bluuebunny/crossref_metadata_2025 huggingface dataset:
CONTEXTUAL CONTROL OF EMERGENT EQUIVALENCE RELATIONS
Authors: Bush Karen M. , Sidman Murray , Rose Tania de
Published: March 2006

Three college students in Experiment 1 and 1 student in Experiment 2 learned visual conditional discriminations under contextual control by tones; the visual comparison stimulus that was correct with a given sample stimulus depended on whether a high tone or a low tone was present. Two of the subjects in Experiment 1 then demonstrated the emergence of two sets of contextually controlled three‐member classes of equivalent stimuli, and the subject in Experiment 2 showed the emergence of contextually controlled four‐member classes; the class membership of each stimulus varied as a function of the tones. Class membership was demonstrated by the subjects' performance of new conditional discriminations that they had never been taught directly. In Experiment 2, the procedures were intended to ensure that the tones exerted second‐order conditional control and did not simply form compounds with each of the visual stimuli, but the subject's verbal description of the tasks suggested that this intention might not have been successful. It could not be ascertained, therefore, whether the tones exerted contextual control as independent second‐order conditional stimuli or simply as common elements of auditory—visual stimulus compounds.
QUANTIFICATION OF THE EFFECTS OF CHLORPROMAZINE ON PERFORMANCE UNDER DELAYED MATCHING TO SAMPLE IN PIGEONS
Authors: Watson Janine E. , Blampied Neville M.
Published: March 2006

The effects of four doses of chlorpromazine (dose range 0.5 to 12.5 mg/kg) on performance under a delayed matching‐to‐sample procedure in pigeons was investigated, using the exponential model of memory (White, 1985). Performance was measured using a bias‐free measure of discriminability, log d (Davison & Tustin, 1978), and negative exponential functions were fitted to individual‐subject and group data at each dose level. A decrease in matching accuracy was found to be caused by an increase in the rate of forgetting, b, and a decrease in the initial discriminability, log do. Changes in rate of forgetting and discriminability occurred at doses that had no statistically significant effect on response latency. The exponential model of memory accounted well for the data and provided a useful way of quantifying the effects of chlorpromazine on the processes involved in delayed matching‐to‐sample performance.
THE SPEAKER AS LISTENER
Authors: Lodhi Seema , Greer R. Douglas
Published: March 2006

This study reports the results of an experiment with 4 female 5‐year‐old children, in which the verbal behavior of the children (talking to themselves) was studied under two conditions—an anthropomorphic toy condition and a nonanthropomorphic toy condition. The anthropomorphic condition consisted of three‐dimensional toys such as dolls, stuffed animals, and figurines. The nonanthropomorphic toy condition consisted of two‐dimensional materials such as puzzles, coloring books, and story books. The independent variables were the toy conditions. The dependent variables were verbal‐behavior units; these included mands, tacts, intraverbals, autoclitics, and conversational units. The conditions were compared using a multiple schedule design. The results showed that more total units occurred in the anthropomorphic toy condition than in the nonanthropomorphic toy condition and that conversational units occurred in the anthropomorphic condition only. Consistent with Skinner's (1957) hypothesis, the children acted as both speaker and listener when emitting verbal behavior to themselves in the anthropomorphic condition.
NAMING IN CONDITIONAL DISCRIMINATION AND STIMULUS EQUIVALENCE
Authors: Saunders Kathryn J.
Published: March 2006

Using a matching‐to‐sample procedure, McIntire, Cleary, and Thompson (1987) taught monkeys the conditional relations A1‐R1‐A1‐R1, A2‐R2‐A2‐R2, A1‐R1‐B1‐R1, A2‐R2‐B2‐R2, B1‐R1‐C1‐R1, and B2‐R2‐C2‐R2, where the first and third terms in each relation refer to the sample and comparison stimuli, respectively, and the second and last terms refer to the emission of a distinctive pattern of responding. The subjects were then tested for the emergent relations A‐C, C‐A, B‐A, C‐B, and B‐B, with the differential response produced by a given stimulus during training also emitted on test trials (e.g., A1‐R1‐C1‐R1). The performances of both subjects were as accurate on the tested relations as they had been on the trained relations. The new relations were characterized as demonstrations of stimulus equivalence. However, the conditional discrimination literature shows that such training procedures generate control of comparison selection by the differential response patterns. Therefore, no emergent relations were demonstrated because all of the trained response‐stimulus relations were preserved on test trials. This paper suggests that these procedures do not provide an appropriate analogy for the kind of emergent stimulus‐stimulus relations exhibited by human subjects in equivalence studies and outlines a paradigm for assessing the relative influence of stimulus‐stimulus and response‐stimulus relations.
NONHUMANS HAVE NOT YET SHOWN STIMULUS EQUIVALENCE
Authors: Hayes Steven C.
Published: March 2006

Recently, two published articles have reported finding stimulus equivalence in nonhumans. One suggested that equivalence was due to the mediation of names. The procedure used trained all components of all tested relations. Because nothing was derived, the defining characteristics of equivalence were not achieved. In the second study a definition of equivalence was proposed that fails to distinguish functional stimulus classes from equivalence classes. The resulting data are not clearly relevant to stimulus equivalence in Sidman's sense of the term. Stimulus equivalence has not yet been shown in nonhumans.
EFFECTS OF ATROPINE ON THE REPEATED ACQUISITION AND PERFORMANCE OF RESPONSE SEQUENCES IN HUMANS
Authors: Higgins Stephen T. , Woodward Beatrice M. , Henningfield Jack E.
Published: March 2006

