bluuebunny/crossref_metadata_2025 huggingface dataset:
AVERAGING EFFECTS IN THE STUDY OF FIXED‐RATIO RESPONSE PATTERNS
Authors: Baron Alan , Herpolsheimer Lisa R.
Published: March 2006

Three rats were exposed to multiple fixed‐ratio schedules in which large and small ratios alternated in an irregular order. Over a series of training phases, one ratio was held constant as the second ratio was increased to higher values. On average, postreinforcement pauses increased in duration as the ratio size was increased. Pausing was controlled by the size of the upcoming ratio; the previous ratio had smaller and less consistent effects. However, more detailed consideration of the aggregated data indicated that the pause distributions were positively skewed and that changes in average performances were more a consequence of increased skew rather than shifts of the entire distributions. Moreover, the distributions of pauses from condition to condition overlapped, and brief pauses were common even at the highest ratios. These results demonstrated that depictions of pausing based on aggregated data can be misleading without corresponding information about variations in the distribution on which the averages are based.
TIME AND MEMORY: TOWARDS A PACEMAKER‐FREE THEORY OF INTERVAL TIMING
Authors: Staddon J. E. R. , Higa J. J.
Published: March 2006

A popular view of interval timing in animals is that it is driven by a discrete pacemaker‐accumulator mechanism that yields a linear scale for encoded time. But these mechanisms are fundamentally at odds with the Weber law property of interval timing, and experiments that support linear encoded time can be interpreted in other ways. We argue that the dominant pacemaker‐accumulator theory, scalar expectancy theory (SET), fails to explain some basic properties of operant behavior on interval‐timing procedures and can only accommodate a number of discrepancies by modifications and elaborations that raise questions about the entire theory. We propose an alternative that is based on principles of memory dynamics derived from the multiple‐time‐scale (MTS) model of habituation. The MTS timing model can account for data from a wide variety of time‐related experiments: proportional and Weber law temporal discrimination, transient as well as persistent effects of reinforcement omission and reinforcement magnitude, bisection, the discrimination of relative as well as absolute duration, and the choose‐short effect and its analogue in number‐discrimination experiments. Resemblances between timing and counting are an automatic consequence of the model. We also argue that the transient and persistent effects of drugs on time estimates can be interpreted as well within MTS theory as in SET. Recent real‐time physiological data conform in surprising detail to the assumptions of the MTS habituation model. Comparisons between the two views suggest a number of novel experiments.
EVALUATION OF QUANTITATIVE THEORIES OF TIMING
Authors: Church Russell M.
Published: March 2006

Scalar timing theory is a clear, complete, modular, and precise theory of timing that explains much of the data from many timing procedures, but not all of the data from all of the procedures. The multiple‐time‐scale theory of timing provides an alternative representation of time that has not yet been tested with respect to its fit to timing data.
MODELING MODELING
Authors: Killeen Peter R.
Published: March 2006

Models are tools; they need to fit both the hand and the task. Presence or absence of a feature such as a pacemaker or a cascade is not in itself good. Or bad. Criteria for model evaluation involve benefit‐cost ratios, with the numerator a function of the range of phenomena explained, goodness of fit, consistency with other nearby models, and intangibles such as beauty. The denominator is a function of complexity, the number of phenomena that must be ignored, and the effort necessary to incorporate the model into one's parlance. Neither part of the ratio can yet be evaluated for MTS, whose authors provide some cogent challenges to SET.
THE WHIRLIGIG OF TIME: SOME THOUGHTS ON STADDON AND HIGA
Authors: Marr Jack
Published: March 2006

Staddon and Higa's theory of timing finds analogy with physics' concern with the relativity of time and irreversible processes. Their model raises general issues about the nature and function of models and, specifically, the extent to which it has captured the stimulus events in temporal control.
TIME, TRACE, MEMORY
Authors: Staddon J. E. R. , Higa J. J. , Chelaru I. M.
Published: March 2006

Objections to a trace hypothesis for interval timing do not apply to the multiple‐time‐scale (MTS) theory, which incorporates a dynamic trace tuned by the system history and can easily accommodate interval timing over a 1,000:1 range. The MTS model can also account for Weber's law as well as systematic deviations from it. Contrary to our critics, we contend that patterns of variance in interval timing experiments are not fully described by scalar expectancy theory, and that attempting to understand timing by assigning variance to different elements of a flexible model that lacks inductive support is a flawed strategy, because the attempt may be successful even if the model is wrong. We further argue that biological plausibility is an unreliable guide to the development of behavioral theory, that prediction is not the same as test, that induction should precede deduction, and that a rat is not a clock.
PRAGMATISM, SCIENCE, AND SOCIETY: A REVIEW OF RICHARD RORTY'S OBJECTIVITY, RELATIVISM, AND TRUTH: PHILOSOPHICAL PAPERS, VOLUME 1
Authors: Leigland Sam
Published: March 2006

