bluuebunny/crossref_metadata_2025 huggingface dataset:
HUMAN CHOICE ON CONCURRENT VARIABLE‐INTERVAL VARIABLE‐RATIO SCHEDULES
Authors: Silberberg Alan , Thomas John R. , Berendzen Natasha
Published: March 2006

Each of 5 adult male humans sat in a 4 °C room where they could warm themselves by illuminating six heat lamps for 10‐second periods according to a concurrent variable‐interval variable‐ratio schedule. Left‐button presses on a response panel switched between the schedules and started a 2‐second changeover delay. Right‐button presses illuminated the heat lamps if assigned by the associated schedule and if the changeover delay had timed out. Panel lights identified the schedule in effect and each effective right‐button press. A discrimination procedure—either a multiple variable‐interval variable‐ratio schedule or the presentation of each schedule individually on alternate days—preceded exposure to the choice procedure for some subjects. For subjects not exposed to a discrimination procedure prior to exposure to choice, or if such exposure failed to result in higher rates to the ratio than to the interval schedule, relative response rates matched relative reinforcement rates. However, if subjects responded at higher rates to the ratio schedule than to the interval schedule during a prior discrimination procedure, relative rates on a subsequent choice procedure deviated from matching in the direction of reinforcement‐rate maximizing. In eight of 11 conditions, choice appeared to be governed by maximizing processes. In all cases, human concurrent ratio‐interval performances differed from those of nonhumans in that matching was never obtained with local ratio‐interval rate differences.
RISK‐SENSITIVE FORAGING THEORY AND OPERANT PSYCHOLOGY
Authors: Houston Alasdair I.
Published: March 2006

Hastjarjo, Silberberg, and Hursh (1990) have presented data on the foraging behavior of rats and discussed it in terms of risk‐sensitive foraging theory. Because risk‐sensitive foraging theory is comprised of several different models, it does not lead to general predictions about when an organism should prefer a foraging option with high variance to a foraging option with low variance. Any comparison of data with the predictions of the theory must be based on an appropriate model. I draw attention to various experiments that are potentially relevant to the results reported by Hastjarjo et al. and show how the time period over which the organism must survive can influence a model's predictions about risk sensitivity.
SIGN‐ VERSUS GOAL‐TRACKING: EFFECTS OF CONDITIONED‐STIMULUS‐TO‐UNCONDITIONED‐STIMULUS DISTANCE
Authors: Silva Francisco J. , Silva KathleenM. , Pear Joseph J.
Published: March 2006

Three pigeons were exposed sequentially across experimental phases to five different distances between the conditioned stimulus and the site of the unconditioned stimulus in a sign‐/goal‐tracking procedure. A computer‐controlled tracking system provided a continuous record of the bird's position by continuously monitoring the location of the bird's head in three‐dimensional space. It was found that birds sign‐tracked (i.e., approached the conditioned stimulus) when the conditioned stimulus was closest to the site of the unconditioned stimulus, goal‐tracked (i.e., approached the site of the unconditioned stimulus in the presence of the conditioned stimulus) when the conditioned stimulus was farthest from the site of the unconditioned stimulus, and engaged in both sign‐ and goal‐tracking (or something intermediate) at intermediate conditioned‐stimulus‐to‐unconditioned‐stimulus distances. When both sign‐ and goal‐tracking occurred, the former tended to occur in the first half and the latter in the second half of the interval in which the conditioned stimulus was present. The results suggest (a) whether sign‐ or goal‐tracking (or both) occurs is a function of the distance of the conditioned stimulus from the site of the unconditioned stimulus, (b) the fact that pigeons but not rats have been found to sign‐track consistently throughout the duration of the conditioned stimulus may be due to quantitatively rather than qualitatively different effects of conditioned‐stimulus‐to‐unconditioned‐stimulus distance across species (i.e., a “short” conditioned‐stimulus‐to‐unconditioned‐stimulus distance for a pigeon may be a “long” one for a rat), and (c) sign‐ and goal‐tracking may be competing behavioral tendencies that can (e.g., at intermediate conditioned‐stimulus‐to‐unconditioned‐stimulus distances) cancel each other out. The findings lend support to theories that specify an interaction between phylogenetic and reinforcement variables in determining whether sign‐ or goal‐tracking will occur in any given experimental preparation.
BEHAVIOR DYNAMICS: ONE PERSPECTIVE
Authors: Marr M. Jackson
Published: March 2006

