bluuebunny/crossref_metadata_2025 huggingface dataset:
TURNING BACK THE CLOCK ON SERIAL‐STIMULUS SIGN TRACKING
Authors: Allan Robert W. , Matthews T. James
Published: March 2006

Two experiments examined the effects of a negative (setback) response contingency on key pecking engendered by a changing light‐intensity stimulus clock (ramp stimulus) signaling fixed‐time 30‐s food deliveries. The response contingency specified that responses would immediately decrease the light‐intensity value, and, because food was delivered only after the highest intensity value was presented, would delay food delivery by 1 s for each response. The first experiment examined the acquisition and maintenance of responding for a group trained with the contingency in effect and for a group trained on a response‐independent schedule with the ramp stimulus prior to introduction of the contingency. The first group acquired low rates of key pecking, and, after considerable exposure to the contingency, those rates were reduced to low levels. The rates of responding for the second group were reduced very rapidly (within four to five trials) after introduction of the setback contingency. For both groups, rates of responding increased for all but 1 bird when the contingency was removed. A second experiment compared the separate effects of each part of the response contingency. One group was exposed only to the stimulus setback (stimulus only), and a second group was exposed only to the delay of the reinforcer (delay only). The stimulus‐only group's rates of responding were immediately reduced to moderate levels, but for most of the birds, these rates recovered quickly when the contingency was removed. The delay‐only group's rates decreased after several trials, to very low levels, and recovery of responding took several sessions once the contingency was removed. The results suggest that (a) sign‐tracking behavior elicited by an added clock stimulus may be reduced rapidly and persistently when a setback contingency is imposed, and (b) the success of the contingency is due both to response‐dependent stimulus change and response‐dependent alterations in the frequency of food delivery. The operation of the contingency is compared with the effects of secondary reinforcement and punishment procedures.
EFFECTS OF VARYING STIMULUS DISPARITY AND THE REINFORCER RATIO IN CONCURRENT‐SCHEDULE AND SIGNAL‐DETECTION PROCEDURES
Authors: Alsop Brent , Davison Michael
Published: March 2006

The present study measured the effects of stimulus and reinforcer variations on pigeons' behavior in two different choice procedures. Two intensities of white light were presented as the stimuli on the main key in a switching‐key concurrent schedule and as the sample stimuli in a signal‐detection procedure. Under both procedures, the scheduled rate of reinforcement was varied across conditions to produce various ratios of obtained reinforcement. These ratios were obtained for seven pairs of light intensities. In the concurrent schedules, the effects of reinforcer‐ratio variations were positively correlated with the physical disparity between the two light intensities. In the signal‐detection procedure, changes in the reinforcer ratio produced greater effects on performance when stimulus disparity was very low or very high compared to those found at intermediate levels of stimulus disparity. This discrepancy creates a dilemma for existing behavioral models of signal‐detection performance.
LOCAL CONTRAST IN BEHAVIOR ALLOCATION DURING MULTIPLE‐SCHEDULE COMPONENTS
Authors: Mclean Anthony P.
Published: March 2006

Allocation of responses between two keys was studied during two alternating multiple‐schedule components. Responses were recorded in successive quarters of each component. Variable‐interval reinforcer schedules on the two keys were constant throughout the experiment for one (constant) component and were varied over conditions on one key for the other, producing changes in reinforcer ratios for the varied component. Behavior allocation for the first quarter of the constant component was inversely related to varied‐component reinforcer ratios, a form of local contrast, but this relationship was not observed later in the component. During the first quarter of the varied component, slopes of matching lines were high and decreased later in the component. It is argued that this form of local contrast cannot be explained in terms of reallocation of extraneous reinforcers between components, and that the matching law for concurrent operants does not capture some sources of control over behavior allocation. A simple extension of the matching law is offered that adequately describes behavior changes during both components. A version of this formulation can predict contrast effects in absolute response rates.
STIMULUS GENERALIZATION, DISCRIMINATION LEARNING, AND PEAK SHIFT IN HORSES
Authors: Dougherty Donald M. , Lewis Paul
Published: March 2006

Using horses, we investigated three aspects of the stimulus control of lever‐pressing behavior: stimulus generalization, discrimination learning, and peak shift. Nine solid black circles, ranging in size from 0.5 in. to 4.5 in. (1.3 cm to 11.4 cm) served as stimuli. Each horse was shaped, using successive approximations, to press a rat lever with its lip in the presence of a positive stimulus, the 2.5‐in. (6.4‐cm) circle. Shaping proceeded quickly and was comparable to that of other laboratory organisms. After responding was maintained on a variable‐interval 30‐s schedule, stimulus generalization gradients were collected from 2 horses prior to discrimination training. During discrimination training, grain followed lever presses in the presence of a positive stimulus (a 2.5‐in circle) and never followed lever presses in the presence of a negative stimulus (a 1.5‐in. [3.8‐cm] circle). Three horses met a criterion of zero responses to the negative stimulus in fewer than 15 sessions. Horses given stimulus generalization testing prior to discrimination training produced symmetrical gradients; horses given discrimination training prior to generalization testing produced asymmetrical gradients. The peak of these gradients shifted away from the negative stimulus. These results are consistent with discrimination, stimulus generalization, and peak‐shift phenomena observed in other organisms.
TEACHING ARBITRARY MATCHING VIA SAMPLE STIMULUS‐CONTROL SHAPING TO YOUNG CHILDREN AND MENTALLY RETARDED INDIVIDUALS: A METHODOLOGICAL NOTE
Authors: Zygmont D. M. , Lazar R. M. , Dube W. V. , Mcilvane W. J.
Published: March 2006

