bluuebunny/crossref_metadata_2025 huggingface dataset:
FREE‐OPERANT FORGETTING: DELAYED STIMULUS CONTROL OF MULTIPLE‐SCHEDULE PERFORMANCE
Authors: White K. Geoffrey , Redman Selina
Published: March 2006

Pigeons' responses were reinforced in two components of several multiple variable‐interval variable‐interval schedules of food reinforcement. In one component, the key was illuminated green for 15 seconds and white for 45 seconds. In the other component, the key was illuminated red for 15 seconds and white for 45 seconds. Values for the exponent of the power functions relating response ratios to reinforcement ratios were higher in the presence of the discriminative stimuli (green or red) than in the presence of white. Sensitivity of response ratios to changes in reinforcement ratios provided an index of the extent to which responding was under delayed stimulus control by prior discriminative stimuli.
DYNAMIC EFFECTS OF FOOD MAGNITUDE ON INTERIM‐TERMINAL INTERACTION
Authors: Reid Alliston K. , Dale Robert H. I.
Published: March 2006

We tested the assumption of a facilitatory relation between periodic food presentation and schedule‐induced drinking by examination of (a) elicited drinking, (b) drinking in anticipation of food delivery, and (c) possible indirect effects of food delivery on drinking. We exposed rats to a fixed‐time 60‐second schedule in which interfood intervals ended in either one or four food pellets with equal probability. In Phases 1 and 3, a stimulus signaled the magnitude of upcoming food presentation. In Phase 2, the stimulus was eliminated. Changes in drinking and “head‐in‐feeder” distributions within interfood intervals demonstrated that head‐in‐feeder was controlled directly by food presentation, but drinking was not. Head‐in‐feeder increased and drinking was reduced when large meals began or ended an interval. In Phases 4 to 6, meal size was manipulated across sessions yielding a positive relation between meal size and schedule‐induced drinking. We conclude: (1) Schedule‐induced drinking is determined by distributions of food‐related behavior and results from indirect effects of food delivery; and (2) the amount of schedule‐induced drinking and the form of the drinking distributions in this experiment can be accurately explained by two assumptions: (a) Food presentation facilitates food‐related behavior through elicitation and anticipation; and (b) food‐related behavior and drinking are reciprocally, linearly related.
POSITIVE BEHAVIORAL CONTRAST WHEN PIGEONS PRESS TREADLES DURING MULTIPLE SCHEDULES
Authors: McSweeney Frances K.
Published: March 2006

Pigeons were placed on multiple variable‐interval 15‐second variable‐interval 15‐second and on multiple variable‐interval 15‐second extinction schedules in which treadle presses produced food reinforcers. Positive behavioral contrast occurred. That is, rates of responding were higher during the variable‐interval 15‐second component when the other component was extinction than when it was another variable‐interval 15‐second schedule. These results contradict the findings of other studies, which failed to find positive contrast when pigeons pressed treadles for food reinforcers. They may also question the additive theories of behavioral contrast that predict that contrast should not occur in this situation.
THE ROLE OF VERBAL BEHAVIOR IN HUMAN LEARNING: INFANT PERFORMANCE ON FIXED‐INTERVAL SCHEDULES
Authors: Lowe C. Fergus , Beasty A. , Bentall R. P.
Published: March 2006

The performances of two infants less than one year old were investigated on fixed‐interval schedules. When the infants touched a cylinder either music or food was presented according to fixed‐interval schedules ranging in value from 10 to 50 seconds. With respect to two principal criteria, namely, pattern of responding and sensitivity to the schedule parameter, the subjects' behavior closely resembled that of animals but differed markedly from that of older children and adults. Negatively accelerated responding in the course of the fixed interval in the early sessions gave way to a scalloped pattern, consisting of a pause after reinforcement followed by an accelerated response rate. This scalloped pattern was the final form of responding on all schedule values. Analysis of data after performance had stabilized showed that postreinforcement pause was a negatively accelerated increasing function, and running rate (calculated after excluding the postreinforcement pause) was a declining function, of schedule value. On each schedule, the durations of mean successive interresponse times declined in the course of the fixed interval and were directly related to schedule value. The results supported Lowe's (1979) suggestion that verbal behavior may be responsible for major differences in the schedule performance of older humans and animals.
DIGITAL FILTERS IN BEHAVIORAL RESEARCH
Authors: Tryon Warren W.
Published: March 2006

Behavioral control is almost always less than perfect. Rate of response is rarely as constant as it could be even when the greatest care is given to experimental procedures. Experimenters should always attempt to identify the causes of variation. Some fluctuations in response rate will be random, i.e., sometimes positive and sometimes negative, usually small but occasionally large. Digital filters are objective methods for reducing or eliminating such unsystematic “noise” components while preserving the systematic changes in response rate under study. Digital filters function in a manner that is strictly analogous to electronic filters. The major purpose of this technical note is to describe digital filters and to provide an example of their usage.
REINFORCEMENT OF INHIBITION
Authors: Anger Douglas
Published: March 2006