Behavior dynamics is a field devoted to analytic descriptions of behavior change. A principal source of both models and methods for these descriptions is found in physics. This approach is an extension of a long conceptual association between behavior analysis and physics. A theme common to both is the role of molar versus molecular events in description and prediction. Similarities and differences in how these events are treated are discussed. Two examples are presented that illustrate possible correspondence between mechanical and behavioral systems. The first demonstrates the use of a mechanical model to describe the molar properties of behavior under changing reinforcement conditions. The second, dealing with some features of concurrent schedules, focuses on the possible utility of nonlinear dynamical systems to the description of both molar and molecular behavioral events as the outcome of a deterministic, but chaotic, process.
COMPUTATIONAL BEHAVIOR DYNAMICS: AN ALTERNATIVE DESCRIPTION OF NEVIN (1969)
Authors: Shimp Charles P.
Published: March 2006

A computational processing behavior‐dynamic model was instantiated in the form of a computer program that “behaved” on the task developed by Nevin (1969). In this classic discrete‐trials experiment, the relative frequency of choosing a response alternative matched the relative frequency of reinforcement for that alternative, the local structure of responding was opposite that predicted by momentary maximizing (i.e., the probability of a changeover decreased with run length), and absolute and relative response rates varied independently. The behavior‐dynamic model developed here qualitatively reproduced these three results (but not in quantitative and specific detail) and also generated some interesting, as‐yet‐untested predictions about performance in Nevin's task. The model was discussed as an example of a stochastic behavior‐dynamic alternative to algebraic behavior theory.
FIXED‐RATIO PAUSING: JOINT EFFECTS OF PAST REINFORCER MAGNITUDE AND STIMULI CORRELATED WITH UPCOMING MAGNITUDE
Authors: Perone Michael , Courtney Karen
Published: March 2006

Pigeons responded on fixed‐ratio schedules ending in small or large reinforcers (grain presentations of different duration) interspersed within each session. In mixed‐schedule conditions, the response key was lit with a single color throughout the session, and pausing was directly related to the past reinforcer (longer pauses after large reinforcers than after small ones). In multiple‐schedule conditions, different colors accompanied the ratios ending in small and large reinforcers, and pausing was affected by the upcoming reinforcer as well as the past one. Pauses were shorter before large reinforcers than before small ones, but they continued to be longer after large reinforcers than after small ones. The influence of the past reinforcer was modulated by the magnitude of the upcoming reinforcer; in the presence of the stimulus before the small reinforcer, the effect of the past reinforcer was enhanced relative to its effect in the stimulus before the large reinforcer. These results show that pausing between ratios is jointly determined by two competing factors: past conditions of reinforcement and stimuli correlated with upcoming conditions.
ORDER AND CHAOS IN FIXED‐INTERVAL SCHEDULES OF REINFORCEMENT
Authors: Hoyert Mark S.
Published: March 2006

Fixed‐interval schedule performance is characterized by high levels of variability. Responding is absent at the onset of the interval and gradually increases in frequency until reinforcer delivery. Measures of behavior also vary drastically and unpredictably between successive intervals. Recent advances in the study of nonlinear dynamics have allowed researchers to study irregular and unpredictable behavior in a number of fields. This paper reviews several concepts and techniques from nonlinear dynamics and examines their utility in predicting the behavior of pigeons responding to a fixed‐interval schedule of reinforcement. The analysis provided fairly accurate a priori accounts of response rates, accounting for 92.8% of the variance when predicting response rate 1 second in the future and 64% of the variance when predicting response rates for each second over the entire next interreinforcer interval. The nonlinear dynamics account suggests that even the “noisiest” behavior might be the product of purely deterministic mechanisms.
DIMINISHING MARGINAL VALUE AS DELAY DISCOUNTING
Authors: Rachlin Howard
Published: March 2006

The fundamental law underlying economic demand and exchange is the tendency for value of marginal units to diminish with increasing amounts of a commodity. The present paper demonstrates that this law follows from three still‐more‐basic psychological assumptions: (a) limited consumption rate, (b) delay discounting, and (c) choice of highest valued alternative. Cases of diminishing marginal value apparently due to pure intensity of reward may plausibly be attributed to the above three factors. The further assumption that maximum consumption rate may vary within and across individuals implies that some substances may be unusually addictive and that some individual animals may be unusually susceptible to addiction.
EFFECTS OF STIMULUS FREQUENCY AND REINFORCEMENT VARIABLES ON REACTION TIME
Authors: Blough Donald S.
Published: March 2006

