bluuebunny/crossref_metadata_2025 huggingface dataset:
THE EFFECTS OF NUMBER OF SAMPLE STIMULI AND NUMBER OF CHOICES IN A DETECTION TASK ON MEASURES OF DISCRIMINABILITY
Authors: Godfrey Rebecca , Davison Michael
Published: March 2006

Six pigeons were trained on a conditional discrimination task involving the discrimination of various intensities of yellow light. The research asked whether stimulus—response discriminability measures between any pair of stimuli would remain constant when a third or fourth sample and reinforced response were added. The numbers of different sample stimuli presented and different responses reinforced were two (Part 1), three (Parts 2 and 4), and four (Part 3). Across conditions within parts, the ratios of reinforcers obtainable for correct responses were varied over at least five levels. In Part 5, the numbers of sample stimuli and reinforced responses were varied among two, three, and four, and the reinforcer ratio between consecutive remaining samples was constant at 2:1. It was found that once a particular response had been reinforced, subjects continued to emit that response when the conditional stimulus for that response was no longer presented. Data analysis using a generalization‐based detection model indicated that this model was able to describe the data effectively. Four findings were in accord with the theory. First, estimates of stimulus—response discriminability usually decreased as the arranged physical disparity between the sample stimuli decreased. Second, stimulus—response discriminability measures were independent of response—reinforcer discriminability measures, preserving parameter invariance between these measures. Third, stimulus—response discriminability measures for constant pairs of conditional stimuli did not change systematically as conditional stimulus—response alternatives were added. Fourth, log stimulus—response discriminability values between physically adjacent conditional stimuli summed to values that were not significantly different from estimates of the discriminability values for conditional stimuli that were spaced further apart.
REWARD DENSITY AND VARIABLE‐INTERVAL SCHEDULE PERFORMANCE IN AN OPEN ECONOMY
Authors: Hall Genae A. , Lattal Kennon A.
Published: March 2006

There is no general agreement regarding the form of the relation between response rate and reinforcement rate when single schedules of reinforcement are studied in an open economy. The present study assessed the form of this relation using reward density, which incorporates both reinforcement rate and duration of access to food, as an independent variable. Reward density was manipulated with 4 pigeons by changing the value of the variable‐interval schedule, the hopper duration, or both. The relations between response rate and reward density were sharply rising and hyperbolic in 3 of 4 pigeons, replicating results obtained by Catania and Reynolds (1968). Because eating efficiency was lower in conditions that provided longer hopper durations, programmed reward densities differed from obtained reward densities. When response rates were examined as a function of obtained reward densities, the same relations were demonstrated more strongly. In further clarifying the relation between response rate and reward density in an open economy, these results lend support to the conclusion that open and closed economies yield different behavioral effects.
BEHAVIORAL ECONOMICS AND WITHIN‐SESSION CHANGES IN RESPONDING
Authors: McSweeney Frances K. , Swindell Samantha
Published: March 2006

Pigeons and rats responded on fixed‐ratio schedules with requirements ranging from 5 to 120 responses. Consistent with past results from several schedules and procedures, responding usually changed systematically within experimental sessions. The within‐session changes were usually larger and were less symmetrical around the middle of the session for schedules that provided higher, rather than lower, rates of reinforcement. These results suggest that similar variables contribute to within‐session changes in responding under different schedules. When an economic demand function was fit to the data, the intensity and elasticity of demand for food and the percentage of the variance accounted for decreased within sessions, although the trend for elasticity did not reach statistical significance for pigeons. These results suggest that relatively short sessions should be used to study economic demand in open economies and that demand may differ at different times in a session and in sessions of different lengths. Within‐session changes in intensity, but not necessarily elasticity, of demand are consistent with behavioral economic theories.
WITHIN‐SESSION ANALYSIS OF VISUAL DISCRIMINATION
Authors: Hinson John M. , Tennison Linda R.
Published: March 2006

Within‐session changes in responding by pigeons during a maintained successive discrimination procedure were examined in four experiments. In the first two experiments, which involved discrimination of visual flicker rate, within‐session changes in responding were minimal or absent. A third experiment, which examined discrimination of rectangular forms, demonstrated that the absence of within‐session changes in responding was not limited to flicker‐rate stimuli. A fourth experiment showed that the absence of within‐session changes in responding was not due to high task difficulty in the previous experiments. For the group of subjects in each experiment, within‐session changes in responding did not influence discrimination performance. Therefore, measures of overall response rate accurately represented responding both within and across sessions. The occasional appearance of within‐session decreases in responding for a few birds may be attributable to satiation.
SATIATION, CAPACITY, AND WITHIN‐SESSION RESPONDING
Authors: DeMarse Thomas B. , Killeen Peter R. , Baker David
Published: March 2006