Richard Rorty's Objectivity, Relativism, and Truth: Philosophical Papers, Volume 1 is a collection of papers that explores the implications of philosophical pragmatism in several areas, including natural science, mind—body issues in philosophy, and perspectives on liberal democracy and social change. Similarities between Rorty's pragmatism and Skinner's radical behaviorism are explored in each of these three areas. Although some important and interesting differences are found regarding the role of science in social change, most areas show remarkable similarities between the two systematic perspectives.
A LOCAL MODEL OF CONCURRENT PERFORMANCE
Authors: MacDonall James S.
Published: March 2006

Concurrent procedures may be conceptualized as consisting of two pairs of schedules with only one pair operating at a time. One schedule of each pair arranges reinforcers for staying in the current alternative, and the other schedule arranges reinforcers for switching to the other alternative. These pairs alternate operation as the animal switches between choices. This analysis of the contingencies suggests that variables operating within an alternative produce behavior that conforms to the generalized matching law. Rats were exposed to one pair of stay and switch schedules in each condition, and the probabilities of reinforcement varied across conditions. Both run length and visit duration were power functions of the ratio of the probabilities of reinforcement for staying and switching. The local model, a model of performance on concurrent procedures, was derived from this power function. Performance on concurrent schedules was synthesized from the performances on the separate pairs. Both the generalized matching law and the local model fitted the synthesized concurrent performances. These results are consistent with the view that the contingencies in the alternative, the probability of stay and switch reinforcement, are responsible for performance consistent with the generalized matching law. These results are compatible with momentary maximizing and molar maximizing accounts of concurrent performance. Models of concurrent performance that posit comparisons among the alternatives are not easily applied to these results.
STIMULUS PRESENTATION RATIOS AND THE OUTCOMES FOR CORRECT RESPONSES IN SIGNAL‐DETECTION PROCEDURES
Authors: Johnstone Victoria , Alsop Brent
Published: March 2006

Three pigeons were trained to discriminate between two line orientations (S1 and S2). A left‐key peck was correct when S1 was presented, and a right key‐peck was correct when S2 was presented. In all procedures, correct responses were occasionally reinforced with food paired with the presentation of the magazine light. Incorrect responses produced a blackout. Six detection procedures were used. In the first, the signal presentation ratio was varied across conditions and the reinforcer ratio was allowed to covary. In the second, the signal presentation ratio was held constant at 1:1 and the reinforcer ratio varied across conditions. In the third, the signal presentation ratio was varied across conditions and the reinforcer ratio was held constant at 1:1. In these three procedures, correct responses that were not scheduled for reinforcement were followed by blackout. The remaining three procedures repeated those described above with one procedural change: Nonreinforced but correct trials were followed by the presentation of the magazine light. Birds showed systematic preferences for the key associated with the stimulus presented or reinforced most often. There was no change in the birds' performance over changes in the feedback for nonreinforced but correct responses.
THE MAN WHO LISTENS TO BEHAVIOR: FOLK WISDOM AND BEHAVIOR ANALYSIS FROM A REAL HORSE WHISPERER
Authors: Farmer‐Dougan Valeri A. , Dougan James D.
Published: March 2006

The popular novel and movie The Horse Whisperer are based on the work of several real‐life horse whisperers, the most famous of whom is Monty Roberts. Over the last 50 years, Roberts has developed a technique for training horses that is both more effective and less aversive than traditional training techniques. An analysis of Roberts' methods (as described in his book, The Man Who Listens to Horses) indicates a deep understanding of behavioral principles including positive reinforcement, timeout, species‐specific defense reactions, “learned helplessness,” and the behavioral analysis of language. Roberts developed his theory and techniques on the basis of personal experience and folk wisdom, and not as the result of formal training in behavior analysis. Behavior analysts can clearly learn from such insightful yet “behaviorally incorrect” practitioners, just as such practitioners can benefit from the objective science of behavior analysts.
DRUG DISCRIMINATION UNDER A CONCURRENT FIXED‐RATIO FIXED‐RATIO SCHEDULE
Authors: McMillan D. E. , Li Mi
Published: March 2006

Pigeons were trained to discriminate 5.0 mg/kg pentobarbital from saline under a two‐key concurrent fixed‐ratio 10 fixed‐ratio 40 schedule of food presentation, in which the fixed‐ratio component with the lower response requirement was programmed to reinforce responding on one key after drug administration (pentobarbital‐biased key) and on the other key after saline administration (saline‐biased key). After responding stabilized, pigeons averaged 98% of their responses on the pentobarbital‐biased key during training sessions preceded by pentobarbital, and they averaged 90% of their responses on the saline‐biased key during training sessions preceded by saline. In test sessions preceded by doses of pentobarbital, chlordiazepoxide, or ethanol, pigeons switched from responding on the saline‐biased key at low doses to responding on the pentobarbital‐biased key at higher doses (the dose—response curve was quantal). High doses of phencyclidine produced responding on both keys, whereas pigeons responded almost exclusively on the saline‐biased key after all doses of methamphetamine. These and previous experiments using concurrent reinforcement schedules to study drug discrimination illustrate that the schedule of reinforcement is an important determinant of the shape of dose—effect curves in drug‐discrimination experiments.
LEAVING PATCHES: EFFECTS OF ECONOMY, DEPRIVATION, AND SESSION DURATION
Authors: Elliffe Douglas , Jones B. Max , Davison Michael
Published: March 2006

