bluuebunny/crossref_metadata_2025 huggingface dataset:
THE EFFECT OF INCREASED RESPONSE REQUIREMENTS ON DISCRIMINATIVE PERFORMANCE OF THE DOMESTIC HEN IN A VISUAL ACUITY TASK
Authors: DeMello Lesley R. , Foster T. Mary , Temple William
Published: March 2006

Six domestic hens were trained in a spatial discrimination task. A controlled reinforcement procedure insured that the ratio of scheduled and obtained reinforcement remained equal. Gray stimuli and gratings ranging in spatial frequency from 1 to 10 cycles per millimeter were presented in seven descending series of probes. The response requirement to the sample key was varied from fixed ratio 1 to fixed ratio 40 in seven experimental conditions. An increase in response requirements from fixed ratio 1 to fixed ratio 5 and fixed ratio 10 resulted in significantly higher accuracy at discriminable grating values. Further increases in response requirements did not consistently improve performance. Generally, response biases increased and occasionally became extreme for probes at finer gratings with increased response requirements.
RESPONDING CHANGES SYSTEMATICALLY WITHIN SESSIONS DURING CONDITIONING PROCEDURES
Authors: McSweeney Frances K. , Roll John M.
Published: March 2006

When the procedure is held constant within an experimental session, responding often changes systematically within that session. Many of these within‐session changes in responding cannot be dismissed as learning curves or by‐products of satiation. They have been observed in studies of positive reinforcement, avoidance, punishment, extinction, discrimination, delayed matching to sample, concept formation, maze and alley running, and laboratory analogues of foraging, as well as in the unconditioned substrates of conditioned behavior. When aversive stimuli are used, responding usually increases early in the session. When positive reinforcers are used, responding changes in a variety of ways, including increasing, decreasing, and bitonic functions. Both strong and minimal reinforcement procedures produce within‐session decreases in positively reinforced behavior. Within‐session changes in responding have substantial theoretical and methodological implications for research in conditioning.
HUMAN d‐AMPHETAMINE DRUG DISCRIMINATION: METHAMPHETAMINE AND HYDROMORPHONE
Authors: Lamb R. J. , Henningfield J. E.
Published: March 2006

Standard measures of subjective and discriminative effects of drugs were compared in 5 human volunteers. Subjects responded on a second‐order color‐tracking procedure, where 30 mg of d‐amphetamine served as a discriminative stimulus for one response and its absence as the discriminative stimulus for another response. Self‐reported subjective effects were assessed concurrently using the single‐dose questionnaire, subscales of the Addiction Research Center Inventory, and several analogue rating scales. On different days following discrimination acquisition, varying doses of d‐amphetamine, methamphetamine, and hydromorphone were administered. In these test sessions, either response was reinforced. Methamphetamine and d‐amphetamine occasioned dose‐related increases in d‐amphetamine appropriate responding; hydromorphone did not. Methamphetamine and d‐amphetamine occasioned dose‐related increases in reports of the drug received being most like “speed”; hydromorphone occasioned dose‐related increases in reports of the drug received being most like “dope.” All three drugs occasioned dose‐related increases in reports of drug liking, and increases in the morphine‐benzedrine group, amphetamine, and benzedrine group scales of the Addiction Research Center Inventory. This experiment demonstrated that although explicit discriminative control of behavior by a drug may covary with drug identification, it does not necessarily covary with other self‐reported subjective effects. Thus, the complementary nature of the data provided by drug discrimination and standard subjective‐effects measures provides quantitative and qualitative data useful in studying both relatively novel compounds and the behavioral biology of psychoactive drugs in general.
A PROCEDURE FOR STUDYING THE WITHIN‐SESSION ONSET OF HUMAN DRUG DISCRIMINATION
Authors: Silverman Kenneth , Mumford Geoffrey K. , Griffiths Roland R.
Published: March 2006

The purpose of the present study was to develop a procedure for measuring the within‐session onset of human drug discrimination. During daily sessions, under double‐blind conditions, caffeine‐abstinent adults ingested a letter‐coded capsule containing 178 mg caffeine or placebo. Trials were presented at 30‐s intervals, beginning immediately after drug ingestion and continuing for 60 min. On each trial, subjects could guess which of their two letter‐coded drugs they had received by pressing a left button (for one drug) or right button (for the other drug); subjects could also press a center “no guess” button instead of guessing. Each trial ended after one button press. After each session, subjects were told which drug they had received. Subjects always earned one point (worth $0.10 per point) for each correct guess. Subjects lost either 0, 1, or 10 points for each incorrect guess; the point‐loss contingencies were varied in random order across sessions. Discrimination earnings accumulated across all sessions. The point‐loss contingencies decreased random responding and delayed the discrimination time course. Overall, this procedure provided an orderly and relatively continuous measure of the within‐session onset of drug discrimination and should have a range of applications in understanding the human behavioral pharmacology of drugs.
EFFECTS OF MESOLIMBIC DOPAMINE DEPLETION ON RESPONDING MAINTAINED BY COCAINE AND FOOD
Authors: Caine S. Barak , Koob George F.
Published: March 2006

