bluuebunny/crossref_metadata_2025 huggingface dataset:
IN SEARCH OF THE FEEDBACK FUNCTION FOR VARIABLE‐INTERVAL SCHEDULES
Authors: Baum William M.
Published: March 2006

Finding a theoretically sound feedback function for variable‐interval schedules remains an important unsolved problem. It is important because interval schedules model a significant feature of the world: the dependence of reinforcement on factors beyond the organism's control. The problem remains unsolved because no feedback function yet proposed satisfies all the theoretical and empirical requirements. Previous suggestions that succeed in fitting data fail theoretically because they violate a newly recognized theoretical requirement: The slope of the function must approach or equal 1.0 at the origin. A function is presented that satisfies all requirements but lacks any theoretical justification. This function and two suggested by Prelec and Herrnstein (1978) and Nevin and Baum (1980) are evaluated against several sets of data. All three fitted the data well. The success of the two theoretically incorrect functions raises an empirical puzzle: Low rates of reinforcement are coupled with response rates that seem anomalously high. It remains to be discovered what this reflects about the temporal patterning of operant behavior at low reinforcement rates. A theoretically and empirically correct function derived from basic assumptions about operant behavior also remains to be discovered.
ON IMMEDIATE FUNCTION
Authors: Zeiler Michael D.
Published: March 2006

Behavior is a property of living organisms, not of inanimate matter. The problems of physical science are to understand how a phenomenon works; biological science adds the questions of what a phenomenon does and how something that does such things came to be. Exclusive dedication to cause‐effect explanations ignores how behavior helps creatures cope with their internal and external environments. Laws of causation describe the precursors to behavior; laws of function describe the effects of behavior. The numerous instances of learning reflect the many ways that selective pressure for altering behavior on the basis of experience has been manifested. Little basis exists for assuming that the various forms of learning reflect either common functions or common processes. Instead, it seems that evolutionary processes have resulted in domain‐specific learning. The rules of learning must be understood in terms of the function that the particular manifestation of learning serves for the organism. Evolutionary theory provides the framework for understanding function as well as relations between function and causal mechanisms.
STIMULUS CONTROL OF BEHAVIORAL HISTORY
Authors: Freeman Timothy J. , Lattal Kennon A.
Published: March 2006

Pigeons were exposed to two different reinforcement schedules under different stimulus conditions in each of two daily sessions separated by 6 hr (Experiments 1 and 2) or in a single session (Experiment 3). Following this, either a fixed‐interval (Experiment 1) or a variable‐interval schedule (Experiments 2 and 3) was effected in both stimulus conditions. In the first two experiments, exposure to fixed‐ratio or differential‐reinforcement‐of‐low‐rate schedules led to response‐rate, but not pattern, differences in subsequent performance on fixed‐ or variable‐interval schedules that persisted for up to 60 sessions. The effects of reinforcement‐schedule history on fixed‐interval schedule performance generally were more persistent. In Experiment 3, a history of high and low response rates in different components of a multiple schedule resulted in subsequent response‐rate differences under identical variable‐interval schedules. Higher response rates initially occurred in the component previously correlated with high response rates. For 3 of 4 subjects, the differences persisted for 20 or more sessions. Previous demonstrations of behavioral history effects have been confined largely to between‐subject comparisons. By contrast, the present results demonstrate strong behavioral effects of schedule histories under stimulus control within individual subjects.
THE DEVELOPMENT OF FUNCTIONAL AND EQUIVALENCE CLASSES IN HIGH‐FUNCTIONING AUTISTIC CHILDREN: THE ROLE OF NAMING
Authors: Eikeseth Svein , Smith Tristram
Published: March 2006

The development of functional and equivalence classes was studied in four high‐functioning, preschool‐aged autistic children. Initially, all subjects failed to demonstrate match‐to‐sample relations indicative of stimulus equivalence among two three‐member classes of visual stimuli. Then, 2 subjects showed emergence of those relations after they were taught to assign the same name to all members in each class. Next, subjects were taught names for new stimuli outside the match‐to‐sample format. On subsequent match‐to‐sample tests, 2 subjects demonstrated untrained conditional relations among the stimuli given a common name. New, unnamed stimuli were then related via match‐to‐sample training to stimuli from sets of named stimuli. Tests for emergent conditional relations between the new unnamed stimuli and the named stimuli yielded positive results for 1 subject and somewhat mixed results for 3 subjects. Finally, without naming, 2 subjects developed stimulus equivalence among two new three‐member classes of visual stimuli. These data suggest that naming may remediate failures to develop untrained conditional relations, some of which are indicative of stimulus equivalence.
PATTERNS OF RESPONDING WITHIN SESSIONS
Authors: McSweeney Frances K. , Hinson John M.
Published: March 2006