Responding may change substantially over the course of a session (McSweeney, Hinson, & Cannon, 1996). The role of satiation in this effect was investigated in three experiments. Experiment 1 showed that the capacity of pigeons to consume milo over a 1‐hr period was relatively stable across three different methods of measurement. In Experiment 2, pigeons were divided into two groups that differed in their capacity based on one of those measures. Key pecking was then reinforced under a variable‐interval 30‐s schedule with hopper durations of 2 or 5 s. According to the satiation hypothesis, subjects with small capacities should satiate faster and therefore show greater decreases in food‐reinforced responding than would subjects with larger capacities. The results confirmed this prediction and showed that the magnitudes of within‐session decreases were better predicted by the amount an animal consumed relative to its capacity than by absolute amount alone. In Experiment 3, each pigeon was prefed 0, 5, 15, or 25 g of milo prior to each session. Consistent with the satiation hypothesis, increases in prefeeding produced lower overall response rates in the smaller capacity subjects than in the larger capacity subjects at each level of prefeeding. These experiments demonstrate the importance of a new variable in the control of behavior, and provide a recommended technique for its measurement.
A REVIEW OF GERALDINE JONÇICH'S THE SANE POSITIVIST: A BIOGRAPHY OF EDWARD L. THORNDIKE
Authors: Cumming William W. , Catania A. Charles
Published: March 2006

This book review, unfinished at the author's death, examines in historical context Thorndike's law of effect, his Animal Intelligence monograph of 1898, and related works on learning and behavior.
THORNDIKE'S PUZZLE BOXES AND THE ORIGINS OF THE EXPERIMENTAL ANALYSIS OF BEHAVIOR
Authors: Chance Paul
Published: March 2006

The year of Thorndike's dissertation on animal intelligence, 1898, may mark the beginning of the field that eventually became known as the experimental analysis of behavior. The dissertation began a major shift in thinking about animal and human learning, provided important methodological innovations, and carried the seeds of later research and theory, particularly by B. F. Skinner. Although Thorndike was an associationist in 1898, the dissertation began the systematic search for fundamental behavioral processes, and laid the foundation for an empirical science of behavior.
EDWARD L. THORNDIKE: THE SELECTIONIST CONNECTIONIST
Authors: Donahoe John W.
Published: March 2006

From the very outset of his work, Thorndike allied himself with the Darwinian proposition that complex phenomena can arise as the cumulative effects of a selection process, here the process envisioned by the law of effect. Thorndike's selectionist approach, when combined with his connectionism, laid the foundation for a synthesis of behavior analysis and neuroscience.
ESTABLISHING FUNCTIONAL CLASSES IN A CHIMPANZEE (PAN TROGLODYTES) WITH A TWO‐ITEM SEQUENTIAL‐RESPONDING PROCEDURE
Authors: Tomonaga Masaki
Published: March 2006

A 9‐year‐old female chimpanzee was trained on a two‐item sequential‐responding task. Attempts were made with successive‐reversal training to establish functional classes. In Experiment 1, the subject was exposed to between‐session successive‐reversal training in which one of two pairs of stimuli was reversed, and transfer of reversal responding to the other pair was tested with nonreinforcement probe trials. She did not show transfer during the course of reversals. Stimulus control established in the original training was maintained on nonreinforcement probe trials. In Experiment 2, within‐session reversals were introduced. She showed transfer from the initially reversed pair to the other. The results were consistent with Vaughan's (1988) results with pigeons on successive discriminations, which indicated the formation of functional classes. In Experiment 3, crossover and wild‐card tests were conducted to clarify the stimulus control of sequential responding. The results suggested that the sequential responding was controlled only by the first stimulus of each pair. To establish control by both first and second stimuli, trial‐unique stimuli or wild cards were substituted for one of the items of the lists in Experiment 4. Further transfer tests, in which stimuli for the two new pairs appeared, were also given to the subject. She successfully responded to these two merged lists and reversed the order as the result of reversal training.
PAVLOVIAN CONTINGENCIES AND RESISTANCE TO CHANGE IN A MULTIPLE SCHEDULE
Authors: Bell Matthew C.
Published: March 2006

According to theoretical accounts of behavioral momentum, the Pavlovian stimulus—reinforcer contingency determines resistance to change. To assess this prediction, 8 pigeons were exposed to an unsignaled delay‐of‐reinforcement schedule (a tandem variable‐interval fixed‐time schedule), a signaled delay‐of‐reinforcement schedule (a chain variable‐interval fixed‐time schedule), and an immediate, zero‐delay schedule of reinforcement in a three‐component multiple schedule. The unsignaled delay and signaled delay schedules employed equal fixed‐time delays, with the only difference being a stimulus change in the signaled delay schedule. Overall rates of reinforcement were equated for the three schedules. The Pavlovian contingency was identical for the unsignaled and immediate schedules, and response—reinforcer contiguity was degraded for the unsignaled schedule. Results from two disruption procedures (prefeeding subjects prior to experimental sessions and adding a variable‐time schedule to timeout periods separating baseline components) demonstrated that response—reinforcer contiguity does play a role in determining resistance to change. The results from the extinction manipulation were not as clear. Responding in the unsignaled delay component was consistently less resistant to change than was responding in both the immediate and presignaled segments of the signaled delay components, contrary to the view that Pavlovian contingencies determine resistance to change. Probe tests further supported the resistance‐to‐change results, indicating consistency between resistance to change and preference, both of which are putative measures of response strength.
DRUG DISCRIMINATION IN RATS UNDER CONCURRENT VARIABLE‐INTERVAL VARIABLE‐INTERVAL SCHEDULES
Authors: McMillan D. E. , Hardwick W. C.
Published: March 2006