A differential‐reinforcement‐of‐other‐behavior (DRO) schedule with trials and delayed reinforcement was investigated. Periodically a wheel was briefly available to rats, followed six seconds later by brief availability of a bar. Variable‐ratio food reinforcement of wheel turns was adjusted to give 95% turns. After variable‐ratio‐five reinforcement of bar presses produced 100% pressing, then separate ratio schedules were used for presses following turns (turn presses) and presses following nonturns (nonturn presses). Increasing nonturn‐press reinforcements decreased turns, even though total reinforcements increased. Reversal by decreasing nonturn‐press reinforcements raised turns, though with hysteresis. Thus food reinforcement increased nonturns even though delayed six to ten seconds after nonturns, a delay that greatly reduces response reinforcement. Those and other results indicate that the turn decrease was not due to reinforcement of competing responses. Evidence against other alternatives, and the reduction of responding by increased reinforcement, indicate that the term inhibition is appropriate for the phenomenon reinforced. Response‐specific inhibition appears appropriate for this particular kind, since its effects are more specific to particular responses than Pavlovian conditioned‐inhibition. Response‐specific inhibition seems best considered a behavioral output comparable to responses (e.g., both reinforcible) but with important properties different from responses (e.g., different reinforcement‐delay gradients).
CONDITIONAL DISCRIMINATION WITH AMBIGUOUS STIMULI
Authors: Meltzer Donald
Published: March 2006

Five pigeons learned a two‐key conditional discrimination. When background color on both keys was red, pecks on the key with a horizontal line produced food. When the color was green, pecks on the key with a vertical line produced food. During part of the experiment, color was presented on only one of the keys. It was found that accuracy was higher when color was combined with the line stimulus correlated with nonreinforcement. In another part of the experiment, color was presented on both keys but a line was present only on one. Accuracy was higher when the line accompanied the nonreinforced option than when the line accompanied the reinforced option. Superior performance when the combined stimuli were displayed on the nonfood key may be explained by the association of different components of the compound stimuli with reinforcement or as the result of rules pigeons follow in solving conditional discriminations.
RESPONSE RATE, LATENCY, AND RESISTANCE TO CHANGE
Authors: Fath Stephen J. , Fields Lanny , Malott M. Kay , Grossett Deborah
Published: March 2006

Pigeons were trained on a multiple variable‐interval/variable‐interval schedule with pacing contingencies that generated high response rates in one component and low response rates in the other. Timeout periods separated the schedule components. During resistance‐to‐change tests, response‐independent food was presented during the timeout periods, and the duration of that food presentation was varied among test sessions. Response rates in the schedule components decreased and latencies to the first response increased as a function of the duration of food presentations during the timeout. Both dependent measures changed about the same amount relative to their own baseline levels. The conclusions are that baseline response rates controlled by pacing contingencies are equally resistant to change, given equal reinforcement densities, and latency is a sensitive measure of resistance to change.
LOCAL CONTRAST IN MULTIPLE SCHEDULES: THE EFFECT OF STIMULUS DISCRIMINABILITY
Authors: Blough Patricia M.
Published: March 2006

A three‐ply multiple schedule assessed responding in a standard component as a function of the just‐preceding schedule. The principal experimental condition was the difference among the wavelengths signaling the schedule components. Only the pigeons working in a narrow wavelength range showed persistent positive local contrast; that is, response rate during the standard component was higher when that component followed extinction than when it followed itself. Birds in both narrow‐ and medium‐range groups showed persistent negative local contrast; that is, rate was lower following a relatively rich component. The dissipation of positive contrast appeared to be most clearly related to the establishment of differential responding. Negative contrast was inversely related to wavelength differences. Theories pertaining to contrast must account for the role of discrimination in both positive and negative types.
DELAY AND AMOUNT OF REWARD IN A CONCURRENT CHAIN
Authors: Snyderman Mark
Published: March 2006

Eight pigeons responded under a concurrent‐chain schedule for rewards differing in both delay and amount, the larger reward being associated with the longer delay. Preference was examined as the absolute durations of the terminal‐link delays were increased at four different delay ratios. Difficulties with other experiments of this type were controlled for by the use of (a) a single‐tape initial link to equalize terminal‐link entries, (b) a blackout following the more immediate reward to equalize terminal‐link length, and (c) a photocell to measure reinforcer duration more accurately. Preference for the larger reward changed systematically as delays increased in all conditions, decreasing for the 6:1, 3:1, and 3:2 ratios, and increasing for the 1:1 ratio. These results were similar to, but significantly different from, those of previous investigations. The implications of these results for various models of concurrent‐chain behavior are discussed.
TEMPORAL CONTROL IN A COMPLEX ENVIRONMENT: AN ANALYSIS OF SCHEDULE‐RELATED BEHAVIOR
Authors: McIntire Kenneth , Lundervold Duane , Calmes Helen , Jones Connie , Allard Susan
Published: March 2006