The present study assessed a 24‐hr time course for the acute effects of intramuscular injections of atropine sulfate (0, 1.5, 3.0, and 6.0 mg/70 kg) in healthy adult humans responding under a two‐component multiple schedule of repeated acquisition and performance of response sequences. Subjects resided in an inpatient research ward for the duration of the study. In each component of the multiple schedule, subjects completed a different sequence of 10 responses in a predetermined order using three keys of a numeric keypad. In the acquisition component, the subjects' task was to acquire a new sequence each session. Eight sessions were conducted daily: one immediately before administration of the drug and then 0.5, 1.5, 3.0, 5.0, 7.0, 9.0, and 24.0 hr after administration. In the performance component, the response sequence always remained the same. Overall percentage of errors increased and overall response rates decreased in the acquisition and performance components as an orderly function of drug dose. However, these effects were selective in that behavior in the acquisition component generally was affected at lower doses than in the performance component. When behavior was affected in both the acquisition and performance components, the time courses of effects were similar. Drug effects began at 0.5 or 1.5 hr, reached peak effects between 3.0 and 5.0 hr, and returned to placebo levels between 7.0 and 9.0 hr postdrug in both schedule components. None of the drug doses produced reliable effects the day after drug administration (24‐hr postdrug) in either schedule component. The present study provides the first within‐subject assessment of the magnitude and duration of the effects of an anticholinergic on repeated acquisition and performance baselines and extends to atropine the selective effects on these two baselines demonstrated previously with other compounds in humans and nonhumans.
THEORIES OF PROBABILISTIC REINFORCEMENT
Authors: Mazur James E.
Published: March 2006

In three experiments, pigeons chose between two alternatives that differed in the probability of reinforcement and the delay to reinforcement. A peck at a red key led to a delay of 5 s and then a possible reinforcer. A peck at a green key led to an adjusting delay and then a certain reinforcer. This delay was adjusted over trials so as to estimate an indifference point, or a duration at which the two alternatives were chosen about equally often. In Experiments 1 and 2, the intertrial interval was varied across conditions, and these variations had no systematic effects on choice. In Experiment 3, the stimuli that followed a choice of the red key differed across conditions. In some conditions, a red houselight was presented for 5 s after each choice of the red key. In other conditions, the red houselight was present on reinforced trials but not on nonreinforced trials. Subjects exhibited greater preference for the red key in the latter case. The results were used to evaluate four different theories of probabilistic reinforcement. The results were most consistent with the view that the value or effectiveness of a probabilistic reinforcer is determined by the total time per reinforcer spent in the presence of stimuli associated with the probabilistic alternative. According to this view, probabilistic reinforcers are analogous to reinforcers that are delivered after variable delays.
CONDITIONAL DISCRIMINATION IN MENTALLY RETARDED ADULTS: THE EFFECT OF TRAINING THE COMPONENT SIMPLE DISCRIMINATIONS
Authors: Saunders Kathryn J. , Spradlin Joseph E.
Published: March 2006

Two subjects with retardation who exhibited generalized identity matching, but who had extensive histories of failure to acquire arbitrary matching, were exposed to a series of conditions designed to train separately the components of a two‐choice conditional discrimination. First, the successive discrimination between the sample stimuli was established by programming a different schedule of reinforcement in the presence of each sample stimulus. Schedule performance was acquired and maintained by both subjects, but neither acquired arbitrary matching. To train the simultaneous discrimination between the comparison stimuli, 1 subject was then exposed to a series of simple discrimination reversals and subsequently failed to acquire arbitrary matching. Both subjects acquired arbitrary matching under a procedure that maintained both the sample and the comparison discrimination by first presenting entire sessions composed of one sample‐comparison relation and then gradually reducing the number of consecutive trials with the same sample until sample presentation was randomized (schedule performance was maintained). Removal of the schedule requirement had no effect on arbitrary matching accuracy. Both subjects subsequently demonstrated control by relations symmetric to the trained relations.
ORAL SELF‐ADMINISTRATION OF PENTOBARBITAL BY RHESUS MONKEYS: MAINTENANCE OF BEHAVIOR BY DIFFERENT CONCURRENTLY AVAILABLE VOLUMES OF DRUG SOLUTION
Authors: Meisch Richard A. , Lemaire Gregory A.
Published: March 2006