Eight rats were trained to discriminate pentobarbital from saline under a concurrent variable‐interval (VI) VI schedule, on which responses on the pentobarbital‐biased lever after pentobarbital were reinforced under VI 20 s and responses on the saline‐biased lever were reinforced under VI 80 s. After saline, the reinforcement contingencies programmed on the two levers were reversed. The rats made 62.3% of their responses on the pentobarbital‐biased lever after pentobarbital and 72.2% on the saline‐biased lever after saline, both of which are lower than predicted by the matching law. When the schedule was changed to concurrent VI 50 s VI 50 s for test sessions with saline and the training dose of pentobarbital, responding on the pentobarbital‐biased lever after the training dose of pentobarbital and on the saline‐biased lever after saline became nearly equal, even during the first 2 min of the session, suggesting that the presence or absence of the training drug was exerting minimal control over responding and making the determination of dose—effect relations of drugs difficult to interpret. When the pentobarbital dose—response curve was determined under the concurrent VI 50‐s VI 50‐s schedule, responding was fairly evenly distributed on both levers for most rats. Therefore, 6 additional rats were trained to respond under a concurrent VI 60‐s VI 240‐s schedule. Under this schedule, the rats made 62.6% of their responses on the pentobarbital‐biased lever after pentobarbital and 73.5% of their responses on the saline‐biased lever after saline, which also is lower than the percentages predicted by perfect matching. When the schedule was changed to a concurrent VI 150‐s VI 150‐s schedule for 5‐min test sessions with additional drugs, the presence or absence of pentobarbital continued to control responding in most rats, and it was possible to generate graded dose—response curves for pentobarbital and other drugs using the data from these 5‐min sessions. The dose—response curves generated under these conditions were similar to the dose—response curves generated using other reinforcement schedules and other species.
HUMAN PERFORMANCE ON NEGATIVE SLOPE SCHEDULES OF POINTS EXCHANGEABLE FOR MONEY: A FAILURE OF MOLAR MAXIMIZATION
Authors: Jacobs Eric A. , Hackenberg Timothy D.
Published: March 2006

Panel pressing was generated and maintained in 5 adult humans by schedules of points exchangeable for money. Following exposure to a variable‐interval 30‐s schedule and to a linear variable‐interval 30‐s schedule (which permitted points to accumulate in an unseen “store” in the absence of responding), subjects were exposed to a series of conditions with a point‐subtraction contingency arranged conjointly with the linear variable‐interval schedule. Specifically, points were added to the store according to the linear‐variable interval 30‐s schedule and were subtracted from the store according to a ratio schedule. Ratio value varied across conditions and was determined individually for each subject such that the subtraction contingency would result in an approximately 50% reduction in the rate of point delivery. Conditions that included the subtraction contingency were termed negative slope schedules because the feedback functions were negatively sloped across all response rates greater than the inverse of the variable‐interval schedule, in this case, two per minute. Overall response rates varied inversely with the subtraction ratio, indicating sensitivity to the negative slope conditions, but were in excess of that required by accounts based on strict maximization of overall reinforcement rate. Performance was also not well described by a matching‐based account. Detailed analyses of response patterning revealed a consistent two‐state pattern in which bursts of high‐rate responding alternated with periods of prolonged pausing, perhaps reflecting the joint influence of local and overall reinforcement rates.
STIMULUS CONTROL AND GENERALIZATION OF POINT‐LOSS PUNISHMENT WITH HUMANS
Authors: O'Donnell Jennifer , Crosbie John , Williams Dean C. , Saunders Kathryn J.
Published: March 2006

Two experiments demonstrated stimulus control and generalization of conditioned punishment with humans. In both studies, responses first were reinforced with points exchangeable for money on a variable‐interval schedule in the presence of one line length (SD). Next, a second line length was introduced, and point loss followed every response in the presence of that line (SDp). In the final training condition, points were deducted at session end. Response rate was lower in the presence of the SDp despite equal rates of points for money in the presence of both stimuli. In generalization testing for Experiment 1, the two lines were included in a 10‐line continuum; SDp fell in the middle and the trained SD was at one end. Lines were presented randomly, and point delivery and loss contingencies were as in training but with points available in the presence of all lines. For all subjects, response rates were lowest around SDp and increased towards the SD end of the continuum. Because testing included only one or two lines beyond SD, this pattern did not rule out SD generalization. Thus, in Experiment 2, stimuli beyond SD were added to generalization tests. Response rates did not decrease as a function of distance from SD, clarifying the demonstration of punishment generalization.
AN OLFACTORY DISCRIMINATION PROCEDURE FOR MICE
Authors: Mihalick Sheila M. , Langlois Jason C. , Krienke Jason D. , Dube William V.
Published: March 2006