Rates of responding changed systematically across sessions for rats pressing levers and keys and for pigeons pressing treadles and pecking keys. A bitonic function in which response rates increased and then decreased across sessions was the most common finding, although an increase in responding also occurred alone. The change in response rate was usually large. The function relating responding to time in session had the following general characteristics: It appeared early in training, and further experience moved and reduced its peak; it was flatter for longer sessions; and it was flatter, more symmetrical, and peaked later for lower than for higher rates of reinforcement. Factors related to reinforcement exerted more control over the location of the peak rate of responding and the steepness of the decline in response rates than did factors related to responding. These within‐session changes in response rates have fundamental theoretical and methodological implications.
CONTINUOUS VERSUS DISCRETE DIMENSIONS OF REINFORCEMENT SCHEDULES: AN INTEGRATIVE ANALYSIS
Authors: Williams Dean C. , Johnston James M.
Published: March 2006

An approach to reinforcement‐schedule contingencies is presented that accommodates continuous as well as discrete effective dimensions of responses and reinforcers. College students' wheel turning was reinforced by projected reading material according to four schedule contingencies that incorporated either a discontinuous (count) or continuous (duration) dimension of the response and the reinforcer. The contingencies arranged a 1:1 correspondence between (a) response count and consequent stimulus count, (b) response duration and stimulus count, (c) response count and stimulus duration, and (d) response duration and stimulus duration. Contingencies incorporating response count produced moderate to high rates of very short‐duration responses. Contingencies incorporating response duration produced very low‐rate, long‐duration responding. The dimension of the reinforcer had minimal or no additional effect. We suggest that incorporating duration and other continuous dimensions into schedule contingencies may improve our understanding of both laboratory and nonlaboratory behavior.
STIMULUS EFFECTS ON CONCURRENT PERFORMANCE IN TRANSITION
Authors: Hanna Elenice S. , Blackman Derek E. , Todorov João Claudio
Published: March 2006

Six experimentally naive pigeons were exposed to concurrent variable‐interval variable‐interval schedules in a three‐key procedure in which food reinforcement followed pecks on the side keys and pecks on the center key served as changeover responses. In Phase 1, 3 birds were exposed to 20 combinations of five variable‐interval values, with each variable‐interval value consistently associated with a different color on the side keys. Another 3 pigeons were exposed to the same 20 conditions, but with a more standard procedure that used a nondifferential discriminative stimulus on the two side keys throughout all conditions. In Phase 2, the differential and nondifferential stimulus conditions were reversed for each pigeon. Each condition lasted for one 5‐hr session and one subsequent 1‐hr session. In the last 14 conditions of each phase, the presence of differential discriminative stimuli decreased the time necessary for differential responding to develop and increased the sensitivity of behavior to reinforcement distribution in the 1st hr of training; during the last hours of training in each condition, however, the effects of the differential discriminative stimuli could not be distinguished from the effects of reinforcement distribution per se. These results show the importance of studying transitions in behavior as well as final performance. They may also be relevant to discrepancies in the results of previous experiments that have used nonhuman and human subjects.
REINFORCEMENT MAGNITUDE AND PAUSING ON PROGRESSIVE‐RATIO SCHEDULES
Authors: Baron Alan , Mikorski Jeffrey , Schlund Michael
Published: March 2006

Rats responded under progressive‐ratio schedules for sweetened milk reinforcers; each session ended when responding ceased for 10 min. Experiment 1 varied the concentration of milk and the duration of postreinforcement timeouts. Postreinforcement pausing increased as a positively accelerated function of the size of the ratio, and the rate of increase was reduced as a function of concentration and by timeouts of 10 s or longer. Experiment 2 varied reinforcement magnitude within sessions (number of dipper operations per reinforcer) in conjunction with stimuli correlated with the upcoming magnitude. In the absence of discriminative stimuli, pausing was longer following a large reinforcer than following a small one. Pauses were reduced by a stimulus signaling a large upcoming reinforcer, particularly at the highest ratios, and the animals tended to quit responding when the past reinforcer was large and the stimulus signaled that the next one would be small. Results of both experiments revealed parallels between responding under progressive‐ratio schedules and other schedules containing ratio contingencies. Relationships between pausing and magnitude suggest that ratio pausing is under the joint control of inhibitory properties of the past reinforcer and excitatory properties of stimuli correlated with the upcoming reinforcer, rather than under the exclusive control of either factor alone.
SCHEDULE‐INDUCED DEFECATION: NO‐FOOD AND MASSED‐FOOD BASELINES
Authors: Wylie A. Michael , Springis Ramona , Johnson Kelly S.
Published: March 2006

Defecation rate was monitored during daily 30‐min periods as 16 rats were exposed to different sequences of the following three experimental conditions: (a) a fixed‐time 60‐s food delivery schedule, (b) a massed‐food presentation baseline, and/or (c) a no‐food baseline. All food delivery was response independent. Rate of defecation increased during fixed‐time 60‐s food delivery when compared to baseline rates of defecation established during no‐food and massed‐food baselines. This effect was present for 12 of 16 rats during four alternative sequences of experimental conditions. Within‐subject reversals established reliability of this effect. Schedule induction of defecation is clearly demonstrated under these conditions.
WAITING IN PIGEONS: THE EFFECTS OF DAILY INTERCALATION ON TEMPORAL DISCRIMINATION
Authors: Wynne C. D. L. , Staddon J. E. R.
Published: March 2006