Pigeons pecked at one of two black forms, “+” or “+,” either of which could appear alone on a white computer monitor screen. In baseline series of sessions, each form appeared equally often, and two pecks at it produced food reinforcement on 10% of trials. Test series varied the relative probability or duration of reinforcement or frequency of appearance of the targets. Peck reaction times, measured from target onset to the first peck, were found to vary as a function of reinforcement probability but not as a function of relative target frequency or of reinforcement duration. Reaction times to the two targets remained approximately equal as long as the probability of reinforcement, per trial, was equal for the targets, even if the relative frequency of the targets differed by as much as 19 to 1. The results address issues raised in visual search experiments and indicate that attentional priming is unimportant when targets are easy to detect. The results also suggest that equalizing reinforcement probability per trial for all targets removes differential reinforcement as an important variable. That reaction time was sensitive to the probability but not the duration of reinforcement raises interesting questions about the processes reflected in reaction time compared with rate as a response measure.
DISCRIMINABILITY BETWEEN ALTERNATIVES IN A SWITCHING‐KEY CONCURRENT SCHEDULE
Authors: Alsop Brent , Davison Michael
Published: March 2006

Six pigeons were trained to discriminate between two intensities of white light in a symbolic matching‐to‐sample procedure. These stimuli were then used to signal which schedule was available on the main key in a switching‐key concurrent schedule. The concurrent schedules led to a symbolic matching‐to‐sample phase in which the subject identified the concurrent schedule to which it last responded before a reinforcer could be obtained. The concurrent schedules were varied across conditions. Discriminability, measured during the symbolic matching‐to‐sample performance, was high throughout and did not differ across the two procedures. Performance in the concurrent schedules was like that typically obtained using these schedules. Delays were then arranged between completion of the concurrent schedules and presentations of the symbolic matching‐to‐sample phase. A series of conditions with an intervening delay of 10 s showed that both concurrent‐schedule performance and symbolic matching‐to‐sample performance were affected by the delay in a similar way; that is, choice responding was closer to indifference.
CHOICE IN SITUATIONS OF TIME‐BASED DIMINISHING RETURNS: IMMEDIATE VERSUS DELAYED CONSEQUENCES OF ACTION
Authors: Hackenberg Timothy D. , Hineline Philip N.
Published: March 2006

Pigeons chose between two schedules of food presentation, a fixed‐interval schedule and a progressive‐interval schedule that began at 0 s and increased by 20 s with each food delivery provided by that schedule. Choosing one schedule disabled the alternate schedule and stimuli until the requirements of the chosen schedule were satisfied, at which point both schedules were again made available. Fixed‐interval duration remained constant within individual sessions but varied across conditions. Under reset conditions, completing the fixed‐interval schedule not only produced food but also reset the progressive interval to its minimum. Blocks of sessions under the reset procedure were interspersed with sessions under a no‐reset procedure, in which the progressive schedule value increased independent of fixed‐interval choices. Median points of switching from the progressive to the fixed schedule varied systematically with fixed‐interval value, and were consistently lower during reset than during no‐reset conditions. Under the latter, each subject's choices of the progressive‐interval schedule persisted beyond the point at which its requirements equaled those of the fixed‐interval schedule at all but the highest fixed‐interval value. Under the reset procedure, switching occurred at or prior to that equality point. These results qualitatively confirm molar analyses of schedule preference and some versions of optimality theory, but they are more adequately characterized by a model of schedule preference based on the cumulated values of multiple reinforcers, weighted in inverse proportion to the delay between the choice and each successive reinforcer.
THE MAGNITUDE‐OF‐REINFORCEMENT FUNCTION IN CLOSED AND OPEN ECONOMIES
Authors: Collier George , Johnson DeanneF. , Morgan Cynthia
Published: March 2006

It has been hypothesized that the magnitude‐of‐reinforcement effect may differ in closed and open experimental economies. We determined the relationship between magnitude of reinforcement and response rate in three feeding conditions: a closed economy in which total intake was unrestricted, a closed economy in which total intake was restricted so as to maintain body weight at 85% of free‐feeding weight, and a traditional open economy in which subjects received food outside the experimental session. In the closed economies, regardless of body weight, the rats responded faster for smaller pellets and when the fixed ratio for pellets was higher. In the open economy, there was no reliable effect of pellet size or pellet cost on response rate. It is concluded that although there are circumstances in which response rate is an immediate function of the parameters of reinforcement, rate is not necessarily a measure of response strength. Response rate may instead, or additionally, contribute to a strategy of reducing the costs associated with resource utilization.
LOW‐DOSE CAFFEINE DISCRIMINATION AND SELF‐REPORTED MOOD EFFECTS IN NORMAL VOLUNTEERS
Authors: Silverman Kenneth , Griffiths Roland R.
Published: March 2006

