bluuebunny/crossref_metadata_2025 huggingface dataset:
SIMULTANEOUS AUDITORY DISCRIMINATION
Authors: Harrison J. M.
Published: March 2006

Stimuli in many visual stimulus control studies typically are presented simultaneously; in contrast the stimuli in auditory discrimination studies are presented successively. Many everyday auditory stimuli that control responding occur simultaneously. This suggests that simultaneous auditory discriminations should be readily acquired. The purpose of the present experiment was to train rats in a simultaneous auditory discrimination. The apparatus consisted of a cage with two response levers mounted on one wall and a speaker mounted adjacent to each lever. A feeder was mounted on the opposite wall. In a go‐right/go‐left procedure, two stimuli were presented on each trial, a wide‐band noise burst through one speaker and a 2‐kHz complex signal through the other. The stimuli alternated randomly from side to side across trials, and the stimulus correlated with reinforcement for presses varied across subjects. The rats acquired the discrimination in 400 to 700 trials, and no response position preference developed during acquisition. The ease with which the simultaneous discrimination was acquired suggests that procedures, such as matching to sample, that require simultaneous presentation of stimuli can be used with auditory stimuli in animals having poor vision.
MATCHING, DELAY‐REDUCTION, AND MAXIMIZING MODELS FOR CHOICE IN CONCURRENT‐CHAINS SCHEDULES
Authors: Luco J. Enrique
Published: March 2006

Models of choice in concurrent‐chains schedules are derived from melioration, generalized matching, and optimization. The resulting models are compared with those based on Fantino's (1969, 1981) delay‐reduction hypothesis. It is found that all models involve the delay reduction factors (T — t2L) and (T — t2R), where T is the expected time to primary reinforcement and t2L, t2R are the durations of the terminal links. In particular, in the case of equal initial links, the model derived from melioration coincides with Fantino's original model for full (reliable) reinforcement and with the model proposed by Spetch and Dunn (1987) for percentage (unreliable) reinforcement. In the general case of unequal initial links, the model derived from melioration differs from the revised model advanced by Squires and Fantino (1971) only in the factors affecting the delay‐reduction terms (T — t2L) and (T — t2R). The models of choice obtained by minimizing the expected time to reinforcement depend on the type of feedback functions used. In particular, if power feedback functions are used, the optimization model coincides with that obtained from melioration.
QUANTITATIVE AND METHODOLOGICAL ASPECTS OF STIMULUS EQUIVALENCE
Authors: O'Mara Henry
Published: March 2006

The number of different ways of linking stimuli in the training phase of a conditional discrimination procedure designed to teach equivalence relations has hitherto been underestimated. An algorithm from graph theory that produces the correct number of such different ways is given. The establishment of equivalence relations requires transitive stimulus control. A misconception in a previous analysis of the conditions necessary for demonstrating transitive stimulus control is indicated. This misconception concerns responding in an unreinforced test trial to a negative rather than a positive comparison stimulus. Such behavior cannot be attributed to discriminative control by degree of association with reinforcement if the negative comparison stimulus has been less associated with reinforcement than the positive comparison stimulus in an antecedent training phase.
ECONOMIC SUBSTITUTABILITY OF ELECTRICAL BRAIN STIMULATION, FOOD, AND WATER
Authors: Green Leonard , Rachlin Howard
Published: March 2006

Concurrent variable‐ratio schedules of electrical brain stimulation, food, and water were paired in various combinations as reinforcement of rats' lever presses. Relative prices of the concurrent reinforcers were varied by changing the ratio of the response requirements on the two levers. Economic substitutability, measured by the sensitivity of response ratio to changes in relative price, was highest with brain stimulation reinforcement of presses on both levers and lowest with food reinforcement of presses on one lever and water reinforcement of presses on the other. Substitutability with brain stimulation reinforcement of presses on one lever and either food or water reinforcement for presses on the other was about as high as with brain stimulation for presses on both levers. Electrical brain stimulation for rats may thus serve as an economic substitute for two reinforcers, neither of which is substitutable for the other.
BEHAVIORAL ECONOMICS OF DRUG SELF‐ADMINISTRATION. II. A UNIT‐PRICE ANALYSIS OF CIGARETTE SMOKING
Authors: Bickel Warren K. , DeGrandpre R. J. , Hughes John R. , Higgins Stephen T.
Published: March 2006

In behavioral economics, the ratio of response requirement to reinforcer magnitude is referred to as unit price. Previous research with nonhuman subjects has demonstrated that (a) comparable amounts of food are consumed at the same unit price even though different response requirements and reinforcer magnitudes comprise that unit price and (b) increases in unit price decrease food consumption in a positively decelerating fashion. The present study assessed the generality of these findings to the cigarette smoking of 5 human volunteers. During approximately 18 3‐hr sessions, various combinations of response requirement (fixed‐ratio 200, 400, and 1,600) and reinforcer magnitude (1, 2, and 4 puffs per bout) were arranged. Consumption (i.e., the number of puffs) generally was comparable at the same unit price independent of the response requirement and reinforcer magnitude comprising that unit price. In addition, increasing unit price generally decreased consumption in a positively decelerating fashion. These results extend the generality of the unit‐price analysis to human cigarette smoking. Moreover, these results further support the position that reinforcer magnitude and response requirement are functionally equivalent and interact to determine consumption. The concept of unit price, by integrating and summarizing the effects of those two operations, provides a more parsimonious explanation of the results than do separate evaluations of the effects of response requirement and reinforcer magnitude.
CHOICE AND CONDITIONED REINFORCEMENT
Authors: Fantino Edmund , Freed Debra , Preston Ray A. , Williams Wendy A.
Published: March 2006