Pigeons trained on cyclic‐interval schedules adjust their postfood pause from interval to interval within each experimental session. But on regular fixed‐interval schedules, many sessions at a given parameter value are usually necessary before the typical fixed‐interval “scallop” appears. In the first case, temporal control appears to act from one interfood interval to the next; in the second, it appears to act over hundreds of interfood intervals. The present experiments look at the intermediate case: daily variation in schedule parameters. In Experiments 1 and 2 we show that pauses proportional to interfood interval develop on short‐valued response‐initiated‐delay schedules when parameters are changed daily, that additional experience under this regimen leads to little further improvement, and that pauses usually change as soon as the schedule parameter is changed. Experiment 3 demonstrates identical waiting behavior on fixed‐interval and response‐initiated‐delay schedules when the food delays are short (<20 s) and conditions are changed daily. In Experiment 4 we show that daily intercalation prevents temporal control when interfood intervals are longer (25 to 60 s). The results of Experiment 5 suggest that downshifts in interfood interval produce more rapid waiting‐time adjustments than upshifts. These and other results suggest that the effects of short interfood intervals seem to be more persistent than those of long intervals.
CHOICE WITH DELAYED AND PROBABILISTIC REINFORCERS: EFFECTS OF VARIABILITY, TIME BETWEEN TRIALS, AND CONDITIONED REINFORCERS
Authors: Mazur James E. , Romano Angela
Published: March 2006

In a discrete‐trials procedure with pigeons, a response on a green key led to a 4‐s delay (during which green houselights were lit) and then a reinforcer might or might not be delivered. A response on a red key led to a delay of adjustable duration (during which red houselights were lit) and then a certain reinforcer. The delay was adjusted so as to estimate an indifference point—a duration for which the two alternatives were equally preferred. Once the green key was chosen, a subject had to continue to respond on the green key until a reinforcer was delivered. Each response on the green key, plus the 4‐s delay that followed every response, was called one “link” of the green‐key schedule. Subjects showed much greater preference for the green key when the number of links before reinforcement was variable (averaging four) than when it was fixed (always exactly four). These findings are consistent with the view that probabilistic reinforcers are analogous to reinforcers delivered after variable delays. When successive links were separated by 4‐s or 8‐s “interlink intervals” with white houselights, preference for the probabilistic alternative decreased somewhat for 2 subjects but was unaffected for the other 2 subjects. When the interlink intervals had the same green houselights that were present during the 4‐s delays, preference for the green key decreased substantially for all subjects. These results provided mixed support for the view that preference for a probabilistic reinforcer is inversely related to the duration of conditioned reinforcers that precede the delivery of food.
EFFECTS OF RESPONSE REQUIREMENT AND ALCOHOL ON HUMAN AGGRESSIVE RESPONDING
Authors: Cherek Don R. , Spiga Ralph , Egli Mark
Published: March 2006

Nine men participated in two experiments to determine the effects of increased response requirement and alcohol administration on free‐operant aggressive responding. Two response buttons (A and B) were available. Pressing Button A was maintained by a fixed‐ratio 100 schedule of point presentation. Subjects were instructed that completion of each fixed‐ratio 100 schedule of point presentation. Subjects were instructed that completion of each fixed‐ratio 10 on Button B resulted in the subtraction of a point from a fictitious second subject. Button B presses were defined as aggressive because they ostensibly resulted in the presentation of an aversive stimulus to another person. Aggressive responses were engendered by a random‐time schedule of point loss and were maintained by initiation of intervals free of point loss. Instructions attributed these point losses to Button B presses of the fictitious other subject. In Experiment 1, increasing the ratio requirement on Button B decreased the number of ratios completed in 4 of 5 subjects. In Experiment 2, the effects of placebo and three alcohol doses (0.125, 0.25, and 0.375 g/kg) were determined when Button B presses were maintained at ratio values of 20, 40 and 80. Three subjects who reduced aggressive responding with increasing fixed‐ratio values reduced aggressive responding further at higher alcohol doses. One subject who did not reduce aggressive responding with increasing fixed‐ratio values increased aggressive responding at the highest alcohol dose. The results of this study support suggestions that alcohol alters aggressive behavior by reducing the control of competing contingencies.
HUMAN CHOICE IN “COUNTERINTUITIVE” SITUATIONS: FIXED‐ VERSUS PROGRESSIVE‐RATIO SCHEDULES
Authors: Wanchisen Barbara A. , Tatham Thomas A. , Hineline Philip N.
Published: March 2006

College undergraduates were given repeated opportunities to choose between a fixed‐ratio and a progressive‐ratio schedule of reinforcement. Completions of a progressive‐ratio schedule produced points (exchangeable for money) and incremented that response requirement by 20 responses with each consecutive choice. In the reset condition, completion of a fixed ratio produced the same number of points and also reset the progressive ratio back to its initial value. In the no‐reset condition, the progressive ratio continued to increase by increments of 20 throughout the session with each successive selection of this schedule, irrespective of fixed‐ratio choices. Subjects' schedule choices were sensitive to parametric manipulations of the size of the fixed‐ratio schedule and were consistent with predictions made on the basis of minimizing the number of responses emitted per point earned, which is a principle of most optimality theories. Also, the present results suggest that if data from human performances are to be compared with results for other species, humans should be exposed to schedules of reinforcement for long periods of time, as is commonly done with nonhuman subjects.
EFFECTS OF COCAINE AND ALCOHOL, ALONE AND IN COMBINATION, ON HUMAN LEARNING AND PERFORMANCE
Authors: Higgins Stephen T. , Rush Craig R. , Hughes John R. , Bickel Warren K. , Lynn Mary , Capeless Mark A.
Published: March 2006