A caffeine versus placebo discrimination procedure was used to determine the lowest caffeine dose that could produce discrimination and self‐reported mood effects in normal volunteers. During daily sessions under double‐blind conditions, caffeine‐abstinent subjects orally ingested a capsule containing 178 mg caffeine or placebo. Before beginning discrimination training, the compounds were identified to subjects by letter codes. Fifteen, 30, and 45 min after capsule ingestion, subjects guessed the capsule's letter code. Correct guesses at 45 min earned money. After each session, subjects received a supplementary capsule containing caffeine or placebo to ensure that, within each phase of the study, subjects received the same daily dose of caffeine equal to the training dose. Five of the 15 subjects acquired the caffeine versus placebo discrimination within the first 20 sessions (≥75% correct); 6 other subjects acquired the discrimination with additional training. Nine subjects who acquired the discrimination were subsequently trained at progressively lower caffeine doses. In general, the lowest dose to produce discrimination (≥75% correct) was also the lowest dose to produce self‐reported mood effects: 4 subjects showed discrimination and self‐reported mood effects at 100 mg caffeine, 2 at 56 mg, 1 at 32 mg, and 1 at 18 mg. One of these subjects also showed self‐reported mood effects at 10 mg. The present study documents discriminative stimulus and self‐reported mood effects of caffeine at doses below those previously shown to affect any behavior in normal volunteers.
EFFECTS OF DELAYED REINFORCEMENT ON INFANT VOCALIZATION RATE
Authors: Reeve Lori , Reeve Kenneth F. , Brown Ann K. , Brown John L. , Poulson Claire L.
Published: March 2006

Three previous studies have failed to demonstrate conditioning in infants using a 3‐s delay of reinforcement. The effects of a delayed reinforcement schedule on vocalization rates therefore were explored in a single‐subject repeated‐reversal experimental design for 3 4‐ to 6‐month‐old normally developing infants. Each infant received delayed social reinforcement from his or her parent for vocalizing. The comparison condition was a schedule of differential reinforcement of behavior other than vocalizations to control for elicitation by social stimulation. An operant level of infant vocalizations was the initial condition, after which the differential reinforcement schedule was implemented in an across‐subjects multiple baseline design. Infants' vocalization rates increased above levels measured during differential reinforcement following onset of the delayed reinforcement condition. Also, vocalization rates decreased during differential reinforcement compared to operant levels. The successful use of delayed reinforcement schedules with infants in this study, as opposed to others, is discussed in terms of procedural differences among them.
EFFECTS OF SELF‐GENERATED RULES ON THE DEVELOPMENT OF SCHEDULE‐CONTROLLED BEHAVIOR
Authors: Rosenfarb Irwin S. , Newland M. Christopher , Brannon Suzanne E. , Howey Donald S.
Published: March 2006

College students responded under a multiple differential‐reinforcement‐of‐low‐rate 5‐s fixed‐ratio 8 schedule, with components alternating every 2 min. After 40 programmed minutes of acquisition and 12 min of maintenance, without notice, both schedules changed to extinction for 28 min. During acquisition, between alternations of the multiple schedule, some subjects were asked to develop rules describing the schedule contingencies. Other subjects were given these same rules between alternations, and a third group neither received nor were asked to develop rules. By the end of the acquisition phase, self‐generated‐rule subjects were more likely to show schedule‐typical behavior than were subjects not asked to generate rules. The behavior of those given rules was similar to those asked to generate rules at the end of acquisition, but yoked‐rule subjects acquired schedule‐typical behavior at a quicker rate. By the end of extinction, during the period corresponding to the previous fixed‐ratio interval, all no‐rule subjects who had earned points during acquisition and maintenance were responding at a rate of less than 30 responses per minute. Only 3 of the 9 self‐generated‐rule subjects and 2 of the 5 yoked‐rule subjects were similarly responding at this low rate. Results suggest that asking subjects to develop self‐rules facilitates acquisition, but can retard extinction. Results also suggest that self‐generated rules function similarly to external rules.
DIRECTED FORGETTING OF ELEMENTS IN COMPOUND SAMPLES
Authors: Jitsumori Masako , Taneya Jun'ichi , Kikawa Junko
Published: March 2006

Pigeons were trained in a delayed matching‐to‐sample procedure in which the sample stimuli consisted of a compound of color (red or green) and spatial location (left or right). A postsample cue (houselight on or off) signaled whether color matching or location matching would be required following the delay. In Experiment 1, the reduction in performance on probe trials (in which the houselight condition was reversed relative to that on regular trials) was greater for location matching than for color matching. The birds showed overt mediational behavior during the delays on location‐matching trials. On color‐matching trials, the birds exhibited behavior during delays that might have interfered with that mediational behavior. In Experiment 2, the houselight condition was changed shortly before presentation of the comparison stimuli on probe trials. Accuracy of location matching was reduced when the cue initially signaled color matching and was then changed to signal location matching, whereas matching accuracy was not reduced by a change in the opposite direction. Accuracy of color matching was reduced by a change in illumination level from dark to light, regardless of type of the relevant dimension signaled by houselight illumination. Discussion of these findings focuses on the variables critical to establishment of an effective cue to forget.
DISCRIMINATIVE PERFORMANCE OF THE DOMESTIC HEN IN A VISUAL ACUITY TASK
Authors: DeMello Lesley R. , Foster T. Mary , Temple William
Published: March 2006