Two experiments demonstrated the efficacy of sample stimulus‐control shaping programs for teaching arbitrary matching to 4 subjects who did not acquire the performances via standard methods (i.e., differential reinforcement and, in two cases, comparison intensity fading). All 4 had previously demonstrated identity matching with two‐dimensional forms. Identity matching performances were then transformed into arbitrary matching by gradually changing the sample stimuli until they no longer resembled the comparison stimuli. Where applicable, these methods may have advantages over others that have been used after the failure of standard techniques.
EFFECTS OF REINFORCER DELAYS ON CHOICE AS A FUNCTION OF INCOME LEVEL
Authors: Hastjarjo Thomas , Silberberg Alan
Published: March 2006

Three rats earned their daily food ration by responding during individual trials either on a lever that delivered one food pellet immediately or on a second lever that delivered three pellets after a delay that was continuously adjusted to ensure substantial responding to both alternatives. Choice of the delayed reinforcer increased when the number of trials per session was reduced. This result suggests that models seeking closure on choice effects must include a parameter reflecting how preference changes with sessionwide income. Moreover, models positing that reinforcer probability and immediacy (1/delay) function equivalently in choice are called into question by the finding that probability and immediacy produce opposing effects when income level is changed.
HUMAN SELF‐CONTROL AND THE DENSITY OF REINFORCEMENT
Authors: Flora Stephen R. , Pavlik William B.
Published: March 2006

Choice responding in adult humans on a discrete‐trial button‐pressing task was examined as a function of amount, delay, and overall density (points per unit time) of reinforcement. Reinforcement consisted of points that were exchangeable for money. In T 0 conditions, an impulsive response produced 4 points immediately and a self‐control response produced 10 points after a delay of 15 s. In T 15 conditions, a constant delay of 15 s was added to both prereinforcer delays. Postreinforcer delays, which consisted of 15 s added to the end of each impulsive trial, equated trial durations regardless of choice, and was manipulated in both T 0 and T 15 conditions. In all conditions, choice was predicted directly from the relative reinforcement densities of the alternatives. Self‐control was observed in all conditions except T 0 without postreinforcer delays, where the impulsive choices produced the higher reinforcement density. These results support previous studies showing that choice is a direct function of the relative reinforcement densities when conditioned (point) reinforcers are used. In contrast, where responding produces intrinsic (immediately consumable) reinforcers, immediacy of reinforcement appears to account for preference when density does not.
CONCEPT LEARNING BY MONKEYS WITH VIDEO PICTURE IMAGES AND A TOUCH SCREEN
Authors: Bhatt Ramesh S. , Wright Anthony A.
Published: March 2006

Two rhesus monkeys were trained in a same/different task to discriminate digitized computer‐stored picture stimuli. The pictures were digitized from 35‐mm slides and presented in pairs on a computer monitor. The monkeys were required to touch the pictures and then make a choice response to indicate whether the pictures were identical or nonidentical. The response areas and stimuli were located to the sides of the picture stimuli. Responses were defined and monitored by an infrared matrix touch screen. After learning the same/different task, both monkeys showed performance accuracy with novel picture stimuli similar to that with training picture stimuli. This accurate novel‐picture transfer indicates that a same/different concept had been learned, a concept similar to the one they had previously demonstrated in a different apparatus with rear‐projected slide stimuli and a response lever.
THE NONEQUIVALENCE OF BEHAVIORAL AND MATHEMATICAL EQUIVALENCE
Authors: Saunders Richard R. , Green Gina
Published: March 2006

Sidman and his colleagues derived behavioral tests for stimulus equivalence from the axiom in logic and mathematics that defines a relation of equivalence. The analogy has generated abundant research in which match‐to‐sample methods have been used almost exclusively to study interesting and complex stimulus control phenomena. It has also stimulated considerable discussion regarding interpretation of the analogy and speculation as to its validity and generality. This article reexamines the Sidman stimulus equivalence analogy in the context of a broader consideration of the mathematical axiom than was included in the original presentation of the analogy and some of the data that have accumulated in the interim. We propose that (a) mathematical and behavioral examples of equivalence relations differ substantially, (b) terminology is being used in ways that can lead to erroneous conclusions about the nature of the stimulus control that develops in stimulus equivalence experiments, and (c) complete analyses of equivalence and other types of stimulus—stimulus relations require more than a simple invocation of the analogy. Implications of our analysis for resolving current issues and prompting new research are discussed.
DYNAMICS IN THE FINE STRUCTURE OF SCHEDULE‐CONTROLLED BEHAVIOR
Authors: Palya William L.
Published: March 2006