A potential weakness of one formulation of delay‐reduction theory is its failure to include a term for rate of conditioned reinforcement, that is, the rate at which the terminal‐link stimuli occur in concurrent‐chains schedules. The present studies assessed whether or not rate of conditioned reinforcement has an independent effect upon choice. Pigeons responded on either modified concurrent‐chains schedules or on comparable concurrent‐tandem schedules. The initial link was shortened on only one of two concurrent‐chains schedules and on only one of two corresponding concurrent‐tandem schedules. This manipulation increased rate of conditioned reinforcement sharply in the chain but not in the tandem schedule. According to a formulation of delay‐reduction theory, when the outcomes chosen (the terminal links) are equal, as in Experiment 1, choice should depend only on rate of primary reinforcement; thus, choice should be equivalent for the tandem and chain schedules despite a large difference in rate of conditioned reinforcement. When the outcomes chosen are unequal, however, as in Experiment 2, choice should depend upon both rate of primary reinforcement and relative signaled delay reduction; thus, larger preferences should occur in the chain than in the tandem schedules. These predictions were confirmed, suggesting that increasing the rate of conditioned reinforcement on concurrent‐chains schedules may have no independent effect on choice.
DISCRIMINATION TRAINING FACILITATES PIGEONS' PERFORMANCE ON ONE‐TRIAL‐PER‐DAY DELAYED MATCHING OF KEY LOCATION
Authors: Willson Robert J. , Wilkie Donald M.
Published: March 2006

Six pigeons were tested on a one‐trial‐per‐day variant of delayed matching of key location. In one condition, a trial began with the illumination of a pair of quasi‐randomly selected pecking keys in a large 10‐key test box. Pigeons' pecks to one key (the sample) were reinforced with 8‐second access to grain on a variable‐interval 30‐second schedule, whereas pecks to the other key (the distractor) had no scheduled consequences. In the second condition, the nonreinforced distractor was not presented. In both conditions, subjects were removed from the apparatus after 15 minutes and placed in a holding cage. Subjects were subsequently replaced in the box after a delay (retention interval) of 30 seconds and were reexposed to the illuminated sample and distractor keys for 1 minute. If a pigeon made more pecks to the sample during this interval, the distractor was extinguished and subsequent pecks to the sample were reinforced on the previous schedule for an additional 15 minutes. If, however, a pigeon made more pecks to the distractor, both keys were extinguished and the subject was returned to its home cage. For all subjects, matching‐to‐sample accuracy was higher in the first condition. In a second experiment, the retention interval was increased to 5, 15, and 30 minutes, and then to 1, 2, 4, 8, 12, and 24 hours. Most subjects remembered the correct key location for up to 4 hours, and in one case, up to 24 hours, demonstrating a spatial‐memory proficiency far better than previously reported in this species on delayed matching tasks. The results are discussed in terms of the commonly held distinction between working and reference memory.
SUBSTITUTABILITY BETWEEN CONDITIONED AND PRIMARY REINFORCERS IN DISCRIMINATION ACQUISITION
Authors: Williams Ben A. , Dunn Roger
Published: March 2006

Rats and pigeons were trained on a series of reversals of a conditional simultaneous discrimination. The percentage of reinforcement for correct trials was varied across reversals. When nonreinforced correct trials produced the same feedback as incorrect trials, the number of errors to reach an acquisition criterion was greater for smaller percentages of reinforcement, but the number of reinforcers required was either approximately constant or smaller for the smaller percentages. When a stimulus paired with food (the conditioned reinforcer) was added on nonreinforced correct trials, both measures were substantially decreased. When the same stimulus was presented, but without a history of food pairing, learning rate was similar to when no stimulus was presented on nonreinforced trials. The results provide direct evidence that conditioned reinforcers may substitute, although imperfectly, for a primary reinforcer, and that pairing with the primary reinforcer is a necessary condition for such substitutability to occur.
SUBJECTIVE PROBABILITY AND DELAY
Authors: Rachlin Howard , Raineri Andres , Cross David
Published: March 2006

Human subjects indicated their preference between a hypothetical $1,000 reward available with various probabilities or delays and a certain reward of variable amount available immediately. The function relating the amount of the certain‐immediate reward subjectively equivalent to the delayed $1,000 reward had the same general shape (hyperbolic) as the function found by Mazur (1987) to describe pigeons' delay discounting. The function relating the certain‐immediate amount of money subjectively equivalent to the probabilistic $1,000 reward was also hyperbolic, provided that the stated probability was transformed to odds against winning. In a second experiment, when human subjects chose between a delayed $1,000 reward and a probabilistic $1,000 reward, delay was proportional to the same odds‐against transformation of the probability to which it was subjectively equivalent.
B. F. SKINNER AND G. H. MEAD: ON BIOLOGICAL SCIENCE AND SOCIAL SCIENCE
Authors: Blackman Derek E.
Published: March 2006