For 4 rhesus monkeys, mouth‐contact responses with either of two brass spouts were reinforced according to fixed‐ratio schedules by 0.65‐mL liquid deliveries during daily 3‐hr sessions. Three experiments were conducted. In each experiment, independent fixed‐ratio schedules were concurrently in effect at the two spouts. Following completion of each fixed ratio on a spout, a specified number of liquid deliveries were available from that spout under a continuous‐reinforcement schedule. The number of such deliveries available at each spout was manipulated independently. In Experiment 1, a 1‐mg/mL pentobarbital solution was simultaneously available with water (the drug vehicle) under concurrent fixed‐ratio schedules of 32 responses for 3 subjects and 64 responses for the remaining subject. The number (N) of liquid deliveries that were available after completion of each fixed ratio was varied in the following order: 8, 4, 2, 1, and 8 (retest). For each subject at each condition, drug maintained more responding than water. The number of drug deliveries obtained per session was directly related to the amount of drug available per fixed ratio (i.e., to N), whereas the number of fixed ratios completed per session generally was inversely related to the value of N. In Experiment 2, fixed‐ratio size was the same for each subject as in Experiment 1, but deliveries of a 1‐mg/mL pentobarbital solution were available at both spouts. The number of drug deliveries available under one fixed‐ratio schedule (Ns, the “standard” reinforcer amount) was held at eight, and the number of drug deliveries available under the second schedule (Nc, the “comparison” reinforcer amount) was changed across blocks of six sessions of stable responding in the following order: 1, 2, 4, 8, 4, 2, and 1. The identical series of comparison reinforcer amounts (Nc) was then tested twice more, but with the standard reinforcer (Ns) held first at four and then at two deliveries. Across the three choice series, reinforcing effects were directly related to reinforcer magnitude. In Experiment 3, deliveries of a 1‐mg/mL pentobarbital solution again were available at both spouts. However, the two reinforcer amounts were held constant at N = 8 deliveries under one schedule and N = 4 deliveries under the second schedule, and fixed‐ratio size was systematically varied. Across the range of fixed‐ratio sizes from low to high, the degree to which behavior was better maintained by the larger of the two drug quantities was an inverted U‐shaped function of fixed‐ratio size. The findings of Experiment 3 are discussed in the context of recent studies that have shown that the relative proportions of behavior maintained by concurrently available reinforcers depend on the absolute values of the concurrent reinforcement conditions, as well as their relative values.
STIMULUS CLASS FORMATION AND CONCEPT LEARNING: ESTABLISHMENT OF WITHIN‐ AND BETWEEN‐SET GENERALIZATION AND TRANSITIVE RELATIONSHIPS VIA CONDITIONAL DISCRIMINATION PROCEDURES
Authors: Haring Thomas G. , Breen Catherine G. , Laitinen Richard E.
Published: March 2006

Three students with moderate mental retardation were taught a complex stimulus class with a two‐choice conditional discrimination procedure applied across eight 10‐member stimulus sets. Each set was composed of five age‐appropriate and five age‐inappropriate examples of clothing, accessories, and leisure items (e.g., a Walkman ® radio). Discrimination training was programmed serially across each set, and generalization probes were conducted concurrently among all sets. Generalization probes consisted of unreinforced conditional matching trials with comparison items being drawn from (a) the set undergoing training (within‐set probes), (b) sets not undergoing training (between‐set probes), and (c) both sample and comparison items from different sets (transitive stimulus control probes). Results indicate that within‐set generalization, between‐set generalization, and transitive stimulus relations controlled responding by all 3 students for items that had been contingently associated with reinforcement. However, items that gained control of responding through within‐set and between‐set generalization alone (i.e., not acquired through contingent reinforcement) remained at baseline levels during transitive stimulus control probes. Results are discussed in terms of a taxonomy of multiple sources of stimulus control that underlie socially defined and maintained stimulus classes.
VARIABLE‐RATIO CONDITIONING HISTORY PRODUCES HIGH‐ AND LOW‐RATE FIXED‐INTERVAL PERFORMANCE IN RATS
Authors: Wanchisen Barbara A. , Tatham Thomas A. , Mooney Susan E.
Published: March 2006

Four rats were exposed to an A‐B‐A‐B series of 30 sessions each of variable‐ratio 20 (A) and fixed‐interval 30‐s (B) schedules. Four other rats received 120 sessions of fixed‐interval 30 s. The rats with a history of variable‐ratio responding subsequently showed primarily high or low response‐rate patterns on the fixed‐interval schedule without evidence of classical scalloping (i.e., increased rates of responding throughout the interreinforcement interval), except infrequently in 1 rat. The rats exposed to only the fixed‐interval 30‐s schedule displayed the expected sequence of scalloping giving way to lower rate break‐run or simply low‐rate responding over time. This experiment shows that when naive rats are exposed to even a simple history of reinforcement (in this case, a variable‐ratio 20), their subsequent fixed‐interval performance is very different from comparable performance in naive rats, and might be said to be more similar to the responding of adult humans. The argument is made that care should be taken in comparing the fixed‐interval performance of humans and nonhumans because humans have a complex history of reinforcement, whereas laboratory nonhumans are typically naive.
EFFECTIVENESS AND PERSISTENCE OF PRECURRENT MEDIATING BEHAVIOR IN DELAYED MATCHING TO SAMPLE AND ODDITY MATCHING WITH CHILDREN
Authors: Torgrud Laine J. , Holborn Stephen W.
Published: March 2006