The acute effects of cocaine hydrochloride (4 to 96 mg/70 kg) and alcohol (0 to 1.0 g/kg), administered alone and in combination, were assessed in two experiments with human volunteers responding under a multiple schedule of repeated acquisition and performance of response chains. Subjects were intermittent users of cocaine and regular drinkers who were not cocaine or alcohol dependent. Alcohol was mixed with orange juice and ingested in six drinks within 30 min; cocaine was administered intranasally 45 min after completion of drinking. In each component of the multiple schedule, subjects completed response sequences using three keys of a numeric keypad. In the acquisition component, a new sequence was learned each session. In the performance component, the response sequence always remained the same. Results were consistent in both experiments, despite variations in the order in which the drugs were tested alone and in combination. Alcohol administered alone increased overall percentage of errors and decreased rates of responding in the acquisition component, whereas responding in the performance component generally was unaffected. Cocaine administered alone decreased rates of responding but did not affect accuracy of responding in the acquisition component, and enhanced accuracy of responding without affecting rates of responding in the performance component. The combined doses of cocaine and alcohol attenuated the effects observed with alcohol and cocaine alone. These results suggest that, under the conditions investigated in this study, (a) alcohol produces greater behavioral disruption than cocaine or cocaine‐alcohol combinations, (b) cocaine and alcohol each attenuate effects of the other, and (c) such attenuation is most pronounced for cocaine attenuating the disruptive effects of alcohol.
EMERGENT EQUIVALENCE RELATIONS BETWEEN INTEROCEPTIVE (DRUG) AND EXTEROCEPTIVE (VISUAL) STIMULI
Authors: DeGrandpre R. J. , Bickel Warren K. , Higgins Stephen T.
Published: March 2006

Conditional “if‐then” relations between drug (interoceptive) stimuli and visual (exteroceptive) stimuli were taught to 4 normal humans. Interoceptive stimuli were the effects produced by 0.32 mg/70 kg triazolam (a prototypical benzodiazepine) and placebo (lactose‐filled capsules); exteroceptive stimuli were black symbols on white flash cards. Following the training of the prerequisite conditional relations, tests of emergent relations were conducted between exteroceptive stimuli and between interoceptive and exteroceptive stimuli. Equivalence relations emerged immediately without explicit training for all 4 subjects. Accuracy of responding during the interoceptive‐exteroceptive equivalence tests and subjects' self‐reports showed consistent discrimination between the drug effects of triazolam and placebo. Finally, a generalization test assessed whether a novel visual stimulus presented in the context of the placebo (i.e., no drug) would generalize to visual stimuli belonging to the placebo stimulus class. All 3 subjects who completed this test reliably chose the visual stimuli belonging to the placebo class and not the visual stimuli belonging to the triazolam stimulus class. The development of equivalence relations between interoceptive and exteroceptive stimuli demonstrates that private and public stimulus events can emerge as members of the same equivalence class. Theoretical and clinical implications are discussed.
MOTION AS A NATURAL CATEGORY FOR PIGEONS: GENERALIZATION AND A FEATURE‐POSITIVE EFFECT
Authors: Dittrich Winand H. , Lea Stephen E. G.
Published: March 2006

Three groups of pigeons were trained with a modified discriminative autoshaping procedure to discriminate video images of other pigeons on the basis of movement. Birds of all groups were shown the same video images of other pigeons, which were either moving or still. The group to whom food was presented only after moving images learned the discrimination very quickly. A second group, to whom food was given only after still images, and a pseudocategory group, to whom food was presented after arbitrarily chosen stimuli, showed no evidence of discrimination during acquisition training. Extinction conditions led to clear differences in peck rates to moving and still images in the second group but not in the pseudocategory group. The result is related to the feature‐positive effect. Generalization tests showed that the discrimination performance was based on visual features of the stimuli but was invariant against changes of size, perspective, brightness, and color. Furthermore, discrimination was maintained when novel images of pigeons under different viewing angles and seven other types of motion categories were presented. It is argued that the discrimination is based not on a common motion feature but on motion concepts or high‐order generalization across motion categories.
“TRANSITIVE INFERENCE” IN MULTIPLE CONDITIONAL DISCRIMINATIONS
Authors: Higa J. J. , Staddon J. E. R.
Published: March 2006

