION, INTERTRIAL INTERVAL, AND RETENTION INTERVAL1
Authors: Nelson Keith R. , Wasserman Edward A.
Published: March 2006

A successive matching‐to‐sample procedure that entails the sequential presentation of sample and test stimuli and the monitoring of response rates in a go/no‐go discrimination of matching and nonmatching stimuli was studied as an alternative to the familiar delayed‐matching paradigm of animal short‐term memory. Three within‐subject experiments studied the effects of sample duration (1 to 12 seconds), intertriai interval (5 to 50 seconds), and retention interval (1 to 50 seconds) on the pigeon's successive‐matching performance. The results revealed that retention was (a) an increasing function of sample duration and intertrial interval, and (b) a decreasing function of retention interval. These results were in accord with those of more traditional short‐term memory paradigms, and reveal the suitability of the successive‐matching procedure for studying memory processes.
A CLARIFICATION OF CONTINUOUS REPERTOIRE DEVELOPMENT
Authors: Scheuerman Karl V. , Wildemann Donald G. , Holland James G.
Published: March 2006

The key‐peck response of five pigeons was reinforced on a schedule whenever the interval between pecks at two response keys was between 1.0 and 2.33 seconds in the presence of a 2,500‐Hertz tone or between 4.66 and 6.0 seconds in the presence of a 1250‐Hertz tone. There was no tendency for responses of intermediate duration to occur when test tones of intermediate frequency were presented. This result clarifies a previous finding using a similar procedure but with a visual intensity stimulus dimension.
MATCHING WITH A KEY PECK RESPONSE IN CONCURRENT NEGATIVE REINFORCEMENT SCHEDULES1
Authors: Hutton Larrie , Gardner Edward T. , Lewis Paul
Published: March 2006

In the absence of responding, pigeons were shocked under a variable‐time schedule. Responses on either of two keys occasionally produced one minute of shock‐free time. That is, pigeons' key pecks were reinforced with shock‐free time under concurrent variable‐interval schedules. The relative frequency of access to the one‐minute shock‐free periods was systematically manipulated. Pigeons tended to match both relative response rate and proportion of time spent on each key to the relative frequency of the shock‐free periods. A best‐fit linear regression equation accounted for over 95% of the variance in both relative response rate and time allocation. The data paralleled closely the results of concurrent schedules of positive reinforcement. These findings are consistent with a description of reinforcement as a transition to a higher‐valued situation and suggest that common laws govern choice for both positive and negative reinforcement.
MULTIPLE SCHEDULE COMPONENT DURATION: A RE‐ANALYSIS OF SHIMP AND WHEATLEY (1971) AND TODOROV (1972)
Authors: Edmon Eugene L.
Published: March 2006

The tendency for relative response rate to approach matching as multiple schedule component duration decreases has been interpreted as confirming a prediction of Herrnstein's multiple schedule equation. However, the equation predicts that absolute response rate will decrease in both multiple schedule components as component duration decreases. The absolute response‐rate data of two studies of component duration do not support this prediction; absolute rate either increased or remained relatively constant.
TEMPORAL CONTROL OF BEHAVIOR: SCHEDULE INTERACTIONS1
Authors: Harzem Peter , Lowe C. Fergus , Spencer Peter T.
Published: March 2006

In Experiment I the response that terminated the postreinforcement pauses occurring under a fixed‐interval 60‐second schedule was reinforced, if the pause duration exceeded 30 seconds. The percentage of such pauses, rather than increasing, decreased. There were complex effects on the discriminative control of the pause by the reinforcer terminating the previous fixed interval, depending on whether the fixed interval and the added reinforcer were the same or different. In Experiments II(a) and II(b), each reinforcement initiated an alternative fixed‐interval interresponse‐time‐greater‐than‐t‐sec schedule, the schedule values being systematically varied. When the response following a pause exceeding a given duration was reinforced, fewer such pauses occurred than when they were not reinforced, i.e., on the comparable simple fixed‐interval schedule. There was no systematic relationship between mean interrinforcement interval and duration of the postreinforcement pause. The pause duration initiated by reinforcement was directly related to the dependency controlling the shortest pause at that time, regardless of changes in mean interreinforcement interval.
PERFORMANCE OF RATS UNDER CONCURRENT VARIABLE‐INTERVAL SCHEDULES OF NEGATIVE REINFORCEMENT
Authors: Poling Alan
Published: March 2006