Three experiments conducted in an automated ten‐compartment chamber recorded collateral activities of rats reinforced for lever pressing on differential‐reinforcement‐of‐low‐rate schedules. In Experiment 1, the rate of lever pressing increased when stimulus support for collateral activities was removed, thus confirming earlier findings. However, there were no temporal or sequential patterns of collateral activities that predicted operant responding. In Experiment 2, the rate of lever pressing increased only if (a) access to all stimulus support for collateral activities was simultaneously prevented, and (b) the rat was forced to remain in the presence of the lever and food tray. The availability of any of the stimuli related to collateral activity was sufficient to keep lever‐pressing rates from increasing. Experiment 3 examined collateral activities under a signaled differential‐reinforcement‐of‐low‐rate schedule. Preventing access to stimuli supporting collateral activities had little effect on stable lever pressing when the signal was maintained. When the signal was removed, collateral activities continued, but lever‐pressing rates increased in three of the four rats and rates of food presentation declined in all rats. Hypotheses that collateral activities have (a) a timekeeping or discriminative function, or (b) directly inhibit operant responding were not supported. The results suggest that collateral activities may facilitate operant responding by simply removing the subject from the presence of reinforcement‐related stimuli.
THE ANALYSIS OF BEHAVIORAL MOMENTUM
Authors: Nevin John A. , Mandell Charlotte , Atak Jean R.
Published: March 2006

Learned behavior varies in its resistance to change, depending on the rate of reinforcement. Resistance to change may be characterized as behavioral momentum, which in turn may be analyzed into terms corresponding to mass and velocity in classical physics. Behavioral mass may be inferred from changes in response rate when experimental conditions are altered. Relevant data were obtained by training pigeons to peck a key on two‐component multiple variable‐interval, variable‐interval schedules. Six pigeons were studied on three pairs of variable‐interval schedules in all possible orders. When performance stabilized, resistance to change was assessed by arranging response‐independent food during periods between components and by extinction. For each operation, the data for all schedule performances converged onto a single function, permitting estimation of the ratio of behavioral masses for each pair of schedules. The response‐independent food data suggested that the ratio of behavioral masses is a power function of the ratio of reinforcement rates and that behavioral mass may be measured on a ratio scale.
THE LOCAL ORGANIZATION OF BEHAVIOR: DISSOCIATIONS BETWEEN A PIGEON'S BEHAVIOR AND SELF‐REPORTS OF THAT BEHAVIOR
Authors: Shimp Charles P.
Published: March 2006

The purpose of the experiment was to study the relation between what an organism does in a setting that demands temporal patterning of behavior and what it reports it has done. More specifically, a pigeon produced two classes, shorter and longer, of temporal patterns of key pecks (interresponse times) on a center key. Occasionally, a symbolic matching‐to‐sample probe arranged on side keys asked the pigeon whether its most recent pattern was a shorter or longer one. The longer reinforced pattern was always three times as long as the shorter one and the two patterns were reinforced equally often. Absolute duration of reinforced patterns was varied. In some conditions, interresponse‐time distributions on the center key were bimodal, indicating a clear behavioral adaptation to the contingency, yet a bird did not report very well by appropriate side‐key responding what its most recent interresponse time had been. In other conditions, the interresponse‐time distributions were less clearly bimodal, yet a bird reported more accurately its previous interresponse time as shorter or longer. Thus, there was a dissociation between how well behavior on the center key conformed to the schedule requirement and how well a bird reported what it was doing on the center key. In addition, as absolute duration of the reinforced patterns was increased, a bird categorized its most recent pattern less well even as its preference for the shorter pattern increased dramatically. These results were interpreted as an example of the phenomenon of dissociation between tacit knowledge and knowledge.
PIGEONS' SPATIAL MEMORY: II. ACQUISITION OF DELAYED MATCHING OF KEY LOCATION AND TRANSFER TO NEW LOCATIONS
Authors: Wilkie Donald M.
Published: March 2006

Five hungry pigeons first received delayed matching of key location training. Trials began with a “ready” stimulus (brief operation of the grain feeder). Then one (randomly chosen) of a set of four keys from a three‐by‐three matrix was lit briefly as the sample. After a short delay (retention interval), the sample key was lit again along with one of the other eight keys. A peck at the key that had served as the sample produced grain reinforcement, whereas a peck to the other key produced only the intertrial interval. After delayed matching of key location was learned, the remaining five key locations were introduced as samples. Four of the five birds performed at considerably above‐chance levels on the novel sample trials during the first as well as subsequent sessions. These results suggest that pigeons sometimes learn the single rule—“choose the location that matches the sample.” The relevance of these results to the issue of whether pigeons learn a generalized matching rule (i.e., a concept of “sameness”) is discussed.
ANALYSIS OF DISCRIMINATIVE CONTROL BY SOCIAL BEHAVIORAL STIMULI
Authors: Hake Don F. , Donaldson Tom , Hyten Cloyd
Published: March 2006