The performance of 6 domestic hens on a visual acuity task was studied using a spatial discrete‐trial conditional discrimination procedure. Gray stimuli and vertical square‐wave gratings, ranging in spatial frequency from 1 to 10 cycles per millimeter, were presented in a descending and ascending series of probes. On each trial, either a grating or gray stimulus was presented. Only one spatial frequency of grating was presented during each session. Between probe sessions, training continued at the coarsest grating value. Stimulus discriminability, measured as values of log d, changed with changes in grating spatial frequency for both probe series. Fitted lines described the linear portion of the psychometric functions. Thresholds estimated from the lines generally ranged from four to six cycles per degree, with slightly greater estimates from data from the descending probe series. There were no systematic changes in response bias as a function of grating spatial frequency.
SAMPLE‐STIMULUS DISCRIMINABILITY AND SENSITIVITY TO REINFORCEMENT IN DELAYED MATCHING TO SAMPLE
Authors: Jones B. Maxwell , White K. Geoffrey
Published: March 2006

Five pigeons were trained in a delayed matching‐to‐sample task with red and green stimuli. The retention interval between sample‐stimulus presentation and the availability of the choice stimuli was varied between 0.01 s and 12 s within each session. The probability of food produced by correct‐red and correct‐green responses was varied across conditions. Sample‐stimulus discriminability and response bias were measured at four different retention intervals. The results of these analyses showed an interaction between the discriminability of the sample stimuli and the control exerted by differential reinforcement. At longer retention intervals, sample discriminability decreased and sensitivity of choice behavior to changes in the red/green reinforcer ratio increased. An analogous relation has been reported in conditional discriminations in which the physical disparity of stimuli has been varied. This correspondence suggests that increasing the delay between presentation of one of two stimuli and an opportunity to respond discriminatively to it may be functionally similar to increasing the physical similarity of the two stimuli.
CONDITIONAL DISCRIMINATION AND EQUIVALENCE RELATIONS: A THEORETICAL ANALYSIS OF CONTROL BY NEGATIVE STIMULI
Authors: Carrigan Philip F. , Sidman Murray
Published: March 2006

A detailed analysis is presented of the ways in which control by the negative stimulus in two‐comparison conditional discriminations may be expected to affect the outcome of tests for the properties of equivalence relations. Control by the negative stimulus should produce the following results: (a) no observable effect on symmetry tests; (b) reflexivity test results should look like “oddity” rather than “identity”; and (c) transitivity tests that involve an odd number of nodes should yield results that are 100% opposite to tests that involve an even number of nodes. The analysis also considers the effects of variation in the type of comparison‐stimulus control between and within baseline conditional discriminations. Methods are suggested for experimentally regulating the type of control, and for verifying the predictions that the analysis generates. If suggested experiments continue to support the analysis, investigators who use two‐comparison conditional discriminations to study equivalence relations will either have to control explicitly whether the positive or the negative comparison governs their subjects' choices, or they will have to abandon two comparisons and use three or more comparisons instead.
BEHAVIORAL VARIABILITY AND FREQUENCY‐DEPENDENT SELECTION
Authors: Machado Armando
Published: March 2006

In Experiment 1, two conditions were compared: (a) a variability schedule in which food reinforcement was delivered for the fourth peck in a sequence that differed from the preceding N four‐peck sequences, with the value of N continuously adjusted to maintain reinforcement probability approximately constant; and (b) a control condition in which the variability constraint was dropped but reinforcement probability remained constant. Pigeons responded approximately randomly under the variability schedule but showed strong stereotyped behavior under the control condition. Experiments 2 and 3 tested the idea that variability is the outcome of a type of frequency‐dependent selection, namely differential reinforcement of infrequent behavior patterns. The results showed that pigeons alternate when frequency‐dependent selection is applied to single pecks because alternation is an easy‐to‐learn stable pattern that satisfies the frequency‐dependent condition. Nevertheless, 2 of 4 pigeons showed random behavior when frequency‐dependent selection was applied to two pecks, even though double alternation is a permissible and stable stereotype under these conditions. It appears that random behavior results when pigeons are unable to acquire the stable stereotyped behavior under a given frequency‐dependent schedule.
KEY PECKING OF PIGEONS UNDER VARIABLE‐INTERVAL SCHEDULES OF BRIEFLY SIGNALED DELAYED REINFORCEMENT: EFFECTS OF VARIABLE‐INTERVAL VALUE
Authors: Schaal David W. , Schuh Kory J. , Branch Marc N.
Published: March 2006