The behavior of rats under concurrent variable‐interval schedules of negative reinforcement was examined. A single one‐minute variable‐interval programmer determined the availability of 30‐second timeouts from electric shock. These were assigned to one or the other of the two component schedules with a probability of 0 to 1.0. The response requirement for the component schedules was standing to the right or left of the center of the experimental chamber. With a six‐second changeover delay, the relative time spent under one component schedule varied directly and linearly with the relative number of timeouts earned under that component schedule. The absolute number of changeovers was highest when a similar number of timeouts was earned under each component schedule, and lowest when all or nearly all timeouts were earned under one component schedule. In general, these relations are similar to those reported with concurrent variable‐interval schedules of positive reinforcement.
AUTOMAINTENANCE IN GUINEA PIGS: EFFECTS OF FEEDING REGIMEN AND OMISSION TRAINING1
Authors: Poling Alan , Poling Teresa
Published: March 2006

Behavior maintained by stimulus‐reinforcer pairings was examined. Guinea pigs maintained at 85 per cent of free‐feeding weights reliably contacted a retractable lever presented before delivery of a single piece of guinea‐pig chow or a 45‐milligram guinea‐pig pellet. When animals were given free access to one food and received the second food preceded by the lever, contact responses persisted. Such responses seldom occurred when a single food was freely available and was also delivered after lever presentation. Introduction of an omission training (negative automaintenance) procedure, in which lever contacts resulted in lever retraction and prevented food delivery, strongly reduced lever contacts. Observation indicated that mouthing the food cup, instead of the lever, became the prominent behavior during the prefood stimulus under the omission training procedure.
VARIABLE SHOCK FREE TIMES WITH INFORMATIVE AND UNINFORMATIVE STIMULI
Authors: Lewin Lewis M.
Published: March 2006

Three rats were trained on a fixed‐ratio escape procedure in which responding produced one of two equiprobable outcomes—a 10‐second or 60‐second shock‐free period. Before the fixed‐ratio requirement was satisfied, brief shocks were presented at irregular intervals averaging either 15 or 30 seconds. Two conditions, differing in the relationship between exteroceptive stimuli and the outcomes, were studied. In the uninformative (uncorrelated) condition, the same stimulus was presented during both outcomes. In the informative (correlated) condition, one stimulus was present during the 10‐second outcome only; another stimulus was present during the 60‐second outcome only. Subjects pressed faster in the uninformative condition than they did in the informative condition. The inadequacy of the information hypothesis in accounting for the findings is discussed, and an alternative hypothesis is offered.
CONTRAST AND INDUCTION IN MULTIPLE SCHEDULES OF DISCRETE‐TRIAL CONCURRENT REINFORCEMENT
Authors: Nevin John A. , Mandell Charlotte , Whittaker Stephen
Published: March 2006

Three pigeons were exposed to two‐key discrete‐trial concurrent schedules of reinforcement. Red and white key colors alternated irregularly and the assignment of reinforcers depended on key color. The red‐key schedules were held constant, with the scheduled relative frequency of reinforcement for left‐key pecks set at 0.75, while the white‐key schedules varied. When the location of white‐key reinforcement was changed from one side to the other, while its overall frequency was constant, red‐key choices shifted in the same direction as white‐key choices, an induction effect. When the overall frequency of white‐key reinforcement was changed while its location remained constant, red key choices shifted in a direction opposite to white‐key choices, a contrast effect. Both induction and contrast effects were clearer when the overall frequency of red‐key reinforcement was reduced. These data demonstrate that the allocation of responding may exhibit schedule interaction effects similar to those commonly reported for response rate.
VARIABILITY OF RESPONSE LOCATION ON FIXED‐RATIO AND FIXED‐INTERVAL SCHEDULES OF REINFORCEMENT1
Authors: Boren John J. , Moerschbaecher Joseph M. , Whyte Adrienne A.
Published: March 2006

Variability of response location was studied in monkeys performing in a six‐lever chamber. Fixed‐ratio schedules, ranging from FR 1 to FR 300, generated a high degree of stereotypy of response location. In contrast, fixed‐interval schedules of comparable reinforcement frequencies (0.06 to 4 minutes) generated much greater variability. These results failed to confirm any simple relationship between response variability and intermittence of reinforcement. Rather, variability seems to be determined by the particular characteristics of the reinforcement schedule.
DIVERSITY AND SUBSTITUTABILITY OF ADJUNCTIVE ACTIVITIES UNDER FIXED‐INTERVAL SCHEDULES OF FOOD REINFORCEMENT
Authors: Roper T. J.
Published: March 2006

