bluuebunny/crossref_metadata_2025 huggingface dataset:
SENSITIVITY OF TIME ALLOCATION TO CONCURRENT‐SCHEDULE REINFORCEMENT
Authors: Aldiss Matthew , Davison Michael
Published: March 2006

Four pigeons were trained on concurrent variable‐interval schedules programmed on a center response key, with access to those schedules controlled by responses on left or right side keys. Two procedures were used. In one, the pigeon was given limited access, in that each side‐key response produced 3‐s access to a center‐key schedule, and in the other procedure, access was unlimited. Data were analyzed using the generalized matching law. Comparison of sensitivities to reinforcement of interchangeover time for both procedures showed them to be of similar magnitude. Response sensitivities were also similar in magnitude for both procedures. From the limited‐access procedure a second time measure that was available, switched‐in time, was relatively uncontaminated by time spent emitting behavior other than key pecking. Sensitivities to reinforcement for the switched‐in time measure were always smaller than interchangeover‐time sensitivities for either procedure, and were approximately equal to response sensitivities for the limited‐access procedure. Two other access times (5 and 7.5 s) were studied to validate the choice of 3 s as the main access time. These results indicate that when time spent emitting other behavior is excluded from interchangeover time, time and response sensitivities will be approximately equal.
REINFORCEMENT PROBABILITY AND ORDINAL POSITION OF RESPONSE IN FIXED‐INTERVAL SCHEDULES
Authors: Rosenberg Jordan
Published: March 2006

Four rats pressed levers and received food pellets under fixed‐interval reinforcement schedules of 20, 60, and 180 seconds. The number of responses in each interval was recorded. From these data, the probability of reinforcement was determined as a function of response count. These functions were generally increasing. This finding is consistent with previous suggestions that increasing response rates within fixed intervals may be a function of response count in addition to or instead of elapsed or remaining time.
HUMAN COFFEE DRINKING: MANIPULATION OF CONCENTRATION AND CAFFEINE DOSE
Authors: Griffiths Roland R. , Bigelow George E. , Liebson Ira A. , O'Keeffe Mary , O'Leary David , Russ Nason
Published: March 2006

In a residential research ward coffee drinking was studied in 9 volunteer human subjects with histories of heavy coffee drinking. A series of five experiments was undertaken to characterize adlibitum coffee consumption and to investigate the effects of manipulating coffee concentration, caffeine dose per cup, and caffeine preloads prior to coffee drinking. Manipulations were double‐blind and scheduled in randomized sequences across days. When cups of coffee were freely available, coffee drinking tended to be rather regularly spaced during the day with intercup intervals becoming progressively longer throughout the day; experimental manipulations showed that this lengthening of intercup intervals was not due to accumulating caffeine levels. Number of cups of coffee consumed was an inverted U‐shaped function of both coffee concentration and caffeine dose per cup; however, coffee‐concentration and dose‐per‐cup manipulations did not produce similar effects on other measures of coffee drinking (intercup interval, time to drink a cup, within‐day distribution of cups). Caffeine preload produced dose‐related decreases in number of cups consumed. As a whole, these experiments provide some limited evidence for both the suppressive and the reinforcing effects of caffeine on coffee consumption. Examination of total daily coffee and caffeine intake across experiments, however, provides no evidence for precise regulation (i.e., titration) of coffee or caffeine intake.
BINOCULAR DEPTH PERCEPTION IN THE PIGEON
Authors: McFadden Sally A. , Wild J. Martin
Published: March 2006

By means of a discrete‐trial simultaneous discrimination procedure, pigeons were trained to respond differentially to visual arrays that were identical except that one of them contained a circle displaced in depth when viewed stereoscopically. Performance was severely disrupted when one eye was occluded. The monocular deficit was peculiar to the depth task, inasmuch as no such decrement was seen on a pattern discrimination. The results imply that presence of the displaced circle was discriminated on the basis of a binocular cue. It was also found that pigeons could discriminate the direction of the displacement. Discrimination of depth was independent of the global form and still occurred when elements of the array were randomly displaced in depth. Performance was not disrupted when the absolute convergence angle of the depth stimulus was changed. The cue that consistently accounted for the behavior seen was the detection of the relative angles of convergence—that is, the retinal disparity of the two planes in depth. Thus, despite the lateral position of the eyes of the pigeon, a small binocular field mediates the binocular discrimination of near objects in depth.
THE MATCHING LAW APPLIES TO WAGTAILS' FORAGING IN THE WILD
Authors: Houston Alasdair
Published: March 2006

Field data concerning the time budgets and foraging success of pied wagtails (Motacilla alba yarrelli, Gould) are reanalyzed. It is found that the data are well described by the generalized matching law, with a marked bias towards spending time on the territory. In this case matching is not the result of maximizing reward rate, but it remains possible that it results from an allocation of time that maximizes survival.
BEHAVIORAL CONTRAST IN FIXED‐INTERVAL COMPONENTS: EFFECTS OF EXTINCTION‐COMPONENT DURATION
Authors: Rose Julio Cesar Coelho de
Published: March 2006