Skinner's contributions to psychology provide a unique bridge between psychology conceptualized as a biological science and psychology conceptualized as a social science. Skinner focused on behavior as a naturally occurring biological phenomenon of interest in its own right, functionally related to surrounding events and, in particular (like phylogenesis), subject to selection by its consequences. This essentially biological orientation was further enhanced by Skinner's emphasis on the empirical foundations provided by laboratory‐based experimental analyses of behavior, often with nonhuman subjects. Skinner's theoretical writings, however, also have affinity with the traditions of constructionist social science. The verbal behavior of humans is said to be subject, like other behavior, to functional analyses in terms of its environment, in this case its social context. Verbal behavior in turn makes it possible for us to relate to private events, a process that ultimately allows for the development of consciousness, which is thus said to be a social product. Such ideas make contact with aspects of G. H. Mead's social behaviorism and, perhaps of more contemporary impact in psychology, L. Vygotsky's general genetic law of cultural development. Failure to articulate both the biological and the social science aspects of Skinner's theoretical approach to psychology does a disservice to his unique contribution to a discipline that remains fragmented between two intellectual traditions.
CONTEXT SPECIFICITY OF OPERANT DISCRIMINATION PERFORMANCE IN PIGEONS
Authors: Thomas David R. , Empedocles Stephen
Published: March 2006

In an experiment designed to investigate odors as potential retrieval cues in pigeons' memory (i.e., as conditional stimuli), 8 pigeons first learned to peck a red keylight (S+, reinforced) and not a blue one (S‐, extinguished) in the presence of either a eucalyptus oil or isoamyl acetate odor. They were repeatedly switched between two chambers with the same odor to habituate any reaction to the switching that would be required for eventual testing for conditional control by the odors. Next, the birds learned the reversal (blue S+, red S‐) in the presence of the alternative odor in one of these chambers. When the birds were then switched to the alternative chamber for additional training, although the odor was still appropriate to the reversal problem, behavior appropriate to the original training condition recurred. Testing indicated that reversal performance was specific to the one chamber in which it had been trained.
THE ROLE OF INSTRUCTIONS IN THE TRANSFER OF ORDINAL FUNCTIONS THROUGH EQUIVALENCE CLASSES
Authors: Green Gina , Sigurdardottir Z. Gabriela , Saunders Richard R.
Published: March 2006

In two experiments, adult subjects completed match‐to‐sample training and testing to establish four equivalence classes of four figures each. Then the subjects were taught one three‐position sequence consisting of one stimulus from Class 1, one from Class 2, and one from Class 3. Inclusion of Class 4 stimuli in sequences was never reinforced, but two different stimuli from Class 4 appeared as distractors on each sequence trial. Tests assessed whether subjects would produce novel three‐position sequences composed of members of Classes 1 through 3 that had not been used in sequence training. Three subjects in Experiment 1 received instructions about the match‐to‐sample and sequencing tasks, in addition to training contingencies. All 3 demonstrated equivalence class formation after match‐to‐sample training. After they were taught one sequence with one member of Classes 1 through 3, none of these subjects produced untrained sequences with other equivalence class members reliably. One additional sequence was trained directly; thereafter 1 subject showed some evidence of transfer of the trained ordinal functions across the remaining members of the equivalence classes, but the other 2 did not. Following a review of equivalence class training and testing and a review of the original sequence training, all 3 subjects produced most of the predicted, untrained sequences on tests. Experiment 2 replicated Experiment 1 with 2 adults but omitted all instructions except the minimal ones necessary to initiate responding. Unlike the subjects in Experiment 1, both of these subjects demonstrated virtually complete transfer of ordinal functions through the equivalence classes after direct training on just one sequence composed of one member of Classes 1 through 3.
STIMULUS GENERALIZATION AND EQUIVALENCE CLASSES: A MODEL FOR NATURAL CATEGORIES
Authors: Fields Lanny , Reeve Kenneth F. , Adams Barbara J. , Verhave Thom
Published: March 2006

Two three‐member classes were formed by training AB and BC using a conditional discrimination procedure. The A and B stimuli were nonsense syllables, and the C stimuli were sets of “short” or “long” lines. To test for equivalence, C1 or C2 was presented as a sample with A1 and A2 as comparisons. Once the class‐related comparison was chosen consistently, different line lengths were substituted for the training lines in the CA tests. In general, the likelihood of choosing a given comparison was an inverse function of the difference in the length of the test line from the training line. Stimuli in an equivalence class became functionally related not only to each other but also to novel stimuli that resembled a member of the equivalence class. The combination of primary generalization and equivalence class formation, then, can serve as a model to account for the development of naturally occurring categories.
IRRELEVANCE OF SAMPLE STIMULI AND DIRECTED FORGETTING IN PIGEONS
Authors: Grant Douglas S. , Barnet Robert C.
Published: March 2006