Three pigeons pecked keys for food reinforcers in a laboratory analogue of foraging in patches. Half the patches contained food (were prey patches). In prey patches, pecks to one key occasionally produced a reinforcer, followed by a fixed travel time and then the start of a new patch. Pecks to another key were exit responses, and immediately produced travel time and then a new patch. Travel time was varied from 0.25 to 16 s at each of three session durations: 1, 4, and 23.5 hr. This part of the experiment arranged a closed economy, in that the only source of food was reinforcers obtained in prey patches. In another part, food deprivation was manipulated by varying postsession feeding so as to maintain the subjects' body weights at percentages ranging from 85% to 95% of their ad lib weights, in 1‐hr sessions with a travel time of 12 s. This was an open economy. Patch residence time, defined as the time between the start of a patch and an exit response, increased with increasing travel time, and consistently exceeded times predicted by an optimal foraging model, supporting previously published results. However, residence times also increased with increasing session duration and, in longer sessions, consistently exceeded previously reported residence times in comparable open‐economy conditions. Residence times were not systematically affected by deprivation levels. In sum, the results show that the long residence times obtained in long closed‐economy sessions should probably be attributed to session duration rather than to economy or deprivation. This conclusion is hard to reconcile with previous interpretations of longer‐than‐optimal residence times but is consistent with, in economic terms, a predicted shift in consumption towards a preferred commodity when income is increased.
AFTER THE PUZZLE BOXES: THORNDIKE IN THE 20TH CENTURY
Authors: Hearst Eliot
Published: March 2006

From the beginning of this century, following the publication of his dissertation, Thorndike made many significant contributions to psychology, some related to animal and human learning and others to various areas of educational psychology. This paper concentrates on the former and mentions some of the latter, in the context of personal and professional aspects of his life.
ANALYZING THORNDIKE'S LAW OF EFFECT: THE QUESTION OF STIMULUS—RESPONSE BONDS
Authors: Nevin John A.
Published: March 2006

The stimulus—response bond postulated by Thorndike's (1911) law of effect is not required in a functional account of behavior in relation to its consequences. Moreover, the notion of a bond has been challenged by the findings of several experiments. Nevertheless, it remains viable in the light of reanalyses of those findings. Thorndike's suggestion that the strength of the bond depends on the magnitude of satisfaction is consistent with current research on resistance to change.
PIGEONS MAY NOT REMEMBER THE STIMULI THAT REINFORCED THEIR RECENT BEHAVIOR
Authors: Schaal David W. , Odum Amy L. , Shahan Timothy A.
Published: March 2006

In two experiments the conditioned reinforcing and delayed discriminative stimulus functions of stimuli that signal delays to reinforcement were studied. Pigeons' pecks to a center key produced delayed‐matching‐to‐sample trials according to a variable‐interval 60‐s (or 30‐s in 1 pigeon) schedule (Experiment 1) or a multiple variable‐interval 20‐s variable‐interval 120‐s schedule (Experiment 2). The trials consisted of a 2‐s illumination of one of two sample key colors followed by delays ranging across phases from 0.1 to 27.0 s followed in turn by the presentation of matching and nonmatching comparison stimuli on the side keys. Pecks to the key color that matched the sample were reinforced with 4‐s access to grain. Under some conditions of Experiment 1, pecks to nonmatching comparison stimuli produced a 4‐s blackout and the start of the next interval. Under other conditions of Experiment 1 and each condition of Experiment 2, pecks to nonmatching stimuli had no effect and trials ended only when pigeons pecked the other, matching stimulus and received food. The functions relating pretrial response rates to delays differed markedly from those relating matching‐to‐sample accuracy to delays. Specifically, response rates remained relatively high until the longest delays (15.0 to 27.0 s) were arranged, at which point they fell to low levels. Matching accuracy was high at short delays, but fell to chance at delays between 3.0 and 9.0 s. In Experiment 2, both matching accuracy and response rates remained high over a wider range of delays in the variable‐interval 120‐s component relative to the variable‐interval 20‐s component. The difference in matching accuracy between the components was not due to an increased tendency in the variable‐interval 20‐s component toward proactive interference following short intervals. Thus, under these experimental conditions the conditioned reinforcing and the delayed discriminative functions of the sample stimulus depended on the same variables (delay and variable‐interval value), but were nevertheless dissociated.
TRANSFER OF PIGEONS' MATCHING TO SAMPLE TO NOVEL SAMPLE LOCATIONS
Authors: Lionello‐DeNolf Karen M. , Urcuioli Peter J.
Published: March 2006

This study examined the conditions under which conditional stimulus control by the sample stimuli in three‐key matching‐to‐sample paradigms would generalize across the different possible sample locations. In Experiments 1 and 2, the samples appeared on the left and right side keys during initial training and then on the center key during testing. Transfer of pigeons' matching performances to the center‐key samples was evident after both identity and symbolic matching training. In Experiment 3, pigeons trained on symbolic matching with two side‐key samples or with a side‐key and a center‐key sample generally transferred their learned matching performances to those samples when they subsequently appeared in the remaining (novel) location. These results indicate that, when two‐choice conditional discriminations are learned with more than one sample location, the visual characteristics of the sample per se predominantly come to control the pigeons' comparison choices. This finding encourages the use of the multiple‐location training procedure as a way of reducing control by location, thus providing a more discriminating test of symmetry in animals.
THREE PREDICTIONS OF THE ECONOMIC CONCEPT OF UNIT PRICE IN A CHOICE CONTEXT
Authors: Madden Gregory J. , Bickel Warren K. , Jacobs Eric A.
Published: March 2006