This paper describes an olfactory discrimination procedure for mice that is inexpensively implemented and leads to rapid discrimination learning. Mice were first trained to dig in small containers of sand to retrieve bits of buried chocolate. For discrimination training, two containers were presented simultaneously for eight trials per session. One container held sand mixed with cinnamon, and the other held sand mixed with nutmeg. Both containers were baited with chocolate buried in the sand. One odor was designated S+, and mice were allowed to dig and retrieve the chocolate from this container. The other odor was S‐, and both containers were removed immediately if subjects began to dig in an S‐ container. After meeting a two‐session acquisition criterion, subjects were given a series of discrimination reversals. In Experiment 1, 12 Swiss‐Webster mice (6 male and 6 female) acquired the olfactory discrimination in three to five sessions and completed 3 to 10 successive discrimination reversals within a 50‐session testing limit. In Experiment 2, subjects were 14 Pahenu2 mice, the mouse mutant for phenylketonuria; 7 were homozygotes in which the disorder was expressed (PKU), and 7 were heterozygotes with normal metabolism (non‐PKU). Thirteen mice completed pretraining in four to seven sessions, acquisition required 3 to 12 sessions, and all mice completed at least three reversals. Learning rates were similar in PKU and non‐PKU mice. We discuss issues related to implementation and several potentially useful procedural variations.
STUDIES OF WHEEL‐RUNNING REINFORCEMENT: PARAMETERS OF HERRNSTEIN'S (1970) RESPONSE‐STRENGTH EQUATION VARY WITH SCHEDULE ORDER
Authors: Belke Terry W.
Published: March 2006

Six male Wistar rats were exposed to different orders of reinforcement schedules to investigate if estimates from Herrnstein's (1970) single‐operant matching law equation would vary systematically with schedule order. Reinforcement schedules were arranged in orders of increasing and decreasing reinforcement rate. Subsequently, all rats were exposed to a single reinforcement schedule within a session to determine within‐session changes in responding. For each condition, the operant was lever pressing and the reinforcing consequence was the opportunity to run for 15 s. Estimates of k and RO were higher when reinforcement schedules were arranged in order of increasing reinforcement rate. Within a session on a single reinforcement schedule, response rates increased between the beginning and the end of a session. A positive correlation between the difference in parameters between schedule orders and the difference in response rates within a session suggests that the within‐session change in response rates may be related to the difference in the asymptotes. These results call into question the validity of parameter estimates from Herrnstein's (1970) equation when reinforcer efficacy changes within a session.
EFFECTS OF SLEEP DEPRIVATION ON FREE‐OPERANT AVOIDANCE
Authors: Kennedy Craig H. , Meyer Kim A. , Werts Margaret Gessler , Cushing Lisa Sharon
Published: March 2006

Two studies examined effects of sleep deprivation on free‐operant avoidance by rats. In Experiment 1, a 5‐s shock—shock (SS) interval and 20‐s response—shock (RS) interval produced baseline performances, which were reestablished after each experimental manipulation. Once baselines were established, animals were exposed to 24, 48, or 96 hr of sleep deprivation and equivalent periods of home cage and food restriction as a control condition. Compared to baseline, sleep deprivation increased response rates by increasing the proportion of brief interresponse times (IRTs); response rates changed little in the control conditions. Percentage of shocks avoided did not systematically change across conditions. In Experiment 2, the RS interval was manipulated (10, 20, and 40 s), while the SS interval (5 s) and level of sleep deprivation (48 hr) were held constant. Across RS intervals, sleep deprivation increased response rates via a shift toward brief IRTs. In addition, sleep deprivation increased the percentage of shocks avoided as an inverse function of RS intervals.
CHOICE BETWEEN CONSTANT AND VARIABLE ALTERNATIVES BY RATS: EFFECTS OF DIFFERENT REINFORCER AMOUNTS AND ENERGY BUDGETS
Authors: Ito Masato , Takatsuru Sachifu , Saeki Daisuke
Published: March 2006

Two experiments, using rats as subjects, investigated the effect of different reinforcer amounts and energy budgets on choice between constant and variable alternatives under a closed economy. Rats were housed in the chamber and were exposed to a modified concurrent‐chains schedule in which the choice phase was separated from a rest phase during which the rats could engage in other activities. In the choice phase, a single variable‐interval schedule arranged entry into one of two equal terminal links (fixed‐interval schedules). The constant terminal link ended with the delivery of a fixed number of food pellets (two or three, depending on the condition), whereas the variable terminal link ended with a variable number of food pellets (means of two or three, depending on the condition). Energy budget was defined as positive when body weights were over 90% of free‐feeding weights, and as negative when they were under 80% of free‐feeding weights. The different body weights were produced by varying the duration of the equal terminal‐link schedules within daily 3‐hr sessions. In Experiment 1, rats chose between a constant and a variable three pellets under both energy budgets. Rats preferred the constant three pellets more under the positive energy budget, whereas they were indifferent under the negative energy budget. In Experiment 2, rats chose between a constant three pellets and a variable two pellets, and chose between a constant two pellets and a variable three pellets under both energy budgets. The rats strongly preferred the constant three pellets over the variable two pellets under both energy budgets. In contrast, rats preferred the variable three pellets over the constant two pellets only under the negative energy budget, whereas they were indifferent under the positive energy budget. These results indicate that rats' choices are sensitive to the difference in reinforcer amounts and to the energy budgets defined by the level of body weight. The present results are consistent with those obtained with small granivorous birds as well as with the predictions of a recent risk‐sensitive foraging theory.
EQUIVALENCE CLASSES IN INDIVIDUALS WITH MINIMAL VERBAL REPERTOIRES
Authors: Carr D. , Wilkinson K. M. , Blackman D. , McIlvane W. J.
Published: March 2006