The variability in the behavioral equilibrium established by six basic schedules was characterized. The measures were the pause preceding the first response in each interreinforcement interval; the mean rate of responding in each interreinforcement interval; and the relative frequency of each interresponse time. The temporal windows ranged across the 780‐session exposure, across a session, and across the interreinforcement interval. A display of individual interresponse times as a function of time in the interreinforcement interval indicated clear recurrent responding at somewhat less than 3 Hz in every bird, even after extended exposure to a schedule and regardless of the contingency. No strong sequential dependencies in the interresponse‐time distributions were identified. A simulator, based on a simple recurrent pulser, was presented that produced output similar to the obtained data. An archival data base of the behavior chronically maintained by the simple schedules was also generated.
RESISTANCE TO CHANGE AND THE LAW OF EFFECT
Authors: Harper David N. , McLean Anthony P.
Published: March 2006

Three experiments using multiple schedules of reinforcement explored the implications of resistance‐to‐change findings for the response‐reinforcer relation described by the law of effect, using both steady‐state responding and responding recorded in the first few sessions of conditions. In Experiment 1, when response‐independent reinforcement was increased during a third component, response rate in Components 1 and 2 decreased. This response‐rate reduction was proportionately greater in a component in which reinforcer magnitude was small (2‐s access to wheat) than in the component in which it was large (6‐s access to wheat). However, when reinforcer rates in the two components were varied together in Experiments 2 and 3, response‐rate change was the same regardless of the magnitude of reinforcers used in the two components, so that sensitivity of response rates to reinforcer rates (Experiment 2) and of response‐rate ratios to reinforcer‐rate ratios (Experiment 3) was unaffected by the magnitude of the reinforcers. Therefore, the principles determining resistance to change, described by behavioral momentum theory, seem not to apply when the source of behavior change is the variation of reinforcement contingencies that maintain the behavior. The use of extinction as a manipulation to study resistance to change is questioned.
APPLYING LINEAR SYSTEMS ANALYSIS TO DYNAMIC BEHAVIOR
Authors: McDowell J. J. , Bass Ronald , Kessel Robert
Published: March 2006

In this paper we present an abbreviated discussion of the linear systems analysis in the time domain. We then consider the qualitative character of the behavioral dynamics predicted using the linear form of the analysis. The analysis is then extended to a second‐order form. We illustrate some relevant new features introduced by the second‐order form with a special case example.
COMPARISON OF VARIANCE AND COVARIANCE PATTERNS IN PARALLEL AND SERIAL THEORIES OF TIMING
Authors: Gibbon John , Church Russell M.
Published: March 2006

Parallel and serial timing processes are analyzed for their account of the dynamics of intertrial responding in the peak procedure. A strictly serial model, such as the behavioral theory of timing (Killeen & Fetterman, 1988), does not fit the dynamic correlation pattern in the location and duration of the middle high‐rate responding portion of peak trials. In contrast, the parallel scalar expectancy theory model, with a sample for memory and threshold, does fit this pattern. A modification of the serial model is presented that also accommodates the within‐trial covariance pattern. The modification, which is formally equivalent to a model for human tapping (Wing & Kristofferson, 1973), entails the addition of concurrent processes operating in parallel with serial timing.
MECHANICS OF THE ANIMATE
Authors: Killeen Peter R.
Published: March 2006

Behavior is treated as basic physics. Dimensions are identified and their transformations from physical specification to axes in behavioral space are suggested. Responses are treated as action patterns arrayed along a continuum of activation energy. Behavior is seen as movement along a trajectory through this behavior space. Incentives or reinforcers are attractors in behavior space, at the centers of basins of lowered potential. Trajectories impinging on such basins may be captured; repeated capture will warp the trajectory toward a geodesic, a process called conditioning. Conditioning is enhanced by contiguity, the proximity between the measured behavior and the incentive at the end of the trajectory, and by contingency, the depth of the trajectory below the average level of the potential energy landscape. Motivation is seen as the potential of an organism for motion under the forces impinging on it. Degree of motivation is characterized by the depth of the potential field, with low motivation corresponding to a flat field and a flat gradient of activation energy. Drives are the forces of incentives propagated through behavior space. Different laws for the attenuation of drive with behavioral distance are discussed, as is the dynamics of action. The basic postulate of behavior mechanics is incentive‐tracking in behavior space, the energy for which is provided by decreases in potential. The relation of temporal gradients to response differentiation and temporal discrimination is analyzed. Various two‐body problems are sketched to illustrate the application of these ideas to association, choice, scalar timing, self‐control, and freedom.
ADVENTITIOUS CONTROL BY THE LOCATION OF COMPARISON STIMULI IN CONDITIONAL DISCRIMINATIONS
Authors: Sidman Murray
Published: March 2006