Seven albino rats were exposed to a multiple schedule of reinforcement in which the two components (fixed interval and extinction) alternated such that a presentation of the extinction component followed each fixed‐interval reinforcement. In baseline sessions, the duration of the extinction component was constant and always one‐third of the fixed‐interval value. Probe sessions contained a probe segment in which the duration of the extinction component was increased; the response rate in fixed‐interval components during the probe segment was compared with the response rate in the segments preceding and following the probe. The effect of increasing the duration of the extinction component was studied under three values of fixed interval: 30 s, 120 s, and 18 s, in three successive conditions. Response rate within fixed intervals was a direct function of duration of the extinction component. Pausing at the beginning of the fixed interval decreased as extinction duration increased. These effects were larger and more consistent for the shorter fixed‐interval values (18 s and 30 s). These results indicate a functional relation between relative component duration and responding. For the component providing more frequent reinforcement, this could be stated as an inverse relationship between relative component duration and response rate. This relation is similar to findings regarding the ratio of trial and intertrial duration in Pavlovian conditioning procedures, and suggests that behavioral contrast may be related to Pavlovian contingencies underlying the multiple schedule.
BRIEF EXPOSURE TO CONTINGENT REINFORCEMENT PRODUCES A SUSTAINED INCREMENT IN THE STRENGTH OF AN ELICITED RESPONSE
Authors: Hutchinson Ronald R. , Emley Grace S.
Published: March 2006

Squirrel monkeys' lever pressing produced by response‐independent shock was measured before, and for an extended period following, exposure to a shock‐avoidance procedure. Following avoidance training, the frequency of responding increased by multiples of 10 to 50 across subjects and evidence little or no decrement for up to 6 months of postreinforcement testing. Manual responding produced by intense environmental stimulation may be substantially strengthened by a brief history of reinforcement, such that it is sustained over long periods without reinforcement.
MOLECULAR ANALYSES OF THE EFFECTS OF d‐AMPHETAMINE ON FIXED‐INTERVAL SCHEDULE PERFORMANCES OF RATS
Authors: McAuley Frank , Leslie Julian C.
Published: March 2006

A series of doses (0.5 to 2.0 mg/kg) of d‐amphetamine was administered to rats whose lever pressing was maintained by fixed‐interval 30‐s, 60‐s, or 120‐s schedules of reinforcement by sucrose delivery. Under both saline and d‐amphetamine conditions, molecular features of responding were reliably described in terms of the distribution of postreinforcement pauses and local response rate following the onset of responding. Postreinforcement pause always varied from interval to interval but, on average, shortened under the drug. Local response rate (response rate exclusive of pause time) tended to decrease under the drug, and where acceleration occurred within runs of responses, it was reduced by the drug. All of these effects were dose‐related. These findings suggest that fixed‐interval behavior can be analyzed effectively at a molecular level, and that the effects of d‐amphetamine are best described as disruption of temporal discrimination.
DRUG—BEHAVIOR INTERACTION HISTORY: MODIFICATION OF THE EFFECTS OF MORPHINE ON PUNISHED BEHAVIOR
Authors: Brady Linda S. , Barrett James E.
Published: March 2006

Squirrel monkeys were trained to respond under a multiple fixed‐interval, fixed‐interval schedule in which the first response after 5 min terminated a visual stimulus in the presence of which electric shocks could occur. During one component of the schedule, correlated with one color of stimulus lights, every 30th response also produced electric shock; responding was suppressed during this component to approximately 10 to 12% of that occurring in the alternate component in which responding was not punished. In contrast to previous research, morphine (0.03 to 1.0 mg/kg) increased punished responding. Unpunished responding, however, was either not affected or decreased at doses of morphine that increased punished responding. Increases in rate of punished responding also occurred when the single‐schedule punishment condition was studied alone in these animals. Subsequent experimentation, which systematically analyzed the development of the rate‐enhancing effects of morphine on punished responding, involved the study of drug effects in additional monkeys trained initially under a single‐schedule punishment condition. The effects of morphine on punished responding were studied before, after, and then during exposure to the multiple schedule that included a component in which responding was not punished. Increases in response rate with morphine did not occur until it was administered during exposure to the multiple schedule that included a component in which responding was not punished. As with the other monkeys, once the rate increases in punished responding occurred under the multiple schedule, these effects of morphine persisted, even when the multiple schedule was removed. These findings indicate that the behavioral effects of a drug can depend on the combined influence of that drug and the specific circumstances under which it is studied. Neither the behavioral experience alone nor exposure to the drug was sufficient to alter morphine's effects. Once this drug‐behavior interaction occurs, however, the behavioral effects of that drug can be changed substantially.
RULE‐GOVERNED BEHAVIOR AND SENSITIVITY TO CHANGING CONSEQUENCES OF RESPONDING
Authors: Hayes Steven C. , Brownstein Aaron J. , Zettle Robert D. , Rosenfarb Irwin , Korn Zamir
Published: March 2006