Studies from two different laboratories tested for equivalence classes in individuals with severe mental retardation and minimal verbal repertoires. In the first study, 3 individuals learned several matching‐to‐sample performances: matching picture comparison stimuli to dictated‐word sample stimuli (AB), matching those same pictures to printed letter samples (CB), and also matching the pictures to nonrepresentative forms (DB). On subsequent tests, all individuals immediately displayed Emergent Relations AC, AD, BC, BD, CD, and DC, together constituting a positive demonstration of equivalence (as defined by Sidman). The second study obtained a positive equivalence test outcome in 1 of 2 individuals with similarly minimal verbal repertoires. Taken together, these studies call into question previous assertions that equivalence classes are demonstrable only in individuals with well‐developed language repertoires.
EFFECTS OF COMPETITIVE REWARD DISTRIBUTION ON AUDITING AND COMPETITIVE RESPONDING
Authors: Schmitt David R.
Published: March 2006

This study allowed subjects to audit each other's responding during a series of competitive contests. Six pairs of female college students competed in 3‐min contests in which the competitive response was a knob pull. A sum of money was divided using a proportional distribution or a 100%/0% reward distribution. In the proportional distribution, a subject's proportion of the sum was her proportion of the total number of responses. Also, in every contest either subject could make a response that would end the contest prematurely and give both subjects the same amount: a sum equal to 33% of the competitive total. Each subject could press either or both of two audit buttons that displayed her own and the other's response total for 10 s. Results replicated earlier findings in showing the superiority of the proportional distribution in total number of competitive responses made. No subject audited continuously, and only 1 audited most of the time. Most audits were interpersonal, including both own and other's scores. Auditing typically was more frequent in 100%/0% contests in which subjects were more likely to stop the contest when they were far behind. Winners were more likely to audit than were losers. Competitive response rates increased when the differences revealed by audits were small and decreased when they were large. Overall audit patterns were consistent with the view that feedback as “news” is more often sought when it can lead to improved outcomes.
TIMEOUT POSTPONEMENT WITHOUT INCREASED REINFORCEMENT FREQUENCY
Authors: Pietras Cynthia J. , Hackenberg Timothy D.
Published: March 2006

Three experiments were conducted to examine pigeons' postponement of signaled extinction periods (timeouts) from a schedule of food reinforcement when such responding neither decreased overall timeout frequency nor increased the overall frequency of food reinforcement. A discrete‐trial procedure was used in which a response during the first 5 s of a trial postponed an otherwise immediate 60‐s timeout to a later part of that same trial but had no effect on whether the timeout occurred. During time‐in periods, responses on a second key produced food according to a random‐interval 20‐s schedule. In Experiment 1, the response—timeout interval was 45 s under postponement conditions and 0 s under extinction conditions (responses were ineffective in postponing timeouts). The percentage of trials with a response was consistently high when the timeout‐postponement contingency was in effect and decreased to low levels when it was discontinued under extinction conditions. In Experiment 2, the response—timeout interval was also 45 s but postponement responses increased the duration of the timeout, which varied from 60 s to 105 s across conditions. Postponement responding was maintained, generally at high levels, at all timeout durations, despite sometimes large decreases in the overall frequency of food reinforcement. In Experiment 3, timeout duration was held constant at 60 s while the response—timeout interval was varied systematically across conditions from 0 s to 45 s. Postponement responding was maintained under all conditions in which the response—timeout interval exceeded 0 s (the timeout interval in the absence of a response). In some conditions of Experiment 3, which were designed to control for the immediacy of food reinforcement and food‐correlated (time‐in) stimuli, responding postponed timeout but the timeout was delayed whether a response occurred or not. Responding was maintained for 2 of 3 subjects, suggesting that behavior was negatively reinforced by timeout postponement rather than positively reinforced by the more immediate presentation of food or food‐correlated (time‐in) stimuli.
COMPARING PREFERENCE AND RESISTANCE TO CHANGE IN CONSTANT‐AND VARIABLE‐DURATION SCHEDULE COMPONENTS
Authors: Grace Randolph C. , Nevin John A.
Published: March 2006