A successive matching procedure was used to investigate which aspect of the test‐omission procedure is responsible for establishing a postsample stimulus as a cue to forget in pigeons. It was found that a postsample stimulus that reliably followed a sample that was irrelevant to performance functioned as a cue to forget. This result was obtained regardless of whether termination of that postsample stimulus was followed by reinforcement or by the presentation of sample‐independent discriminative stimuli. It was also found that a postsample stimulus that functioned as a cue to forget at the beginning of training lost that function when it was repeatedly presented on trials in which the sample was relevant to performance. These findings reveal that (a) neither a reduction in reinforcement rate nor the omission of the opportunity for discriminated responding is necessary to establish an effective cue to forget and (b) irrelevance of the sample to performance is a sufficient condition to establish a cue to forget. These results suggest that a postsample stimulus that is presented on trials in which remembering the sample is not reinforced differentially will come to set the occasion for not remembering the sample.
SUPERIOR‐SUBORDINATE DYADS: DEPENDENCE OF LEADER EFFECTIVENESS ON MUTUAL REINFORCEMENT CONTINGENCIES
Authors: Rao Ram K. , Mawhinney T. C.
Published: March 2006

Task contingencies were modeled from bureaucratic organizations in which vague job descriptions provide incomplete contingency specifications. Response rates within dyads were examined using two nonsocial, two social, and two control contingencies. In the first social contingency, responses by the superior produced monetary reinforcement for a subordinate while the superior received no reinforcement from his subordinate. A second social contingency was identical to the first except that the subordinate's rate of responding determined the rate of reinforcement delivered to his superior. Within this contingency, mutual reinforcement occurred whenever rates of superior and subordinate responding were correlated. Two control contingencies were identical to the second social contingency except that either the superior or the subordinate received a rate of response‐independent reinforcement virtually identical to the rate received during the second social contingency. Leadership, in this context, was the difference between rates of subordinate responding produced by a nonsocial contingency and rates produced by each of the two social contingencies. The two nonsocial contingencies supported almost no responding among subjects. The first social contingency produced minimal levels of leadership within every dyad. The second social contingency produced high levels of leadership. Response‐independent reinforcement generally reduced or eliminated responding.
THE TRANSFER OF SPECIFIC AND GENERAL CONSEQUENTIAL FUNCTIONS THROUGH SIMPLE AND CONDITIONAL EQUIVALENCE RELATIONS
Authors: Hayes Steven C. , Kohlenberg BarbaraS. , Hayes Linda J.
Published: March 2006

The purpose of this study was to examine the transfer of consequential (reinforcement and punishment) functions through equivalence relations. In Experiment 1, 9 subjects acquired three three‐member equivalence classes through matching‐to‐sample training using arbitrary visual forms. Comparison stimuli were then given conditioned reinforcement or punishment functions by pairing them with verbal feedback during a sorting task. For 8 of the 9 subjects, trained consequential functions transferred through their respective equivalence classes without additional training. In Experiment 2, transfer of function was initially tested before equivalence testing per se. Three of 4 subjects showed the transfer without a formal equivalence test. In Experiment 3, 3 subjects were given training that gave rise to six new three‐member conditional equivalence classes. For 2 of the subjects, the same stimulus could have either a reinforcement or punishment function on the basis of contextual cues that defined its class membership. Experiment 4 assessed whether equivalence training had established general or specific consequential functions primarily by adding novel stimuli in the transfer test. Subjects treated even novel feedback stimuli in the transfer test as consequences, but the direction of consequential effects depended upon the transfer of specific consequential functions through equivalence relations.
TRANSIENT EFFECTS OF ACQUISITION HISTORY ON GENERALIZATION IN A MATCHING‐TO‐SAMPLE TASK
Authors: Michael Renee L. , Bernstein Daniel J.
Published: March 2006

This study examined the role of learning history on the acquisition of a matching‐to‐sample task. Twelve preschool children learned four stimulus classes through instructions, shaping, or imitation. After reaching criterion, the subjects were exposed to changed discrimination contingencies to determine how each learning history affected the acquisition of responses appropriate to the new contingencies. All subjects reached criterion on the new relations, although the subjects with a shaping history adapted slightly more quickly than those subjects with a history of instructions or imitation. Given sufficient exposure to changed contingencies, rule‐driven insensitivity to contingencies was overcome by experience with consequences. This result may be specific to younger subjects, but it suggests that instructions can be used in education without creating insensitivity to contingencies.
RAT AA‐26: BEHAVIORAL PHARMACOLOGY SCIENCE PIONEER
Authors: Brady Joseph V.
Published: March 2006

Rat AA‐26, despite 1950s “state of the art,” nonetheless generated the first set of behavioral pharmacology cumulative records to appear in the weekly journal Science, the century‐old publication of the American Association for the Advancement of Science. The laboratory exploits of this dedicated animal called early attention to the methodological fruits of a marriage between pharmacology and the experimental analysis of behavior.
VARIABLE‐RATIO SCHEDULES OF TIMEOUT FROM AVOIDANCE: EFFECTS OF d‐AMPHETAMINE AND MORPHINE
Authors: Galizio Mark , Allen Angela R.
Published: March 2006