Economic theory makes three predictions about consumption and response output in a choice situation: (a) When plotted on logarithmic coordinates, total consumption (i.e., summed across concurrent sources of reinforcement) should be a positively decelerating function, and total response output should be a bitonic function of unit price increases; (b) total consumption and response output should be determined by the value of the unit price ratio, independent of its cost and benefit components; and (c) when a reinforcer is available at the same unit price across all sources of reinforcement, consumption should be equal between these sources. These predictions were assessed in human cigarette smokers who earned cigarette puffs in a two‐choice situation at a range of unit prices. In some sessions, smokers chose between different amounts of puffs, both available at identical unit prices. Individual subjects' data supported the first two predictions but failed to support the third. Instead, at low unit prices, the relatively larger reinforcer (and larger response requirement) was preferred, whereas at high unit prices, the smaller reinforcer (and smaller response requirement) was preferred. An expansion of unit price is proposed in which handling costs and the discounted value of reinforcers available according to ratio schedules are incorporated.
TESTING FOR SYMMETRY IN THE CONDITIONAL DISCRIMINATIONS OF LANGUAGE‐TRAINED CHIMPANZEES
Authors: Dugdale Neil , Lowe C. Fergus
Published: March 2006

If subjects are taught to match Stimulus A to B and then, without further training, match B to A, they have passed a test of symmetry. It has been suggested that nonhumans' lack of success on symmetry tests might be overcome by giving them a history of symmetry exemplar training, that is, by directly teaching a large number of conditional relations (e.g., AB, CD, EF, …) and also directly training the “reverse” of these relations (e.g., BA, DC, FE, …). The chimpanzee subjects of the present study, Sherman, Austin, and Lana, had already received extensive symmetry exemplar training as a result of attempts to teach a selection‐based language system of lexigrams. The present study systematically subjected 2 of these chimps (Sherman and Lana), for the first time, to standard symmetry tests in controlled conditions. Both chimps failed the tests, even when their correct responses on test trials were reinforced. The findings do not support the exemplar training hypothesis, and cast doubt upon whether the chimps can pass tests of stimulus equivalence.
TRAVEL TIME AND CONCURRENT‐SCHEDULE CHOICE: RETROSPECTIVE VERSUS PROSPECTIVE CONTROL
Authors: Davison Michael , Elliffe Douglas
Published: March 2006

Six pigeons were trained on concurrent variable‐interval schedules in which two different travel times between alternatives, 4.5 and 0.5 s, were randomly arranged. In Part 1, the next travel time was signaled while the subjects were responding on each alternative. Generalized matching analyses of performance in the presence of the two travel‐time signals showed significantly higher response and time sensitivity when the longer travel time was signaled compared to when the shorter time was signaled. When the data were analyzed as a function of the previous travel time, there were no differences in sensitivity. Dwell times on the alternatives were consistently longer in the presence of the stimulus that signaled the longer travel time than they were in the presence of the stimulus that signaled the shorter travel time. These results are in accord with a recent quantitative account of the effects of travel time. In Part 2, no signals indicating the next travel time were given. When these data were analyzed as a function of the previous travel time, time‐allocation sensitivity after the 4.5‐s travel time was significantly greater than that after the 0.5‐s travel time, but no such difference was found for response allocation. Dwell times were also longer when the previous travel time had been longer.
PIGEONS' CHOICES BETWEEN FIXED‐RATIO AND LINEAR OR GEOMETRIC ESCALATING SCHEDULES
Authors: Neuman Paul , Ahearn William H. , Hineline Philip N.
Published: March 2006

Four related procedures provided a basis for comparing the linear‐optimality principle with a principle based on the sums of reciprocals of distances to reinforcement, and to explore the generality of the sums‐of‐reciprocals principle as a description of choice patterns in situations of diminishing returns. The procedures all arranged choices between fixed‐ratio schedules and progressive‐ratio schedules, which escalated with each consecutive choice. In contrast to previous work that involved constant ratio increments, two sets of procedures in this study involved relatively small increments that are similar to the early values when a progressive schedule is increasing proportionally. The remaining two sets of procedures examined progressive schedules with proportional increments. In addition, the initial value of the progressive alternative was manipulated to determine its effects on patterns of choice with both linear and proportional types of escalation. With the exception of one phase, regardless of the initial/reset value and the patterns of escalation, patterns of choice with pigeons were well characterized by the sums‐of‐reciprocals principle. This supports previous research with pigeons using fixed‐increment progressive schedules, as well as situations in which the progressive schedule increased by constant proportions instead of by constant increments. The findings are attributed to the feature of this averaging technique whereby it differentially values reinforcers based on their relative proximity to a particular choice point.
DIFFERENTIAL OUTCOME EFFECT IN THE HORSE
Authors: Miyashita Yukako , Nakajima Sadahiko , Imada Hiroshi
Published: March 2006