Two experiments explored preference and resistance to change in concurrent chains in which the terminal links were variable‐interval schedules that ended either after a single reinforcer had been delivered (variable duration) or after a fixed period of access to the schedule (constant duration). In Experiment 1, pigeons' preference between the same pair of terminal links overmatched relative reinforcement rate when the terminal links were of constant duration, but not when they were of variable duration. Responding during the richer terminal link decreased less, relative to baseline, when response‐independent food was presented during the initial links according to a variable‐time schedule. In Experiment 2, all subjects consistently preferred a terminal link that consisted of 20‐s access to a variable‐interval 20‐s schedule over a terminal link that ended after one reinforcer had been delivered by the same schedule. Results of resistance‐to‐change tests corresponded to preference, as responding during the constant‐duration terminal link decreased less, relative to baseline, when disrupted by both response‐independent food during the initial links and prefeeding. Overall, these data extend the general covariation of preference and resistance to change seen in previous studies. However, they suggest that reinforcement numerosity, including variability in the number of reinforcers per terminal‐link entry, may sometimes affect preference and resistance to change in ways that are difficult to explain in terms of current models.
DERIVED RELATIONAL RESPONDING AS GENERALIZED OPERANT BEHAVIOR
Authors: Healy Olive , Barnes‐Holmes Dermot , Smeets Paul M.
Published: March 2006

The major aim of the present study was to demonstrate that derived relational responding may be viewed as a form of generalized operant behavior. In Experiment 1, 4 subjects were divided into two conditions (2 in each condition). Using a two‐comparison matching‐to‐sample procedure, all subjects were trained and tested for the formation of two combinatorially entailed relations. Subjects were trained and tested across multiple stimulus sets. Each set was composed of novel stimuli. Both Conditions 1 and 2 involved explicit performance‐contingent feedback presented at the end of each block of test trials (i.e., delayed feedback). In Condition 1, feedback was accurate (consistent with the experimenter‐designated relations) following exposure to the initial stimulus sets. When subjects' responding reached a predefined mastery criterion, the feedback then switched to inaccurate (not consistent with the experimenter‐designated relations) until responding once again reached a predefined criterion. Condition 2 was similar to Condition 1, except that exposure to the initial stimulus sets was followed by inaccurate feedback and once the criterion was reached feedback switched to accurate. Once relational responding emerged and stabilized, response patterns on novel stimulus sets were controlled by the feedback delivered for previous stimulus sets. Experiment 2 replicated Experiment 1, except that during Conditions 3 and 4 four comparison stimuli were employed during training and testing. Experiment 3 was similar to Condition 1 of Experiment 1, except that after the mastery criterion was reached for class‐consistent responding, feedback alternated from accurate to inaccurate across each successive stimulus set. Experiment 4 involved two types of feedback, one type following tests for mutual entailment and the other type following tests for combinatorial entailment. Results from this experiment demonstrated that mutual and combinatorial entailment may be controlled independently by accurate and inaccurate feedback. Overall, the data support the suggestion, made by relational frame theory, that derived relational responding is a form of generalized operant behavior.
THE EFFECTS OF MORPHINE ON FIXED‐INTERVAL PATTERNING AND TEMPORAL DISCRIMINATION
Authors: Odum Amy L. , Schaal David W.
Published: March 2006

Changes produced by drugs in response patterns under fixed‐interval schedules of reinforcement have been interpreted to result from changes in temporal discrimination. To examine this possibility, this experiment determined the effects of morphine on the response patterning of 4 pigeons during a fixed‐interval 1‐min schedule of food delivery with interpolated temporal discrimination trials. Twenty of the 50 total intervals were interrupted by choice trials. Pecks to one key color produced food if the interval was interrupted after a short time (after 2 or 4.64 s). Pecks to another key color produced food if the interval was interrupted after a long time (after 24.99 or 58 s). Morphine (1.0 to 10.0 mg/kg) decreased the index of curvature (a measure of response patterning) during fixed intervals and accuracy during temporal discrimination trials. Accuracy was equally disrupted following short and long sample durations. Although morphine disrupted temporal discrimination in the context of a fixed‐interval schedule, these effects are inconsistent with interpretations of the disruption of response patterning as a selective overestimation of elapsed time. The effects of morphine may be related to the effects of more conventional external stimuli on response patterning.
SHIFTS IN THE PSYCHOMETRIC FUNCTION AND THEIR IMPLICATIONS FOR MODELS OF TIMING
Authors: Machado Armando , Guilhardi Paulo
Published: March 2006