Humans were presented with a task that required moving a light through a matrix. Button presses could produce light movements according to a multiple fixed‐ratio 18/differential‐reinforcement‐of‐low‐rate 6‐s schedule, with components alternating every 2 min. Moving the light through the maze earned points worth chances on money prizes. In Experiment 1 four conditions were assessed through between‐subject comparisons: minimal instructions, instructions to press rapidly, instructions to press slowly, and instructions that sometimes rapid responding would work while at other times a slow rate would work best. Subjects responded in three successive sessions of 32 min each. The results suggested that instructions affected the nature of the contact made with the programmed consequences and thus subsequent performance. In some cases, responding seemed to result from added contingencies introduced by stating rules. In Experiment 2 the relative contribution of these two effects was assessed by presenting and then withdrawing two lights that had been paired with two specific instructions: “Go Fast” or “Go Slow.” There were three conditions. In one condition, only the Go Fast light was on; in a second, only the Go Slow light was on; and in a third, the lights alternated each minute. In each condition, half the subjects had all instruction lights turned off after the first session. The results once again showed an effect of instructions on contact with the programmed consequences. However, responding sometimes continued in a manner consistent with added contingencies for rule‐following even when the programmed consequences had been contacted and would have controlled a different type of responding in the absence of instructions. The relevance of added contingencies for rule‐following in determining the effects of explicitly programmed consequences is emphasized.
ALLOCATION OF COMPLEX, SEQUENTIAL OPERANTS ON MULTIPLE AND CONCURRENT SCHEDULES OF REINFORCEMENT
Authors: Schwartz Barry
Published: March 2006

Pigeons could produce food by pecking exactly four times on each of two keys, in any order. In the first experiment, these response sequences were reinforced on a series of multiple schedules of variable‐interval reinforcement. In the second experiment, these response sequences were reinforced on a series of concurrent schedules of reinforcement. In both experiments, highly stereotyped response sequences developed. If these response sequences were treated as individual responses, the resulting data conformed to what is typically reported in studies of multiple and concurrent schedules involving individual responses. For example, behavioral contrast was observed with the multiple schedules, and matching was observed with the concurrent schedules. However, schedule manipulation had no effect on within‐sequence characteristics of responses like accuracy, stereotypy, or rate. These data constitute further evidence that response sequences can become functional behavioral units.
CHOICE WITH A FIXED REQUIREMENT FOR FOOD, AND THE GENERALITY OF THE MATCHING RELATION
Authors: Stubbs D. Alan , Dreyfus Leon R. , Fetterman J. Gregor , Dorman Lana G.
Published: March 2006

Pigeons were trained on choice procedures in which responses on each of two keys were reinforced probabilistically, but only after a schedule requirement had been met. Under one arrangement, a fixed‐interval choice procedure was used in which responses were not reinforced until the interval was over; then a response on one key would be reinforced, with the effective key changing irregularly from interval to interval. Under a second, fixed‐ratio choice procedure, responses on either key counted towards completion of the ratio and then, once the ratio had been completed, a response on the probabilistically selected key would produce food. In one experiment, the schedule requirements were varied for both fixed‐interval and fixed‐ratio schedules. In the second experiment, relative reinforcement rate was varied. And in a third experiment, the duration of an intertrial interval separating choices was varied. The results for 11 pigeons across all three experiments indicate that there were often large deviations between relative response rates and relative reinforcement rates. Overall performance measures were characterized by a great deal of variability across conditions. More detailed measures of choice across the schedule requirement were also quite variable across conditions. In spite of this variability, performance was consistent across conditions in its efficiency of producing food. The absence of matching of behavior allocation to reinforcement rate indicates an important difference between the present procedures and other choice procedures; that difference raises questions about the specific conditions that lead to matching as an outcome.
AN EQUATION FOR BEHAVIORAL CONTRAST
Authors: Williams Ben A. , Wixted John T.
Published: March 2006

Pigeons were trained on a three‐component multiple schedule in which the rates of reinforcement in the various components were systematically varied. Response rates were described by an equation that posits that the response‐strengthening effects of reinforcement are inversely related to the context of reinforcement in which it occurs, and that the context is calculated as the weighted average of the various sources of reinforcement in the situation. The quality of fits was comparable to that found with previous quantitative analyses of concurrent schedules, especially for relative response rates, with over 90% of the variance accounted for in every case. As with previous research, reinforcements in the component that was to follow received greater weights in determining the context than did reinforcements in the preceding component.
THE TEMPORAL PATTERN OF UNCONSTRAINED DRINKING: RATS' RESPONSES TO INVERSION AND IDENTITY CONSTRAINTS
Authors: Allison James , Moore Kevin E. , Gawley Don J. , Mondloch Catherine J. , Mondloch Michael V.
Published: March 2006