Key pecking of 4 pigeons was maintained under a multiple variable‐interval 20‐s variable‐interval 120‐s schedule of food reinforcement. When rates of key pecking were stable, a 5‐s unsignaled, nonresetting delay to reinforcement separated the first peck after an interval elapsed from reinforcement in both components. Rates of pecking decreased substantially in both components. When rates were stable, the situation was changed such that the peck that began the 5‐s delay also changed the color of the keylight for 0.5 s (i.e., the delay was briefly signaled). Rates increased to near‐immediate reinforcement levels. In subsequent conditions, delays of 10 and 20 s, still briefly signaled, were tested. Although rates of key pecking during the component with the variable‐interval 120‐s schedule did not change appreciably across conditions, rates during the variable‐interval 20‐s component decreased greatly in 1 pigeon at the 10‐s delay and decreased in all pigeons at the 20‐s delay. In a control condition, the variable‐interval 20‐s schedule with 20‐s delays was changed to a variable‐interval 35‐s schedule with 5‐s delays, thus equating nominal rates of reinforcement. Rates of pecking increased to baseline levels. Rates of pecking, then, depended on the value of the briefly signaled delay relative to the programmed interfood times, rather than on the absolute delay value. These results are discussed in terms of similar findings in the literature on conditioned reinforcement, delayed matching to sample, and classical conditioning.
COMPETITION BETWEEN STIMULUS‐REINFORCER CONTINGENCIES AND ANTICIPATORY CONTRAST
Authors: Williams Ben A.
Published: March 2006

Procedures used to study anticipatory contrast are conceptually similar to those used to study autoshaping, in that two target stimuli signal either higher or lower rates of reinforcement in the following components of the schedule. Despite this signal contingency, anticipatory contrast entails response rates that are higher to the target stimulus followed by the lower rate of reinforcement. To determine the relation between such effects and autoshaping, different variations of the procedure were used in which the signal contingency was presented in the absence of reinforcement in the target components themselves and in which the reinforcement schedules in the different following components were signaled by the same stimulus. Autoshaping effects of this signal contingency were demonstrated when no reinforcement was available during the target‐component signals themselves. Intermediate patterns of behavior occurred when reinforcement was available during the target‐component signals and when their different following schedules were correlated with the same stimulus. Attempts to isolate these signal and contrast effects functionally by using the signal‐key procedure were unsuccessful. The results demonstrate that Pavlovian stimulus contingencies are in competition with the dynamics of anticipatory contrast, thus reducing its occurrence under some circumstances.
INVERSE RELATIONS BETWEEN PREFERENCE AND CONTRAST
Authors: Williams Ben A.
Published: March 2006

Pigeons were trained on a multiple schedule in which two target components with identical reinforcement schedules were followed by either the same‐valued schedule or by extinction. Response rate increased in both target components but was higher in the target component followed by extinction, replicating previous findings of positive anticipatory contrast. A similar design was used to study negative contrast, in that the two target components were followed either by the same‐valued schedule or by a higher valued schedule. Negative contrast occurred equally, on average, in both target components, thus failing to demonstrate negative contrast that is specifically anticipatory in nature. When the stimuli correlated with the two target components were paired in choice tests, the pattern of preference was in the opposite direction. For the positive contrast procedure, no significant preference between the two target stimuli was evident. But for the negative contrast procedure, preference favored the stimulus followed by the higher valued schedule. The results demonstrate a functional dissociation between positive and negative contrast in relation to stimulus value. More generally, the results demonstrate an inverse relation between response rate and preference and challenge existing accounts of contrast in terms of the concept of relative value.
SUCCESSIVE INDEPENDENCE AND BEHAVIORAL CONTRAST IN A CLOSED ECONOMY
Authors: White K. Geoffrey , Alsop Brent , McLean Anthony P.
Published: March 2006