Two kinds of mediating behavior were compared with respect to their effectiveness in variable‐delay matching‐to‐sample and oddity‐matching tasks. Each of four 5‐year‐old children was trained to emit either differential or common mediating responses. The differential mediating response consisted of pressing a specific computer key corresponding to either of two possible sample stimuli (a red or a green square). The common mediating response consisted of pressing one of the two response keys regardless of the sample. The differential‐response subjects did not show the typical, delay‐related decrease in matching‐to‐sample performance that characterized the behavior of common‐response subjects. An oddity‐matching task was then introduced, and subjects were instructed to use the mediating keys however they preferred, including not at all. Differential‐response subjects continued to respond on the originally trained mediating keys in response to sample presentation and later reversed their choice responding, thus accommodating the oddity‐matching requirements. Common‐response subjects continued to emit the previously trained mediating response and experienced limited success in oddity matching. Results were interpreted in terms of stimulus control, instructional control, and experimental history.
CONTRAST AS SEEN IN VISUAL SEARCH REACTION TIMES
Authors: Blough Donald S.
Published: March 2006

Three pigeons searched arrays of alphabetic letters displayed on computer monitors. On each trial, either an A or an E appeared, and the reaction time and accuracy with which the bird pecked at this target were measured. In each block of trials, each target (A or E) was displayed alone, or together with a number of distractor letters (2 or 18) that varied in their similarity to the target. During a baseline series of sessions, responses to the A and to the E each yielded food reinforcement on 10% of the trials. In the next series of sessions, reinforcement continued at 10% for A, but rose to 30% for E. In a final series, these reinforcement conditions were reversed. As expected, reaction times increased with target‐distractor similarity and (for similar distractors) with the number of distractors. Increased reinforcement of E had no effect on reaction times to E, but produced a very consistent increase in reaction times to A; the average increase was constant across the various display conditions. Reversal of the differential reinforcement conditions reversed this contrast effect. Analysis of the reaction time distributions indicated that increased reinforcement to E decreased the momentary probability of response to A by a constant amount, regardless of display conditions. These results are discussed in relation to theories of contrast, memory, and of the search image.
SECONDARY GENERALIZATION AND CATEGORIZATION IN PIGEONS
Authors: Bhatt R. S. , Wasserman E. A.
Published: March 2006

In Experiment 1, one group of pigeons learned to classify a set of stimuli into the human language classes cat, flower, car, and chair (categorization); another group learned to classify the same set into arbitrary classes (pseudocategorization). Then, both groups were trained on a new categorization task and their performance compared to that of a control group that had no initial classification training. Hull's (1943) notion of secondary generalization (generalization that is not based on physical similarity but on mediating associations) predicts that categorization experience will facilitate the learning of a new categorization task, whereas pseudocategorization experience will impair it. However, in Experiment 1, performance on the new categorization task was not differently affected by prior experience. In Experiment 2, pigeons initially trained to classify a set of 48 stimuli (original training) were later trained to classify a subset of four of these stimuli using new responses (reassignment training). Then, they were tested on the 44 remaining stimuli. Performance better accorded with original than with reassignment training, indicating that categorization training did not lead to the formation of equivalence classes of stimuli, in which the equivalence relationship is mediated by secondary generalization. The lack of evidence of secondary generalization implies that our pigeons failed to meet Lea's (1984) criterion for conceptual behavior.
RELATIONAL AND ABSOLUTE STIMULUS LEARNING BY MONKEYS IN A MEMORY TASK
Authors: Wright Anthony A. , Cook Robert G. , Kendrick Donald F.
Published: March 2006

Three experiments showed stimulus control by either the absolute properties of probe stimuli, relational properties of the probe‐list relationship, or both in a serial probe recognition memory task in which a four‐item memory list was followed by a single probe (test) item. In Experiment 1, 3 rhesus monkeys received 39 to 75 repetitions of the same 24‐trial stimulus sequence. Special tests showed stimulus control by the absolute properties of the probe stimuli. Retention of previous relational control was demonstrated by the good transfer (83%) to novel list and probe stimuli at the beginning of Experiment 2. During Experiment 2, control by absolute properties of the probe stimuli gradually reoccurred. Only a small measure of control by list stimuli could be detected or promoted. In Experiment 3, 4 monkeys were shown to have largely lost their ability to perform on the basis of the list‐probe relationship, and were performing primarily on the basis of the absolute properties of the probe stimuli. Over the next 15 weeks, these monkeys were transferred to new stimuli at the beginning of each week. Control by the relational aspects of the task gradually returned. As transfer performance increased, control by the absolute properties of the probe stimuli was eliminated. The results are discussed in terms of stimulus control and performance strategies used by the monkeys.
DOES CONDITIONAL DISCRIMINATION LEARNING BY PIGEONS NECESSARILY INVOLVE HIERARCHICAL RELATIONSHIPS?
Authors: Thomas David R. , Schmidt Eric K.
Published: March 2006