We used multiple conditional discriminations to study the inferential abilities of pigeons. Using a five‐term stimulus series, pigeons were trained to respond differentially to four overlapping pairs of concurrently presented stimuli: A+B−, B+C−, C+D−, and D+E−, where plus and minus indicate the stimulus associated with reinforcement and extinction, respectively. Transitive inference in such situations has been defined as a preference for Stimulus B over Stimulus D in a transfer test. We measured this and other untrained preferences (A vs. C, A vs. D, B vs. E, etc.) during nonreinforced test trials. In three experiments using a novel, rapid training procedure (termed autorun), we attempted to identify the necessary and sufficient conditions for transitive inference. We used two versions of autorun: response‐based, in which the subject was repeatedly presented with the least well‐discriminated stimulus pair; and time‐based, in which the subject was repeatedly presented with the least‐experienced stimulus pair. In Experiment 1, using response‐based autorun, we showed that subjects learned the four stimulus pairs faster than, but at a level comparable to, a previous study on transitive inference in pigeons (Fersen, Wynne, Delius, & Staddon, 1991), but our animals failed to show transitive inference. Experiments 2 and 3 compared time‐ and response‐based autorun. Discrimination performance was maintained, but transitive inference was observed only on the second exposure to the response‐based procedure. These results show that inferential behavior in pigeons is not a reliable concomitant of good performance on a series of overlapping discriminations. The necessary and sufficient conditions for transitive inference in pigeons remain to be fully defined.
DETERMINANTS OF HUMAN PERFORMANCE ON CONCURRENT SCHEDULES
Authors: Horne P. J. , Lowe C. F.
Published: March 2006

Six experiments, each with 5 human adults, were conducted to investigate the determinants of human performance on multiple concurrent variable‐interval schedules. A two‐key procedure was employed in which subjects' key presses produced points exchangeable for money. Variables manipulated across experiments were (a) changeover delay (Experiments 2, 4, and 6), (b) ordinal cues related to scheduled reinforcement frequencies (Experiments 3 and 4), and (c) instructions describing the ordinal relations between schedule‐correlated stimuli and scheduled reinforcement frequency (Experiments 5 and 6). The performances of only 13 of the 30 subjects could be described by the generalized matching equation and were within a range of values typical of those reported in the animal literature. Eight subjects showed indifference, 9 undermatched, 7 approximated matching, 3 overmatched, and a further 3 responded exclusively to the richer component of the concurrent schedules. These differing modes of responding were closely related to the different types of performance rules reported by subjects in postexperimental questionnaires. The results are in good agreement with those from studies of human performance on single schedules, suggesting that rule‐governed behavior, in interaction with contingencies, may be an important determinant of human choice.
CONDITIONAL DISCRIMINATION AND EQUIVALENCE RELATIONS: CONTROL BY NEGATIVE STIMULI
Authors: Johnson Cammarie , Sidman Murray
Published: March 2006

Three adult subjects were taught the following two‐sample, two‐comparison conditional discriminations (each sample is shown with its positive and negative comparison, in that order): A1‐B1B2, A2‐B2B1; B1‐C1C2, B2‐C2C1; and C1‐D1D2, C2‐D2D1. A teaching procedure was designed to encourage control by negative comparisons. Subjects were then tested for emergent performances that would indicate whether the baseline conditional discriminations were reflexive, symmetric, and transitive. The tests documented the emergence of two classes of equivalent stimuli: A1, B2, C1, D2 and A2, B1, C2, D1. These were the classes to be expected if the negative comparisons were the controlling comparisons in the baseline conditional discriminations. The negative comparisons, however, were not the comparisons that subjects were recorded as having chosen in the baseline conditional discriminations. Differential test results confirmed predictions arising from a stimulus‐control analysis: In reflexivity tests (AA, BB, CC, DD), subjects chose comparisons that differed from the sample; one‐node transitivity (AC, BD) and “equivalence” (CA, DB) tests also yielded results that were the opposite of those to be expected from control by positive comparisons; symmetry tests (BA, CB, DC), two‐node transitivity (AD) tests, and two‐node “equivalence” (DA) tests yielded results that were to be expected from control by either positive or negative comparisons.
ACQUISITION OF A SPATIALLY DEFINED OPERANT WITH DELAYED REINFORCEMENT
Authors: Critchfield Thomas S. , Lattal Kennon A.
Published: March 2006

Two experiments investigated the role of an immediate, response‐produced auditory stimulus during acquisition, via delayed reinforcement, of a response selected to control for possible unprogrammed, operandum‐related sources of response feedback. Experimentally naive rats were exposed to a delayed‐food reinforcement condition, specifically a tandem fixed‐ratio 1 differential‐reinforcement‐of‐other‐behavior 30‐s schedule. The response was defined as breaking a photocell beam located near the ceiling at the rear of the operant conditioning chamber. In Experiment 1, rates of photobeam breaking by each rat increased from near zero, regardless of the presence or absence of a tone that immediately followed the response initiating the delay interval. Though not essential, the tone facilitated response acquisition and resulted in more efficient response patterns at stability. Experiment 2 demonstrated that photobeam‐breaking response rates under the delayed reinforcement contingency exceeded those in a preceding baseline condition in which no food was delivered. In addition, upon introduction of the delayed reinforcement procedure, correspondence between response patterns and the requirements of the reinforcement schedule increased over baseline levels in the absence of a food contingency. Together with a previous report of Lattal and Gleeson (1990), the present results suggest that response acquisition with delayed reinforcement is a robust phenomenon that may not depend on a mechanically defined response or an immediate external stimulus change to mediate the temporal gap between response and reinforcer.
TO WAIT OR TO RESPOND?
Authors: Zeiler Michael D.
Published: March 2006