This study examined how two models of timing, scalar expectancy theory (SET) and learning to time (LeT), conceptualize the learning process in temporal tasks, and then reports two experiments to test these conceptualizations. Pigeons responded on a two‐alternative free‐operant psychophysical procedure in which responses on the left key were reinforceable during the first two, but not the last two, quarters of a 60‐s trial, and responses on the right key were reinforceable during the last two, but not the first two, quarters of the trial. In Experiment 1 three groups of birds experienced a difference in reinforcement rates between the two keys only at the end segments of the trial (i.e., between the first and fourth quarters), only around the middle segments of the trial (i.e., between the second and third quarters), or in both end and middle segments. In Condition 1 the difference in reinforcement rate favored the left key; in Condition 2 it favored the right key. When the reinforcement rates differed in the end segments of the trial, the psychometric function—the proportion of right responses across the trial—did not shift across conditions; when it occurred around the middle of the trial or in both end and middle segments, the psychometric function shifted across conditions. Experiment 2 showed that the psychometric function shifts even when the overall reinforcement rate for the two keys is equal, provided the rates differ around the middle of the trial. This pattern of shifts of the psychometric function is inconsistent with SET. In contrast, LeT provided a good quantitative fit to the data.
CHOICE, CHANGING OVER, AND REINFORCEMENT DELAYS
Authors: Shahan Timothy A. , Lattal Kennon A.
Published: March 2006

In three experiments, pigeons were used to examine the independent effects of two normally confounded delays to reinforcement associated with changing between concurrently available variable‐interval schedules of reinforcement. In Experiments 1 and 2, combinations of changeover‐delay durations and fixed‐interval travel requirements were arranged in a changeover‐key procedure. The delay from a changeover‐produced stimulus change to a reinforcer was varied while the delay between the last response on one alternative and a reinforcer on the other (the total obtained delay) was held constant. Changeover rates decreased as a negative power function of the total obtained delay. The delay between a changeover‐produced stimulus change had a small and inconsistent effect on changeover rates. In Experiment 3, changeover delays and fixed‐interval travel requirements were arranged independently. Changeover rates decreased as a negative power function of the total obtained delay despite variations in the delay from a change in stimulus conditions to a reinforcer. Periods of high‐rate responding following a changeover, however, were higher near the end of the delay from a change in stimulus conditions to a reinforcer. The results of these experiments suggest that the effects of changeover delays and travel requirements primarily result from changes in the delay between a response at one alternative and a reinforcer at the other, but the pattern of responding immediately after a changeover depends on the delay from a changeover‐produced change in stimulus conditions to a reinforcer.
BEHAVIOR ANALYSIS AND REVALUATION
Authors: Donahoe John W. , Burgos José E.
Published: March 2006

Revaluation refers to phenomena in which the strength of an operant is altered by reinforcer‐related manipulations that take place outside the conditioning situation in which the operant was selected. As an example, if lever pressing is acquired using food as a reinforcer and food is later paired with an aversive stimulus, the frequency of lever pressing decreases when subsequently tested. Associationist psychology infers from such findings that conditioning produces a response—outcome (i.e., reinforcer) association and that the operant decreased in strength because pairing the reinforcer with the aversive stimulus changed the value of the outcome. Here, we present an approach to the interpretation of these and related findings that employs neural network simulations grounded in the experimental analysis of behavior and neuroscience. In so doing, we address some general issues regarding the relations among behavior analysis, neuroscience, and associationism.
CRITICISMS OF THE SATIETY HYPOTHESIS AS AN EXPLANATION FOR WITHIN‐SESSION DECREASES IN RESPONDING
Authors: McSweeney Frances K. , Murphy Eric S.
Published: March 2006

The authors of four papers recently reported that satiation provides a better explanation than habituation for within‐session decreases in conditioned responding. Several arguments question this conclusion. First, the contribution of habituation to within‐session changes in responding seems clearly established. Information that is consistent with habituation, but that is difficult to reconcile with satiation, is not adequately addressed. Second, the limited evidence offered in support of satiation is ambiguous because the results are just as compatible with habituation as with other satiety variables. Finally, the term satiation is used in an intuitive way that is sometimes contradicted by research about the termination of ingestion. Use of the technical term satiation in a way that differs from its conventional usage will only isolate operant psychology from other areas of psychological research.
SITUATIONAL DESCRIPTIONS OF BEHAVIORAL PROCEDURES: THE IN SITU TESTBED
Authors: Kemp Steven M. , Eckerman David A.
Published: March 2006

We demonstrate the In Situ testbed, a system that aids in evaluating computational models of learning, including artificial neural networks. The testbed models contingencies of reinforcement using an extension of Mechner's (1959) notational system for the description of behavioral procedures. These contingencies are input to the model under test. The model's output is displayed as cumulative records. The cumulative record can then be compared to one produced by a pigeon exposed to the same contingencies. The testbed is tried with three published models of learning. Each model is exposed to up to three reinforcement schedules (testing ends when the model does not produce acceptable cumulative records): continuous reinforcement and extinction, fixed ratio, and fixed interval. The In Situ testbed appears to be a reliable and valid testing procedure for comparing models of learning.
BEHAVIORAL MOMENTUM IN COMPUTER‐PRESENTED DISCRIMINATIONS IN INDIVIDUALS WITH SEVERE MENTAL RETARDATION
Authors: Dube William V. , McIlvane William J.
Published: March 2006