The hypothesis that mesolimbic dopamine is selectively involved in cocaine reinforcement was investigated in the rat. Animals were trained under a multiple schedule in which responding was reinforced by intravenous cocaine (0.75 mg/kg/injection) or food (45‐mg pellets) under fixed‐ratio 15 schedule requirements in alternate 30‐min components of a 2‐hr daily session. Infusion of the catecholaminergic neurotoxin 6‐hydroxydopamine, but not the vehicle solution, into the region of the nucleus accumbens and olfactory tubercle produced selective reductions in cocaine self‐administration without significantly altering responding maintained by food within the same sessions. This effect was reproduced in intact animals by substituting saline for cocaine in the self‐administration component. These results support the hypothesis that the reinforcing effects of cocaine are dependent upon mesolimbic dopamine and demonstrate that cocaine self‐administration can be disrupted in animals without altering behavior maintained by a nondrug reinforcer.
PRECURRENT CONTINGENCIES: BEHAVIOR REINFORCED BY ALTERING REINFORCEMENT PROBABILITY FOR OTHER BEHAVIOR
Authors: Polson David A. D. , Parsons Joseph A.
Published: March 2006

The present study explored the effects of a precurrent contingency in which one (precurrent) activity increased the reinforcement probability for another (current) activity. Four human subjects responded on a two‐key computer mouse. Each right‐key press was reinforced (points exchangeable for money) with .02 probability. In one condition (no precurrent contingency), pressing the left key had no scheduled consequence; in another condition (precurrent contingency), pressing the left key increased the reinforcement probability for right‐key responding to .08 for 15 s. Initial exposure to the precurrent contingency resulted in acquisition of precurrent left‐key responding for 3 subjects, but for the 4th subject a special contingency was required. Right‐key responding occurred at a high stable rate across the conditions. Changeovers to left‐key responding dropped to near zero when the precurrent contingency was absent and were maintained at enhanced levels when the precurrent contingency was present. Contacts with the left key consisted of short response runs. Right‐key responses were more frequently emitted within 15 s of a left‐key response when the precurrent contingency was present, an efficient adaptation to the contingency. Continued research on precurrent behavior may produce insights into complex phenomena such as autoclitics and self‐control.
EFFECTS OF THE DISCRIMINABILITY OF ALTERNATIVES IN THREE‐ALTERNATIVE CONCURRENT‐SCHEDULE PERFORMANCE
Authors: Davison Michael , McCarthy Dianne
Published: March 2006

Six pigeons were trained on two‐ and three‐alternative concurrent schedules in which the alternatives were signaled by different wavelengths of light on the main pecking key. The schedules were arranged according to a switching‐key procedure in which pecks on a white side key produced a 3‐s blackout and, intermittently, a change in the variable‐interval schedule of food programmed on the main (center) key after the blackout. In Part 1, a two‐alternative concurrent variable‐interval schedule was arranged in which the alternatives were signaled by 560 nm and 630 nm. Parts 2 and 3 arranged three‐alternative concurrent variable‐interval schedules with the alternatives signaled by 560 nm, 600 nm, and 630 nm (Part 2) and 560 nm, 623 nm, and 630 nm (Part 3). Within each part, the relative rate of food reinforcers available on the alternatives was varied across a wide range. In all parts of the experiment, the ratios of responses emitted between pairs of alternatives were more extreme than the ratios of reinforcers obtained on the pairs of alternatives, a result termed overmatching. In Parts 2 and 3, generalized matching sensitivities between pairs of alternatives were found to be higher when the reinforcer rate on the third alternative was low than when it was high—an apparent failure of the constant‐ratio rule. The data were well described by an extension of the Davison and Jenkins (1985) model, which assumes differing discriminabilities between concurrent‐schedule alternatives in combination with a punishing effect of blackout following changeovers.
EFFECTS OF CHLORDIAZEPOXIDE AND COCAINE ON CONCURRENT FOOD AND AVOIDANCE‐OF‐TIMEOUT SCHEDULES
Authors: van Haaren Frans , Zarcone Troy J.
Published: March 2006

Five rats were trained on a concurrent schedule in which responses on one lever produced a food pellet on a random‐interval 30‐s schedule during 10 s of food availability associated with distinctive exteroceptive stimuli. Responses on another lever postponed for 20 s the presentation of a 50‐s timeout, during which all stimuli were extinguished and the schedule contingencies on the food lever were suspended. The response rates maintained by the random‐interval schedule exceeded those maintained by the avoidance contingency, but both provided a stable baseline to assess the behavioral effects of different drugs. Low doses of cocaine hydrochloride (1 and 3 mg/kg) did not affect food‐reinforced responding or avoidance response rates. Intermediate doses (5.6, 10, and 13 mg/kg) produced a dose‐dependent decrease in food‐maintained and avoidance response rates, and both types of responding were virtually eliminated after administration of the highest doses (17 and 30 mg/kg) of cocaine. Low doses of chlordiazepoxide (1 and 3 mg/kg) increased food‐maintained and avoidance response rates, and both rates decreased systematically after 10 and 30 mg/kg of this drug. The effects of cocaine and chlordiazepoxide on response rates maintained by avoidance of timeout from food presentation were unlike those reported when subjects responded to avoid shock presentation. The results of this experiment thus provide evidence to suggest that the effects of drug administration on avoidance behavior may be a function of the nature of the consequent event to be avoided.
EFFECTS OF INTERTRIAL REINFORCERS ON SELF‐CONTROL CHOICE
Authors: Mazur James E.
Published: March 2006