Emitting a certain response and waiting for a specified time without making that response had the same consequence. In Experiment 1, food‐deprived pigeons were as likely to wait as to respond only if waiting provided food at a much higher frequency than did pecking. In Experiment 2, the consequence for humans was a brief light flash and tone. People were not biased for responding over waiting. Instead, their choices suggested crude payoff maximization. In Experiment 3, pigeons again obtained food, but they were not food deprived and could eat freely at each opportunity. Their behavior was more like that of the humans of Experiment 2 than that of food‐deprived pigeons given small quantities of food at each feeding opportunity. The three experiments together showed that biases for responding over waiting were neither inherent characteristics of species nor inevitable outcomes of particular schedules. Choice between active search and waiting depended on ecological‐motivational factors even when species and schedules were held constant.
HUMANS' CHOICES IN SITUATIONS OF TIME‐BASED DIMINISHING RETURNS
Authors: Hackenberg Timothy D. , Axtell Sara A. M.
Published: March 2006

Three experiments examined adult humans' choices in situations with contrasting short‐term and long‐term consequences. Subjects were given repeated choices between two time‐based schedules of points exchangeable for money: a fixed schedule and a progressive schedule that began at 0 s and increased by 5 s with each point delivered by that schedule. Under “reset” conditions, choosing the fixed schedule not only produced a point but it also reset the requirements of the progressive schedule to 0 s. In the first two experiments, reset conditions alternated with “no‐reset” conditions, in which progressive‐schedule requirements were independent of fixed‐schedule choices. Experiment 1 entailed choices between a progressive‐interval schedule and a fixed‐interval schedule, the duration of which varied across conditions. Switching from the progressive‐ to the fixed‐interval schedule was systematically related to fixed‐interval size in 4 of 8 subjects, and in all subjects occurred consistently sooner in the progressive‐schedule sequence under reset than under no‐reset procedures. The latter result was replicated in a second experiment, in which choices between progressive‐ and fixed‐interval schedules were compared with choices between progressive‐ and fixed‐time schedules. In Experiment 3, switching patterns under reset conditions were unrelated to variations in intertrial interval. In none of the experiments did orderly choice patterns depend on verbal descriptions of the contingencies or on schedule‐controlled response patterns in the presence of the chosen schedules. The overall pattern of results indicates control of choices by temporally remote consequences, and is consistent with versions of optimality theory that address performance in situations of diminishing returns.
EFFECTS OF INCOME ON DRUG CHOICE IN HUMANS
Authors: DeGrandpre R. J. , Bickel Warren K. , Rizvi S. Abu Turab , Hughes John R.
Published: March 2006

The effects of income (money available to spend during the experimental session) on human choice were examined in a concurrent‐schedule arrangement. Subjects were 7 nicotine‐dependent smokers, and reinforcers were puffs on the subject's usual brand of cigarette (“own”) and puffs on a less preferred brand of cigarette with equal nicotine content (“other”). Across sessions, income varied and the price of the two reinforcers was held constant, with the other puffs one fifth the price of the own puffs. As income increased, consumption of own puffs increased while consumption of the less expensive other puffs decreased. These effects of income on choice were highly consistent across subjects. For some subjects, however, income had little effect on total puff consumption. Finally, an additional condition examined whether price and income manipulations would have functionally equivalent effects on choice by repeating an income condition in which the price of the other brand was increased. Although the increased price of the other puffs decreased their consumption in 4 subjects, 2 subjects showed increased consumption of the other puffs at the higher price. The results, when defined in economic terms, indicate that the own puffs were a normal good (consumption and income are directly related), the other puffs were an inferior good (consumption and income are inversely related), and the direct relationship between consumption of the other puffs and their price is defined as a Giffen‐good effect. The latter result also suggests that for these 2 subjects, price and income manipulations had equivalent effects on choice. These results extend findings from previous studies that have examined the effects of income on choice responding to human subjects and drug reinforcers, and provide a framework for further experimental tests of the effects of income on human choice behavior. Methodological and theoretical implications for the study of choice and for behavioral pharmacology are discussed.
GENERALIZATION OF A TACTILE STIMULUS IN HORSES
Authors: Dougherty Donald M. , Lewis Paul
Published: March 2006