In a conditional discrimination procedure, samples appeared in a center key, and comparisons appeared in two of four outer keys. The location of comparison keys varied from trial to trial. Separate learning curves for each of the six possible pairs of comparison keys were plotted in a signal‐detection space, revealing different patterns of progress on each pair. Also, when learned conditional discriminations were disrupted, pairs of keys differed in their patterns of disruption. Varying the location of comparison stimuli among six different pairs of keys had not eliminated key position as a controlling aspect of the stimuli. The variations simply increased the number of stimulus compounds—key position and experimental stimuli—that the subject learned. Plotting conditional‐discrimination learning curves in a signal‐detection space reveals relations among hits, false alarms, accuracy, and comparison preference that help to define a subject's progress.
THE AUTOSHAPING PROCEDURE AS A RESIDUAL BLOCK CLOCK
Authors: Dinsmoor James A. , Dougan James D. , Pfister John , Thiels Edda
Published: March 2006

In the first experiment, 4 pigeons were each presented with a recurring sequence of four key colors followed by the delivery of grain (block clock). Once the rate of pecking had stabilized, three of the colors were replaced, during different series of sessions, by a darkening of the key. The rate of pecking was reduced within those segments of the interval between deliveries of food during which the key was dark; when the key was dark during the final portion of the interval, rates were reduced throughout the entire interval. In the second experiment, 3 new pigeons were exposed to a different sequence of colors, and the final stimulus was replaced in successive conditions by a novel color, a darkened key, and a restoration of the original color. The data indicated that darkening the key had a more severe, more extensive, and more persistent effect than did a mere change in color. These results suggest that it may be fruitful to conceptualize the autoshaping procedure as a special version of the block clock in which pecking is suppressed throughout the greater part of the interval by darkening the key. In the final condition, the same stimulus appeared in each of the last three portions of the interval. The rate of pecking was lower during the last two portions than when distinctive colors were presented, with the peak rate now appearing in the fifth of seven equal temporal components.
MAXIMIZING VERSUS MATCHING ON CONCURRENT VARIABLE‐INTERVAL SCHEDULES
Authors: Vyse Stuart A. , Belke Terry W.
Published: March 2006

Maximization and matching predictions were examined for a time‐based analogue of the concurrent variable‐interval variable‐ratio schedule. One alternative was a variable interval whose time base operated relatively independent of the schedule chosen, and the other was a discontinuous variable interval for which timing progressed only when selected. Pigeons switched between schedules by pecking a changeover key. The maximization hypothesis predicts that subjects will show a bias toward the discontinuous variable interval and undermatching; however the obtained results conformed closely to the predictions of the matching law. Finally, a quantitative comparison was made of the bias and sensitivity estimates obtained in published concurrent variable‐interval variable‐ratio analogue studies. Results indicated that only the ratio‐based analogue of the concurrent variable interval variable ratio studied by Green, Rachlin, and Hanson (1983) produced significant bias toward the variable‐ratio alternative and undermatching, as predicted by reinforcement maximization.
CONJOINT SCHEDULES OF TIMEOUT DELETION IN PIGEONS
Authors: Hackenberg Timothy D.
Published: March 2006

This experiment attempted to bring behavior under joint control of two distinct contingencies, one that provided food and a second that extended the periods during which that food was available. Pigeons' responses on each of two keys were reinforced according to a single random‐interval schedule of food presentation except during signaled timeout periods during which the schedule was temporarily disabled. By means of a conjoint schedule, responses on the initially less preferred key not only produced food but also canceled impending timeouts. When behavior came to predominate on this conjoint alternative, the consequences of responding on the two keys were reversed. Responding in 3 of 4 pigeons proved sensitive to the conjoint scheduled consequences, as evidenced by systematic shifts in response rates favoring the conjoint key. In 2 of these 3 pigeons, sensitivity to the conjoint contingency was evident under time‐in: timeout ratios of 2:1 (time‐in / 120 s, timeout / 60 s) and 1:5 (time‐in / 30 s, timeout = 150 s), whereas for the other pigeon preference for the conjoint key was observed only under the latter sequence of conditions. There was only weak evidence of control by the conjoint scheduled consequences in the 4th subject, despite extended training and forced exposure to the conjoint alternative. The overall pattern of results in consistent with studies of timeout avoidance but also shares features in common with positively reinforced behavior.
CHOICE BETWEEN FIXED‐INTERVAL SCHEDULES: GRADED VERSUS STEP‐LIKE CHOICE FUNCTIONS
Authors: Shull Richard L.
Published: March 2006

Pigeons chose between two fixed‐interval schedules of food reinforcement. A single peck on one of two lighted keys started the fixed‐interval schedule correlated with that key. The schedule had to be completed before the next choice opportunity. The durations of the fixed intervals were varied over conditions from 15 s to 40 s. To maximize the rate of reinforcement, the pigeons had to choose exclusively the shorter of the two schedules. Nevertheless, choice was not all‐or‐none. Instead, relative choice, and the rates of producing the fixed intervals, varied in a graded fashion with the disparity between the two schedules. Choice ratios under this procedure (single response to choose) were highly sensitive to the ratios of the fixed‐interval schedules.
THE INFLUENCE OF “PREPAREDNESS” ON AUTOSHAPING, SCHEDULE PERFORMANCE, AND CHOICE
Authors: Burns James D. , Malone John C.
Published: March 2006