Visual discriminative control of the behavior of one rat by the behavior of another was studied in a two‐compartment chamber. Each rat's compartment had a food cup and two response keys arranged vertically next to the clear partition that separated the two rats. Illumination of the leader's key lights signaled a “search” period when a response by the leader on the unsignaled and randomly selected correct key for that trial illuminated the follower's keys. Then, a response by the follower on the corresponding key was reinforced, or a response on the incorrect key terminated the trial without reinforcement. Accuracy of following the leader increased to 85% within 15 sessions. Blocking the view of the leader reduced accuracy but not to chance levels. Apparent control by visual behavioral stimuli was also affected by auditory stimuli and a correction procedure. When white noise eliminated auditory cues, social learning was not acquired as fast nor as completely. A reductionistic position holds that behavioral stimuli are the same as nonsocial stimuli; however, that does not mean that they do not require any separate treatment. Behavioral stimuli are usually more variable than nonsocial stimuli, and further study is required to disentangle behavioral and nonsocial contributions to the stimulus control of social interactions.
SAMPLE‐SPECIFIC RATIO EFFECTS IN MATCHING TO SAMPLE
Authors: Paul Coleman
Published: March 2006

In a symbolic matching‐to‐sample task, pigeons were trained using sample‐specific, fixed‐ratio “observing responses.” Subsequently, in a mixed condition, each sample was presented equally often with each ratio requirement, i.e., the ratios were no longer correlated with the samples. In a second experiment, pigeons were trained initially in the mixed condition and subsequently shifted to the sample‐specific condition in which the required ratios were correlated with the samples. Results of both experiments suggested joint control of choices by ratio value and by the exteroceptive stimuli. The discriminative properties of the ratios appeared to outweigh absolute ratio‐size effects.
CHOICE: SOME QUANTITATIVE RELATIONS
Authors: Fantino Edmund , Davison Michael
Published: March 2006

Six pigeons responded in fifty‐six conditions on a concurrent‐chains procedure. Conditions included several with equal initial links and unequal terminal links, several with unequal initial links and equal terminal links, and several with both unequal initial and terminal links. Although the delay‐reduction hypothesis accounted well for choice when the initial links were equal (mean deviation of .04), it fit the data poorly when the initial links were unequal (mean deviation of .18). A modification of the delay‐reduction hypothesis, replacing the rates of reinforcement with the square roots of these rates, fit the data better than either the unmodified delay‐reduction equation or Killeen's (1982) model. The modified delay‐reduction equation was also consistent with data from prior studies using concurrent chains. The absolute rates of responding in each terminal link were well described by the same hyperbola (Herrnstein, 1970) that describes response rates on simple interval schedules.
CONTROL RATE OF RESPONSE OR REINFORCEMENT AND AMPHETAMINE'S EFFECT ON BEHAVIOR
Authors: Lucki Irwin , DeLong Robert E.
Published: March 2006

The roles of control response rate and reinforcement frequency in producing amphetamine's effect on operant behavior were evaluated independently in rats. Two multiple schedules were arranged in which one variable, either response rate or reinforcement frequency, was held constant and the other variable manipulated. A multiple differential‐reinforcement‐of‐low‐rate seven‐second yoked variable‐interval schedule was used to equate reinforcement frequencies at different control response rates between multiple‐schedule components. Amphetamine increased responding under the differential‐reinforcement‐of‐low‐rate component but decreased responding under the variable‐interval component. In contrast, amphetamine decreased responding equivalently between components of a multiple random‐ratio schedule that produced similar control response rates at different reinforcement frequencies. The results provide experimental support to the rate‐dependency principle that control rate of responding is an important determinant of amphetamine's effect on operant behavior.
HUMAN OBSERVING: MAINTAINED BY STIMULI CORRELATED WITH REINFORCEMENT BUT NOT EXTINCTION
Authors: Fantino Edmund , Case David A.
Published: March 2006

College students received points exchangeable for money (reinforcement) on a variable‐time 60‐second schedule that alternated randomly with an extinction component. Subjects were informed that responding would not influence either the rate or distribution of reinforcement. Instead, presses on either of two levers (“observing responses”) produced stimuli. In each of four experiments, stimuli positively correlated with reinforcement and/or stimuli uncorrelated with reinforcement were each chosen over stimuli correlated with extinction. These results are consistent with prior results from pigeons in supporting the conditioned‐reinforcement hypothesis of observing and in not supporting the uncertainty‐reduction hypothesis.
MATCHING AND MAXIMIZING WITH CONCURRENT RATIO‐INTERVAL SCHEDULES
Authors: Green Leonard , Rachlin Howard , Hanson John
Published: March 2006

Animals exposed to standard concurrent variable‐ratio variable‐interval schedules could maximize overall reinforcement rate if, in responding, they showed a strong response bias toward the variable‐ratio schedule. Tests with the standard schedules have failed to find such a bias and have been widely cited as evidence against maximization as an explanation of animal choice behavior. However, those experiments were confounded in that the value of leisure (behavior other than the instrumental response) partially offsets the value of reinforcement. The present experiment provides another such test using a concurrent procedure in which the confounding effects of leisure were mostly eliminated while the critical aspects of the concurrent variable‐ratio variable‐interval contingency were maintained: Responding in one component advanced only its ratio schedule while responding in the other component advanced both ratio schedules. The bias toward the latter component predicted by maximization theory was found.
ON THE EFFECTS OF FOOD DEPRIVATION AND COMPONENT REINFORCER RATES ON MULTIPLE‐SCHEDULE PERFORMANCE
Authors: Charman Lesle , Davison Michael
Published: March 2006