Rats were trained on concurrent schedules in which pressing one lever postponed shock and pressing the other lever produced periods of signaled timeout from avoidance on variable‐ratio schedules. These procedures generated high rates of timeout‐reinforced responding and provided a baseline for studying the effects of drugs on behavior maintained by different types of negative reinforcement (shock postponement vs. timeout). Morphine (2.5 to 10.0 mg/kg) reduced behavior maintained by timeout at doses that increased or had no effect on avoidance responding. In contrast, d‐amphetamine (0.125 to 2.0 mg/kg) produced large increases in timeout responding at doses that had minimal effect on avoidance in rats trained on variable‐interval and variable‐ratio schedules. Thus, the event‐dependent effects of morphine, observed in previous studies in which timeout responding was maintained at low rates by interval schedules, were replicated with high timeout rates maintained by variable‐ratio schedules. The effects of d‐amphetamine could also be described as “event dependent” because timeout responding was stimulated more than avoidance regardless of the maintenance schedule or baseline rate.
CONTROL OVER RESPONSE NUMBER BY A TARGETED PERCENTILE SCHEDULE: REINFORCEMENT LOSS AND THE ACUTE EFFECTS OF d‐AMPHETAMINE
Authors: Galbicka Gregory , Fowler Kelly P. , Ritch Zoeth J.
Published: March 2006

Two fixed‐consecutive‐number‐like procedures were used to examine effects of acute d‐amphetamine administration on control over response number. In both procedures, rats were required to press the left lever at least once and then press the right lever to complete a trial. The consecutive left‐lever presses on each trial comprised a “run.” Under the targeted percentile schedule, reinforcement was provided if the current run length was closer to the target length (16) than half of the most recent 24 runs. This differentially reinforced run length while holding reinforcement probability constant at .5. A second group acquired the differentiation under the targeted percentile schedule, but were then shifted to a procedure that yoked reinforcement probability by subject and run length to that obtained under the targeted percentile schedule. The two procedures generated practically identical control run lengths, response rates, reinforcement probabilities, and reinforcement rates. Administration of d‐amphetamine disrupted percentile responding to a greater degree than yoked control responding. This disruption decreased reinforcement frequency less in the former than the latter procedure. The similar baseline responding under these two procedures suggests that this difference in sensitivity was due to behavioral adjustments to drug prompted by reduction of reinforcement density in the yoked control but not the percentile schedule. These adjustments attenuate the drug's effects under the former, but not the latter, procedure.
PREFERENCE FOR LESS FREQUENT SHOCK UNDER FIXED‐INTERVAL SCHEDULES OF ELECTRIC‐SHOCK PRESENTATION
Authors: Pitts Raymond C. , Malagodi E. F.
Published: March 2006

Lever pressing by 2 squirrel monkeys was maintained under fixed‐interval 6‐min and fixed‐interval 2‐min schedules of electric‐shock presentation. Preference for these schedules was assessed during three experimental phases. In all phases, responses on one lever produced shock according to one or the other fixed‐interval schedule, and responses on a second, changeover, lever switched between schedules. The opportunity to change over was presented during separate choice periods (during which the fixed‐interval schedules did not operate) that followed the first through fourth shocks in each schedule. If no changeover occurred during those choice periods, a changeover automatically occurred following the fifth shock. In Phase I, durations of the choice periods were fixed. In Phase II, the choice periods equaled a proportion of their respective fixed interval. During Phase III (completed with 1 monkey) a response on the changeover lever during a given choice period reinstated the most recent fixed interval, and a failure to respond resulted in a changeover. During each of these phases, distinct preferences developed for the 6‐min schedule. These results suggest that the maintenance of lever pressing by fixed‐interval presentation of electric shock may not be an example of positive reinforcement, and that the response‐maintaining characteristics of shock presentation may derive from other properties of the schedule.
THE EFFECTS OF DIAZEPAM AND TRIAZOLAM ON REPEATED ACQUISITION AND PERFORMANCE OF RESPONSE SEQUENCES WITH AN OBSERVING RESPONSE
Authors: Bickel Warren K. , Higgins Stephen T. , Hughes John R.
Published: March 2006

Drugs often disrupt the acquisition of new response sequences at doses that fail to disrupt the performance of a previously acquired response sequence. This selective drug effect may result from differences in the control exerted by the stimuli presented after each response in the acquisition and performance sequences. To examine the function of these stimuli, an observing procedure was incorporated into a multiple schedule of repeated acquisition and performance of response sequences, in which stimulus presentations were contingent upon an observing response. Three experiments were conducted with humans. Experiment 1 compared responding with and without the observing contingency. No difference was found in the overall percentage of errors across the two conditions. Within the observing condition, observing behavior was maintained in the acquisition component as long as errors occurred, but was not maintained in the performance component. Experiment 2 examined whether a contingency that increased errors also would increase observing in both the acquisition and performance components. Specifically, reinforcer delivery in each component was contingent upon emitting 10 correct responses and one, two, or four errors. Observing responses increased in the acquisition component as the error requirement increased, whereas observing responses in the performance component increased only when the error requirement was four. Experiment 3 assessed the effects of diazepam (0, 7.5, 15, and 30 mg/70 kg, p.o.) and triazolam (0, 0.375, and 0.75 mg/70 kg, p.o.) on repeated acquisition and performance baselines with the observing contingency. Selective drug effects were obtained in this modified procedure; that is, the percentage of errors in the acquisition component increased at doses that failed to affect the percentage of errors in the performance components. Importantly, drug effects were selective, even though observing responses were not emitted in the performance component and, hence, the stimulus presentations did not occur in that component. These findings suggest that alternative explanations for these differential effects are needed; in that regard, a response‐unit account of the selective drug effects is discussed.
COCAINE AND FOOD AS REINFORCERS: EFFECTS OF REINFORCER MAGNITUDE AND RESPONSE REQUIREMENT UNDER SECOND‐ORDER FIXED‐RATIO AND PROGRESSIVE‐RATIO SCHEDULES
Authors: Spear D. J. , Katz J. L.
Published: March 2006