In three experiments, pigeons chose between a small amount of food delivered after a short delay and a larger amount delivered after a longer delay. A discrete‐trial adjusting‐delay procedure was used to estimate indifference points—pairs of delay—amount combinations that were chosen about equally often. In Experiment 1, when additional reinforcers were available during intertrial intervals on a variable‐interval schedule, preference for the smaller, more immediate reinforcer increased. Experiment 2 found that this shift in preference occurred partly because the variable‐interval schedule started sooner after the smaller, more immediate reinforcer, but there was still a small shift in preference when the durations and temporal locations of the variable‐interval schedules were identical for both alternatives. Experiment 3 found greater increases in preference for the smaller, more immediate reinforcer with a variable‐interval 15‐s schedule than with a variable‐interval 90‐s schedule. The results were generally consistent with a model that states that the impact of any event that follows a choice response declines according to a hyperbolic function with increasing time since the moment of choice.
EFFECTS OF SOCIAL CONTEXT, REINFORCER PROBABILITY, AND REINFORCER MAGNITUDE ON HUMANS' CHOICES TO COMPETE OR NOT TO COMPETE
Authors: Dougherty Donald M. , Cherek Don R.
Published: March 2006

In the first two experiments, subjects' choices to earn points (exchangeable for money) either by competing with a fictitious opponent or by not competing were studied. Buskist, Barry, Morgan, and Rossi's (1984) competitive fixed‐interval schedule was modified to include a second response option, a noncompetitive fixed‐interval schedule. After choosing to enter either option, the opportunity for reinforcers became available after the fixed‐interval's duration had elapsed. Under the no‐competition condition, points were always available after the interval had elapsed. Under the competition condition, points were available based on a predetermined probability of delivery. Experiments 1 and 2 examined how reinforcer probabilities and reinforcer magnitudes affected subjects' choices to compete. Several general conclusions can be made about the results: (a) Strong preferences to compete were observed at high and moderate reinforcer probabilities; (b) competing was observed even at very low reinforcer probabilities; (c) response rates were always higher in the competition component than in the no‐competition component; and (d) response rates and choices to compete were insensitive to reinforcer‐magnitude manipulations. In Experiment 3, the social context of this choice schedule was removed to determine whether the high levels of competing observed in the first two experiments were due to a response preference engendered by the social context provided by the experimenters through instructions. In contrast to the first two experiments, these subjects preferred the 60‐s fixed‐interval schedule (formerly the no‐competition option), indicating that the instructions themselves were responsible for the preference to compete. This choice paradigm may be useful to future researchers interested in the effects of other independent variables (e.g., drugs, social context, instructions) on competitive behavior.
DURATION COMPARISON: RELATIVE STIMULUS DIFFERENCES, STIMULUS AGE, AND STIMULUS PREDICTIVENESS
Authors: Stubbs D. Alan , Dreyfus Leon R. , Fetterman J. Gregor , Boynton David M. , Locklin Noreen , Smith Laurence D.
Published: March 2006

Under a psychophysical trials procedure, pigeons were presented with a red light of one duration followed by a green light of a second duration. Eight geometrically spaced base durations were paired with one of four shorter and four longer durations as the alternate member of a duration pair, with different pairs randomly intermixed. One choice was reinforced if red had lasted longer than green, and a second choice was reinforced if green had lasted longer. Performance was compared when all the base durations and their pair members were included (entire‐range condition) or when only the four longest base durations and their comparison durations (restricted‐range condition) were used. Discrimination sensitivity decreased for longer duration pairs under both conditions, supporting a memory‐based account. Sensitivity was lower under the restricted‐range condition. Under both conditions, a bias to report “green as longer” increased as the second green duration increased. Bias changed as a matching function of the green‐duration predictiveness of the correct choice. The results are related to a quantitative model of timing and remembering proposed by Staddon.
TOLERANCE TO COCAINE'S RATE‐INCREASING EFFECTS UPON REPEATED ADMINISTRATION
Authors: Schama Kevin F. , Branch Marc N.
Published: March 2006

Four squirrel monkeys responded daily under a fixed‐interval 5‐min or 8‐min schedule of food‐pellet delivery. Cocaine (0.03 to 1.7 mg/kg) and saline were injected before occasional daily sessions (acute administration). Some doses of cocaine produced substantial overall increases in response rate for 3 of the subjects; effects were less substantial for the remaining subject, who exhibited modest increases in response rate early in the session and during the middle portion of the intervals. A dose that increased response rate when administered acutely was then administered before each session (chronic administration). Chronic administration resulted in a reduction in the increases in response rate seen under acute administration for all subjects.
DIFFERENTIAL VOCALIZATION IN BUDGERIGARS: TOWARDS AN EXPERIMENTAL ANALYSIS OF NAMING
Authors: Manabe Kazuchika , Kawashima Takashi , Staddon J. E. R.
Published: March 2006