Four experiments demonstrate that when putative conditional and discriminative cues are presented simultaneously in the single reversal procedure, it is not possible to ascribe a uniquely conditional or uniquely discriminative function to either of the cues. In Experiment 1, pigeons were trained to respond to a blue key and not to a red key while the houselight was on; then in a different session they learned the reversal of this discrimination with the houselight off (single reversal). Separate groups were tested for color generalization with houselight conditions alternating in blocks of trials or for houselight intensity generalization with blue and red key colors alternating in blocks of trials. Both test procedures revealed a conditional relationship between houselight and key color conditions. Experiment 2 produced the same result following training in which the key colors were held constant across training sessions while the houselight and no houselight conditions varied within sessions. In Experiment 3, separate groups were trained with the two procedures but were tested with randomly ordered combinations of key colors and houselight intensities. The two groups yielded indistinguishable bidimensional generalization gradients with peaks at both previously reinforced stimulus combinations. In Experiment 4 the subjects were switched from one of these training procedures to the other with no decrement in their discriminative performance. We conclude that for successive discriminations between conditional‐ and discriminative‐stimulus combinations, the notion of a hierarchical relation between conditional and discriminative stimuli must be extended to include a symmetrical relationship or the notion should be abandoned altogether.
FUNCTIONAL CLASSES AND EQUIVALENCE RELATIONS
Authors: Sidman Murray , Wynne Constance K. , Maguire Russell W. , Barnes Thomas
Published: March 2006

Three adult subjects were taught a set of two‐choice simultaneous discriminations, with three positive and three negative stimuli; all possible combinations of positive and negative stimuli yielded nine different pairs. The discriminations were repeatedly reversed and rereversed, the former positive stimuli becoming negative and the former negative stimuli becoming positive. With all subjects, a reversal of the contingencies for one pair of stimuli became sufficient to change their responses to all of the other pairs. The reversals had produced functional stimulus classes. Then, all subjects showed conditional discriminations emerging between members of a functional class; given a sample from one class and comparisons from both classes, they selected the comparison that was in the same class as the sample. Next, 2 of the subjects showed that the within‐class conditional relations possessed the symmetric and transitive properties of equivalence relations; after having been taught to relate new stimuli to existing class members, the subjects then matched other class members to the new stimuli. Subsequent tests of two‐choice discriminations showed that the conditional discriminations had transferred functional class membership to the new stimuli. The 3rd subject, who did not show equivalence relations among functional class members, was also found to have lost the within‐class conditional relations after the equivalence tests.
ALGORITHMIC SHAPING AND MISBEHAVIOR IN THE ACQUISITION OF TOKEN DEPOSIT BY RATS
Authors: Midgley Marie , Lea Stephen E. G. , Kirby Rachel M.
Published: March 2006

In two experiments, rats were trained to deposit ball bearings down a hole in the floor, using an algorithmic version of shaping. The experimenter coded responses expected to be precursors of the target response, ball bearing deposit; a computer program reinforced these responses, or not, according to an algorithm that mimicked the processes thought to occur in conventional shaping. In the first experiment, 8 of 10 rats were successfully shaped; in the second, 5 of 5 were successfully shaped, and the median number of sessions required was the same as for a control group trained using conventional shaping. In both experiments, “misbehavior,” that is, excessive handling and chewing of the ball bearings, was observed, and when the algorithmic shaping procedure was used, misbehavior could be shown to occur in spite of reduced reinforcement for the responses involved.
STIMULUS EQUIVALENCE AND RULE FOLLOWING
Authors: Hayes Linda J. , Thompson Scott , Hayes Steven C.
Published: March 2006

The present study examined the occurrence of a novel behavior pattern with respect to a novel configuration of stimuli enabled by the participation of those stimuli in equivalence classes. In Experiment 1, functional substitutabilities were established via equivalence between two independent sets of musical stimuli. Aspects of stimuli from the two sets were then compounded to produce novel stimulus configurations. Behavioral components enabled by each separate class combined to produce novel musical performances and accurate descriptions of them. In Experiment 2, the impact of experimenter‐provided names for equivalence classes on the musical performances was investigated in naive subjects by establishing similar classes without experimenter‐provided names. The results indicated few differences in the playing performances under these conditions. These experiments demonstrated a possible method for the analysis of rule following.
INSTRUCTIONAL CONTROL OF GENERALIZED RELATIONAL MATCHING TO SAMPLE IN CHILDREN
Authors: Lowenkron Barry
Published: March 2006

Three experiments examined the performance of 4‐year‐old children in matching geometric stimuli. Performance was developed as a simulation in which all components of the behavior were overt and directly measured. A correct match depended on the state of an instructional stimulus: the background color of the display. In the first two experiments, on nonidentity trials (signified by a green background) the next longer length, larger size, or greater distance was correct. With a blue background, a comparison identical to the sample was correct. In Experiment 3, red was added for which shorter, smaller, or nearer was correct. Also here, on nonidentity trials, if a comparison of the correct length was not presented, the children adjusted their search target to the comparison of the next succeeding size (larger or smaller) so as to maintain a constant matching relation. Subsequently, when exposure to the instructional stimulus was reduced to presentation only at the beginning of each trial, performance simulated matching based on instructions about abstract relations. In all experiments, accurate matching generalized across novel stimuli and reduced exposure to the instructional stimuli.
TIMING MULTIMODAL EVENTS IN PIGEONS
Authors: Cheng Ken , Roberts William A.
Published: March 2006