Two pigeons had access to multiple concurrent schedules of reinforcement for 24 hours per day in their home cages. The variable‐interval schedules comprising the multiple concurrent schedules were varied across 16 conditions. In three sets of conditions, one schedule was varied while its concurrent alternative and the concurrent schedules in the other component were held constant. Behavioral contrast was observed; that is, as the rate of reinforcement arranged by the varied schedule decreased, response rates on the constant schedules typically increased. These conditions formed part of two larger sets of conditions in which the concurrent schedules in one multiple‐schedule component remained constant while the concurrent schedules in the other component were varied. Successive independence was found, in that behavior allocation during the constant component did not vary as a function of the reinforcer ratios in the varied component. Successive independence between components in multiple concurrent schedules is a robust result that occurs in closed economies and under conditions that promote behavioral contrast.
MOLECULAR CONTINGENCIES IN SCHEDULES OF INTERMITTENT PUNISHMENT
Authors: Arbuckle Jeffery L. , Lattal Kennon A.
Published: March 2006

In two experiments, key pecking of pigeons was maintained by a variable‐interval 180‐s schedule of food presentation. Conjointly, a second schedule delivered response‐dependent electric shock. In the first experiment, shocks were presented according to either a variable‐interval or a nondifferential interval‐percentile schedule. The variable‐interval shock schedule differentially delivered shocks following long interresponse times. Although the nondifferential shock schedules delivered shocks less differentially with respect to interresponse times, the two shock schedules equally reduced the relative frequency of long interresponse times. The second experiment differentially shocked long or short interresponse times in different conditions, with resulting decreases in the relative frequency of the targeted interresponse times. These experiments highlight the importance of selecting the appropriate level of analysis for the interaction of behavior and environment. Orderly relations present at one level of analysis (e.g., interresponse times) may not be revealed at other levels of analysis (e.g., overall response rate).
INELASTIC SUPPLY: AN ECONOMIC APPROACH TO SIMPLE INTERVAL SCHEDULES
Authors: Dougan James D.
Published: March 2006

Economic theory predicts an inverse relationship between the quantity of a commodity supplied to the marketplace and the equilibrium market price of that commodity. This prediction was tested in three experiments. Pigeons responded on simple variable‐interval schedules, and quantity of reinforcement supplied was varied in a different way in each experiment. In Experiment 1, quantity supplied was varied by manipulating reinforcement rate while keeping session length constant. In Experiment 2, quantity supplied was varied by manipulating reinforcement rate while keeping reinforcers per session constant. In Experiment 3, quantity supplied was varied by manipulating reinforcer magnitude while keeping number of reinforcers constant. As predicted by economic theory, the obtained behavioral cost (responses per reinforcer) increased as supply decreased. The results could not be explained by simple artifacts such as satiation and time available to respond. In addition, the function relating response rate to reinforcement rate was bitonic in 7 of 9 animals in Experiments 1 and 2, which supports economic and regulatory theories over more traditional reinforcement theories.
ACQUISITION OF LEVER‐PRESS RESPONDING IN RATS WITH DELAYED REINFORCEMENT: A COMPARISON OF THREE PROCEDURES
Authors: Wilkenfield Jayson , Nickel Mark , Blakely Elbert , Poling Alan
Published: March 2006

The present study examined the acquisition of lever pressing in rats under three procedures in which food delivery was delayed by 4, 8, and 16 seconds relative to the response. Under the nonresetting delay procedure, food followed the response selected for reinforcement after a specified interval elapsed; responses during this interval had no programmed effect. Under the resetting procedure, the response selected for reinforcement initiated an interval to food delivery that was reset by each subsequent response. Under the stacked delay procedure, every response programmed delivery of food t seconds after its occurrence. Two control groups were studied, one that received food immediately after each lever press and another that never received food. With the exception of the group that did not receive food, responding was established with every procedure at every delay value without autoshaping or shaping. Although responding was established under the resetting delay procedure, response rates were generally not as high as under the other two procedures. These findings support the results of other recent investigations in demonstrating that a response not previously reinforced can be brought to strength by delayed reinforcement in the absence of explicit training.
CHOICE BETWEEN REPLETING/DEPLETING PATCHES: A CONCURRENT‐SCHEDULE PROCEDURE
Authors: Davison Michael
Published: March 2006

Six pigeons responded on two concurrently available keys that defined patches with the following characteristics. Reinforcer stores repleted on a patch as a linear function of time when the bird had last responded to the other patch, or else did not replete. Repletion schedules thus timed only when the bird was absent from the patch. Reinforcer stores on a patch could be depleted and reinforcers obtained, again as a linear function of time, when the bird responded on a key. Depletion schedules thus timed only when the birds were present at a patch. Experiment 1 investigated changing relative depletion rates when repletion rates were constant and equal (Part 1) and changing relative repletion rates when the depletion rates were constant and equal (Part 2). Response‐ and time‐allocation ratios conformed to a generalized matching relation with obtained reinforcer ratios, and there appeared to be no control by the size of the reinforcer stores. In Experiment 2, absolute depletion rates were varied with a pair of unequal repletion rates (Part 3), and absolute repletion rates were varied with a pair of unequal depletion rates (Part 4). Dwell times in the patches were not affected by either variation. Melioration theory predicted the results of Experiment 1 quite closely but erroneously predicted changing dwell times in Experiment 2. Molar maximization theory did not accurately predict the results of either experiment.
SELECTIVE SENSITIVITY OF SCHEDULE‐INDUCED ACTIVITY TO AN OPERANT SUPPRESSION CONTINGENCY
Authors: Allan Robert W. , Matthews T. James
Published: March 2006