Rats obtained all of their water by licking a metal tube during a series of daily 1‐hour sessions. When the tube was freely available throughout, each rat showed the classic temporal pattern of unconstrained drinking: As the session progressed, drinking bouts generally grew shorter and pauses grew longer. In subsequent sessions the tube was opened and closed independently of the rat's behavior, on a schedule that gave the rat a chance to duplicate the exact inverse of its unconstrained baseline pattern. Thus, as the inversion session progressed, the opportunities to drink generally grew longer and the enforced pauses grew shorter. When the rats were forced away from their unconstrained patterns of drinking and pausing, their total time spent drinking consistently fell short of previous values, but total licks and volumetric intake remained at previous levels. The same results occurred under an identity schedule, a series of openings and closings that duplicated the unconstrained pattern of drinking and pausing. The results have implications for theories that assume that instrumental performance under schedule constraint derives from the animal's defense of a measured set‐point.
ON THE FALSIFIABILITY OF MATCHING THEORY
Authors: McDowell J. J.
Published: March 2006

Herrnstein's matching theory requires the parameter, k, which appears in the single‐alternative form of the matching equation, to remain invariant with respect to changes in reinforcement parameters like magnitude or immediacy. Recent experiments have disconfirmed matching theory by showing that the invariant‐k requirement does not hold. However, the theory can be asserted in a purely algebraic form that does not require an invariant k and that is not disconfirmed by the recent findings. In addition, both the original and the purely algebraic versions of matching theory can be asserted in forms that allow for commonly observed deviations from matching (bias, undermatching, and overmatching). The recent finding of a variable k does not disconfirm these versions of matching theory either. As a consequence, matching remains a viable theory of behavior, the strength of which lies in its general conceptualization of all behavior as choice, and in its unified mathematical treatment of single‐ and multialternative environments.
COMPARING THE EFFECTS OF TWO CORRECTION PROCEDURES ON HUMAN ACQUISITION OF SEQUENTIAL BEHAVIOR PATTERNS
Authors: Deitz Samuel M. , Fredrick Laura D. , Quinn Patrick C. , Brasher Lynda D.
Published: March 2006

Thirty‐one college undergraduates learned to touch abstract stimuli on a computer screen in arbitrarily designated “correct” sequential orders. Four sets of seven stimuli were used; the stimuli were arrayed horizontally on the screen in random sequences. A correct response (i.e., touching first the stimulus designated as first) resulted in that stimulus appearing near the top of the screen in its correct sequential position (left to right), and remaining there until the end of the trial. Incorrect responses (i.e., touching a stimulus out of sequence) terminated the trial. New trials displayed either the same sequence as the one on which an error had occurred (same‐order correction procedure), or a new random sequence (new‐order correction procedure). Whenever all responses occurred in the correct sequence, the next trial displayed a new random sequence. Each phase ended when five consecutive correct response sequences occurred. Initially, the same‐order correction procedure increased control by the position as well as by the shape of the stimuli; also, it produced more errors, more total trials, more trials to mastery, and more individual patterns of reacquisition than were produced by the new‐order procedure.
THE ECONOMICS OF THE LAW OF EFFECT
Authors: Collier George H. , Johnson Deanne F. , Hill Wendy L. , Kaufman Lynn W.
Published: March 2006

A corollary of the law of effect predicts that the larger the reinforcement, the greater the rate of responding. However, an animal must eat more small portions than large portions to obtain the same daily intake, and one would predict, therefore, that when eating smaller portions an efficient animal would eat less (conserving time and energy) and/or respond faster (conserving time). The latter of these predictions was supported by the present experiments with free‐feeding rats for which portion size (pellet size or duration of feeder presentation) and portion price within meals were varied. Response rate was a function of the unit price (responses/g) of food: Rats responded faster when portions were smaller or when prices were higher. Meal size and frequency were relatively unaffected by unit price, but were influenced by the price of meal initiation. The results are discussed in relation to the economic differences between traditional operant and free‐feeding paradigms and to both traditional and more recent formulations of the law of effect.
COLLEGE STUDENTS' RESPONDING TO AND RATING OF CONTINGENCY RELATIONS: THE ROLE OF TEMPORAL CONTIGUITY
Authors: Wasserman Edward A. , Neunaber Danny J.
Published: March 2006

Two experiments investigated the role of temporal contiguity in college students' responding to and rating of contingency relations during operant conditioning. Schedules were devised that determined when but not whether appetitive or aversive events would occur. Subjects' reports concerning the schedules were obtained by means of a 200‐point rating scale, anchored by the phrases “prevents the light from occurring” (–100) and “causes the light to occur” (+100). When tapping a telegraph key advanced the time of point gain, responding was maintained or increased and subjects gave positive ratings. When tapping a telegraph key advanced the time of point loss, subjects also gave positive ratings, but responding now decreased. When key tapping delayed the time of point gain, responding decreased and subjects gave negative ratings. When key tapping delayed the time of point loss, subjects also gave negative ratings, but responding now increased. These findings implicate response‐outcome contiguity as an important contributor to causal perception and to reinforcement and punishment effects. Other accounts—such as those stressing the local probabilistic relation between response and outcome or the molar correlation between response rate and outcome rate—were seen to be less preferred interpretations of these and other results.
PREFERENCE FOR LESS SEGMENTED FIXED‐TIME COMPONENTS IN CONCURRENT‐CHAIN SCHEDULES OF REINFORCEMENT
Authors: Leung Jin‐Pang , Winton Alan S. W.
Published: March 2006