In Experiment 1, 3 budgerigars (Melopsittacus undulatus) were trained with food reinforcement to make low‐ or high‐frequency calls in response to different color stimuli, C1 and C2 (a color‐naming task), using a gradual response‐differentiation procedure and an automatic call‐recognition system. Thus, a call within a certain frequency band was reinforced in the presence of C1 (“C1 call”), and a call within a different band was reinforced in the presence of C2 (“C2 call”). In Experiment 2, all 3 budgerigars were trained in a form‐to‐color matching‐to‐sample task, alternating trial by trial with either the color‐naming task (2 birds) or an identity color matching‐to‐sample task (1 bird). Sample stimuli for the new matching‐to‐sample task were forms (F1 or F2) and comparisons were the same two colors (C1 and C2). Given Sample F1 or F2, birds had to make a call to produce Comparison Pair C1 and C2. With F1 as the sample, a peck on C1 was reinforced; with F2 as the sample, a peck on C2 was reinforced. Although no particular call was specified in the presence of F1 and F2, 2 birds made the C1 call in the presence of F1 and the C2 call in the presence of F2. In Experiment 3, the bird that failed to match form and color calls in Experiment 2 and another bird were first trained in a color‐to‐form matching‐to‐sample task: C1 to F3 and C2 to F4. In this task, to produce the comparison pair of forms, a high call (or low for the other bird) was required in the presence of C1, and a low call (or high) was required in the presence of C2. Both birds were then trained with an identity matching‐to‐sample task in which sample and comparison stimuli were the same two forms, F3 and F4. Trials on the identity task alternated with the color‐to‐form trials. Although no particular call was required in the presence of Samples F3 and F4, both birds came to make the C1 call in the presence of F3 and the C2 call in the presence of F4. Our technique promises to be useful for the study of emergent vocal relations in budgerigars and other animals.
MOST DIRECTED FORGETTING IN PIGEONS CAN BE ATTRIBUTED TO THE ABSENCE OF REINFORCEMENT ON FORGET TRIALS DURING TRAINING OR TO OTHER PROCEDURAL ARTIFACTS
Authors: Zentall Thomas R. , Roper Karen L. , Sherburne Lou M.
Published: March 2006

In research on directed forgetting in pigeons using delayed matching procedures, remember cues, presented in the delay interval between sample and comparisons, have been followed by comparisons (i.e., a memory test), whereas forget cues have been followed by one of a number of different sample‐independent events. The source of directed forgetting in delayed matching to sample in pigeons was examined in a 2 × 2 design by independently manipulating whether or not forget‐cue trials in training ended with reinforcement and whether or not forget‐cue trials in training included a simultaneous discrimination (involving stimuli other than those used in the matching task). Results were consistent with the hypothesis that reinforced responding following forget cues is sufficient to eliminate performance deficits on forget‐cue probe trials. Only when reinforcement was omitted on forget‐cue trials in training (whether a discrimination was required or not) was there a decrement in accuracy on forget‐cue probe trials. When reinforcement is present, however, the pattern of responding established during and following a forget cue in training may also play a role in the directed forgetting effect. These findings support the view that much of the evidence for directed forgetting using matching procedures may result from motivational and behavioral artifacts rather than the loss of memory.
CONDITIONED REINFORCEMENT AND CHOICE WITH DELAYED AND UNCERTAIN PRIMARY REINFORCERS
Authors: Mazur James E.
Published: March 2006

In an adjusting‐delay choice procedure, pigeons could peck on either a red key or a green key. A peck on the red key always led to a delay associated with red houselights and then food. The delay was adjusted over trials to estimate an indifference point—a delay at which the two keys were chosen about equally often. In some conditions, a peck on the green key led to food on all trials after delays of either 10 s or 30 s, and green houselights were lit during the delays. In other conditions, food was presented on only half of the green‐key trials. If the green houselights continued to occur on both reinforcement and nonreinforcement trials, preference for the green key always decreased. Preference for the green key also decreased if half of the trials had 30‐s houselights followed by food and the other half had no green houselights and no food. However, preference for the green key actually increased if half of the trials had 10‐s green houselights followed by food and the other half had no green houselights followed by no food. The latter condition therefore demonstrated a case in which preference for an alternative increased when food was removed from half of the trials. The results suggest that the red and green houselights served as conditioned reinforcers. A hyperbolic decay model (Mazur, 1989) provided good predictions for all conditions by assuming that the strength of a conditioned reinforcer is inversely related to the total time spent in its presence before food is delivered.
CHANGEOVER DELAY AND CONCURRENT‐SCHEDULE PERFORMANCE IN DOMESTIC HENS
Authors: Temple William , Scown Jan M. , Foster T. Mary
Published: March 2006