Six rats received food contingent on pressing a lever on fixed‐ratio 1, fixed‐interval 30‐second, and fixed‐interval 60‐second schedules, with concurrent access to a drinking spout, a running wheel, and a block of wood. Drinking, running, and chewing were monitored automatically, and these and other activities were observed directly during selected sessions. Because all sessions ended after delivery of 60 pellets, total time available for activities other than eating increased over the three schedules. Time spent contacting the lever and visiting the food tray increased in proportion to total available time, whereas the time spent in other activities changed in a complex manner such that drinking was the dominant adjunctive behavior in the 30‐second condition, and running or chewing the dominant adjunctive behavior in five of six rats in the 60‐second condition. General activity and grooming also occupied significant amounts of time. In a subsequent part of the experiment, running and chewing were prevented, and the majority of other activities, especially drinking and grooming, increased. The results show that (a) FI schedules of food reinforcement are accompanied by a wide variety of adjunctive activities; (b) the preferred activity differs according to the schedule duration; and (c) the extent to which activities substitute for one another is limited by the tendency for different activities to occupy different parts of the interreinforcement interval.
SIGNAL‐CONTROLLED RESPONDING
Authors: Lewis Paul , Stoyak Michael
Published: March 2006

Pigeons' key pecks were reinforced with grain, then extinguished. An 8‐second tone preceded the availability of peck‐dependent grain 1 second after tone offset. When a tone signalled grain and an 8‐second clicking sound did not, three pigeons pecked during a high percentage of tone periods, but they pecked during a low percentage of click periods. When the roles of the tone and clicking sound were reversed, performance reversed. For other birds, when a key peck during the tone cancelled the availability of grain (omission procedure), the tendency to key peck during the tone decreased some, but still remained high. A third group of pigeons received the omission procedure with the addition that the tone could not end unless 2 seconds had elapsed without a key peck. The pigeons continued to respond in a high percentage of tone periods. The experiments favor an explanation based on the pairing of the tone with a reinforced response, such as Pavlovian conditioning.
EFFECTS OF COCAINE AND d‐AMPHETAMINE ON THE REPEATED ACQUISITION AND PERFORMANCE OF CONDITIONAL DISCRIMINATIONS1
Authors: Moerschbaecher Joseph M. , Boren John J. , Schrot John , Fontes Jose Carlos Simoes
Published: March 2006

The acute and chronic effects of cocaine and d‐amphetamine on food‐reinforced behavior were investigated in pigeons responding on a two‐component multiple schedule. In one component, the behavioral task consisted of the same chain of conditional discriminations each session (performance). In the other component, the chain of conditional discriminations was changed from session to session (learning). In comparison to control sessions, both acute cocaine and d‐amphetamine increased errors in each component of the multiple schedule. Responding in the learning component, however, was generally disrupted at lower doses than those that affected responding in the performance component. At high doses, both drugs produced pauses in responding in each component in three of the four subjects. Pausing engendered by d‐amphetamine was approximately twice as long as that under cocaine. Upon chronic administration, both the pausing and error‐increasing effects of each drug diminished. Drug‐induced changes in timeout responding, however, did not decrease during chronic administration. Redeterminations of the d‐amphetamine dose‐effect curves following chronic cocaine administration suggested the existence of cross‐tolerance between cocaine and d‐amphetamine. Both the acute and chronic data are consistent with the view that conditions of stimulus control may modulate the behavioral effects of drugs.
REINFORCEMENT CONTINGENCIES AS DISCRIMINATIVE STIMULI: II. EFFECTS OF CHANGES IN STIMULUS PROBABILITY
Authors: Lattal Kennon A.
Published: March 2006

Three pigeons were trained on a matching procedure involving a sample component and a choice component. Responding in the sample component, according to either a differential‐reinforcement‐of‐low‐rate schedule on some trials or a differential‐reinforcement‐of‐other‐behavior schedule on other trials, produced access to the choice component in which each of two keys was illuminated with a unique color. The correct choice response was defined by the contingency that was met to produce the choice. The food hopper operated for 1.5 seconds following an appropriate sample response and for 3 seconds following a correct choice response. A signal‐detection analysis showed that variations in the probability of presentation of the different contingencies systematically affected response bias but not sensitivity to the contingencies as stimuli. Substitution of a blackout for food at the end of the sample component did not differentially affect performance, but elimination of the delay between sample and choice components generally increased the sensitivity measure. The findings suggest a role for reinforcement contingency discrimination in schedule‐controlled responding.
IS MATCHING COMPATIBLE WITH REINFORCEMENT MAXIMIZATION ON CONCURRENT VARIABLE INTERVAL, VARIABLE RATIO?1
Authors: Herrnstein R. J. , Heyman G. M.
Published: March 2006