Two groups of experimentally naive pigeons were exposed to an autoshaping procedure in which the response key was mounted on the wall (the conventional location) or on the floor of the chamber. In two experiments, subjects readily responded to the wall key, but floor‐key subjects required shaping. A subsequent experiment compared performance of wall‐ and floor‐key groups on an ascending series of fixed‐ratio schedule values, resistance to extinction, differential reinforcement of other behavior, and reversal of key assignment. Each experiment was followed by several sessions of fixed‐ratio training; the performance of the wall‐ and floor‐key groups was almost identical throughout. In the final experiment, a fixed‐ratio requirement could be completed on either or both keys. Birds initially chose the key on which they had responded during the preceding (reversal of key assignment) experiment. However, within a few sessions both groups showed almost exclusive preference for the floor key. Preference for a key located on the floor may follow from the fact that pigeons are ground feeders and may thus be more “prepared” to peck the floor than to peck a wall. However, autoshaping, under the conditions prevailing here, occurred much more readily to the wall key, suggesting that pecking a vertical surface is more highly prepared. Difficulties in determining relative preparedness seem moot, however, given the lack of between‐group differences in the intervening experiments. It is thus unlikely that schedule performances critically depend upon the specific operant response involved.
CONTRAST AND REALLOCATION OF EXTRANEOUS REINFORCERS BETWEEN MULTIPLE‐SCHEDULE COMPONENTS
Authors: Mclean Anthony P.
Published: March 2006

Four pigeons responded in components of multiple schedules in which two responses were available and reinforced with food. Pecks on the left key (“main” key) were reinforced at a constant rate in one component and at a rate that varied over conditions in the other component. When reinforcer rate was varied, behavioral contrast occurred in the constant component. On the right key (“extra” key), five variable‐interval schedules and one variable‐ratio schedule, presented conjointly, arranged reinforcers for responses in all conditions. These conjoint schedules were common to both multiple‐schedule components—rather than unique to particular components—and reinforcers from these schedules could therefore be arranged in one component and obtained during the other component. In this way, the additional reinforcers were analogous to the “extraneous” reinforcers thought to maintain behavior other than pecking in conventional multiple schedules. Response rate on the extra key did not change systematically over conditions in the constant component, and in the varied component extra responding was inversely related to main‐key reinforcement. All subjects obtained more extra‐key reinforcers in whichever component arranged fewer main‐key reinforcers. Consistent with the theory that reallocation of extraneous reinforcers may cause behavioral contrast, absolute reinforcer rate for the extra key in the constant component was low in conditions that produced positive contrast on the main key and high in those that produced negative contrast. Also consistent with this theory, behavioral contrast was reduced in two conditions that canceled extra‐key reinforcers that had been arranged but not obtained at the end of components. Thus, a constraint on reallocation markedly reduced the extent of contrast.
INTERTRIAL‐INTERVAL EFFECTS ON SENSITIVITY (A′) AND RESPONSE BIAS (B″) IN A TEMPORAL DISCRIMINATION BY RATS
Authors: Raslear Thomas G. , Shurtleff David , Simmons Larry
Published: March 2006

Killeen and Fetterman's (1988) behavioral theory of animal timing predicts that decreases in the rate of reinforcement should produce decreases in the sensitivity (A′) of temporal discriminations and a decrease in miss and correct rejection rates (decrease in bias toward “long” responses). Eight rats were trained on a 10‐ versus 0.1‐s temporal discrimination with an intertrial interval of 5 s and were subsequently tested on probe days on the same discrimination with intertrial intervals of 1, 2.5, 5, 10, or 20 s. The rate of reinforcement declined for all animals as intertrial interval increased. Although sensitivity (A′) decreased with increasing intertrial interval, all rats showed an increase in bias to make long responses.
SEQUENCES OF SPACED RESPONSES: BEHAVIORAL UNITS AND THE ROLE OF CONTIGUITY
Authors: Schneider Susan M. , Morris Edward K.
Published: March 2006

Sequences of temporally spaced responses were reinforced to investigate the effects of delay of reinforcement on the formation of functional behavioral units. In Experiment 1, rats' two‐ and three‐response demarcated sequences of left and right lever presses were reinforced such that different response distributions would occur depending on whether the sequences themselves or individual responses were functional units. The matching law could thus be obeyed either by individual responses or by sequences, but not by both; intermediate results were possible. Both regular (nonretractable) and retractable levers were used; the retractable levers precluded the occurrence of insufficiently spaced responses. At a minimum interresponse time of 5 s for regular levers and 7 s for retractable ones, matching results were intermediate, with greater evidence of sequence conditionability in the two‐response sequences than in the three‐response sequences. In Experiment 2, the required minimum interresponse spacing for two‐response retractable‐lever sequences was varied in an attempt to locate the sequence matching threshold. This attempt was unsuccessful, but the sequences (instead of individual responses) more closely obeyed the matching law. In the shortest spaced condition, conditional probability data on Lag 1 sequence emission order showed marked, highly similar patterning for all rats, indicating sequential control of the sequences. Post hoc definition of the behavioral unit in these studies is ambiguous. Although reinforcement contiguity was important, aspects of the results could support both molar‐ and molecular‐level interpretations.
CONDITIONED REINFORCEMENT OF HUMAN OBSERVING BEHAVIOR BY DESCRIPTIVE AND ARBITRARY VERBAL STIMULI
Authors: Perone Michael , Kaminski Barbara J.
Published: March 2006