Six domestic hens were exposed to a series of five pairs of two‐key concurrent variable‐interval schedules with a range of changeover delays from no delay to 15 s. Times spent responding on each alternative and total, within_, and post‐changeover‐delay response ratios were analyzed in terms of the generalized matching law. The sensitivity parameters, a, for response and time data were generally low when no changeover delay was programmed but were not 0.0. They were higher for all other changeover‐delay values, with some tendency to increase as the changeover delay lengthened at very short delays. Within‐delay responding was insensitive to reinforcement‐rate differences at all changeover delays (a values close to 0.0). As a result of this insensitivity, post‐changeover‐delay responding was more sensitive to reinforcement‐rate changes than was total responding. Interchangeover intervals increased systematically with changeover‐delay duration. Responding, particularly after the changeover delay, was well predicted by an equation based on a reinforcer‐loss model.
HOW TO TEACH A PIGEON TO MAXIMIZE OVERALL REINFORCEMENT RATE
Authors: Heyman Gene M. , Tanz Lawrence
Published: March 2006

In two experiments deviations from matching earned higher overall reinforcement rates than did matching. In Experiment 1 response proportions were calculated over a 360‐response moving average, updated with each response. Response proportions that differed from the nominal reinforcement proportions, by a criterion that was gradually increased, were eligible for reinforcement. Response proportions that did not differ from matching were not eligible for reinforcement. When the deviation requirement was relatively small, the contingency proved to be effective. However, there was a limit as to how far response proportions could be pushed from matching. Consequently, when the deviation requirement was large, overall reinforcement rate decreased and pecking was eventually extinguished. In Experiment 2 a discriminative stimulus was added to the procedure. The houselight was correlated with the relationship between response proportions and the nominal (programmed) reinforcement proportions. When the difference between response and reinforcement proportions met the deviation requirement, the light was white and responses were eligible for reinforcement. When the difference between response and reinforcement proportions failed to exceed the deviation requirement, the light was blue and responses were not eligible for reinforcement. With the addition of the light, it proved to be possible to shape deviations from matching without any apparent limit. Thus, in Experiment 2 overall reinforcement rate predicted choice proportions and relative reinforcement rate did not. In contrast, in previous experiments on the relationship between matching and overall reinforcement maximization, relative reinforcement rate was usually the better predictor of responding. The results show that whether overall or relative reinforcement rate better predicts choice proportions may in part be determined by stimulus conditions.
PIGEONS' PREFERENCE FOR VARIABLE‐INTERVAL WATER REINFORCEMENT UNDER WIDELY VARIED WATER BUDGETS
Authors: Case David A. , Nichols Paul , Fantino Edmund
Published: March 2006

Water budget of pigeons was varied to assess the dependence of risk‐sensitive preferences upon economic context such as has been reported for energy‐budget manipulations with small animals in behavioral ecology research. Fixed‐ and variable‐interval terminal‐link water schedules reinforced choice between equal variable‐interval initial‐link schedules arranged on two pecking keys. While keeping a severely restrictive budget the same across three phases of the experiment, a contrasting distinct ample budget was arranged in each. To mimic typical methods in behavioral ecology studies, in each ample budget a more than three‐fold increase in amount of water per reinforcer presentation was instituted simultaneously with significantly increased overall access to water. Total choice response rates plummeted in the ample budgets, and body weights either increased significantly or remained unchanged in different phases as expected by the nature of the different manipulations. Clear preferences for the variable‐interval schedule were found throughout the experiment, except for rare instances of key bias. The results agree with similar operant food‐reinforcement studies and extend conditions under which risk preference apparently does not depend upon economic context.
CONCURRENT‐SCHEDULE PERFORMANCE IN DAIRY COWS: PERSISTENT UNDERMATCHING
Authors: Foster T. Mary , Temple William , Robertson Brett , Nair Vijayen , Poling Alan
Published: March 2006

Performance of dairy cows responding under concurrent variable‐interval variable‐interval schedules of food delivery was examined, with results analyzed in terms of the generalized matching equation. In Experiment 1, bias measures indicated that crushed barley was preferred over meatmeal when these foods were available under the alternative schedules. For whole‐session data, substantial undermatching of response and time‐allocation ratios to obtained reinforcement ratios was evident. Postreinforcement pause time ratios approximately matched obtained reinforcement rates. Subtracting these times from total time‐allocation values yielded net time‐allocation ratios that undermatched obtained reinforcement ratios to a greater degree than did whole‐session time‐allocation ratios. In Experiment 2, substantial undermatching was evident when the same foods (hay for 2 cows, crushed barley for 2 others) were available under the alternative schedules. Food‐related activities and other defined behavior not related to food were quantified by direct observation, and were found to occupy a substantial proportion (roughly 40% to 80%) of experimental sessions. Subtracting the time spent in these activities from the time allocated to each component schedule did not reduce the degree of undermatching obtained. Across all conditions in both experiments, slopes of regression lines relating behavioral outputs to environmental inputs characteristically were below 0.6, which agrees with prior findings and suggests that, contrary to suggestions in the literature, undermatching in dairy cows is not the result of using different foods under alternative schedules or differential pausing under those schedules.
SPEED ANALYSES OF STIMULUS EQUIVALENCE
Authors: Spencer Thomas J. , Chase Philip N.
Published: March 2006