Four pigeons on concurrent variable interval, variable ratio approximated the matching relationship with biases toward the variable interval when time spent responding was the measure of behavior and toward the variable ratio when frequency of pecking was the measure of behavior. The local rates of responding were consistently higher on the variable ratio, even when there was overall preference for the variable interval. Matching on concurrent variable interval, variable ratio was shown to be incompatible with maximization of total reinforcement, given the observed local rates of responding and rates of alternation between the schedules. Furthermore, it was shown that the subjects were losing reinforcements at a rate of about 60 per hour by matching rather than maximizing.
CONDITIONING OF TWO‐RESPONSE PATTERNS OF KEY PECKING IN PIGEONS1
Authors: Grayson Rebecca J. , Wasserman Edward A.
Published: March 2006

On discrete trials, two response keys were made available to hungry pigeons and food reinforcement depended on the order in which the required two key pecks occurred. In different phases, only one of the four possible two‐peck sequences (left‐left, left‐right, right‐left, and right‐right) produced food reinforcement. In each case, the pigeons learned to perform the correct two‐peck sequence more often than the incorrect sequences. Furthermore, the course of differentiation mastery indicated that both reinforcement history and response‐reinforcer contiguity influenced performance. These results reveal that response patterns comprising two instances of the same response left‐left and right‐right) or instances of two different responses (left‐right and right‐left) may function as operants, thereby extending the generality of conditioning principles from discrete responses to structured sequences of behavior. These and other results are discussed in terms of contiguity‐based and memory‐based models of learning.
THE EFFECTS OF NUMBER OF RESPONSES ON THE POSTREINFORCEMENT PAUSE IN FIXED‐INTERVAL SCHEDULES
Authors: Nunes Dennis L. , Alferink Larry A. , Crossman Edward K.
Published: March 2006

The present study manipulated the number of responses in a modified fixed‐interval schedule by imposing a blackout after each unreinforced response during the interval. The blackout duration was varied, and the duration of the fixed interval was held constant. The subjects were initially exposed to a fixed‐interval 300‐sec schedule. Blackout durations of 0, 10, and 50 sec were used. Following this, a fixed‐interval 30‐sec schedule was used with blackout durations of 0, 1, and 5 sec. Under the fixed‐interval 300‐sec schedule, the number of interreinforcement responses varied over a wider range than occurred under the fixed‐interval 30‐sec schedule. The duration of the postreinforcement pause decreased as blackout durations were increased and number of responses decreased on the fixed‐interval 300‐sec schedule, but pause length did not vary with changes in blackout duration and number of responses for the fixed‐interval 30‐sec schedule. The differences in the effects of blackout duration and response manipulation on the two fixed‐interval schedules were attributed to relatively greater changes in the number of interreinforcement responses for the fixed‐interval 300‐sec schedule.
MATCHING‐TO‐SAMPLE AND ODDITY‐FROM‐SAMPLE IN GOLDFISH1
Authors: Goldman Marjorie , Shapiro Sandra
Published: March 2006

Acquisition of three‐alternative simultaneous matching‐to‐sample and oddity‐from‐sample was investigated. Five goldfish were trained on matching and five on oddity for a minimum of 70 days. Subsequently, six of the fish were trained for 70 days on the other task. Acquisition was similar for oddity and matching. Correct responding started at about chance level and slowly increased to about 75%, with some animals performing at levels of over 85%. Acquisition of oddity following matching and matching following oddity began below chance. Maximal level of performance on second‐task oddity was comparable to that on first‐task matching. By contrast, the maximal levels of performance when matching was the second task were not as high as that of the same subjects at the end of first‐task oddity. All fish exhibited strong color preferences during matching acquisition but not during oddity acquisition. The data demonstrated that goldfish can acquire a discrimination in which the stimulus associated with reinforcement depends on the identity of a second stimulus.
SUGGESTED GREEK TRANSLATIONS OF EXPRESSIONS IN THE EXPERIMENTAL ANALYSIS OF BEHAVIOR
Authors: Charalambous Neophytos , Cramer Owen , Roberts Carl L.
Published: March 2006

Greek‐English and English‐Greek translations of expressions in the experimental analysis of behavior are presented. Included is a short discussion of some of the problems which arose, partly because of the mentalistic nature of Greek science.
INTERRESPONSE‐TIME SHAPING BY VARIABLE‐INTERVAL‐LIKE INTERRESPONSE‐TIME REINFORCEMENT CONTINGENCIES1
Authors: Platt John R.
Published: March 2006