College students earned monetary reinforcers by pressing a key according to a compound schedule with variable‐interval and extinction components. Pressing additional keys occasionally produced displays of either of two verbal stimuli; one was uncorrelated with the schedule components, and the other was correlated with the extinction component. In Experiments 1 and 2, the display area of the apparatus was blank unless an observing key was pressed, whereupon a descriptive message appeared. Most students preferred an uncorrelated stimulus stating that “Some of this time scores are TWICE AS LIKELY as normal, and some of this time NO SCORES can be earned” over a stimulus stating that “At this time NO SCORES can be earned.” In Experiment 3, the display area indicated that “The Current Status of the Program is: NOT SHOWN.” Presses on the observing keys replaced this message with stimuli that provided arbitrary labels for the schedule conditions. All of the students preferred a stimulus stating that “The Current Status of the Program is: B” over an uncorrelated stimulus stating that “The Current Status of the Program is: either A or B.” Thus, under some circumstances, observing was maintained by a stimulus correlated with extinction—a finding that poses a challenge for Pavlovian accounts of conditioned reinforcement. Differences in the maintenance of observing by the descriptive and arbitrary stimuli may be attributed to differences in either the strength or nature of the instructional control exerted by the verbal stimuli.
MOLAR VERSUS LOCAL REINFORCEMENT PROBABILITY AS DETERMINANTS OF STIMULUS VALUE
Authors: Williams Ben A.
Published: March 2006

During one component of a multiple schedule, pigeons were trained on a discrete‐trial concurrent variable‐interval variable‐interval schedule in which one alternative had a high scheduled rate of reinforcement and the other a low scheduled rate of reinforcement. When the choice proportion between the alternatives matched their respective relative reinforcement frequencies, the obtained probabilities of reinforcement (reinforcer per peck) were approximately equal. In alternate components of the multiple schedule, a single response alternative was presented with an intermediate scheduled rate of reinforcement. During probe trials, each alternative of the concurrent schedule was paired with the constant alternative. The stimulus correlated with the high reinforcement rate was preferred over that with the intermediate rate, whereas the stimulus correlated with the intermediate rate of reinforcement was preferred over that correlated with the low rate of reinforcement. Preference on probe tests was thus determined by the scheduled rate of reinforcement. Other subjects were presented all three alternatives individually, but with a distribution of trial frequency and reinforcement probability similar to that produced by the choice patterns of the original subjects. Here, preferences on probe tests were determined by the obtained probabilities of reinforcement. Comparison of the two sets of results indicates that the availability of a choice alternative, even when not responded to, affects the preference for that alternative. The results imply that models of choice that invoke only obtained probability of reinforcement as the controlling variable (e.g., melioration) are inadequate.
TESTING A STOCHASTIC FORAGING MODEL IN AN OPERANT SIMULATION: AGREEMENT WITH QUALITATIVE BUT NOT QUANTITATIVE PREDICTIONS
Authors: Roberts William A.
Published: March 2006

An operant simulation of foraging through baited and empty patches was studied with 4 pigeons. On a three‐key panel, side keys were designated as patches, and successive opportunities to complete 16 fixed‐ratio 10 schedules on side keys were defined as encounters with feeders. In a random half of the patches in any session, some of the fixed‐ratio 10 schedules yielded reinforcement (baited feeders) and the other schedules yielded nonreinforcement (empty feeders). In the other half of the patches, all feeders were empty. Pigeons could travel between patches at any time by completing a fixed‐ratio schedule on the center key. An optimal foraging model was tested in Experiments 1 and 2 by varying center‐key travel time and number of baited feeders in baited patches. The ordinal predictions that number of feeders visited in empty patches would increase with travel time and decrease as number of baited feeders increased were supported, but pigeons visited far more feeders in empty patches than the optimal number predicted by the model to maximize energy/time. In Experiment 3, evidence was found to suggest that the number of empty feeders encountered before the first baited feeder in baited patches is an important factor controlling leaving empty patches.
PSYCHOLOGICAL DISTANCE TO REWARD: SEGMENTATION OF APERIODIC SCHEDULES OF REINFORCEMENT
Authors: Leung Jin‐Pang
Published: March 2006