A concurrent‐chain procedure was used to examine choice between segmented and less segmented response‐independent schedules of reinforcement. A pair of independent, concurrent variable‐interval 60‐s schedules were presented in the initial link, along with a 1.5‐s changeover delay. A chained fixed‐interval fixed‐time and its corresponding tandem schedule constituted the terminal links. The length of the fixed‐interval schedule in the terminal link was varied between 5 s and 30 s while that of the fixed‐time schedule was kept at 5 s over conditions. The first components of both terminal‐link schedules were accompanied by the same stimulus. Except in the baseline condition, the onset of the second component of the terminal‐link chained schedule was accompanied by either a localized (key color) or a nonlocalized (dark houselight) stimulus change. Stimulus conditions were constant during the terminal‐link tandem schedule. With three exceptions, pigeons demonstrated a slight preference for the tandem over the chained schedule in the terminal link. Furthermore, this preference varied inversely with the length of the first component. In general, these results are consistent with previous studies that reported an adverse effect on choice by segmenting an interval schedule into two or more components, but they are inconsistent with studies that reported preference for signaled over unsignaled delay of reinforcement.
BEHAVIORAL CONTRAST IN COMPETITIVE AND NONCOMPETITIVE ENVIRONMENTS
Authors: Dougan James D. , Mcsweeney Frances K. , Farmer‐Dougan Valeri A.
Published: March 2006

Three experiments examined the effects of opportunities for an alternative response (drinking) on positive behavioral contrast of rats' food‐reinforced bar pressing. In both Experiments 1 and 2 the baseline multiple variable‐interval schedules were rich (variable interval 10‐s), and contrast was examined both with and without a water bottle present. In Experiment 1, the rats were not water deprived. When one component of the multiple schedule was changed to extinction, the rate of bar pressing increased in the constant component (positive behavioral contrast). The magnitude of contrast was larger when the bottle was absent than when it was present, as predicted by the matching law. Drinking did not shift from the constant variable‐interval component to the extinction component, as might have been expected from competition theory. In Experiment 2, the rats were water deprived. Contrast was larger when the bottle was present than when it was absent, and drinking did shift to the extinction component, as predicted by competition theory. In Experiment 3, water‐deprived rats responded on leaner multiple variable‐interval schedules (60‐s) in the presence of a water bottle. When one component was changed to extinction, contrast did not occur, and drinking did not shift to the extinction component. The present results suggest that there are at least two different sources of behavioral contrast: “competitive” contrast, observed when an alternative response occurs with high probability, and “noncompetitive” contrast, observed when an alternative response occurs with low probability. The results, in conjunction with earlier studies, also suggest that the form of the alternative response and the rate of food reinforcement provided by the multiple schedule combine to determine the amount of contrast.
EQUIVALENCE CLASS FORMATION IN LANGUAGE‐ABLE AND LANGUAGE‐DISABLED CHILDREN
Authors: Devany Jeanne M. , Hayes Steven C. , Nelson Rosemery O.
Published: March 2006

Stimulus equivalence seems to have relevance to the study of semantics and of language more generally. If so, there may be a relation between language use and the demonstration of stimulus equivalence. This was examined in three groups of children ranging in chronological age and matched on a conventional measure of mental age: normally developing preschoolers, retarded children who used speech or signs spontaneously and appropriately, and retarded children who did not. All children were taught a series of four related discriminations and were then tested to determine if classes of equivalent stimuli had formed. All of the language‐able children (retarded and normal) formed equivalence classes, whereas none of the language‐disabled children did so. Although the exact nature of the relation between stimulus equivalence and language remains to be clarified, these results support the view that stimulus equivalence is a phenomenon with relevance to language.
ESCAPE FROM SERIAL STIMULI LEADING TO FOOD
Authors: Dinsmoor James A. , Lee Diana M. , Brown Marceline M.
Published: March 2006

If the functional relations governing the strength of a conditioned reinforcer correspond to those obtained with other Pavlovian procedures (e.g., Kaplan, 1984), the termination of stimuli appearing early in the interval between successive food deliveries should be reinforcing. During initial training we presented four key colors, followed by food, in a recurrent sequence to each of 6 pigeons. This established a baseline level of autoshaped pecking. In later sessions, we terminated each of these colors or only the first color for a brief period following each peck, replacing the original color with a standard substitute to avoid darkening the key. Pecking decreased in the presence of the last color in the sequence but increased in the presence of the first. In accord with contemporary models of Pavlovian conditioning, these and other data suggest that the behavioral effects of stimuli in a chain may be better understood in terms of what each stimulus predicts, as measured by relative time to the terminal reinforcer, than in the exclusively positive terms of the traditional formulation (Skinner, 1938). The same model may also account for the initial pause under fixed‐interval and fixed‐ratio schedules of reinforcement.
THE EFFECT OF NEGATIVE STIMULUS PRESENTATIONS ON OBSERVING‐RESPONSE RATES
Authors: Mueller Kay L. , Dinsmoor James A.
Published: March 2006