The peak procedure was used in two experiments to study pigeons' ability to time multimodal events. In the first experiment, birds were trained to time a single event consisting of a 9‐s tone or light followed by a 21‐s fixed interval associated with a signal of light or tone (signal of the other modality). On occasional empty trials, different lengths of the first signal were followed by a long period of the second signal. Peak response times as a function of the duration of the first signal were linear and had a slope of close to one in all birds. This indicates that the birds were timing only the second signal. In a second experiment, two complex events were used in training. One consisted of a 9‐s tone or light followed by a 21‐s fixed interval associated with a light or tone. The other consisted of a 21‐s tone or light followed by a 9‐s fixed interval associated with a light or tone. Different durations of the first signal were again used on empty trials. Peak response times as a function of the duration of the first signal were again linear in all birds. The slope of the function was less than one but greater than zero for 3 birds. This indicates that these birds were partly timing the entire complex event of 30‐s duration and partly timing only the second signal of the event. A model is proposed in which the bird takes as a criterion for timing a weighted average of different target criteria. Comparisons with the performance of rats are made.
INCOME MAXIMIZING IN CONCURRENT INTERVAL‐RATIO SCHEDULES
Authors: Sakagami Takayuki , Hursh Steven R. , Christensen Joyce , Silberberg Alan
Published: March 2006

Three mice chose between concurrent variable‐ratio variable‐interval schedules to produce a warm air stream while they were housed in a cold chamber. Across conditions, the duration of the warm air stream was varied between 10 and 80 s and was equal for both schedules. Preference for the VI schedule covaried with reinforcer duration as predicted by maximizing accounts of choice.
REPEATED DIAZEPAM ADMINISTRATION: EFFECTS ON THE ACQUISITION AND PERFORMANCE OF RESPONSE CHAINS IN HUMANS
Authors: Bickel Warren K. , Higgins Stephen T. , Griffiths Roland R.
Published: March 2006

The effects of repeated diazepam administration (80 mg) were assessed across a 12‐hr time course with humans responding under a two‐component multiple schedule of repeated acquisition and performance of response sequences. Subjects resided in an inpatient clinical research ward for the duration of the study. In each component of the multiple schedule, subjects completed sequences of 10 responses in a predetermined order using three keys of a numeric keypad. In the acquisition component, a new response sequence was to be acquired each session. In the performance component, the response sequence always remained the same. After stable responding was obtained and the effects of the placebo assessed, diazepam was administered for 3 consecutive days. The effects of repeated diazepam administration on overall percentage of errors across the two components of the multiple schedule were selective. In the acquisition component, the first dose of diazepam increased percentage errors with the magnitude of effects decreasing across the second and third days of diazepam administration. In the performance component, the percentage of errors was either minimally affected across all 3 days of diazepam administration or substantively increased on Day 1 with subsequent diazepam administrations having minimal effects. Effects on response rate were not selective. Diazepam decreased rates of responding in both schedule components, with the magnitude of effects decreasing across successive administrations. These results replicate previous findings in humans and nonhumans on the selective effects of diazepam on acquisition versus performance baselines. Also, the results suggest that the selective effects do not result from differences in reinforcement rate. Finally, the present results demonstrate that the selective recovery from repeated drug administration previously demonstrated in nonhumans using a repeated acquisition arrangement has generality to human behavior.
STOCHASTIC CHOICE MODELS: A COMPARISON BETWEEN BUSH‐MOSTELLER AND A SOURCE‐INDEPENDENT REWARD‐FOLLOWING MODEL
Authors: Staddon J. E. R. , Horner J. M.
Published: March 2006

Horner and Staddon (1987) argued that a class of reward‐following processes defined by a property they termed ratio invariance is a better model for the probabilistic choice performance of pigeons than competing molecular accounts such as momentary maximizing, melioration, and the Bush‐Mosteller model. The critical data were provided by choice distributions—distributions of a variable S, the proportion of Right choices, defined on a moving window typically 32 choices long—obtained under a frequency‐dependent schedule. The schedule prescribed equal payoff probabilities, p(S), for both choices. p(S) was a maximum when S = 0.5 and declined linearly for S values above and below 0.5. Pigeons showed generally bimodal choice distributions with the modes at equal p(S) values. These data do not follow easily from melioration or momentary maximizing and are inconsistent with molar maximizing, but they may be consistent with Bush‐Mosteller. We present here the results of computer simulations showing that the ratio‐invariance model studied yields, as expected, choice modes at equal p(S) values, but that Bush‐Mosteller, although capable of generating bimodal choice distributions, does not have choice modes at equal p(S) values.
TEMPORAL REPRODUCTION
Authors: Zeiler Michael D. , Hoyert Mark S.
Published: March 2006

A signal appeared for a certain time period. After the period elapsed, pigeons had to begin and complete a sequence of 15 responses in a time window ranging from the signal duration to 50% longer. Sessions involved as many as 10 different signal durations occurring in a random sequence. The times produced by pigeons often were in the same ranges as those that have been found with adult human subjects. The average times were described equally well as linear or power functions of signal duration. However, instead of the overestimation of durations usually found when animals have timed the duration of antecedent stimuli, the linear functions suggested that the pigeons underestimated the durations of their own behavior. The birds showing the strongest control when the conditions involved eight or 10 different duration requirements revealed the constant coefficients of variation that support Weber's law and scalar timing theory. Scalar timing in temporal differentiation appears to depend on non‐ambiguous information about the duration required for reinforcement and on a high degree of sensitivity to the duration requirement.
SYNERGISTIC EFFECTS OF ETHANOL AND COCAINE ON BRAIN STIMULATION REWARD
Authors: Lewis Michael J. , June Harry L.
Published: March 2006