Three horses were trained with a discrimination task in which the color (blue or yellow) of a center panel signaled the correct (left or right) response (lever press). Reinforcing outcomes for the two correct color—position combinations (blue—left and yellow—right) were varied across phases. Discrimination performance was better when the combinations were differentially reinforced by two types of food (chopped carrot pieces and a solid food pellet) than when the combinations were randomly reinforced by these outcomes or when there was a common reinforcer for each of the correct combinations. However, the discrimination performance established by the differential outcome procedure was still 80% to 90% correct, and an analysis of two‐trial sequences revealed that the stimulus color of the preceding trial interfered with discrimination performance on a given trial. Our demonstration of the differential outcome effect in the horse and its further analysis might contribute to more efficient control of equine behavior in the laboratory as well as in horse sports.
THE PHILOSOPHICAL TERRAIN OF BEHAVIOR ANALYSIS: A REVIEW OF B. A. THYER (ED.), THE PHILOSOPHICAL LEGACY OF BEHAVIORISM
Authors: Lamal P. A.
Published: March 2006

The Philosophical Legacy of Behaviorism, edited by Bruce A. Thyer, is a set of original contributions, each dealing, from a behavioral stance, with one of the following major topics of philosophy: epistemology, ethics, consciousness, language, free will and determinism, and self‐control. Confusions about radical behaviorism and its similarities to, and differences from, other behavioral and non‐behavioral approaches are described in the book, which provides a state‐of‐the‐art description of the philosophical underpinnings of behavior analysis.
DRUG DISCRIMINATION UNDER TWO CONCURRENT FIXED‐INTERVAL FIXED‐INTERVAL SCHEDULES
Authors: McMillan D. E. , Li Mi
Published: March 2006

Pigeons were trained to discriminate 5.0 mg/kg pentobarbital from saline under a two‐key concurrent fixed‐interval (FI) 100‐s FI 200‐s schedule of food presentation, and later under a concurrent FI 40‐s FI 80‐s schedule, in which the FI component with the shorter time requirement reinforced responding on one key after drug administration (pentobarbital‐biased key) and on the other key after saline administration (saline‐biased key). After responding stabilized under the concurrent FI 100‐s FI 200‐s schedule, pigeons earned an average of 66% (after pentobarbital) to 68% (after saline) of their reinforcers for responding under the FI 100‐s component of the concurrent schedule. These birds made an average of 70% of their responses on both the pentobarbital‐biased key after the training dose of pentobarbital and the saline‐biased key after saline. After responding stabilized under the concurrent FI 40‐s FI 80‐s schedule, pigeons earned an average of 67% of their reinforcers for responding under the FI 40 component after both saline and the training dose of pentobarbital. These birds made an average of 75% of their responses on the pentobarbital‐biased key after the training dose of pentobarbital, but only 55% of their responses on the saline‐biased key after saline. In test sessions preceded by doses of pentobarbital, chlordiazepoxide, ethanol, phencyclidine, or methamphetamine, the dose—response curves were similar under these two concurrent schedules. Pentobarbital, chlordiazepoxide, and ethanol produced dose‐dependent increases in responding on the pentobarbital‐biased key as the doses increased. For some birds, at the highest doses of these drugs, the dose—response curve turned over. Increasing doses of phencyclidine produced increased responding on the pentobarbital‐biased key in some, but not all, birds. After methamphetamine, responding was largely confined to the saline‐biased key. These data show that pigeons can perform drug discriminations under concurrent schedules in which the reinforcement frequency under the schedule components differs only by a factor of two, and that when other drugs are substituted for the training drugs they produce dose—response curves similar to the curves produced by these drugs under other concurrent interval schedules.
PREFERENCE AND RESISTANCE TO CHANGE WITH CONSTANT‐DURATION SCHEDULE COMPONENTS
Authors: Nevin John A. , Grace Randolph C.
Published: March 2006

Previous research on preference between variable‐interval terminal links in concurrent chains has most often used variable‐duration terminal links ending with a single reinforcer. By contrast, most research on resistance to change in multiple schedules has used constant‐duration components that include variable numbers of reinforcers in each presentation. Grace and Nevin (1997) examined both preference and resistance in variable‐duration components; here, preference and resistance were examined in constant‐duration components. Reinforcer rates were varied across eight conditions, and a generalized‐matching‐law analysis showed that initial‐link preference strongly overmatched terminal‐link reinforcer ratios. In multiple schedules, baseline response rates were unaffected by reinforcer rates, but resistance to intercomponent food, to extinction, and to intercomponent food plus extinction was greater in the richer component. The between‐component difference in resistance to change exhibited additive effects for the three resistance tests, and was systematically related to reinforcer ratios. However, resistance was less sensitive to reinforcer ratios than was preference. Resistance to intercomponent food and to intercomponent food plus extinction was more sensitive to reinforcer ratios in the present study than in Grace and Nevin (1997). Thus, relative to variable‐duration components, constant‐duration components increased the sensitivity of both preference and relative resistance, supporting the proposition that these are independent and convergent measures of the effects of a history of reinforcement.
CHANGING BEHAVIOR WITHIN SESSION: CYCLICITY AND PERSEVERANCE PRODUCED BY VARYING THE MINIMUM RATIO OF A VARIABLE‐RATIO SCHEDULE
Authors: Andrzejewski Matthew E. , Field Douglas P. , Hineline Philip N.
Published: March 2006