Six pigeons were used to investigate the effects of varying body weight and component reinforcer rates in two‐component multiple variable‐interval variable‐interval schedules. In Parts 1 and 3 of the experiment, unequal component reinforcer rates were arranged, and body weights were respectively increased and decreased. At 80% ad lib weight, response‐rate ratios were closer to unity than reinforcer‐rate ratios, but at 100% or more of ad lib weight, response‐rate ratios generally equaled reinforcer‐rate ratios. In Part 2, component reinforcer‐rate ratios were varied over five conditions with the subjects maintained at 100% or more of their ad lib weights, and response‐rate ratios matched reinforcer‐rate ratios. The data thus support the empirical finding that response allocation in multiple schedules is a function of deprivation. Although this qualitative result is predicted by three models of multiple‐schedule performance, only a model that assumes no direct component interaction adequately describes the data.
REACTION TIMES OF YOUNGER AND OLDER MEN AND TEMPORAL CONTINGENCIES OF REINFORCEMENT
Authors: Baron Alan , Menich Stephen R. , Perone Michael
Published: March 2006

Influences of extended training and temporal contingencies on reaction time were studied in relation to developmental differences. Older and younger men were trained on a chained schedule in which completion of a variable interval produced a terminal link in which reaction time was measured. The reaction‐time procedure involved a conditional discrimination with matching to sample in one component and oddity matching in the other. During baseline training, no time limit was placed on the response to the discrimination choice stimuli. Subsequently, increasingly severe time limits were imposed over a series of sessions. Older and younger men showed increased speeds (decreased reaction times) when temporal contingencies were imposed, and these changes were maintained during post‐training baseline sessions when there was unlimited time in which to respond. The younger men generally responded faster than the older ones, and age differences were not appreciably reduced during the course of the experiment. The results indicated the feasibility of studying reaction time in human subjects using operant procedures analogous to those developed for the study of nonverbal organisms.
FORMATION OF THE SAMENESS‐DIFFERENCE CONCEPT BY JAPANESE MONKEYS FROM A SMALL NUMBER OF COLOR STIMULI
Authors: Fujita Kazuo
Published: March 2006

Japanese monkeys were trained to form the sameness‐difference concept. In Experiment 1, four monkeys were trained with two colors to discriminate matching stimulus pairs from nonmatching pairs by reinforcing only lever‐pressing responses to matching pairs with a variable‐interval schedule. Three monkeys showed successful transfer of this discrimination to two new colors, thus demonstrating that some Japanese monkeys are able to form this relational concept from a minimum number of stimuli. In Experiment 2, two monkeys were trained, in a Yes/No procedure with three colors, to press one lever under matching pairs and another lever under nonmatching pairs. Poor transfer performances to three new colors suggest that simultaneously establishing two different response patterns to matching and nonmatching pairs is ineffective in forming the concept. In Experiment 3, the amount of transfer to three new colors after mastering a standard three‐color matching‐to‐sample task was compared with that of a modified task in which correct responses were reinforced with a within‐trial variable‐interval schedule. All three monkeys showed greater transfer with the modified procedure. The results suggest that the variable‐interval schedule adopted within trials is effective in forming the sameness‐difference concept.
THE STATE OF THE ART AND THE FATE OF THE EARTH
Authors: Mook Douglas G.
Published: March 2006

A recent review by Nevin of Jonathan Schell's The Fate of the Earth applies a “behavioral perspective” to the problem of species survival in a nuclear age. It is suggested that no perspective, in this context as in others where less is at stake, should dismiss prematurely some useful ideas from other perspectives. A sampling of “cognitive” concepts is offered to illustrate what actions, aimed at resisting species extinction, might follow from them—not instead of, but in addition to, the guidelines for action a behavioral perspective provides.
CONCURRENT SCHEDULES: SPATIAL SEPARATION OF RESPONSE ALTERNATIVES
Authors: Boelens Harrie , Kop Pieter F. M.
Published: March 2006

Four pigeons were exposed to independent concurrent variable‐interval 20‐second variable‐interval 60‐second schedules of reinforcement. A transparent partition was inserted midway between the two response keys. The length of the partition was systematically manipulated. Increasing partition length produced a decrease in changeover rate in Experiment 1. Overmatching was observed with a partition length of 20 centimeters. In Experiment 2 a four‐second limited hold was added to the schedules. Increasing partition length produced a decrease in changeover rate that exceeded the decrease observed in Experiment 1. This manipulation produced nearly exclusive choice of the variable‐interval 20‐second component. The present results, together with results obtained in related research, suggest that deviation from matching is a function of procedural variables that determine the consequences of a changeover response.
AUTOSHAPING IN THE RAT: THE EFFECTS OF LOCALIZABLE VISUAL AND AUDITORY SIGNALS FOR FOOD
Authors: Cleland Gary G. , Davey Graham C. L.
Published: March 2006