Reinforcer magnitude and fixed‐ratio requirement were varied under two second‐order schedules. Under one, the first sequence of a fixed number of responses completed after the lapse of a 10‐min fixed interval produced reinforcement. Under the second, a second‐order progressive‐ratio schedule, the fixed number of responses increased after each reinforcement. Either cocaine (0 to 300 μg/kg/inj) or food (0 to 5,700 mg/delivery) reinforcers were delivered. Under some conditions, a 2‐s illumination of stimulus lights occurred on completion of each ratio sequence. Under the second‐order schedule, as cocaine dose or amount of food increased, rates of responding increased; at the highest values, rates of responding decreased. Increases in the ratio requirement from 10 to 170 responses minimally decreased overall response rates. Under the second‐order progressive‐ratio schedule, increases in dose of cocaine or amount of food increased rates of responding; at the highest amounts of food, rates of responding decreased but response rates at the highest dose of cocaine remained relatively high. The highest ratio requirement that was completed (breaking point) depended on the dose of cocaine but was less dependent on the amount of food. Removing brief‐stimulus presentations had a greater effect on completion of ratio requirements with cocaine compared to food.
EFFECTS OF SCHEDULE OF REINFORCEMENT ON A PENTOBARBITAL DISCRIMINATION IN RATS
Authors: Snodgrass Samuel H. , Mcmillan D. E.
Published: March 2006

The purpose of this study was to determine the effects of the schedule of reinforcement on a pentobarbital discrimination in rats. Five rats were trained to discriminate 10 mg/kg pentobarbital from saline under a multiple fixed‐interval 180‐s fixed‐ratio 20 schedule of reinforcement. During both saline and pentobarbital training sessions, subjects emitted a higher percentage of correct responses under the fixed‐ratio component as compared to the fixed‐interval component of the multiple schedule. Determination of the pentobarbital dose‐response curve under the fixed‐ratio component resulted in a steep curve characterized by responding on the saline lever at low doses and on the drug lever at higher doses. Under the fixed‐interval component, a graded dose‐effect curve was produced, with considerable responding on both levers after intermediate doses of pentobarbital. The administration of phencyclidine and MK‐801 resulted in an intermediate level of drug‐lever responding for some subjects. Administration of d‐amphetamine resulted in saline (nondrug) appropriate responding. The results of this study demonstrate that the schedule of reinforcement is a determinant of drug stimulus control, just as it is a determinant of other drug effects.
AN EXPERIMENTAL ANALYSIS OF THE COST OF FOOD IN A CLOSED ECONOMY
Authors: Bauman Richard
Published: March 2006

Rats lived in individual chambers in which the only food available was delivered for lever pressing. During Stage I, a fixed number of presses was required for each food pellet. As this fixed ratio of presses per food pellet was increased daily, a rat's daily intake of food was reduced. During Stage II, the cost of a food pellet was increased by replacing each fixed ratio with its interval equivalent. Each interval was a rat's mean time between the first press of a ratio and the delivery of a pellet during Stage I. During Stage II, only two presses were every required for a food pellet: The first press initiated a delay and the second activated the pellet dispenser after that delay elapsed. Food intakes for the series of fixed ratios and a rat's series of delay equivalents were very similar when plotted as a function of delay, but not when plotted as a function of presses per pellet. Consequently, the fixed ratio reduced food intake because larger ratios increased delay to food from the first press of a ratio. Observations and an analysis of interresponse times further revealed that as the fixed ratio increased, and local as well as overall rate of food intake decreased, lever pressing became more stereotyped. Because this increased stereotypy resulted in greatly increased rates of lever pressing, delay to food was minimized, and perhaps more importantly, so too was the reduction of a rat's baseline daily intake.
ANALYSIS OF FIXED‐RATIO BEHAVIOR MAINTAINED BY DRUG REINFORCERS
Authors: Skjoldager Paul , Winger Gail , Woods James H.
Published: March 2006