Four pigeons repeatedly chose between a fixed‐ratio (FR) 20 and a variable‐ratio (VR) 40 schedule of reinforcement, in which the minimum ratio of the VR cycled within each session. The minimum ratio ascended and descended (ASCDESC), descended and ascended (DESCASC), or remained constant (unchanging). In Phase 1, 2 birds (Group 1) were exposed to ASCDESC series and 2 birds (Group 2) were exposed to the DESCASC series. Choice proportions changed with the cycling minimum ratio for Group 2 but not for Group 1. In Phase 2, Group 1 subjects were exposed to the DESCASC series and Group 2 subjects were exposed to the unchanging condition. Although Group 1's choice proportions appeared to be undifferentiated in Phase 2, Group 2's choice proportions continued to cycle for more than 100 sessions. Group 2 subjects were then moved to the ASCDESC series in the third phase, and choice proportions cycled with the minimum ratio as in the first phase. The descending portion of the series was the more powerful determinant of cyclicity. Response rates also changed with the minimum component ratio, a finding that goes against the claim of universality of a rise‐and‐fall within‐session pattern of responding. That preference varied despite the constancy of the average ratio requirement suggests nonlinear averaging in quantitatively representing a variable schedule's value. The strong perseverance observed also lends support to a growing body of literature on history effects.
EFFECTS OF COCAINE ON FIXED‐INTERVAL RESPONDING REINFORCED BY THE OPPORTUNITY TO RUN
Authors: Belke Terry W. , Dunbar Michelle J.
Published: March 2006

Rate‐dependent drug effects have been observed for operant responding maintained by food, water, heat, light onset, electrical brain stimulation, shock‐stimulus termination, and shock presentation. The present study sought to determine if the effects of cocaine on lever pressing maintained by the opportunity to run could also be described as rate dependent. Seven male Wistar rats were trained to respond on levers for the opportunity to run in a wheel. The schedule of reinforcement was fixed‐interval 60 s, and the reinforcing consequence was the opportunity to run for 60 s. On this schedule, overall rates of responding were low, usually below six presses per minute, and pauses frequently exceeded the 60‐s interval. Despite these differences, an overall scalloped pattern of lever pressing was evident for each rat. Doses of 1, 2, 4, 8, and 16 mg/kg cocaine were administered 10 min prior to a session. Only at the 16 mg/kg dose did the responding of the majority of rats change in a manner suggestive of a rate‐dependent drug effect. Specifically, lower response rates at the beginning of the intervals increased and higher rates at the end of the intervals decreased, as indicated by the fact that slopes from the regression of drug rates on control rates decreased. These data provide tentative support for the generalization of rate‐dependent effects to operant responding maintained by wheel running. Differences in the baseline performance maintained by wheel running compared to those for food and water point to the need for further experimentation before this effect can be firmly established.
RESPONSE‐INDEPENDENT MILK DELIVERY ENHANCES PERSISTENCE OF PELLET‐REINFORCED LEVER PRESSING BY RATS
Authors: Grimes Julie A. , Shull Richard L.
Published: March 2006

If, during training, one stimulus is correlated with a higher rate of reinforcement than another, responding will be more resistant to extinction in the presence of that higher rate signal, even if many of the reinforcers have been presented independently of responding. For the present study we asked if the response‐independent reinforcers must be the same as the response‐dependent reinforcers to enhance the response's persistence. Twelve Long‐Evans hooded rats obtained 45‐mg food pellets by lever pressing (variable‐interval 100‐s schedules) in the presence of two discriminative stimuli (blinking vs. steady lights) that alternated every minute during daily sessions. Also, in the presence of one of the stimuli (counterbalanced across rats), the rats received additional response‐independent deliveries of sweetened condensed milk (a variable‐time schedule). Extinction sessions were exactly like training sessions except that neither pellets nor milk were presented. Lever pressing was more resistant to extinction in the presence of the milk‐correlated stimulus when (a) the size of the milk deliveries during training (under a variable‐time 30 s schedule) was 0.04 ml (vs. 0.01 ml) and (b) 120‐s or 240‐s blackouts separated components. Response‐independent reinforcers do not have to be the same as the response‐dependent reinforcers to enhance persistence.
GROUP CHOICE: THE IDEAL FREE DISTRIBUTION OF HUMAN SOCIAL BEHAVIOR
Authors: Kraft John R. , Baum William M.
Published: March 2006