Two experiments investigated autoshaping in rats to localizable visual and auditory conditioned stimuli predicting response‐independent food. In Experiment 1 considerable conditioned‐stimulus approach behavior was generated by a localizable visual conditioned stimulus that was situated approximately 35 cm from the food tray. Using the same apparatus in Experiment 2 we found that the conditioned‐stimulus approach was generated only to a visual conditioned stimulus and not to a localizable auditory conditioned stimulus even though subjects (1) could discriminate presentations of the auditory conditioned stimulus, (2) had associated it with food, (3) could localize it, and (4) would approach the auditory stimulus if this behavior constituted an instrumental response to food. The predominant conditioned responses to the auditory stimuli were goal tracking (entering the food tray) and orienting towards the food‐paired conditioned stimulus by head turning and rearing and turning. These results imply that rats do not invariably approach a localizable appetitive Pavlovian conditioned stimulus but that stimulus‐approach responses depend on the nature and modality of the conditioned stimulus.
THE DEVELOPMENT OF DERIVED STIMULUS RELATIONS THROUGH TRAINING IN ARBITRARY‐MATCHING SEQUENCES
Authors: Wetherby Bruce , Karlan George R. , Spradlin Joseph E.
Published: March 2006

Five‐year‐old children were taught three‐stage sequences of arbitrary matching: A‐C, B‐C, A‐D; A‐C, B‐D, B‐C; or A‐C, A‐D, B‐C. Each stage refers to a sample‐comparison relation between stimuli. Unreinforced test probes revealed untrained arbitrary matches (B‐D, A‐D, and B‐D, respectively), derivable by substitution of stimuli with a common sample or comparison function. Additional probes revealed further untrained sample‐comparison relations derivable by substitution and identity, including the commuted relations D‐B, D‐A, and D‐B, respectively. These processes may have relevance to conceptual and verbal behavior.
CHOICE, EXPERIENCE, AND THE GENERALIZED MATCHING LAW
Authors: Todorov João Claudio , Castro Jorge Mendes de Oliveira , Hanna Elenice Seixas , Sa Maria Cristina Neves Bittencourt de , Barreto Marcio de Queiroz
Published: March 2006

Five pigeons were exposed to different pairs of concurrent variable‐interval, variable‐interval schedules on nine experimental conditions of 30 sessions each. For every session, the parameters of the generalized matching equation were computed for the first five, six, seven, eight, and nine experimental conditions. The exponent a, both for response and time distribution, tended to decrease with increases in number of experimental conditions and to increase with number of sessions per condition, but values of k (bias) varied unsystematically. When the subjects were exposed to five new pairs of schedules, with 55 sessions per condition, the findings were confirmed. Data from the literature on the generalized matching law suggest that the variability of exponent values may be explained in part by the use of naive or experienced subjects in different investigations and by the variability in number of experimental conditions and in number of sessions per condition.
ARE THEORIES OF PERCEPTION NECESSARY? A REVIEW OF GIBSON'S THE ECOLOGICAL APPROACH TO VISUAL PERCEPTION
Authors: Costall A. P.
Published: March 2006

Representational theories of perception postulate an isolated and automonous “subject” set apart from its real environment, and then go on to invoke processes of mental representation, construction, or hypothesizing to explain how perception can nevertheless take place. Although James Gibson's most conspicuous contribution has been to challenge representational theory, his ultimate concern was the cognitivism which now prevails in psychology. He was convinced that the so‐called cognitive revolution merely perpetuates, and even promotes, many of psychology's oldest mistakes. This review article considers Gibson's final statement of his “ecological” alternative to cognitivism (Gibson, 1979). It is intended not as a complete account of Gibson's alternative, however, but primarily as an appreciation of his critical contribution. Gibson's sustained attempt to counter representational theory served not only to reveal the variety of arguments used in support of this theory, but also to expose the questionable metaphysical assumptions upon which they rest. In concentrating upon Gibson's criticisms of representational theory, therefore, this paper aims to emphasize the point of his alternative scheme and to explain some of the important concerns shared by Gibson's ecological approach and operant psychology.
A TEMPORAL LIMIT ON THE EFFECT OF FUTURE FOOD ON CURRENT PERFORMANCE IN AN ANALOGUE OF FORAGING AND WELFARE
Authors: Timberlake William
Published: March 2006

Rats obtained access to food twice each 24‐hour period. The first session was a work session in which food was available on a progressive‐ratio schedule. During the second session, which occurred between 1 and 23 hours after the work session, food was freely available up to a fixed total intake each 24 hours. The situation resembled elements of several real world circumstances, including the choice between continuing to forage in a rapidly depleting patch and waiting for a better patch, and between working now and receiving a guaranteed income later. The purpose of the experiment was to explore the time period over which future access to reward could affect current responding. Contrary to what might be expected from recent theorizing, anticipation of future food delayed by an hour or more after the start of the work session had no effect on current performance. Food intake was high and constant during work sessions except for a prefeeding effect that occurred when the free session closely preceded the next day's work session. Also, an increase in the difficulty of the work schedule increased the amount of work and the maximum price paid for food as if the work session were the only time food was available. The results indicate the importance of considering temporal limits in theories that require animals to integrate input over time to determine the allocation of resources among alternatives.
REPRODUCTION MEMORY OF TWO‐EVENT SEQUENCES IN PIGEONS
Authors: Parker B. Kent
Published: March 2006