The effects of two widely abused drugs, ethanol and cocaine, were examined alone and in combination on intracranial reward processes. In agreement with previous research, higher doses of both cocaine and ethanol alone produced facilitation of behavior maintained by brain stimulation reward. Low intraperitoneal doses of ethanol and cocaine, which alone did not affect performance, were found to reduce stimulation reward threshold and modestly increase response rate. The enhancement of brain stimulation reward by the combination of ethanol and cocaine suggests that both drugs may produce their rewarding effects through common neuronal substrates and that they may potentiate the abuse of each other.
EFFECTS OF COCAINE ON SIMPLE REACTION TIMES AND SENSORY THRESHOLDS IN BABOONS
Authors: Hienz Robert D. , Spear Debra J. , Bowers Danielle A.
Published: March 2006

The effects of chronic, daily administration of cocaine on auditory and visual reaction times and thresholds were studied in baboons. Single intramuscular injections of cocaine hydrochloride (0.1 to 5.6 mg/kg) were given once daily for periods of 10 to 25 days, and were followed immediately by psychophysical tests designed to assess cocaine's effects on simple reaction times as well as on auditory and visual threshold functions. Consistent reductions in reaction times were frequently observed over the cocaine dose range of 0.32 to 1.0 mg/kg; at higher doses, either decreases or increases in reaction times were observed, depending upon the animal. Lowered reaction times generally occurred immediately following the 1st day's cocaine injection, and continued through all subsequent days during the dose administration period, suggesting little development of tolerance or sensitivity to these reaction‐time effects. Reaction‐time decreases showed a U‐shaped dose‐effect function. The greatest decreases in reaction times occurred from 0.32 to 1.0 mg/kg, and produced an average reaction‐time decrease of 10 to 12%. Concurrently measured auditory and visual thresholds showed no systematic changes as a function of cocaine dose. Pausing was observed during performance of the psychophysical tasks, with the length of total session pause times being directly related to cocaine dose.
BIOBEHAVIORAL EFFECTS OF EXTENDED SALT LOADING AND CONFLICT STRESS IN INTACT BABOONS
Authors: Turkkan Jaylan S.
Published: March 2006

Behavioral stressors may inhibit sodium excretion, potentially increasing plasma volume and elevating blood pressure during chronic exposure. Blood pressure regulation may be especially deranged during manipulations that further challenge the kidney, such as a diet high in salt content. The effects on blood pressure and other variables of combined behavioral stress (food/shock conflict) and dietary salt (12 g NaCl per day; 218 mEq Na+ per day) were examined in adult male baboons over the course of 1 year. Mean arterial pressure was not significantly elevated over baseline after 5 months of high dietary salt alone (6 ± 5 mmHg) but was maximally elevated by an average of 17 (±3 SEM) mmHg after 5 months of combined salt and conflict stress. Control baboons showed no significant trends in mean arterial pressure across the same time period. Individual subjects whose blood pressure was “salt+stress resistant” or “salt+stress sensitive” were differentiated by their degree of pressure diuresis and natriuresis, urinary free cortisol, and a behavioral index of stress sensitivity. The data indicate additive effects of chronic high dietary salt intake and behavioral stressors on blood pressure in nonhuman primates that are dependent on renal function and pituitary‐adrenocortical activity.
AN OPERANT APPROACH TO REHABILITATION MEDICINE: OVERCOMING LEARNED NONUSE BY SHAPING
Authors: Taub Edward , Crago Jean E. , Burgio Louis D. , Groomes Thomas E. , Cook Edwin W. , DeLuca Stephanie C. , Miller Neal E.
Published: March 2006

A new approach to the rehabilitation of movement, based primarily on the principles of operant conditioning, was derived from research with deafferented monkeys. The analysis suggests that a certain proportion of excess motor disability after certain types of injury involves a learned suppression of movement and may be termed learned nonuse. Learned nonuse can be overcome by changing the contingencies of reinforcement so that they strongly favor use of an affected upper extremity in the chronic postinjury situation. The techniques employed here involved 2 weeks of restricting movement of the opposite (unaffected) extremity and training of the affected limb. Initial work with humans has been with chronic stroke patients for whom the approach has yielded large improvements in motor ability and functional independence. We report here preliminary data suggesting that shaping with verbal feedback further enhances the motor recovery.
AN EIGHT‐ALTERNATIVE CONCURRENT SCHEDULE: FORAGING IN A RADIAL MAZE
Authors: Elsmore Timothy F. , McBride Sharon A.
Published: March 2006