Theories of observing differ in predicting whether or not a signal for absence of reinforcement (S–) is capable of reinforcing observing responses. Experiments in which S– was first removed from and then restored to the procedure have yielded mixed results. The present experiments suggest that failure to control for the direct effect of presenting S– may have been responsible. Pigeons and operant procedures were used. Experiment 1 showed that presentations of S–, even when not contingent on observing, can raise the rate of an observing response that was reinforced only by presentations of a signal (S+) that accompanied a schedule of food delivery. Experiment 2 showed that this effect resulted from bursts of responding that followed offsets of S–. Experiment 3 showed that, when the presence of S– was held constant, lower rates occurred when S– was dependent on, rather than independent of, observing. These results support theories that characterize S– as incapable of reinforcing observing responses.
DELAYED REINFORCEMENT AND DELAYED CHOICE IN SYMBOLIC MATCHING TO SAMPLE: EFFECTS ON STIMULUS DISCRIMINABILITY
Authors: McCarthy Dianne , Davison Michael
Published: March 2006

Six pigeons were trained to peck a red side key when the brighter of two white lights (S1) had been presented on the center key, and to peck a green side key when the dimmer of two white lights (S2) had been presented on the center key. Equal frequencies of reinforcers were provided for the two types of correct choice. Incorrect choices, red side‐key pecks following S2 presentations and green side‐key pecks following S1 presentations, resulted in blackout. With 0‐s delay between choice and reinforcement, the delay between sample presentation and choice was varied from 0 to 20 s. Then, with 0‐s delay between sample presentation and choice, the delay between choice and reinforcement was varied from 0 to 20 s. Both types of delay resulted in decreased discriminability (defined in terms of a signal‐detection analysis) of the center‐key stimuli, but delayed choice had more effect on discriminability than did delayed reinforcement. These data are consistent with the view that the two kinds of delay operate differently. The effect of a sample‐choice delay may result from a degradation of the conditional discriminative stimuli during the delay; the effect of a choice‐reinforcer delay may result from a decrement in control by differential reinforcement.
ON THE MEASUREMENT OF TIME ALLOCATION ON MULTIPLE VARIABLE‐INTERVAL SCHEDULES
Authors: Davison Michael , Charman Lesle
Published: March 2006

Six pigeons were trained on a modified multiple‐schedule procedure. In a three‐key chamber, the center key was lighted red or green, depending upon which component schedule was in effect. A response on this key transferred this color to each of two side keys, and responses on one of those keys produced reinforcers according to the component schedule. After 2 s, the side‐key lights were extinguished, the center key was reilluminated, and a further center‐key response was required to give access, as before, to the component schedules. Components alternated every 3 min. This limited‐access procedure allowed both times spent switched into the side keys and time spent not switched in to be measured in the two components. Component reinforcer rates were varied over eight experimental conditions. Both component response rate and component time allocation were increasing functions of relative component reinforcer rate, and these functions were not significantly different. This finding implies that local response rates (responses divided by time switched in) were unaffected by changing component reinforcer rates on multiple schedules. Because a similar result was recently obtained for concurrent schedules, models of multiple and concurrent‐schedule performance may need to consider only the time allocation of behavior emitted at equal tempo in the component schedules.
A PHARMACOLOGICAL EXAMINATION OF THE RESISTANCE‐TO‐CHANGE HYPOTHESIS OF RESPONSE STRENGTH
Authors: Cohen Steven L.
Published: March 2006

The effects of d‐amphetamine sulfate, sodium pentobarbital, haloperidol, and cholecystokinin‐octapeptide were examined within the context of Nevin's (1974, 1979) resistance‐to‐change hypothesis of response strength. In three experiments, rats' responding was reinforced by delivery of food under chained random‐interval 30‐s random‐interval 30‐s, multiple fixed‐interval 30‐s fixed‐interval 120‐s, or multiple random‐interval 30‐s random‐interval 120‐s schedules. Each rat received several doses of each drug and changes in response rate were measured. The resistance‐to‐change hypothesis predicts greater disruption of response rate relative to baseline in the initial component of the chained schedule and in the 120‐s component of the multiple schedules. In the chained schedule cholecystokinin‐octapeptide produced greater reductions in response rate relative to baseline in the initial component. However, no differences between components were observed with haloperidol or sodium pentobarbital, and high doses of d‐amphetamine reduced response rate in the terminal component relatively more than in the initial component. In the multiple schedules either no differences were observed between components or response rate was reduced more relative to baseline in the 30‐s component. The data fail to support the notion that drugs may be viewed within the same context as other response disruptors such as extinction, satiation, and the presentation of alternative reinforcement.
MONEY VERSUS PAIN: EXPERIMENTAL STUDY OF A CONFLICT IN HUMANS
Authors: Cabanac M.
Published: March 2006