Behavior maintained by intravenously delivered alfentanil, cocaine, or ketamine was assessed using a fixed‐ratio schedule of reinforcement. As the dose of each drug was increased, rate of responding also increased up to a maximum. Further increases in dose resulted in decreased response rates (inverted U‐shaped curve). An analysis of postreinforcement‐pause‐time and run‐time measures for the ascending limb of the inverted U‐shaped functions revealed that behavior was characterized by systematic decreases in both pause time and run time as dose and rate increased. An examination of the descending limb of the dose‐response functions revealed that lowered response rates for cocaine and ketamine were correlated with increases in run time and small and inconsistent effects on postreinforcement pause time. Behavior maintained by rate‐reducing doses of alfentanil was characterized by lengthened postreinforcement pauses with small increases in run time. These data suggest that at larger doses, drug reinforcers may have unconditioned or direct effects on the behavior that the drug is maintaining, and more important, that the nature of these unconditioned effects depends on the drug that is maintaining behavior.
TOLERANCE TO AND RESIDUAL EFFECTS OF COCAINE IN SQUIRREL MONKEYS DEPEND ON REINFORCEMENT‐SCHEDULE PARAMETER
Authors: Hughes Christine E. , Branch Marc N.
Published: March 2006

Lever pressing by 4 squirrel monkeys was maintained under a three‐component multiple fixed‐ratio schedule of food presentation; components differed with respect to ratio size. For each monkey, acute administration of cocaine (0.03 to 1.3 mg/kg, i.m.) produced dose‐dependent decreases in overall response rate in each component. During repeated daily administration of 1.0 mg/kg of cocaine, tolerance developed to the rate‐decreasing effects under each of the ratio contingencies, but developed to a greater extent and was evident in earlier parts of sessions for performance under the smaller ratios. Response rates of 2 monkeys increased above nondrug control levels despite the putative reinforcer not being consumed during the session. When saline or a smaller dose of cocaine was substituted for 1.0 mg/kg, response rates often were suppressed below nondrug control‐level responding. This suppressive effect was observed in each monkey and was more likely to be observed and/ or to be of greater magnitude in large‐ratio components for 3 of the 4 monkeys. When saline was administered chronically at the end of the chronic‐drug phase, response rates remained suppressed in the large‐ratio component for 2 of the monkeys. There was, therefore, a schedule‐dependent dissociation between behavioral tolerance and the residual effects: Tolerance was greater when small ratios were arranged, whereas the residual effects were more pronounced when larger ratios were arranged.
NEUROCHEMICAL CHANGES CORRELATED WITH BEHAVIOR MAINTAINED UNDER FIXED‐INTERVAL AND FIXED‐RATIO SCHEDULES OF REINFORCEMENT
Authors: Barrett James E. , Hoffmann Susan M.
Published: March 2006

Key pecking of 4 pigeons was maintained under a multiple 3‐min fixed‐interval, 30‐response fixed‐ratio schedule of food presentation. Only one schedule was in effect during an experimental session, and each was correlated with a different keylight stimulus and location (left vs. right). The different schedule components alternated across days or weeks. Cerebrospinal fluid was collected from chronically implanted intracerebroventricular cannulae following sessions with the different schedules, as well as following sessions in which reinforcement was withheld (extinction), when response‐independent food was delivered, and when the experimental chamber was dark and there were no scheduled events. Metabolites of the neurotransmitters serotonin, norepinephrine, and dopamine were assayed in cerebrospinal fluid using high‐performance liquid chromatography with electrochemical detection. Compared to the fixed‐ratio condition, responding maintained under the fixed‐interval schedule resulted in consistently higher levels of the serotonin metabolite 5‐hydroxyindoleacetic acid and of the dopamine metabolite homovanillic acid in all pigeons. Levels of 3‐methoxy‐4‐hydroxyphenylethylene glycol, a metabolite of norepinephrine, and dihydroxyphenylacetic acid, another dopamine metabolite, were also higher in 3 of the 4 pigeons following exposure to the fixed‐interval schedules when compared to levels of these metabolites after exposure to the fixed‐ratio schedule. Extinction of fixed‐ratio responding resulted in large increases in 5‐hydroxyindoleacetic acid compared to levels of this metabolite under the fixed‐ratio schedule, whereas this serotonin metabolite decreased during extinction of responding under the fixed‐interval schedule. Control procedures suggested that the neurochemical changes were not related to the rate of responding but were a function of the specific experimental conditions. Distinctive neurochemical changes that accompany schedule‐controlled responding show the sensitivity of the neurochemical environment to behavioral contingencies and demonstrate further the profound impact that such contingencies have on biobehavioral processes.
CHOICE AS A FUNCTION OF LOCAL VERSUS MOLAR REINFORCEMENT CONTINGENCIES
Authors: Williams Ben A.
Published: March 2006