In two experiments conducted in an eight‐arm radial maze, food pellets were delivered when a photocell beam was broken at the end of each arm via a nose poke, according to either fixed‐interval or random‐interval schedules of reinforcement, with each arm providing a different frequency of reinforcement. The behavior of rats exposed to these procedures was well described by the generalized matching law; that is, the relationships between log behavior ratios and log pellet ratios were approximated by linear functions. The slopes of these log‐log functions, an index of sensitivity to reinforcement frequency, were greatest for nose pokes, intermediate for time spent in an arm, and least for arm entries. Similar results were obtained with both fixed‐interval and random‐interval schedules. Addition of a 10‐s changeover delay in both experiments eliminated the slope differentials between nose pokes and time spent in an arm by reducing the slopes of the nose‐poke functions. These results suggest that different aspects of foraging may be differentially sensitive to reinforcement frequency. With concurrent fixed‐interval schedules, the degree of temporal control exerted by individual fixed‐interval schedules was directly related to reinforcement frequency.
CHOICE IN THE TIME‐LEFT PROCEDURE AND IN CONCURRENT CHAINS WITH A TIME‐LEFT TERMINAL LINK
Authors: Preston Ray A.
Published: March 2006

In two experiments, rats chose between a standard fixed‐duration food‐associated stimulus and a stimulus whose duration was the time remaining to reinforcement in an elapsing comparison interval. In Experiment 1, 4 rats responded in a time‐left procedure wherein a single initial‐link variable‐interval schedule set up two potential terminal links simultaneously. As time elapsed in the initial‐link schedule, the choice was between a standard fixed‐interval 30‐s terminal link and a time‐left terminal link whose programmed interval requirement equaled 90 s minus the elapsed time in the initial link. Rats generally responded more on the lever with the shortest programmed terminal‐link duration, but the temporal parameters of the procedure were found to vary with response distributions. Contrary to previous reports, therefore, time‐left data were well predicted by choice models that make no assumptions about animal timing. In Experiment 2, 8 rats responded on a concurrent‐chains schedule with independent variable‐interval initial links and a time‐left terminal link in one of the choice schedules. On the time‐left lever, the programmed terminal‐link delay equaled 90 s minus the elapsed time in the time‐left initial link. On the standard lever, terminal‐link responses were reinforced according to a variable‐interval schedule whose average value varied over four conditions. Relative time‐left initial‐link responses increased in the elapsing time‐left initial‐link schedule as the time‐left terminal link became shorter relative to the standard terminal link. Scalar expectancy theory failed to predict the resultant data, but a modified version of the delay‐reduction model made good predictions. An analysis of the elaboration of scalar expectancy theory for variable delays demonstrated that the model is poorly formulated for arithmetically distributed delays.
DELAY REDUCTION AND OPTIMAL FORAGING: VARIABLE‐RATIO SEARCH IN A FORAGING ANALOGUE
Authors: Williams Wendy A. , Fantino Edmund
Published: March 2006

The present study investigated conditions under which the conditioned reinforcement principles of delay‐reduction theory and views based on simple maximization of reinforcement rate make ordinally opposing predictions with respect to foraging‐related choice behavior. The use of variable‐ratio schedules in the choice phase also represents an extension of delay‐reduction theory to schedules that may better mimic the effort involved in searching. Pigeons responded on modified concurrent‐chains schedules in which equal variable‐ratio schedules led to unequal variable‐interval outcomes and unequal reinforcer amounts. All 4 subjects completed a minimum of two replications of conditions for which the predictions of delay‐reduction theory and a simple rate‐maximizing theory were opposed. Results were consistent with delay reduction's ordinal predictions in 11 of 11 replications of the divergent predictions favoring the smaller, more immediate alternative. The predictions of rate maximization were upheld only when they were consistent with those of delay reduction. Results are discussed in terms of conditioned reinforcement, sensitivity to reductions in delay to food, and possible rules of thumb that may be useful in characterizing foraging.
TRANSFER OF RELATIONAL STIMULUS CONTROL IN CONDITIONAL DISCRIMINATIONS
Authors: Pérez‐González Luis Antonio
Published: March 2006

Four adults were trained, using instructions and a matching‐to‐sample procedure, to select Stimulus B1 in the presence of Stimulus A1, B2 in the presence of A2, and B3 in the presence of A3 (the AB relations). Analogous PQ relations were trained. Afterwards, one stimulus in Set A and another stimulus in Set B appeared together as a sample, and novel Stimuli X1 and X2 were the comparisons. Responses to X1 were reinforced if the two stimuli in the sample had been related in the previous training (e.g., A1 and B1), and responses to X2 were reinforced if the two samples had not been related (e.g., A1 and B2). These were the ABX relations. In a test in which a stimulus of Set P and another of Set Q were the samples and X1 and X2 were the comparisons, 2 subjects selected X1 when the samples were P1 and Q1, P2 and Q2, and P3 and Q3, and selected X2 in the presence of the other six sample combinations (P1Q2, P1Q3, P2Q1, P2Q3, P3Q1, and P3Q2). Another subject showed the same responding after additional training. In the second experiment, 3 adults and an 11‐year‐old child were trained on AB, PQ, and ABX relations, and they showed the symmetrical relations BA and QP upon testing. Then all 4 of these subjects responded accurately to the PQX test. Results of Experiments 1 and 2 showed novel, consistent comparison selection based on the previously established relation between the two stimuli in the sample. In a third experiment, 3 of the subjects who had shown PQX relations were trained on EFX relations, with pairs of E and F stimuli as samples and X stimuli as comparisons. When the EF relations were tested, all 3 subjects consistently selected F1 in the presence of E1, F2 in the presence of E2, and F3 in the presence of E3 from the first trial. The results of Experiment 3 showed novel stimulus relations after training with a more complex conditional discrimination format.