The interresponse‐time reinforcement contingencies and distributions of interreinforcement intervals characteristic of certain variable‐interval schedules were mimicked by reinforcing each key peck with a probability equal to the duration of the interresponse time it terminated, divided by the scheduled mean interreinforcement interval. The interresponse‐time reinforcement contingency was then eliminated by basing the probability of reinforcement on the fifth interresponse time preceding the key peck. Even though distributions of interreinforcement intervals were unaffected by this manipulation, response rates consistently increased. A second experiment replicated this effect and showed it to combine additively with that of mean reinforcement rate. These results provide strong support for the contention that current analyses of variable‐interval response rates that ignore the inherent interresponse‐time reinforcement contingency may be seriously in error.
THE EFFECTS OF THE STIMULUS‐REINFORCER CORRELATION IN A DISCRETE‐TRIALS IRT>t PROCEDURE1
Authors: Wessells Michael G.
Published: March 2006

The correlation between a keylight and food in a discrete‐trials, interresponse‐time‐greater‐than 6‐sec (IRT>6‐sec) procedure was varied by manipulating the rate of response‐independent food presentation in the intertrial interval. When the correlation was positive, the rates of pecking in the IRT>6‐sec condition were high and food was obtained on only about 5% of the trials. Likewise, responding was maintained at a high rate in yoked birds that received the same presentations of the light and food as the birds in the IRT>6‐sec condition. When the rate of reinforcement between trials was equated to or made greater than the rate of reinforcement within trials, the response rate decreased for all birds, and those decreases were considerably larger for the yoked birds. However, the percentage of trials in which reinforced responses occurred under the IRT> 6‐sec procedure did not increase substantially when the light and food were either uncorrelated or negatively correlated. The percentage of trials in which a reinforcer was obtained increased when the keylight was left on continuously and the discriminative stimulus was not presented on the key. The results show that the stimulus‐reinforcer correlation affects responding in the discrete‐trials IRT>6‐sec procedure, but that the effects of the stimulus‐reinforcer correlation vary as a function of whether reinforcement is response‐dependent or response‐independent. The differences between the effects of response‐independent and response‐dependent pairings and nonpairings of the light and food are best accounted for in terms of differences in the control of responding by background stimuli.
TEMPORAL DISTRIBUTIONS OF RESPONDING DURING DISCRETE‐TRIAL OMISSION TRAINING IN RATS
Authors: O'Connell Michael F.
Published: March 2006

Within‐session temporal distributions of responding were investigated in three experiments using rats pressing a lever in a discrete‐trial omission procedure. This schedule entailed 60, one‐minute trials, and a sucrose solution was made available at the end of each trial in which no lever press occurred. In Experiment I, nonnaive rats acquired and maintained responding during this training. Moreover, the probability of a response during any session showed a strong and reliable tendency to increase from the beginning to the end of the session. These results were replicated in Experiment II, using naive animals. In Experiment III, alterations were made in the training procedure, including elimination of response‐contingent and noncontingent stimulus changes. Results indicate that stimulus change may be sufficient to maintain low levels of responding whether or not this change is contingent on responding.
PARTIAL AVOIDANCE CONTINGENCIES: ABSOLUTE OMISSION AND PUNISHMENT PROBABILITIES1
Authors: Flye Barbaba L. , Gibbon John
Published: March 2006

Avoidance contingencies were defined by the absolute probability of the conjunction of responding or not responding with shock or no shock. The “omission” probability (p00) is the probability of no response and no shock. The “punishment” probability (p11) is the probability of both a response and a shock. The traditional avoidance contingency never omits shock on nonresponse trials (p00 = 0) and never presents shock on response trials (p11 = 0). Rats were trained on a discrete‐trial paradigm with no intertrial interval. The first lever response changed an auditory stimulus for the remainder of the trial. Shocks were delivered only at the end of each trial cycle. After initial training under the traditional avoidance contingency, one group of rats experienced changes in omission probability (p00 > 0), holding punishment probability at zero. The second group of rats were studied under different punishment probability values (p11 > 0), holding omission probability at zero. Data from subjects in the omission group looked similar, showing graded decrements in responding with increasing probability of omission. These subjects approximately “matched” their nonresponse frequencies to the programmed probability of shock omission on nonresponse trials, producing a very low and approximately constant conditional probability of shock given no response. Subjects in the punishment group showed different sensitivity to increasing absolute punishment probability. Some subjects decreased responding to low values as punishment probability increased, while others continued to respond at substantial levels even when shock was inevitable on all trials (noncontingent shock schedule). These results confirm an asymmetry between two dimensions of partial avoidance contingencies. When the consequences of not responding included occasional omission of shock, all subjects showed graded sensitivity to changes in omission frequency. When the consequences of responding included occasional shock delivery, some subjects showed graded sensitivity to punishment frequency while others showed control by overall shock frequency as well.
AUTOMAINTENANCE WITHOUT STIMULUS‐CHANGE REINFORCEMENT: TEMPORAL CONTROL OF KEY PECKS1
Authors: Myerson Joel , Myerson William A. , Parker B. Kent
Published: March 2006