College students responded for monetary rewards in two experiments on choice between differentially segmented aperiodic schedules of reinforcement. On a microcomputer, the concurrent chains were simulated as an air‐defense video game in which subjects used two radars for detecting and destroying enemy aircraft. To earn more cash‐exchangeable points, subjects had to shoot down as many planes as possible within a given period of time. For both experiments, access to one of two radar systems (terminal link) was controlled by a pair of independent concurrent variable‐interval 60‐s schedules (initial link) with a 4‐s changeover delay always in effect. In Experiment 1, the appearance of an enemy aircraft in the terminal link was determined by a variable‐interval (15 s or 60 s) schedule or a two‐component chained variable‐interval schedule of equal duration. Experiment 2 was similar to Experiment 1 except for the segmented schedule, which had three components. Subjects preferred the unsegmented schedule over its segmented counterpart in the conditions with variable‐interval 60 s, and preference tended to be more pronounced with more components in the segmented schedule. These findings are compatible with those from previous studies of periodic and aperiodic schedules with pigeons or humans as subjects.
CONCURRENT ACTIVITIES AND INSTRUCTED HUMAN FIXED‐INTERVAL PERFORMANCE
Authors: Barnes Dermot , Keenan Michael
Published: March 2006

Two experiments explored the effects of two types of concurrent activity on human fixed‐interval performance. Eight adult subjects were given access to either reading material or a working television set across three fixed‐interval values (60 s, 300 s, and 600 s). During Experiment 1, 2 subjects produced “scalloped” patterns and reported no verbal regulation (e.g., counting) in the presence of the reading material, but shifted to low‐rate patterns and reported verbal regulation when the reading material was withdrawn. The 2 other subjects in Experiment 1 produced consistent low‐rate performances and reported verbal regulation during access to reading material. However, when these subjects were given access to a working television set, they produced scalloped patterns and reported no verbal regulation. During Experiment 2, 4 experimentally naive subjects showed consistent scalloped patterning and no verbal regulation across fixed‐interval values when they were allowed to watch television. When access to the television was denied, subjects reliably reported verbal regulation, and low‐rate patterns emerged. These behavioral effects focus our attention on the contingencies that control human performance on fixed‐interval schedules.
A TRANSFER OF FUNCTIONS THROUGH DERIVED ARBITRARY AND NONARBITRARY STIMULUS RELATIONS
Authors: Barnes Dermot , Keenan Michael
Published: March 2006

During Experiments 1 and 2, subjects were trained in a series of related conditional discriminations in a matching‐to‐sample format (A1‐B1, A1‐C1 and A2‐B2, A2‐C2). A low‐rate performance was then explicitly trained in the presence of B1, and a high‐rate performance was explicitly trained in the presence of B2. The two types of schedule performance transferred to the C stimuli for all subjects in both experiments, in the absence of explicit reinforcement through equivalence (i.e., C1 / low rate and C2 = high rate). In Experiment 2, it was also shown that these discriminative functions transferred from the C1‐C2 stimuli to two novel stimuli that were physically similar to the C stimuli (SC1 and SC2, respectively). For both these experiments, subjects demonstrated the predicted equivalence responding during matching‐to‐sample equivalence tests. In Experiments 3 and 4, the conditional discrimination training from the first two experiments was modified in that two further conditional discrimination tasks were trained (C1‐D1 and C2‐D2). However, for these tasks the D stimuli served only as positive comparisons, and ND1 and ND2 stimuli served as negative comparisons (i.e., C1 × ND1 and C2 × ND2). Subsequent to training, the negatively related stimuli (ND1 and ND2) did not become discriminative for the schedule performances explicitly trained in the presence of B1 and B2, respectively. Instead, the ND1 stimulus became discriminative for the schedule performance trained in the presence of B2, and ND2 became discriminative for the schedule performance trained in the presence of B1. All subjects from Experiment 4 showed that the novel stimulus SND1, which was physically similar to ND1, became discriminative for the same response pattern as that controlled by ND1. Similarly, SND2, which was physically similar to ND2, became discriminative for the same response pattern as that controlled by ND2. Subjects from both Experiments 3 and 4 also produced equivalence responding on matching‐to‐sample equivalence tests that corresponded perfectly to the derived performances shown on the transfer of discriminative control tests.
SESSION DURATION AND THE VI RESPONSE FUNCTION: WITHIN‐SESSION PROSPECTIVE AND RETROSPECTIVE EFFECTS
Authors: Dougan James D. , Kuh J. Alfred , Vink K. L.
Published: March 2006

Two experiments examined the effects of session duration on responding during simple variable‐interval schedules. In Experiment 1, rats were exposed to a series of simple variable‐interval schedules differing in both session duration (10 min or 30 min) and scheduled reinforcement rate (7.5 s, 15 s, 30 s, and 480 s). The functions relating response rate to reinforcement rate were predominantly monotonic for the short (10‐min) sessions but were predominantly bitonic for the long (30‐min) sessions, when data from the entire session were considered. Examination of responding within sessions suggested that differences in the whole‐session data were produced by a combination of prospective processes (i.e., processes based on events scheduled to occur later in the session) and retrospective processes (i.e., processes based on events that had already occurred in the session). In Experiment 2, rats were exposed to a modified discrimination procedure in which pellet flavor (standard or banana) predicted session duration (10 min or 30 min). All rats came to respond faster during the short (10‐min) sessions than during the first 10 min of the long sessions. As in Experiment 1, the results seemed to reflect the simultaneous operation of both prospective and retrospective processes. The results shed light on the recent controversy over the form of the variable‐interval response function by identifying one variable (session duration) and two types of processes (prospective and retrospective) that influence responding on these schedules.
SCHEDULE‐INDUCED DEFECATION BY RATS DURING RATIO AND INTERVAL SCHEDULES OF FOOD REINFORCEMENT
Authors: Wylie A. Michael , Layng Michael P. , Meyer Kim A.
Published: March 2006