The functional substitutability of stimuli in equivalence classes was examined through analyses of the speed of college students' accurate responding. After training subjects to respond to 18 conditional relations, subjects' accuracy and speed of accurate responding were compared across trial types (baseline, symmetry, transitivity, and combined transitivity and symmetry) and nodal distance (one‐ through five‐node transitive and combined transitive and symmetric relations). Differences in accuracy across nodal distance and trial type were significant only on the first tests of equivalence, whereas differences in speed were significant even after extended testing. Response speed was inversely related to the number of nodes on which the tested relations were based. Significant differences in response speed were also found across trial types, except between transitivity and combined trials. To determine the generality of these comparisons, three groups of subjects were included: An instructed group was given an instruction that specified the interchangeability of stimuli related through training; a queried group was queried about the basis for test‐trial responding; and a standard group was neither instructed nor queried. There were no significant differences among groups. These results suggest the use of response speed and response accuracy to measure the strength of matching relations.
EFFECTS OF REINFORCEMENT AMOUNT ON ATTACK INDUCED UNDER A FIXED‐INTERVAL SCHEDULE IN PIGEONS
Authors: Pitts Raymond C. , Malagodi E. F.
Published: March 2006

Key pecking by pigeons was maintained on a chained fixed‐interval 4‐min (12‐min for 1 subject) fixed‐ratio 1 schedule of food presentation. Attacks toward a restrained and protected conspecific were recorded. In the first experiment, the amount of food presented per interval was manipulated across phases by varying the number of fixed ratios required in the terminal link of the chain. Measures of attack for all pigeons during the fixed‐interval component increased monotonically as a function of food amount. In the second experiment, two different food amounts alternated within each experimental session under a multiple schedule. For both pigeons in this experiment, measures of attack were higher during the component that delivered the larger food amount per interval. The differences in levels of attack induced by the two food amounts in Experiment 2, however, were not as great as in Experiment 1; apparently this was because attack during the first interval of each component was controlled in part (P‐5626) or entirely (P‐7848) by the reinforcement amount delivered at the end of the previous component. Attack was also a function of the location of the interfood interval within the session. For both pigeons, attack tended to decrease throughout the session. The results of both experiments suggest that attack is an increasing function of reinforcement amount under fixed‐interval schedules, but that this function may be influenced by the manner in which reinforcement amount is manipulated, by the duration of the interfood interval, and by the location of the interfood interval within the experimental session. In general, these results are compatible with theories of induced attack and other schedule‐induced behavior that emphasize aversive aftereffects of reinforcement presentation.
POINTING AT SMALLER FOOD AMOUNTS IN AN ANALOGUE OF BOYSEN AND BERNTSON'S (1995) PROCEDURE
Authors: Silberberg Alan , Fujita Kazuo
Published: March 2006

Boysen and Berntson (1995) showed that apes could not learn to point to a small amount of candy in order to get a larger amount when pointing to the larger amount was reinforced by receipt of the alternate, smaller amount. They explained this result as an unlearned predisposition to reach for higher value foods that overrides the effects of reinforcement. This report tests their thesis. In the first condition, 3 monkeys chose between one raisin held in one hand by the experimenter and four raisins held in the other hand. If a monkey pointed at four raisins, it received one. If it pointed at one, it received four. Over ten 20‐trial sessions, no monkey learned to point at the one‐raisin alternative, a result similar to that of Boysen and Berntson. In the second condition, pointing at one raisin still produced four; however, pointing at four raisins now produced no reinforcement. In five 20‐trial sessions, all monkeys learned to point at one raisin in order to get four. This finding demonstrates that at least in monkeys there is no predisposition to reach for higher value foods that cannot be readily overridden by reinforcement contingencies, and casts doubt on Boysen and Berntson's claim to have demonstrated such a process in apes.
HUMAN SIGNAL‐DETECTION PERFORMANCE: EFFECTS OF SIGNAL PRESENTATION PROBABILITIES AND REINFORCER DISTRIBUTIONS
Authors: Johnstone Victoria , Alsop Brent
Published: March 2006

University students participated in one of four standard two‐choice signal‐detection experiments in which signal presentation probability was varied and the reinforcement distribution was held constant and equal. In Experiments 1, 3 and 4, subjects' performance showed a systematic response bias for reporting the stimulus presented least often. Experiments 1 and 4 showed that this effect was reliable with extended training and monetary, rather than point, reinforcement. In Experiment 2, all correct responses were signaled in some way, and this produced the opposite relationship between signal presentation probability and response bias. Experiments 1 and 3 found that explicitly deducting money (intended as punishment) for equal numbers of incorrect responses on each alternative, or varying the obtained overall rate of reinforcement, produced no clear change in response bias. The bias, shown by humans, for reporting the stimulus presented least often remains a challenge for theories of stimulus detection.
RESURGENCE OF DERIVED STIMULUS RELATIONS
Authors: Wilson Kelly G. , Hayes Steven C.
Published: March 2006