Ten healthy human males volunteered to be subjects in an experiment in which they were to be paid to endure a painful sensation. This sensation was produced by isometric muscular contraction in the thighs. For each of six sessions the subjects received either a payment that was changed for each session (0.2, 0.5, 1.25, 3.125, 7.8125 French francs per 20 s) or a lump sum. At the beginning of a session, the subjects assumed a seated position against a wall, but without a seat, and the duration for which they could hold this position was the chief variable measured. Heart rate, blood pressure, and magnitude estimation of pain were also recorded periodically throughout each session. Pain was reported after a mean delay of 15 ± 7 s (SE), and the magnitude estimates then increased linearly with time. The duration of maintaining the painful position increased linearly in relation to the logarithm of the increase in the amount of payment. Thus, utility of money decreased when pitted against pain.
SIMILARITIES IN THE RATE‐ALTERING EFFECTS OF WHITE NOISE AND COCAINE
Authors: Howell Leonard L. , Byrd Larry D. , Marr M. Jackson
Published: March 2006

The effects of white noise and cocaine on squirrel monkeys' fixed‐interval responding were compared to determine whether the presentation of an exteroceptive stimulus could produce rate‐altering effects of the type typically observed following drug administration. To investigate the relationship between control response rate and response rate in the presence of drug or noise, the monkeys were trained under a fixed‐interval 300‐s stimulus‐shock termination schedule in order to generate a wide range of local response rates. A light illuminated the experimental chamber during the interval and, after 300 s elapsed, a lever press during a 3‐s period terminated the light and precluded the occurrence of a harmless electrical stimulus that otherwise was delivered at the end of the 3‐s period. Each interval was followed by a 30‐s timeout during which the chamber was darkened and responses had no consequences. Following intramuscular administration of cocaine, different rates of responding characteristic of control performance converged toward a common rate and, at an appropriately high dose, response rate during the fixed interval became more uniform. When white noise was presented continuously during a given session, different response rates also converged toward a common rate and, at an appropriate intensity, response rate became more uniform. Interactions were obtained when cocaine and white noise were presented together, indicating the possibility of a common behavioral mechanism of action. The results suggest that rate‐altering drug effects may be, in part, a result of the ability of drugs to produce nonspecific stimulus effects similar to those observed for exteroceptive stimuli.
OBSERVATIONAL LEARNING OF TWO VISUAL DISCRIMINATIONS BY PIGEONS: A WITHIN‐SUBJECTS DESIGN
Authors: Biederman G. B. , Robertson Heather A. , Vanayan Marina
Published: March 2006

Pigeons' observational learning of successive visual discriminations was studied using within‐subject comparisons of data from three experimental conditions. Two pairs of discriminative stimuli were used; each bird was exposed to two of the three experimental conditions, with different pairs of stimuli used in a given bird's two conditions. In one condition, observers were exposed to visual discriminative stimuli only. In a second condition, subjects were exposed to a randomly alternating sequence of two stimuli where the one that would subsequently be used as S+ was paired with the operation of the grain magazine. In a third experimental condition, subjects were exposed to the performance of a conspecific in the operant discrimination procedure. After exposures to conspecific performances, there was facilitation of discriminative learning, relative to that which followed exposures to stimulus and reinforcement sequences or exposures to stimulus sequences alone. Exposure to stimulus and food‐delivery sequences enhanced performance relative to exposure to stimulus sequences alone. The differential effects of these three types of exposure were not attributable to order effects or to task difficulty; rather, they clearly were due to the type of exposure.
RESISTANCE TO CHANGE PRODUCED BY ACCESS TO FIXED‐DELAY VERSUS VARIABLE‐DELAY TERMINAL LINKS
Authors: Mellon Robert C. , Shull Richard L.
Published: March 2006

Pigeons' responding was reinforced on a multiple schedule consisting of two two‐link chain schedules presented in regular alternation. Responding in initial links (always variable‐interval 60‐s) produced a key‐color change and access to a terminal link. The terminal link for one chain provided food after a fixed delay (fixed‐interval or fixed‐time); the terminal link for the other provided food after a variable delay (variable‐interval or variable‐time). The average duration of the terminal‐link schedules was varied across conditions, but in every condition the arithmetic mean of the variable‐delay terminal‐link schedule was equal to the duration of the fixed delay. Response rates were higher in the initial links of the chains with the variable‐delay terminal links. Response‐decreasing operations (satiation, extinction) were used after performances reached asymptote. Response rates maintained by access to variable‐delay terminal links tended to be more resistant to change than were rates maintained by access to fixed‐delay terminal links. These results are consistent with the preference for variable‐ over fixed‐interval terminal links observed with concurrent‐chains schedules, suggesting (1) that immediacy of reinforcement influences the conditioned reinforcing potency of access to a terminal link and (2) that choice in concurrent chains and resistance of responding to change may be manifestations of the same effect of reinforcement.
CHOICE, FORAGING, AND REINFORCER DURATION
Authors: Ito Masato , Fantino Edmund
Published: March 2006