Lever pressing in rats was maintained by continuous and intermittent schedules of food while defecation was monitored. In Experiment 1, reinforcement densities were matched across variable‐ratio and variable‐interval schedules for three pairs of rats. Defecation occurred in all 3 rats on the variable‐ratio schedule and in all 3 rats on the yoked variable‐interval schedule. In Experiment 2, fixed‐ratio and fixed‐interval schedules with similar reinforcement densities maintained lever pressing. Defecation occurred in 3 of 4 rats on the fixed‐ratio schedule and in 4 of 4 rats on the fixed‐interval schedule. Almost no defecation occurred during continuous reinforcement in either experiment. These results demonstrate that defecation may occur during both ratio and interval schedules and that the interreinforcement interval is more important than the behavioral requirements of the schedule in generating schedule‐induced defecation.
UNIT PRICE AS A USEFUL METRIC IN ANALYZING EFFECTS OF REINFORCER MAGNITUDE
Authors: DeGrandpre R. J. , Bickel Warren K. , Hughes John R. , Layng Michael P. , Badger Gary
Published: March 2006

In this paper, we applied the behavioral‐economic concept of unit price to the study of reinforcer magnitude in an attempt to provide a consistent account of the effects of reinforcer magnitude on behavior. Recent research in the experimental analysis of behavior and in behavioral pharmacology suggests that reinforcer magnitude interacts with the schedule of reinforcement to determine response rate and total consumption. The utility of the unit‐price concept thus stems from its ability to quantify this interaction as a cost‐benefit ratio (i.e., unit price = characteristics of the schedule of reinforcement divided by magnitude of reinforcement). Research employing the unit‐price concept has shown that as unit price increases, a positively decelerating function exists for consumption (i.e., a function with an increasingly negative slope, when plotted on log coordinates) and a bitonic function exists for response rate. Based on these findings, the present analysis applied the unit‐price concept to those studies of reinforcer magnitude and drug self‐administration that examined the effects of reinforcer magnitude on response rate using simple schedules of reinforcement (e.g., fixed‐ratio schedule). This resulted in three findings: (a) Reinforcer‐magnitude manipulations and schedule manipulations interact in a manner that can be quantified in terms of unit price as benefit and cost factors, respectively; (b) different reinforcer‐magnitude manipulations are functionally interchangeable as benefit factors in the unit‐price ratio; and (c) these conclusions appear warranted despite differences in reinforcers (food or drug), species (dogs, monkeys, or rats), and schedules (interval or ratio), and despite the fact that these studies were not designed for a unit‐price analysis. In methodological terms, these results provide further evidence that employing the unit‐price concept is a parsimonious method for examining the effects of reinforcer magnitude. In theoretical terms, these results suggest that a single process may underlie the effect of combined reinforcer‐magnitude and schedule manipulations.
THE ROLE OF AUTOSHAPING IN COOPERATIVE TWO‐PLAYER GAMES BETWEEN STARLINGS
Authors: Reboreda Juan C. , Kacelnik Alejandro
Published: March 2006

We report a study of the behavior of starlings in laboratory situations inspired by the “prisoner's dilemma.” Our purpose is to investigate some possible mechanisms for the maintenance of cooperation by reciprocity and to investigate the process of autoshaping at a trial‐by‐trial level. In Experiment 1, pairs of starlings housed in adjacent cages played a discrete‐trial “game” in which food could be obtained only by “cooperation.” In this game, pecking at a response key eliminated the opportunity to obtain food but produced food for the partner. If neither bird pecked, neither had the opportunity to obtain food in that trial. Some level of cooperation persisted for several sessions whether the birds had been pretrained for a high or low probability of pecking at the key. The probability of a cooperative response was higher after trials in which the partner responded (and a reward was obtained) than after trials in which neither bird responded (and no reward was obtained), but the probability of a response was even higher after trials in which the same bird had responded, even though no reward was obtained by the actor in these trials. This behavior did not require visual presence of another player, because similar results were obtained in Experiment 2 (a replicate of Experiment 1 in which the members of the pair could not see each other) and in Experiment 3, a game in which each starling played with a computer responding with “tit for tat.” Using an omission schedule, in which food was given in all trials in which the bird did not peck, Experiment 4 showed that pecking could be maintained by autoshaping. In this experiment, overall probability of pecking decreased with experience, due to a drop in the tendency to peck in consecutive trials. The probability of pecking in trials following a reinforced trial did not decrease with experience. An implementation of the Rescorla‐Wagner model for this situation was capable of reproducing molar, but not molecular, aspects of our results. The results violate the predictions of several game‐theoretical models for the evolution of cooperation, including tit for tat, generous tit for tat, and the superior win‐stay‐lose‐shift.