Resurgence has been shown in human and nonhuman operant behavior, but not in derived relational responses. The present study examined this issue. Twenty‐three undergraduates were trained to make conditional discriminations in a three‐choice matching‐to‐sample paradigm. The training resulted in three equivalence classes, each consisting of four arbitrarily configured visual stimuli. The same 12 stimuli were then reorganized, and the conditional discrimination training was repeated such that three new classes were possible. In a subsequent test of derived relations, most subjects showed response patterns that were consistent with the altered conditional discriminations. Subjects were then exposed to conditional discrimination trials under extinction. Most subjects continued to respond consistently with the most recently reinforced conditional discrimination trials. During the next phase, subjects were exposed to symmetry and equivalence trials. Responses consistent with the most recent training produced feedback saying that the responses were incorrect, whereas other responses produced no feedback. Most subjects showed a resurgence of responding that was consistent with their earlier training. Finally, subjects were exposed to conditional discrimination trials carried out in extinction. Most subjects continued to show a resurgence of responding that was consistent with their early training.
TEMPORAL CONTROL BY PROGRESSIVE‐INTERVAL SCHEDULES OF REINFORCEMENT
Authors: Leinenweber Antoinette , Nietzel Shannon M. , Baron Alan
Published: March 2006

Progressive‐interval performances are described using measures that have proven to be successful in the analysis of fixed‐interval responding. Five rats were trained with schedules in which the durations of consecutive intervals increased arithmetically as each interval was completed (either 6‐s or 12‐s steps for different subjects). The response patterns that emerged with extended training (90 sessions) indicated that performances had come under temporal control. Postreinforcement pausing increased as a function of the interval duration, the pauses were proportional to the prevailing duration, and the likelihood of the first response within an interval increased as the interval elapsed. To assess the resistance of these patterns to disruption, subjects were trained with a schedule that generated high response rates and short pauses (variable ratio). When the progressive‐interval schedule was reinstated, pausing was attenuated and rates were elevated, but performances reverted to earlier patterns with continued exposure. The results indicated that temporal control by progressive‐interval schedules, although slow to develop, is similar in many respects to that for fixed‐interval schedules.
ASSESSMENT AND CHOICE: AN OPERANT SIMULATION OF FORAGING IN PATCHES
Authors: Roche John P. , Stubbs D. Alan , Glanz William E.
Published: March 2006

Pigeons were presented with an operant simulation of two prey patches using concurrent random‐ratio schedules of reinforcement. An unstable patch offered a higher initial reinforcement probability, which then declined unpredictably to a zero reinforcement probability in each session. A stable patch offered a low but unvarying reinforcement probability. When the reinforcement probability declined to zero in a single step, the birds displayed shorter giving‐up times in the unstable patch when the ratio between the initial reinforcement probabilities in the unstable and stable patches was greater and when the combined magnitude of the reinforcement probabilities in the two patches was greater. When the unstable patch declined in two steps, the birds behaved as if their giving‐up times were influenced heavily by events encountered during the most recent step of the double‐step change. This effect was observed, however, only when the reinforcement probability in that step was .04, not when it was .06. All of these data agree with the predictions of a capture‐probability model based on a comparison of the estimated probability of receiving a reinforcer in the current patch with that in alternative patches.
WITHIN‐SESSION CHANGES IN RESPONDING DURING AUTOSHAPING AND AUTOMAINTENANCE PROCEDURES
Authors: McSweeney Frances K. , Swindell Samantha , Weatherly Jeffrey N.
Published: March 2006

Four pigeons were exposed to autoshaping procedures in which an 8‐second light on a response key was followed by food. Pecks on the key had no scheduled consequences. Subjects were also exposed to negative automaintenance procedures in which a peck on the illuminated key canceled the following food. The intertrial interval varied from an average of 7 seconds to an average of 232 seconds in different conditions. Rate of responding usually changed within sessions during autoshaping. Responding also changed within sessions for the 1 subject that responded during negative automaintenance. The within‐session patterns of responding were flatter, peaked later, and were more symmetrical around the middle of the sessions at lower rates of food presentation, regardless of whether subjects responded on autoshaping, negative automaintenance, or previously reported variable‐interval schedules. These results imply that similar variables produce within‐session changes in responding during both classical (Pavlovian) and operant conditioning procedures.
CHOICE WITH CERTAIN AND UNCERTAIN REINFORCERS IN AN ADJUSTING‐DELAY PROCEDURE
Authors: Mazur James E.
Published: March 2006

A discrete‐trials adjusting‐delay procedure was used to investigate the conditions under which pigeons might show a preference for partial reinforcement over 100% reinforcement, an effect reported in a number of previous experiments. A peck on a red key always led to a delay with red houselights and then food. In each condition, the duration of the red‐houselight delay was adjusted to estimate an indifference point. In 100% reinforcement conditions, a peck on a green key always led to a delay with green houselights and then food. In partial‐reinforcement conditions, a peck on the green key led either to the green houselights and food or to white houselights and no food. In some phases of the experiment, statistically significant preference for partial reinforcement over 100% reinforcement was found, but this effect was observed in only about half of the pigeons. The effect was largely eliminated when variability in the delay stimulus colors was equated for 50% reinforcement conditions and 100% reinforcement conditions. Idiosyncratic preferences for certain colors or for stimulus variability may be at least partially responsible for the effect.
WITHIN‐SESSION CHANGES IN RESPONDING DURING CONCURRENT VARIABLE‐INTERVAL SCHEDULES
Authors: McSweeney Frances K. , Weatherly Jeffrey N. , Swindell Samantha
Published: March 2006