Six pigeons were trained to reproduce two‐event sequences in an experiment that employed a discrete‐trial procedure that required subjects to peck one of four possible sample sequences (left‐left, left‐right, right‐right, right‐left) signaled on a given trial by the successive illumination of response keys. Following a retention interval (0.1 to 30 seconds), a reinforcer was delivered if a subject reproduced the prior sample sequence during a test condition in which both left and right keys were illuminated. The pigeons readily reproduced the orders in which they had just seen and pecked two illuminated keys. Reproduction accuracy declined as the retention interval was increased. Homogeneous sequences (left‐left, right‐right) were reproduced with greater accuracy than heterogeneous sequences.
THE EFFECTS OF DELAYED REINFORCEMENT ON FREE‐OPERANT RESPONDING
Authors: Weil Jeffrey Lee
Published: March 2006

In previous studies of delayed reinforcement, response rate has been found to vary inversely with the response‐reinforcer interval. However, in all of these studies the independent variable, response‐reinforcer time, was confounded with the number of reinforcers presented in a fixed period of time (reinforcer frequency). In the present study, the frequency of available reinforcers was held constant, while temporal separation between response and reinforcer was independently manipulated. A repeating time cycle, T, was divided into two alternating time periods, tD and t▴. The first response in tD was reinforced at the end of the prevailing T cycle and extinction prevailed in t▴. Two placements for tD were defined, an early tD placement in which tD precedes t▴ and a late tD placement in which tD follows t▴. The duration of the early and late tD was systematically decreased from 30 seconds (i.e., tD = T) to 0.1 second. Manipulation of tD placement and duration controlled the temporal separation between response and reinforcement, but it did not affect the frequency of programmed reinforcers, which was 1/T. The results show that early and late tD placements of equal duration have similar overall effects upon response rate, reinforcer frequency, responses per reinforcer, and obtained response‐reinforcer temporal separation. A stepwise regression analysis using log response rate as the dependent variable showed that the obtained delay was a significant first‐step variable for six of eight subjects, with obtained reinforcer frequency significant for the remaining two subjects.
CHOICE FOR CONDITIONED REINFORCERS IN THE SIGNALED ABSENCE OF PRIMARY REINFORCEMENT
Authors: Horney Julie , Fantino Edmund
Published: March 2006

Pigeons responded in a multiple schedule in which concurrent schedules of brief‐stimulus presentation alternated with a component in which food was available (concurrent‐chains component). In the initial links of the concurrent‐chains component subjects chose either of two stimuli each correlated with the terminal link of one chain. The terminal links involved either variable‐interval 30‐second or variable‐interval 60‐second schedules. In the brief‐stimulus component subjects chose between 0.5‐second presentations of the terminal‐link stimuli from the concurrent‐chains component. Responding was generally maintained in the brief‐stimulus component in two subjects for more than 300 sessions, suggesting that brief stimuli were conditioned reinforcers. During the brief‐stimulus component, in 17 of 21 cases for which a minimal number of responses occurred, choice proportions above 0.55 were obtained for the brief‐stimulus presentations correlated with the higher rate of primary reinforcement in the concurrent‐chains component. These results support the suggestion that choice in conventional concurrent‐chains procedures is partially controlled by production of the terminal‐link stimuli.
RESPONDING DURING REINFORCEMENT DELAY IN A SELF‐CONTROL PARADIGM
Authors: Logue A. W. , Peña‐Correal T. E.
Published: March 2006

Eight pigeons chose between a small, immediate reinforcer and a large, increasingly delayed reinforcer. Responding during the large‐reinforcer delays was examined. During large‐reinforcer delays, pecks on one key produced the small, immediate reinforcer; pecks on the other key had no effect. Thus, a pigeon could reverse its initial choice of the large, delayed reinforcer, or it could maintain its original choice. Pigeons that made a relatively high number of initial large‐reinforcer choices tended to maintain these choices. Those pigeons that made a relatively high number of initial large‐reinforcer choices, and those pigeons that actually Received a relatively high number of large reinforcers, tended to respond more frequently on the ineffective key during the delay periods. The findings suggest that some previous studies of self‐control training in pigeons may have resulted in increased self‐control partially due to a lack of opportunity for the pigeons to change their choices.
GRADED DIFFERENTIAL REINFORCEMENT: RESPONSE‐DEPENDENT REINFORCER AMOUNT
Authors: Gentry G. David , Eskew Rhea T.
Published: March 2006

After key pecking had been autoshaped, six pigeons were exposed to a condition in which the duration of grain availability at the end of an 8‐second trial depended on the number of responses emitted during the trial (0.25‐second access to grain per response). This procedure, called correlated reinforcement, alternated across conditions with the automaintenance baseline in which the 8‐second trial terminated with a constant 2.5‐second access to grain. Two control procedures were run; in both, the reinforcer durations were yoked to those obtained in the last correlated session. In the yoked control no responses were required, but in the single‐response yoked control at least one response was required to receive the yoked duration. The correlated condition maintained response rates above those produced by the two control conditions. These results may be accounted for by differential reinforcement.
KNOWING BEFORE DOING: DISCRIMINATION BY RATS OF A BRIEF INTERRUPTION OF A TONE
Authors: Eisler Hannes
Published: March 2006