Yoked pairs of experimentally naive pigeons were exposed to a modified autoshaping procedure in which key pecking by the leader birds postponed both keylight termination and access to grain for the leader and the follower bird. Key pecking developed and was maintained in all birds and continued through two reversals of roles in the yoked procedure. Although temporal control developed more slowly in follower birds, asymptotic temporal distributions of key pecking were similar for all birds in both leader and follower roles; maximum responding occurred soon after keylight onset and decreased to a minimum prior to reinforcement. Response distributions for both leader and follower birds were described by Killeen's (1975) mathematical model of temporal control. Follower birds received response‐independent reinforcement, and the development by these birds of temporal distributions which are minimal immediately prior to reinforcement is without precedent in Pavlovian appetitive conditioning. However, maintenance of key pecking by the leader birds, whose responses postponed both stimulus‐change and food reinforcement, supports an interpretation of autoshaped and automaintained key pecking as responding elicited by signaled grain presentation.
DEVIATIONS FROM MATCHING AS A MEASURE OF PREFERENCE FOR ALTERNATIVES IN PIGEONS
Authors: Leigland Sam M.
Published: March 2006

Preferences for larger or smaller formally defined response classes were investigated in a concurrent schedule procedure. Twelve pigeons were run on a series of concurrent variable‐interval reinforcement schedules, from which baseline matching functions were obtained. An experimental phase followed, in which a second response key was available in one concurrent schedule alternative. For half the birds, the second key was programmed identically with the first; for the other half, the added key was programmed for extinction, with position irrelevant. Comparison of baseline and experimental matching functions revealed no systematic changes in either slope or intercept for birds in the latter group. Systematic shifts in function intercepts in the former group indicate a response bias toward the response‐constrained (single‐key) schedule alternative. Although contrary to the literature of preference for choice, this finding may be interpretable through an account dealing with imposed variability of responding.
SERIAL LEARNING IN THE PIGEON
Authors: Straub R. O. , Seidenberg M. S. , Bever T. G. , Terrace H. S.
Published: March 2006

Three pigeons learned to peck four colors in a particular sequence, regardless of how these colors were positioned on four response keys and without feedback following each response. This demonstrates that serial learning is possible in subprimate animals.
THE CONTROL OF RESPONDING BY SOUNDS: UNUSUAL EFFECT OF REINFORCEMENT
Authors: Harrison J. M.
Published: March 2006

Naive rats were trained to respond on one lever in the presence of noise bursts from one speaker and on a second lever in the presence of noise bursts from a second speaker. The speakers were mounted behind the levers. When responding on the lever adjacent to the sounding speaker was reinforced, control developed within fewer than five trials. When responding on the nonadjacent lever was selectively reinforced, responding on the lever adjacent to the sounding speaker increased in probability for several sessions. Naive rats were trained to respond on the nonadjacent lever following preexposure to the sound. Responding on the lever adjacent to the sounding speaker increased in probability, showing that novelty was not responsible for the effect. Naive rats were run on automaintenance procedures in which there was no explicit pairing of sound and magazine operation, 100% pairing of sound and magazine operation, or magazine operation following 40% of sound presentations. None of the rats acquired the response of approaching and sniffing the sounding speaker, indicating that sound‐magazine pairing was not responsible for the effect.
FREE‐OPERANT CHOICE BEHAVIOR: A MOLECULAR ANALYSIS
Authors: Navarick Douglas J.
Published: March 2006

Pigeons' pecks to two concurrent initial‐link stimuli occasionally produced one of two mutually exclusive terminal links. Further responding to the terminal‐link stimulus produced food under fixed‐interval or fixed‐ratio schedules. In such concurrent chained schedules, investigators rarely use a changeover delay to control superstitious switching, although it is customary to use a changeover delay in simple concurrent schedules in which choice responses produce food directly. When terminal‐link fixed‐interval schedules were equal or similar in duration and no changeover delay was employed, conditional probabilities of choice for a schedule were found to be lower if the last choice was for that schedule than if the last choice was for the other schedule (“switching dependency”). Imposition of a changeover delay with equal or unequal terminal links produced the opposite pattern: conditional probabilities of choice for a schedule were higher if the last choice was for that schedule than if the last choice was for the other schedule. Turning off all chamber lights during the changeover delay interval attenuated these “repetition dependencies.” The results indicate that excessive switching can complicate the interpretation of data from concurrent chains much as from simple concurrent schedules, and that using blackouts to control switching may be preferable to using a changeover delay.
CONCURRENT SCHEDULES: UNDERMATCHING AND CONTROL BY PREVIOUS EXPERIMENTAL CONDITIONS
Authors: Davison M. C. , Hunter I. W.
Published: March 2006