Five rats and 4 pigeons responded for food delivered by several concurrent variable‐interval schedules. The sum of the rates of reinforcement programmed for the two components varied from 15 to 480 reinforcers per hour in different conditions. Rates of responding usually changed within the experimental session in a similar manner for the two components of each concurrent schedule. The within‐session changes were similar to previously reported changes during simple schedules that provided rates of reinforcement equal to the sum of all reinforcers obtained from the concurrent schedules. The number of changeovers also changed within sessions in a manner similar to the changes in instrumental responding. These results suggest that changeovers are governed by the same variables that govern instrumental responding. They also suggest that the within‐session change in responding during each component of a concurrent schedule is determined by approximately the sum of the reinforcers obtained from both components when both components provide the same type of reinforcer.
DIFFERENCES IN DELAY, NOT RATIOS, CONTROL CHOICE IN CONCURRENT CHAINS
Authors: Savastano Hernán I. , Fantino Edmund
Published: March 2006

In two experiments, pigeons were trained with concurrent‐chains schedules, wherein responding to equal initial links measured preference between variable‐interval terminal links. Absolute terminal‐link duration was varied by keeping constant the difference between the terminal‐link delays and forcing their ratio to change. Delay‐reduction theory scales value relative to a common temporal context and requires that delay differences control choice. Thus, preference should remain invariant. Most competing accounts, including the matching law and a strong form of Weber's law, require that preference vary with the delay ratio. Experiment 1 employed standard concurrent chains, in which terminal‐link position and color were confounded. Although average preference remained constant, individual preferences were highly variable and inconsistent, possibly due to carryover of position biases across conditions. In an attempt to reduce variability, Experiment 2 used a modified concurrent‐chains procedure. Preference at different terminal‐link durations was assessed simultaneously to prevent order effects, and terminal‐link position was alternated randomly across trials to minimize the impact of position biases. In Experiment 2, both individual and mean preferences showed the constant‐difference invariance. Overall, choice was controlled by terminal‐link differences, not ratios.
BODY WEIGHT AND RESPONSE ACQUISITION WITH DELAYED REINFORCEMENT
Authors: Lattal Kennon A. , Williams April Michele
Published: March 2006

The relation between body weight and responding established with unsignaled delayed reinforcement was investigated. In three experiments, naive rats were deprived to either 70%, 80%, or 90% of ad libitum weight and were then exposed to tandem variable‐interval 15‐s differential‐reinforcement‐of‐other‐behavior 30‐s schedules. The tandem schedule defined a resetting unsignaled delay‐of‐reinforcement procedure. In the first experiment, speed of magazine training, acquisition of lever pressing, and final rate of lever pressing were related to body weight. In the next experiment, lever pressing was established and maintained in rats that were magazine trained at 70% of ad libitum weight but that were then exposed to the delay procedure at 90% of ad libitum weight. Responding did not change consistently either across or within subjects in subsequent conditions in which body weight was manipulated. In the final experiment, lever pressing was established and maintained with delayed reinforcement in the absence of magazine training for each of 2 rats at 70% and for 1 of 2 rats at 90% of ad libitum weight. The results further illuminate the conditions under which responding can be established in the absence of training and when such responses are reinforced only following an unsignaled delay period.
A TRANSFORMATION OF RESPONDENTLY CONDITIONED STIMULUS FUNCTION IN ACCORDANCE WITH ARBITRARILY APPLICABLE RELATIONS
Authors: Roche Bryan , Barnes Dermot
Published: March 2006

Adult male subjects saw a sexual film clip paired with a nonsense syllable (C1). Similarly, an emotionally neutral film clip was paired with a second nonsense syllable (C3). Responses to the nonsense syllables were recorded as skin resistance responses. Subjects were also trained in a series of related conditional discriminations, using the C1 and C3 stimuli, from which the following equivalence relations were predicted; A1‐B1‐C1, A2‐B2‐C2, and A3‐B3‐C3. Some subjects were given matching‐to‐sample (equivalence) tests after the conditional discrimination training (Experiment 1), whereas others were not (Experiment 2). Subjects were tested for a transformation of eliciting functions by presenting the A1 and A3 stimuli, which were related through equivalence to C1 and C3, respectively. Five of the 6 subjects who showed significantly greater conditioned responses to C1 than to C3, also showed significantly greater skin resistance responses to A1 than to A3. Two additional subjects demonstrated a transformation of an eliciting stimulus function in accordance with five‐member equivalence relations (Experiment 3), and another 5 subjects demonstrated similar effects in accordance with the relations of sameness and opposition (Experiment 4).