Group choice refers to the distribution of group members between two choice alternatives over time. The ideal free distribution (IFD), an optimal foraging model from behavioral ecology, predicts that the ratio of foragers at two resource sites should equal the ratio of obtained resources, a prediction that is formally analogous to the matching law of individual choice, except that group choice is a social phenomenon. Two experiments investigated the usefulness of IFD analyses of human group choice and individual‐based explanations that might account for the group‐level events. Instead of nonhuman animals foraging at two sites for resources, a group of humans chose blue and red cards to receive points that could earn cash prizes. The groups chose blue and red cards in ratios in positive relation to the ratios of points associated with the cards. When group choice ratios and point ratios were plotted on logarithmic coordinates and fitted with regression lines, the slopes (i.e., sensitivity measures) approached 1.0 but tended to fall short of it (i.e., undermatching), with little bias and little unaccounted for variance. These experiments demonstrate that an IFD analysis of group choice is possible and useful, and suggest that group choice may be explained by the individual members' tendency to optimize reinforcement.
STOCK OPTIMIZING IN CHOICE WHEN A TOKEN DEPOSIT IS THE OPERANT
Authors: Widholm John J. , Silberberg Alan , Hursh Steven R. , Imam Abdulrazaq A. , Warren‐Boulton Frederick R.
Published: March 2006

Each of 2 monkeys typically earned their daily food ration by depositing tokens in one of two slots. Tokens deposited in one slot dropped into a bin where they were kept (token kept). Deposits to a second slot dropped into a bin where they could be obtained again (token returned). In Experiment 1, a fixed‐ratio (FR) 5 schedule that provided two food pellets was associated with each slot. Both monkeys preferred the token‐returned slot. In Experiment 2, both subjects chose between unequal FR schedules with the token‐returned slot always associated with the leaner schedule. When the FRs were 2 versus 3 and 2 versus 6, preferences were maintained for the token‐returned slot; however, when the ratios were 2 versus 12, preference shifted to the token‐kept slot. In Experiment 3, both monkeys chose between equal‐valued concurrent variable‐interval variable‐interval schedules. Both monkeys preferred the slot that returned tokens. In Experiment 4, both monkeys chose between FRs that typically differed in size by a factor of 10. Both monkeys preferred the FR schedule that provided more food per trial. These data show that monkeys will choose so as to increase the number of reinforcers earned (stock optimizing) even when this preference reduces the rate of reinforcement (all reinforcers divided by session time).
SPEED CONTINGENCIES, NUMBER OF STIMULUS PRESENTATIONS, AND THE NODALITY EFFECT IN EQUIVALENCE CLASS FORMATION
Authors: Imam Abdulrazaq A.
Published: March 2006

Two experiments compared performances on conditional discrimination tasks using single‐participant designs with and without speed contingencies. Experiment 1 was a systematic replication of Spencer and Chase (1996). Experiment 2 presented equal numbers of training and testing trials. In each experiment, 2 female undergraduates participated. Each formed three five‐member and three seven‐member equivalence classes in Experiments 1 and 2, respectively. Response speed was an inverse function of nodal number and relational type in Experiment 1, but only of relational type (i.e., baseline, symmetry, transitivity, and equivalence) in Experiment 2, with and without the speed contingency. Accuracy tended to peak without the speed contingency in both experiments. Adding the speed contingency increased response speeds in both experiments, more so in Experiment 2 with a lower limited hold for 1 participant. The results of Experiment 2 cast doubt on previous reports of the nodality effect and on the notion of “relatedness” among class members, and they support a reinforcement‐contingency, rather than a structural, account of equivalence class formation.
THE DEVELOPMENT OF FUNCTIONAL RESPONSE UNITS: THE ROLE OF DEMARCATING STIMULI
Authors: Reid Alliston K. , Chadwick Cynthia Z. , Dunham Myila , Miller Angela
Published: March 2006

An experiment with rats examined the roles of demarcating stimuli and differential reinforcement probability on the development of functional response units. It examined the development of units in a probabilistic, free‐operant situation in which the presence of demarcating stimuli was manipulated. In all conditions, behavior became organized into two‐response sequences framed by changes in local reinforcement probability. A tone demarcating the beginning and end of contingent response sequences facilitated the development of functional response units, as in chunking, but the same units developed slowly in the absence of the tone. Complex functional response units developed even though reinforcement contingencies remained constant. These findings demonstrate that models of operant learning must include a mechanism for changing the response unit as a function of reinforcement history. Markov models may seem to be a natural technique for modeling response sequences because of their ability to predict individual responses as a function of reinforcement history; however, no class of Markov chain can incorporate changing response units in their predictions.
PERCEPTUAL CLASSES ESTABLISHED WITH FORCED‐CHOICE PRIMARY GENERALIZATION TESTS AND TRANSFER OF FUNCTION
Authors: Reeve Kenneth F. , Fields Lanny
Published: March 2006