Rats were trained on a discrete‐trial probability learning task. In Experiment 1, the molar reinforcement probabilities for the two response alternatives were equal, and the local contingencies of reinforcement differentially reinforced a win‐stay, lose‐shift response pattern. The win‐stay portion was learned substantially more easily and appeared from the outset of training, suggesting that its occurrence did not depend upon discrimination of the local contingencies but rather only upon simple strengthening effects of individual reinforcements. Control by both types of local contingencies decreased with increases in the intertrial interval, although some control remained with intertrial intervals as long as 30 s. In Experiment 2, the local contingencies always favored win‐shift and lose‐shift response patterns but were asymmetrical for the two responses, causing the molar reinforcement rates for the two responses to differ. Some learning of the alternation pattern occurred with short intertrial intervals, although win‐stay behavior occurred for some subjects. The local reinforcement contingencies were discriminated poorly with longer intertrial intervals. In the absence of control by the local contingencies, choice proportion was determined by the molar contingencies, as indicated by high exponent values for the generalized matching law with long intertrial intervals, and lower values with short intertrial intervals. The results show that when molar contingencies of reinforcement and local contingencies are in opposition, both may have independent roles. Control by molar contingencies cannot generally be explained by local contingencies.
ELICITED RESPONDING IN CHAIN SCHEDULES
Authors: Dougherty Donald M. , Lewis Paul
Published: March 2006

An omission procedure was employed to study elicited pecking in the first component of a two‐component chain schedule. Both components were fixed‐interval schedules correlated with colored keylights. The first response following the initial‐link schedule produced a second fixed‐interval schedule. We studied several fixed‐interval lengths in two conditions: a standard response‐dependent condition and an omission‐contingent condition. The omission‐contingent condition differed from the response‐dependent condition in that responses during the initial fixed interval terminated the trial (omitting the terminal component and grain). If the terminal component was not omitted, a response following the terminal link's requirement produced 4‐s access to grain. Pigeons responded during more than 70% of the initial links in the omission‐contingent condition and responded during more than 90% of the initial links in the response‐dependent condition. In general, rates of responding were consistent with the percentage data. The responding in the omission condition suggests that there may be elicited pecking, in chain schedules using pigeons, that is not the result of contingent conditioned reinforcement.
PROTOCOL ANALYSIS OF THE CORRESPONDENCE OF VERBAL BEHAVIOR AND EQUIVALENCE CLASS FORMATION
Authors: Wulfert Edelgard , Dougher Michael J. , Greenway David E.
Published: March 2006

In two equivalence experiments, a “think aloud” procedure modeled after Ericsson and Simon's (1980) protocol analysis was implemented to examine subjects' covert verbal responses during matching to sample. The purpose was to identify variables that might explain individual differences in equivalence class formation. The results from Experiment 1 suggested that subjects who formed equivalence classes described the relations among stimuli, whereas those not showing equivalence described sample and comparison stimuli as unitary compounds. Because Experiment 1 only demonstrated a correlation between describing stimulus compounds and the absence of equivalence classes, a second study was conducted. In Experiment 2, equivalence class formation was brought under experimental control through pretraining manipulations that facilitated responding either to stimulus compounds or to relations among stimuli. The results demonstrated that a history of describing stimulus compounds, when compared with describing the relations among the stimuli, interfered with the emergence of stimulus equivalence. These findings clarify individual differences in stimulus equivalence. They also demonstrate the utility of analyzing verbal reports to identify possible variables that can be manipulated experimentally.
THE TRANSFER OF CONTEXTUAL CONTROL OVER EQUIVALENCE CLASSES THROUGH EQUIVALENCE CLASSES: A POSSIBLE MODEL OF SOCIAL STEREOTYPING
Authors: Kohlenberg Barbara S. , Hayes Steven C. , Hayes Linda J.
Published: March 2006

In Experiment 1, subjects acquired conditional equivalence classes controlled by three male and three female names as contextual stimuli. When equivalence relations were tested using new names not used in training (three male and three female), contextual control remained intact. Thus, generalized control of the composition of conditional equivalence classes by characteristically gender‐identified names was shown. A basic analysis of this finding was tested in Experiment 2. Contextual equivalence classes were established using as contextual stimuli nonrepresentational visual figures that were members of additional pretrained three‐member equivalence classes. When other stimuli in the pretrained equivalence classes were used as contextual stimuli, the conditional equivalence classes remained intact. Control subjects showed that this effect depended on the equivalence relations established in pretraining. The results show that contextual control over equivalence classes can transfer through equivalence classes. The implications of this phenomenon for social stereotyping are discussed.
THE INTERACTION BETWEEN STIMULUS AND REINFORCER CONTROL ON REMEMBERING
Authors: McCarthy Dianne C. , Davison Michael
Published: March 2006

In a symbolic matching‐to‐sample task, 6 pigeons obtained food by pecking a red side key when the brighter of two white lights had been presented on the center key and by pecking a green side key when the dimmer of two white lights had been presented on the center key. Across Part 1 and Parts 6 to 10, the delay between sample‐stimulus presentation and the availability of the choice keys was varied between 0 s and 25 s. Across Parts 1 to 5, the delay between the emission of a correct choice and the delivery of a reinforcer was varied between 0 s and 30 s. Although increasing both types of delay decreased stimulus discriminability, lengthening the stimulus‐choice delay produced a greater decrement in choice accuracy than did lengthening the choice‐reinforcer delay. Additionally, the relative reinforcer rate for correct choice was varied across both types of delay. The sensitivity of behavior to the distribution of reinforcers decreased as discriminability decreased under both procedures. These data are consistent with the view, based on the generalized matching law, that sample stimuli and reinforcers interact in their control over remembering.