Using horses, we investigated the control of operant behavior by a tactile stimulus (the training stimulus) and the generalization of behavior to six other similar test stimuli. In a stall, the experimenters mounted a response panel in the doorway. Located on this panel were a response lever and a grain dispenser. The experimenters secured a tactile‐stimulus belt to the horse's back. The stimulus belt was constructed by mounting seven solenoids along a piece of burlap in a manner that allowed each to provide the delivery of a tactile stimulus, a repetitive light tapping, at different locations (spaced 10.0 cm apart) along the horse's back. Two preliminary steps were necessary before generalization testing: training a measurable response (lip pressing) and training on several reinforcement schedules in the presence of a training stimulus (tapping by one of the solenoids). We then gave each horse two generalization test sessions. Results indicated that the horses' behavior was effectively controlled by the training stimulus. Horses made the greatest number of responses to the training stimulus, and the tendency to respond to the other test stimuli diminished as the stimuli became farther away from the training stimulus. These findings are discussed in the context of behavioral principles and their relevance to the training of horses.
ASSESSING CONTROL BY ELEMENTS OF COMPLEX STIMULI IN DELAYED MATCHING TO SAMPLE
Authors: Stromer Robert , Mcilvane William J. , Dube William V. , Mackay Harry A.
Published: March 2006

A series of six experiments examined delayed identity matching‐to‐sample performances of subjects with mental retardation. The stimuli were either one or two simultaneously displayed forms. When the reinforcement contingencies required that only one form exert discriminative control, all subjects achieved high accuracy scores. However, accuracy scores were substantially lower when the contingencies required discriminative control by two forms, suggesting restricted stimulus control. The decline in matching accuracy appeared to reflect selective losses of conditional control by sample stimuli and shifts in control to features of the comparison stimulus displays. The experiments suggest improved techniques for assessing control by complex stimuli and for evaluating the effects of procedures that seek to broaden restricted stimulus control. The results challenge interpretations based on stimulus‐generalization decrement or shared attention.
BEHAVIOR SYSTEMS AND REINFORCEMENT: AN INTEGRATIVE APPROACH
Authors: Timberlake William
Published: March 2006

Most traditional conceptions of reinforcement are based on a simple causal model in which responding is strengthened by the presentation of a reinforcer. I argue that reinforcement is better viewed as the outcome of constraint of a functioning causal system comprised of multiple interrelated causal sequences, complex linkages between causes and effects, and a set of initial conditions. Using a simplified system conception of the reinforcement situation, I review the similarities and drawbacks of traditional reinforcement models and analyze the recent contributions of cognitive, regulatory, and ecological approaches. Finally, I show how the concept of behavior systems can begin to incorporate both traditional and recent conceptions of reinforcement in an integrative approach.
A SELECTIONIST APPROACH TO REINFORCEMENT
Authors: Donahoe John W. , Burgos Jose E. , Palmer David C.
Published: March 2006

We describe a principle of reinforcement that draws upon experimental analyses of both behavior and the neurosciences. Some of the implications of this principle for the interpretation of behavior are explored using computer simulations of adaptive neural networks. The simulations indicate that a single reinforcement principle, implemented in a biologically plausible neural network, is competent to produce as its cumulative product networks that can mediate a substantial number of the phenomena generated by respondent and operant contingencies. These include acquisition, extinction, reacquisition, conditioned reinforcement, and stimulus‐control phenomena such as blocking and stimulus discrimination. The characteristics of the environment‐behavior relations selected by the action of reinforcement on the connectivity of the network are consistent with behavior‐analytic formulations: Operants are not elicited but, instead, the network permits them to be guided by the environment. Moreover, the guidance of behavior is context dependent, with the pathways activated by a stimulus determined in part by what other stimuli are acting on the network at that moment. In keeping with a selectionist approach to complexity, the cumulative effects of relatively simple reinforcement processes give promise of simulating the complex behavior of living organisms when acting upon adaptive neural networks.
SCALING PIGEONS' CHOICE OF FEEDS: BIGGER IS BETTER
Authors: Killeen Peter R. , Cate Heather , Tran Trung
Published: March 2006

Preferences of hungry pigeons among 10 grains and pellets were analyzed using a Thurstone scaling procedure. The recovered scales were positively correlated with size of the feed. The correlations improved when the Thurstonian assumption of equal‐sized discriminal dispersions (Case V) was replaced with the assumption of proportional‐sized dispersions (Case VI), as entailed by Weber's law. The correlations weakened when the experiments were conducted with the pigeons close to their free‐feeding weights, where the probability of sampling alternative grains increased. In the final experiment, exposure to a large pellet shifted the preferences between two smaller pellets.
BIPOLAR CONTROL IN FIXED INTERFOOD INTERVALS
Authors: Palya William L.
Published: March 2006

The ability of stimuli correlated with successive periods in a fixed interfood interval to support a response that produced or removed them was examined using pigeons. The degree to which those correlated stimuli elicited directed key pecks was also obtained. Stimuli early in the interval functioned as negative reinforcers, and stimuli late in the interval functioned as positive reinforcers. Stimuli correlated with successively later portions of the second half of the interval supported successively higher rates of elicited pecking and, with the exception of the final stimulus, supported successively higher rates of stimulus production. Stimuli in successively earlier portions of the first half of the interval supported successively higher rates of correlated‐stimulus removal. This effect occurred in spite of the addition of a conjoint variable‐interval dependency for food. An ogive fit to the mean normalized response distributions resulted in r2s demonstrating that most of the variance in the temporal organization of the behavior was accounted for. The findings were taken to indicate that fixed interfood intervals establish bipolar control.
A CELLULAR ANALOGUE OF OPERANT CONDITIONING
Authors: Stein Larry , Xue Bao G. , Belluzzi James D.
Published: March 2006