In Experiment 1, 20 college students learned two identity conditional discriminations using squares that differed in interior‐fill percentage (called Fill23 and Fill77). A two‐choice generalization test was then presented with number of test trials varied across groups of subjects. The test samples were 19 squares that ranged in fill value from 23% to 77%; the comparisons were squares with Fill23 and Fill77. The resulting gradients did not vary as a function of number of test trials. When the generalization test was repeated with a third comparison, “neither,” the ranges of fill values that occasioned the exclusive selection of Fill23 or Fill77 were direct functions of the number of prior two‐choice generalization trials. Finally, a discriminability test revealed that Fill23 and Fill77 were discriminable from the intermediate fill values. In Experiment 2, perceptual classes were established with 5 new students using 760 forced‐choice generalization test trials. The students were then trained to select a different glyph in the presence of Fill23 and Fill77, followed by a three‐choice generalization test in which the 19 fill stimuli served as samples and the two glyphs served as comparisons. The gradients overlapped with those previously obtained during the three‐choice generalization test that used Fill23 and Fill77 as comparisons. Finally, a discriminability test showed that many adjacent stimuli along the fill dimension were discriminable from each other. Together, the results of both experiments suggest that ranges of fill‐based stimuli functioned as members of perceptual classes, and each class also functioned as a transfer network for a new selection‐based response.
WITHIN‐SUBJECT COMPARISON OF REAL AND HYPOTHETICAL MONEY REWARDS IN DELAY DISCOUNTING
Authors: Johnson Matthew W. , Bickel Warren K.
Published: March 2006

A within‐subject design, using human participants, compared delay discounting functions for real and hypothetical money rewards. Both real and hypothetical rewards were studied across a range that included $10 to $250. For 5 of the 6 participants, no systematic difference in discount rate was observed in response to real and hypothetical choices, suggesting that hypothetical rewards may often serve as a valid proxy for real rewards in delay discounting research. By measuring discounting at an unprecedented range of real rewards, this study has also systematically replicated the robust finding in human delay discounting research that discount rates decrease with increasing magnitude of reward. A hyperbolic decay model described the data better than an exponential model.
HIGH‐PROBABILITY STIMULUS CONTROL TOPOGRAPHIES WITH DELAYED S+ ONSET IN A SIMULTANEOUS DISCRIMINATION PROCEDURE
Authors: McIlvane William J. , Kledaras Joanne B. , Callahan T. C. , Dube William V.
Published: March 2006

Experimenters and teachers use discrimination learning procedures to encourage reliable attending to stimulus differences defined as relevant for their purposes. Put another way, the goal of discrimination training is to establish high‐probability stimulus control topographies that are coherent with experimenter or teacher specifications. The present research was conducted to investigate a novel procedure for encouraging stimulus control topography coherence. Participants were 13 adolescents with severe intellectual handicaps. During an initial Condition A, all were exposed to a simultaneous discrimination procedure. Participants could select a form alternating with a black field (S1) or an identical form that did not alternate (S2). Accuracy scores were typically low, and there was little evidence of coherent stimulus control topographies. Subsequently, the procedure was changed. During Condition B, every trial initially presented two identical nonalternating S2 forms (Trial State 1). If the participant made no selection for 5 s, one of the forms began to alternate with the black field, and he or she could make the S1/S2 discrimination (Trial State 2). Selections during Trial State 1 prolonged the delay to Trial State 2 until there had been no response for 5 s. During Condition B, S1/S2 discrimination accuracy scores improved rapidly and markedly for most participants. Reinstating Condition A often resulted in diminished accuracy scores. This study thus (a) demonstrated a novel procedure for encouraging stimulus control topography coherence and (b) provided support for the interpretation that intermediate accuracy scores may be due to different topographies of stimulus control that co‐occur in the same discriminative baseline.
THE HARVARD PIGEON LAB UNDER HERRNSTEIN
Authors: Baum William M.
Published: March 2006

The history of the Harvard Pigeon Lab is a history of two periods of remarkable productivity, the first under Skinner's leadership and the second under Herrnstein's. In each period, graduate students flocked to the leader and then began stimulating one another. Chance favored Herrnstein's leadership, too, because an unusually large number of graduate students were admitted in the fall of 1962. In each period, productivity declined as the leader lost interest in the laboratory and withdrew. Directly and indirectly, the laboratory finally died as a result of the cognitive “revolution.” Skinner and his students saw the possibility of a natural science of behavior and set about establishing that science based on concepts such as response rate, stimulus control, and schedules of reinforcement. Herrnstein and his students saw that the science could be quantitative and set about making it so, with relative response rate, the matching law, and the psychophysics of choice (analogous to S. S. Stevens' psychophysics). The history might provide a golden research opportunity for someone interested in the impact of such self‐organizing research groups on the progress of science.
THE LIVING LEGACY OF THE HARVARD PIGEON LAB: QUANTITATIVE ANALYSIS IN THE WIDE WORLD
Authors: Logue A. W.
Published: March 2006

From the Harvard Pigeon Lab of the 1960s arose a behavior‐analytic approach that was quantitative and rigorous, rooted in Herrnstein's matching law. Researchers modified the matching law to describe choice behavior in a variety of different settings and examined its relations with other quantitative models. Beginning in the early 1970s, researchers began using the Harvard Pigeon Lab's quantitative framework to study in the laboratory specific aspects of the world outside the laboratory. Much of this work concerned investigations of self‐control—choice of a larger, more delayed reinforcer over a smaller, less delayed reinforcer. Experiments using a quantitative framework derived from the matching law have also been conducted outside the laboratory; however, these have been far less frequent. Current and future researchers will benefit the field by devising new, creative ways to investigate the matching law and related quantitative models outside the laboratory. Such research can help to demonstrate the validity of these models as basic principles of behavior, can enhance public opinion of and rewards for such research, and can stimulate further development of the Harvard Pigeon Lab's quantitative approach by using that approach with new variables.