Pigeons were exposed to a foraging schedule characterized by three different states, beginning with a search state in which completion of a variable interval on a white key led to a choice state. In the choice state the subject could, by appropriate responding on a fixed ratio of three, either accept or reject the schedule offered. If the subject accepted the schedule, it entered a handling state in which the appropriate reinforcer amount was presented according to a variable‐interval schedule. In Experiment 1 the shorter duration reinforcer was more likely to be accepted the longer the duration of the search state and the shorter the equal durations of the handling states. In Experiment 2 the shorter duration reinforcer was more likely to be accepted the longer the handling time preceding the longer duration reinforcer. All of the results were in qualitative—and some were in quantitative—agreement with those predicted by the delay‐reduction hypothesis and the optimal‐diet model.
COMPETITIVE FIXED‐INTERVAL PERFORMANCE IN HUMANS
Authors: Buskist William , Morgan David
Published: March 2006

Two persons responded in the same session in separate cubicles, but under a single schedule of reinforcement. Each time reinforcement was programmed, only the first response to occur, that is, the response of only one of the subjects, was reinforced. “Competitive” behavior that developed under these conditions was examined in three experiments. In Experiment 1 subjects responded under fixed‐interval (FI) 30‐s, 60‐s, and 90‐s schedules of reinforcement. Under the competition condition, relative to baseline conditions, the response rates were higher and the pattern was “break‐and‐run.” In Experiment 2, subjects were exposed first to a conventional FI schedule and then to an FI competition schedule. Next, they were trained to respond under either a differential‐reinforcement‐of‐low‐rate (DRL) or fixed‐ratio (FR) schedule, and finally, the initial FI competition condition was reinstated. In this second exposure to the FI competition procedure, DRL subjects responded at lower rates than were emitted during the initial exposure to that condition and FR subjects responded at higher rates. For all subjects, however, responding gradually returned to the break‐and‐run pattern that had occurred during the first FI competition condition. Experiment 3 assessed potential variables contributing to the effects of the competitive FI contingencies during Experiments 1 and 2. Subjects were exposed to FI schedules where (a) probability of reinforcement at completion of each fixed interval was varied, or (b) a limited hold was in effect for reinforcement. Only under the limited hold was responding similar to that observed in previous experiments.
STIMULUS CLASS MEMBERSHIP ESTABLISHED VIA STIMULUS—REINFORCER RELATIONS
Authors: Dube William V. , McIlvane William J. , Mackay Harry A. , Stoddard Lawrence T.
Published: March 2006

In an arbitrary matching‐to‐sample procedure, two mentally retarded subjects learned conditional discriminations with two sets of stimuli. Each set included a spoken name (N1 or N2), an object (O1 or O2), and a printed symbol (S1 or S2). One subject selected conditionally (a) O1 upon N1, and O2 upon N2, and (b) S1 upon O1, and S2 upon O2. The other subject selected conditionally (a) S1 upon N1, and S2 upon N2, and (b) O1 upon S1, and O2 upon S2. For both subjects, selections of O1 and S1 produced one type of food, F1; selections of O2 and S2 produced a different type of food, F2. Both subjects also learned identity‐matching performances, selecting O1, O2, S1, S2, F1, and F2 conditionally upon those stimuli as samples; F1 followed selections of O1, S1, and F1; F2 followed selections of O2, S2, and F2. Matching performances consistent with stimulus class formation involving the names, objects, symbols, and foods were demonstrated on probe trials, even though these performances had not been taught explicitly. Next, new objects, X1 and X2, were presented on identity‐matching trials, producing F1 and F2, respectively. Without further training, X1 was selected conditionally upon N1, S1, and O1, and X2 was selected upon N2, S2, and O2. When the contingencies were changed so that selections of X1 and X2 were now followed by F2 and F1, respectively, X2 was selected conditionally upon N1, S1, and O1, and X1 was selected upon N2, S2, and O2. Class membership of X1 and X2 had apparently changed. This study provides evidence that reinforcers may become members of stimulus classes, and that new stimuli may become class members through relations with reinforcers.
CONSUMPTION‐LEISURE TRADEOFFS IN PIGEONS: EFFECTS OF CHANGING MARGINAL WAGE RATES BY VARYING AMOUNT OF REINFORCEMENT
Authors: Green Leonard , Kagel John H. , Battalio Raymond C.
Published: March 2006

Pigeons' rates of responding and food reinforcement under simple random‐ratio schedules were compared with those obtained under comparable ratio schedules in which free food deliveries were added, but the duration of each food delivery was halved. These ratio‐with‐free‐food schedules were constructed so that, were the pigeon to maintain the same rate of responding as it had under the simple ratio schedule, total food obtained (earned plus free) would remain unchanged. However, any reduction in responding would reduce total food consumption below that under the simple ratio schedule. These “compensated wage decreases” led to decreases in responding and decreases in food consumption, as predicted by an economic model of labor supply. Moreover, the reductions in responding increased as the ratio value increased (i.e., as wage rates decreased). Pigeons, therefore, substituted leisure for consumption. The relationship between these procedures and negative‐income‐tax programs is noted.