Five pigeons were trained on concurrent variable‐interval schedules. A series of conditions in which the ratio of reinforcement rates on two keys was progressively increased and then decreased was arranged twice. The birds were then exposed to an irregular sequence of conditions. Each condition in which reinforcement was available on both keys lasted six sessions. Performance in the first, third, and sixth sessions after a condition change was analyzed. Following a condition change, preference was biased toward the preference in the last condition, but this effect largely disappeared before the sixth session of training. The birds' preferences also appeared less sensitive to reinforcement rates in early sessions after a transition. Preference in a session was a function of both the reinforcements in that session and the reinforcements obtained in as many as four or five previous sessions. The effects of reinforcements in previous sessions could be summarized by the performance in the immediately preceding session, giving a relatively simple relation between present performance and a combination of present reinforcement and prior session performance. While such hysteresis could cause undermatching when only a small number of sessions are arranged in a condition, undermatching in a stable‐state performance probably arises elsewhere.
MATCHING, UNDERMATCHING, AND OVERMATCHING IN STUDIES OF CHOICE
Authors: William Baum M.
Published: March 2006

Almost all of 103 sets of data from 23 different studies of choice conformed closely to the equation: log (B1/B2) = a log (r1/r2) + log b, where B1 and B2 are either numbers of responses or times spent at Alternatives 1 and 2, r1 and r2 are the rates of reinforcement obtained from Alternatives 1 and 2, and a and b are empirical constants. Although the matching relation requires the slope a to equal 1.0, the best‐fitting values of a frequently deviated from this. For B1 and B2 measured as numbers of responses, a tended to fall short of 1.0 (undermatching). For B1 and B2 measured as times, a fell to both sides of 1.0, with the largest mode at about 1.0. Those experiments that produced values of a for both responses and time revealed only a rough correspondence between the two values; a was often noticeably larger for time. Statistical techniques for assessing significance of a deviation of a from 1.0 suggested that values of a between .90 and 1.11 can be considered good approximations to matching. Of the two experimenters who contributed the most data, one generally found undermatching, while the other generally found matching. The difference in results probably arises from differences in procedure. The procedural variations that lead to undermatching appear to be those that produce (a) asymmetrical pausing that favors the poorer alternative; (b) systematic temporal variation in preference that favors the poorer alternative; and (c) patterns of responding that involve changing over between alternatives or brief bouts at the alternatives.
STIMULUS PROPERTIES OF CONSPECIFIC BEHAVIOR
Authors: Millard W. J.
Published: March 2006

Two experiments identified the conditions in which the behavior of one bird acquired discriminative control of the behavior of a second bird. The schedule‐controlled behaviors of the “stimulus” bird were differentially correlated with the components of a multiple schedule according to which the pecking of an “experimental” bird produced food. In Experiment 1, three pairs of pigeons acquired a successive discrimination and two reversals with the conspecific stimuli. Experiment 2 included a control condition in which no systematic relationship existed between the conspecific stimuli and the component schedules. While differential responding during the components of the multiple schedule was again found when the conspecific stimuli were available, differential responding did not occur in the control condition. Test conditions included in the experiments indicated that (a) the differential responding was not dependent on the discriminative properties of reinforcement, (b) the pecking of the stimulus and experimental birds was temporally interrelated, (c) the visual conspecific stimuli were critical to the maintenance of the discrimination, and (d) the observed stimulus control immediately generalized to an unfamiliar conspecific.
RESPONSE REQUIREMENTS AS CONSTRAINTS ON OUTPUT
Authors: Zeiler Michael D. , Buchman Irvin B.
Published: March 2006

Two experiments studied how added response requirements affected fixed‐interval schedule performance. Experiment 1 involved tandem fixed‐interval fixed‐ratio schedules, and Experiment 2 studied conjunctive fixed‐interval fixed‐ratio schedules. In both, pigeons' output, defined as overall response rate or as responses during the interval, first increased and then decreased as the ratio was raised. With small ratio requirements, the frequency of reinforcement in time either did not change or decreased slightly. With progressively larger ratios, reinforcement frequency decreased consistently. Alternative explanations were discussed. The first, a reinforcement theory account, was that response strength is an increasing monotonic function of both the response requirement and reinforcement frequency, and the bitonic output function represents interacting effects. Increases in the response requirement accompanied by small changes in reinforcement frequency enhance output, but further increases result in large enough decrements in reinforcement frequency so that output is lowered. The second explanation does not view reinforcement as a basic process but, instead, derives from concepts of economics and conservation. Organisms allocate their behavior among alternatives so as to maximize value, where value is a function of the responses that can occur in a given situation under the set of restrictions imposed by particular schedules. One, form of this theory explicitly predicts that output is a bitonic function of ratio requirements in simple ratio schedules. However, it was not clear that this model could explain the present effects involving joint ratio and interval schedule restrictions.
GROOMING MOVEMENTS AS OPERANTS IN THE RAT
Authors: Annable A. , Wearden J. H.
Published: March 2006