Behavioral momentum was examined in 2 individuals with severe mental retardation via within‐subject manipulations of obtained reinforcer rates. Subjects performed self‐paced discrimination problems presented on a touch screen computer monitor. Two different problems, Tasks A and B, alternated in blocks of 15 trials on a multiple schedule. Reinforcers were snack foods. The reinforcement schedule for Task A was continuous (fixed‐ratio 1), and the schedule for Task B was continuous in some conditions and variable ratio in other conditions. Behavioral momentum was assessed in test sessions by prefeeding, presenting response‐independent food, and making available alternatives to the tasks. When the obtained reinforcer rate for Task A was at least twice that for Task B, resistance to change was greater for Task A. When both reinforcer rates and response rates were approximately equal for the two tasks, resistance to change was approximately equal. These results are consistent with behavioral momentum effects. They extend previous findings with humans by examining momentum in self‐initiated discrete‐trial discrimination tasks with ratio schedules, and by isolating relative reinforcer rates as a controlling variable via within‐subject manipulations.
EFFECTS OF RESPONSE DISPARITY ON STIMULUS AND REINFORCER CONTROL IN HUMAN DETECTION TASKS
Authors: Gallagher Stephen , Alsop Brent
Published: March 2006

In two detection experiments, university students reported whether the second of two sequentially presented tones was longer or shorter than the first by responding to stimuli presented on a touch screen. Stimulus disparity and response disparity were manipulated to compare their effects on measures of discrimination and response bias when the reinforcement ratio for correct responses was asymmetric. Choice stimuli consisted of squares filled with different pixel densities. Response disparity was manipulated by varying the difference in density between the two choice stimuli. In both experiments, decreasing stimulus disparity reduced discrimination but had no consistent effect on bias. Decreasing response disparity also reduced discrimination in both experiments, and often reduced estimates of bias. The effects of response disparity on bias were most clear in Experiment 2, in which a greater overall level of response disparity was arranged. The data show that, like corresponding research with pigeons, detection performance of human subjects can be conceptualized as discriminated operants.
REINFORCER‐RATIO VARIATION AND ITS EFFECTS ON RATE OF ADAPTATION
Authors: Landon Jason , Davison Michael
Published: March 2006

Six pigeons were trained in sessions that consisted of six or seven concurrent‐schedule components, each of which could have a different reinforcer ratio arranged in it. The components were unsignaled and occurred in a random order separated by 10‐s blackouts. The overall reinforcer rate arranged in each component was 2.22 reinforcers per minute. In Experiment 1, the range of reinforcer ratios in the seven components was varied from a condition in which the ratios were always 1:1, to a condition in which the ratios varied between concurrent variable‐interval 27 s extinction (EXT) and concurrent extinction variable‐interval 27 s (ratios of 1:EXT, 9:1, 3:1, 1:1, 1:3, 1:9, EXT:1). In Experiment 2, the range of reinforcer ratios was always 27:1 to 1:27, and the presence and absence of the intermediate reinforcer ratios used in Experiment 1 (9:1, 3:1, 1:1, 1:3, 1:9) were investigated. Log response‐allocation ratios in components changed rapidly with increasing numbers of reinforcers in components, and Experiment 1 showed that sensitivity to reinforcement was usually higher when the range of reinforcer ratios was greater. When the range of reinforcer ratios was kept constant in Experiment 2, the presence or absence of less extreme reinforcer ratios had no clear effect on sensitivity. At a local level, individual reinforcers had predictable quantitative effects on response ratios: Successive same‐alternative reinforcers in a component had rapidly diminishing effects in both experiments. Reinforcers obtained on the opposite alternative to one or more prior reinforcers always had large effects on preference, and these changes were greater when the range of reinforcer ratios was greater. The effects of such reinforcers in changing preference were enhanced, and produced clear preference reversals, when intermediate reinforcer ratios were absent in Experiment 2. Two processes, one local to reinforcers and one with a longer time course, may be necessary to account for these results.
RESPONSE RATE VIEWED AS ENGAGEMENT BOUTS: EFFECTS OF RELATIVE REINFORCEMENT AND SCHEDULE TYPE
Authors: Shull Richard L. , Gaynor Scott T. , Grimes Julie A.
Published: March 2006

The rate of a reinforced response is conceptualized as a composite of engagement bouts (visits) and responding during visits. Part 1 of this paper describes a method for estimating the rate of visit initiations and the average number of responses per visit from log survivor plots: the proportion of interresponse times (IRTs) longer than some elapsed time (log scale) plotted as a function of elapsed time. In Part 2 the method is applied to IRT distributions from rats that obtained food pellets by nose poking a lighted key under various multiple schedules of reinforcement. As expected, total response rate increased as a function of (a) increasing the rate of reinforcement (i.e., variable‐interval [VI] 4 min vs. VI 1 min), (b) increasing the amount of the reinforcer (one food pellet vs. four pellets), (c) increasing the percentage of reinforcers that were contingent on nose poking (25% vs. 100%), and (d) requiring additional responses after the end of the VI schedule (i.e., adding a tandem variable‐ratio [VR] 9 requirement). The first three of these variables (relative reinforcement) increased the visit‐initiation rate. The tandem VR, in contrast, increased the number of responses per visit. Thus, variables that have similar effects on total response rate can be differentiated based on their effects on the components of response rate.