Using the hippocampal‐slice preparation, we attempted to model operant conditioning in vitro by reinforcing pyramidal cell bursting responses with local micropressure applications of transmitters and drugs. The same injections were administered independently of bursting to provide a “noncontingent” control for direct pharmacological stimulation or facilitation of firing. The results suggested that the bursting responses of individual CA1 pyramidal neurons may be reinforced in a dose‐related manner by response‐contingent (but not noncontingent) injections of dopamine and the selective dopamine D2 agonist, N‐0923. N‐0924, a stereoisomer of N‐0923 that is largely devoid of D2‐agonist activity, failed to reinforce CA1 bursting. Burst‐contingent injections of the excitatory neurotransmitter glutamate also failed to reinforce CA1 bursting; indeed, the glutamate applications (whether contingent or random) reduced the likelihood of bursts while increasing the frequency of solitary spikes. Reinforcement delays exceeding 200 ms largely eliminated the reinforcing efficacy of the D2 agonist N‐0437 in CA1 operant conditioning. The results are consistent with the suggestion that the behaviorally reinforcing effects of dopaminergic agents can be modeled in vitro in the hippocampal‐slice preparation.
MOMENTARY MAXIMIZING IN CONCURRENT SCHEDULES WITH A MINIMUM INTERCHANGEOVER INTERVAL
Authors: Todorov João Claudio , Souza Deisy G. , Bori Carolina M.
Published: March 2006

Eight pigeons were trained on concurrent variable‐interval variable‐interval schedules with a minimum interchangeover time programmed as a consequence of changeovers. In Experiment 1 the reinforcement schedules remained constant while the minimum interchangeover time varied from 0 to 200 s. Relative response rates and relative time deviated from relative reinforcement rates toward indifference with long minimum interchangeover times. In Experiment 2 different reinforcement ratios were scheduled in successive experimental conditions with the minimum interchangeover time constant at 0, 2, 10, or 120 s. The exponent of the generalized matching equation was close to 1.0 when the minimum interchangeover time was 0 s (the typical procedure for concurrent schedules without a changeover delay) and decreased as that duration was increased. The data support the momentary maximizing theory and contradict molar maximizing theories and the melioration theory.
A PARAMETRIC VARIATION OF DELAYED REINFORCEMENT IN INFANTS
Authors: Reeve Lori , Reeve Kenneth F. , Poulson Claire L.
Published: March 2006

This study is an exploration of the parameters of delayed reinforcement with 6 infants (2 to 6 months old) in two experiments using single‐subject repeated‐reversal designs. In Experiment 1, unsignaled 3‐s delayed reinforcement was used to increase infant vocalization rate when compared to a differential‐reinforcement‐of‐other‐than‐vocalization condition and a yoked, no‐contingency comparison condition. In Experiment 2, unsignaled 5‐s delayed reinforcement was used to increase infant vocalization rate when compared to an alternating‐treatments comparison condition. The alternating‐treatments comparison consisted of 3‐min components of differential reinforcement of other behavior and 3‐min components of a nontreatment baseline. Successful conditioning was obtained in both experiments. These results contrast with those of previous infancy researchers who did not obtain conditioning with delays of 3 s and who attributed their findings to the limitations of the infant's memory capacity. We present an alternative conceptual framework and methodology for the analysis of delayed reinforcement in infants.
A QUANTITATIVE ANALYSIS OF SENSITIVITY TO THE CONDITIONED REINFORCING VALUE OF TERMINAL‐LINK STIMULI IN A CONCURRENT‐CHAINS SCHEDULE
Authors: Omino Takashi
Published: March 2006

Pigeons were exposed to a concurrent‐chains schedule in which a single variable‐interval 30‐s schedule was used in the initial links and fixed‐time schedules were used in the terminal links. Three types of keylight conditions were used in the terminal links. In the first condition, different delays were associated with different keylight stimuli (cued condition). In the second condition, different delays were associated with the same stimulus, either a blackout (uncued blackout condition) or a white key (uncued white condition). Paired values of terminal‐link fixed‐time schedules differed by a constant ratio of 3:1, while the absolute value of delays was varied from 3 s to 54 s. The results showed that choice proportions for the shorter of two delays increased when the absolute size of the delays was increased for all keylight conditions. Further, the choice proportions for the shorter delay increased from the uncued blackout condition, to the uncued white condition, to the cued condition. A modified version of Fantino's (1969) delay‐reduction model (expressed as a function relating the response ratio to the delay‐reduction ratio) can be applied to these data by showing that sensitivity to delay reduction increased from the uncued blackout condition, to the uncued white condition, to the cued condition. Thus, the present study demonstrated that a modified version of the delay‐reduction model can be used to assess quantitative differences in the terminal‐link keylight condition in terms of sensitivity to delay reduction (i.e., the conditioned reinforcing value of the terminal‐link keylight stimuli).