Two experiments investigated the effect of contingent food deliveries on grooming movements in rats. The grooming sequence was divided into three topographically distinct behaviors: paw washing, face washing, and body washing. The first experiment found that rates of paw washing and body washing increased reliably under a food contingency, but face washing did not. A second experiment replicated these findings, and, in addition, showed that the average duration of paw washing and body washing decreased in length when followed by food. Placing a contingency on face washing, however, produced an increase in the rate of paw washing but no increase in face washing. It was concluded that, on the one hand, paw washing and body washing may be influenced by operant contingencies in the same way as behaviors such as lever pressing. On the other hand, increases in paw washing under the face washing contingency suggested that increases in the rate of grooming movements may occur by means other than operant relations.
OPERANT AND NONOPERANT VOCAL RESPONDING IN THE MYNAH: COMPLEX SCHEDULE CONTROL AND DEPRIVATION‐INDUCED RESPONDING
Authors: Hake D. F. , Mabry J.
Published: March 2006

Several recent studies have been concerned with operant responses that are also affected by nonoperant factors, (e.g., biological constraints, innate behavior patterns, respondent processes). The major reason for studying mynah vocal responding concerned the special relation of avian vocalizations to nonoperant emotional and reflexive systems. The research strategy was to evaluate operant and nonoperant control by comparing the schedule control obtained with the vocal response to that characteristic of the motor responses of other animals. We selected single, multiple, and chain schedules that ordinarily produce disparate response rates at predictable times. In multiple schedules with one component where vocal responding (“Awk”) was reinforced with food (fixed‐ratio or fixed‐interval schedule) and one where the absence of vocal responding was reinforced (differential reinforcement of other behavior), response rates never exceeded 15 responses per minute, but clear schedule differences developed in response rate and pause time. Nonoperant vocal responding was evident when responding endured across 50 extinction sessions at 25% to 40% of the rate during reinforcement. The “enduring extinction responding” was largely deprivation induced, because the operant‐level of naive mynahs under food deprivation was comparable in magnitude, but without deprivation the operant level was much lower. Food deprivation can induce vocal responding, but the relatively precise schedule control indicated that operant contingencies predominate when they are introduced.
SCHEDULE‐INDUCED DRINKING: RATE OF FOOD DELIVERY AND HERRNSTEIN'S EQUATION
Authors: Wetherington Cora Lee
Published: March 2006

Schedule‐induced drinking was measured in four rats exposed to fixed‐time schedules of food ranging from 30 to 480 seconds. Herrnstein's (1970, 1974) equation relating rate of a single response as a hyperbolic function of reinforcement rate provided a good fit to three measures of drinking: lick rate, ingestion rate, and relative time spent drinking. The functions relating the three measures of drinking to reinforcement rate were of similar form. Herrnstein's equation also provided a good description of some already published data on schedule‐induced drinking. The fit both to the present data and to the already published data was improved somewhat by computing the measures by subtracting from the time base a latency constant representing the minimal time required to consume the food pellet and travel to the water source. The data from this study provide two correspondences between operant behavior and schedule‐induced behavior: (a) conformity to Herrnstein's equation and (b) equivalence of rate and relative time measures.
PERCENTAGE REINFORCEMENT AND CHOICE
Authors: Fantino Edmund , Dunn Roger , Meck Warren
Published: March 2006

Pigeons responded on identical concurrent variable‐interval schedules (choice phase), producing outcomes of either periodic reinforcement schedules always terminating in reinforcement (reliable schedule) or otherwise identical schedules providing reinforcement on only a percentage of instances (percentage reinforcement schedule). Comparisons of this type constituted two assessments of the generality of preference for percentage reinforcement reported by Kendall (1974). In a third set of conditions, a reliable schedule was pitted against a percentage reinforcement schedule in which the more negative outcome was a leaner schedule of reinforcement (rather than nonreinforcement, as in the other two conditions). In all three types of conditions, the schedule providing the higher rate of reinforcement was preferred. Results from a subsequent manipulation suggest that Kendall's contrasting results may have depended on the fact that the stimuli in his choice phase (unlit keys) were physically identical to the stimulus correlated with the nonchosen outcome in his outcome phase.