Eight rats' lever presses were reinforced after an interruption in a tone, provided the lever had not been pressed before the tone interruption. After a few sessions, long before the animals reliably refrained from lever pressing before the interruption, the latencies of postinterruption presses (time from the termination of the interruption to the moment of the lever press) dissociated into two classes: short ones for to‐be‐rewarded presses, and long ones for presses in the other trials, which contained no reward because one or more lever presses had occurred before the interruption. Thus discrimination of impending reinforcement in the current trial occurred before there was evidence of sensitivity to reinforcement in the reinforcement‐producing aspect of behavior. This finding is related to Shimp's (1981) contention that the temporal properties of recent behavior are reinforceable, if remembered. The present finding shows that learning to discriminate whether one's behavior has met a contingency, and learning to carry out this behavior, need not go together, implying that memory of temporal properties is probably a necessary but not a sufficient condition for learning the latter.
INDUCTION BY REINFORCER SCHEDULES
Authors: Cohen Perrin S. , Looney Thomas A.
Published: March 2006

Traditional strategies for determining whether a reinforcer schedule enhances the occurrence of an activity are reviewed and critically evaluated. A basic assumption underlying these strategies is that it is possible to isolate the effect of reinforcer intermittency on schedule induction. It is concluded that this is not, in fact, possible. An alternative approach is proposed that emphasizes the inductive effects of the reinforcer schedule as a unit and the effects of particular aspects of the reinforcer schedule (e.g., interreinforcer interval, repetition of the reinforcer, reinforcer magnitude).
PREFERENCE IN RHESUS MONKEYS GIVEN A CHOICE BETWEEN COCAINE AND d,l‐CATHINONE
Authors: Woolverton William L. , Johanson Chris E.
Published: March 2006

Previous experiments have shown that both cocaine and d,l‐cathinone can function as positive reinforcers when delivered intravenously to rhesus monkeys. However, the relative reinforcing efficacies of these compounds have not been established. In the present experiment, three rhesus monkeys were allowed to choose between saline and several doses of d,l‐cathinone or cocaine as well as between several doses of both drugs in a discrete‐trial choice procedure. Sufficient doses (.05 to .2 mg/kg/injection) of either drug maintained self‐administration and the higher doses were reliably preferred to saline. Doses of d,l‐cathinone that were preferred to saline were then compared to a range of cocaine doses in drug‐drug choice. As the dose of d,l‐cathinone that was available was increased, an increase in cocaine dose was necessary to maintain cocaine preference. Comparison of drug‐drug choice data to dose combinations predicted to be chosen with equal frequency revealed that the reinforcing efficacy of d,l‐cathinone was equivalent to that of cocaine.
PREFERENCE FOR SIGNALED OVER UNSIGNALED SHOCK SCHEDULES: RULING OUT ASYMMETRY AND RESPONSE FIXATION AS FACTORS
Authors: Abbott Bruce B. , Badia Pietro
Published: March 2006

Experiment 1 tested whether a “symmetrical” choice procedure yields results different from those previously reported using the “unidirectional” standard changeover procedure (e.g., Badia & Culbertson, 1972). Subjects could change at any time from unsignaled to signaled shock by pressing a lever and from signaled to unsignaled shock by pressing a second lever. Results were identical to those of the standard procedure and showed that the standard procedure is fully adequate. Experiment 2 tested whether choice of high density signaled shock over low‐density unsignaled shock (Badia, Coker, & Harsh, 1973) resulted from initial training with equal‐density schedules. Subjects were trained and tested with signaled shock twice as dense as unsignaled shock. Three of four subjects strongly preferred the signaled condition, thus ruling out carry‐over and “response fixation” as alternative explanations.
STIMULUS AND REINFORCER RELATIVITY IN MULTIPLE SCHEDULES: LOCAL AND DIMENSIONAL EFFECTS ON SENSITIVITY TO REINFORCEMENT
Authors: White K. Geoffrey , Pipe Margaret‐Ellen , McLean Anthony P.
Published: March 2006

Pigeons' responses in two successive components of multiple schedules were reinforced according to variable‐interval schedules of reinforcement that varied over five different conditions. Within each session of all conditions, line orientations of 0°, 30°, or 45° in Component 1 alternated with orientations of 45°, 60°, or 90° in Component 2. Response rates were recorded in three successive subintervals of each component. Ratios were taken between the response rate in each Component 1 line orientation and the response rate in each Component 2 orientation. These ratios were found to be power functions of the corresponding ratios of obtained reinforcement rates. Sensitivity of response ratios to changes in reinforcer ratios, given by the value of the exponent of the power function, increased systematically with increasing disparity between the dimensional values of orientation stimuli. In addition, sensitivity decreased systematically over successive subintervals of components, that is, with increasing time since component alternation. Dimensional and local (subinterval) effects interacted in that sensitivity increased with stimulus disparity to a far greater extent in the first subinterval than later in components. The data could be described by a combination of rectangular hyperbolae which attributed the interaction between local and dimensional effects to limits set by local effects on the extent that stimulus differences could affect sensitivity.