The sensitivity of pigeons' schedule‐induced activity to operant consequences was studied in two experiments. During a 30‐s interval between food presentations, a keylight stimulus brightened incrementally. Stable terminal key pecking and interim locomotor activity developed. An operant “setback” contingency was applied to activity. The contingency arranged for locomotor movements (detected by a nine‐panel floorboard) to be followed by a resetting of the keylight brightness to a dimmer value and a 1‐s delay of reinforcement (for individual responses). Experiment 1 showed that activity patterns were highly sensitive to their operant consequences. Accompanying key‐peck rates were only transiently affected. In Experiment 2, the setback contingency was imposed during restricted portions of the trial, and differential operant control of activity was demonstrated. However, birds in this study produced higher rates of key pecking as activity rates were reduced. These results suggest that although schedule‐induced activity arises in response to the temporal arrangement of stimulus events, this behavior may retain considerable sensitivity to response‐consequence relations.
REDUCTIONS IN SHOCK FREQUENCY AND RESPONSE EFFORT AS FACTORS IN REINFORCEMENT BY TIMEOUT FROM AVOIDANCE
Authors: Courtney Karen , Perone Michael
Published: March 2006

Rats' presses on one lever canceled shocks programmed after variable cycles, while presses on a second lever occasionally produced a 2‐min timeout during which the shock‐deletion schedule was suspended and its correlated stimuli removed. These concurrent schedules of avoidance and timeout were embedded in a multiple schedule whose components differed, within and across conditions, in terms of the programmed shock rate associated with the shock‐deletion schedule. Analyses based on the generalized matching law suggest that the reduction in the response requirement correlated with termination of the avoidance schedule was a more important factor in the reinforcing effectiveness of timeout than was shock‐frequency reduction, at least in 2 of 3 rats. After training in each condition, responding on the timeout lever was extinguished by withholding timeouts in both components over seven sessions. Resistance to extinction varied directly with the rates of both shock‐frequency reduction and avoidance‐response reduction experienced during training. Although reduction in response effort appeared to dominate shock‐frequency reduction in the maintenance of responding, neither factor had a clear advantage in predicting the course of extinction.
THE TEMPORAL ORGANIZATION OF BEHAVIOR ON PERIODIC FOOD SCHEDULES
Authors: Reid Alliston K. , Bacha Gustavo , Morán Concepción
Published: March 2006

Various theories of temporal control and schedule induction imply that periodic schedules temporally modulate an organism's motivational states within interreinforcement intervals. This speculation has been fueled by frequently observed multimodal activity distributions created by averaging across interreinforcement intervals. We tested this hypothesis by manipulating the cost associated with schedule‐induced activities and the availability of other activities to determine the degree to which (a) the temporal distributions of activities within the interreinforcement interval are fixed or can be temporally displaced, (b) rats can reallocate activities across different interreinforcement intervals, and (c) noninduced activities can substitute for schedule‐induced activities. Obtained multimodal activity distributions created by averaging across interreinforcement intervals were not representative of the transitions occurring within individual intervals, so the averaged multimodal distributions should not be assumed to represent changes in the subject's motivational states within the interval. Rather, the multimodal distributions often result from averaging across interreinforcement intervals in which only a single activity occurs. A direct influence of the periodic schedule on the motivational states implies that drinking and running should occur at different periods within the interval, but in three experiments the starting times of drinking and running within interreinforcement intervals were equal. Thus, the sequential pattern of drinking and running on periodic schedules does not result from temporal modulation of motivational states within interreinforcement intervals.
AUDITORY SUCCESSIVE CONDITIONAL DISCRIMINATION AND AUDITORY STIMULUS EQUIVALENCE CLASSES
Authors: Dube William V. , Green Gina , Serna Richard W.
Published: March 2006

This paper describes an experimental demonstration of stimulus equivalence classes consisting entirely of auditory stimuli. Stimuli were digitized arbitrary syllables (e.g., “cug,” “vek”) presented via microcomputer. Training and testing were conducted with a two‐choice auditory successive conditional discrimination procedure. On each trial, auditory samples and comparisons were presented successively. As each comparison was presented, a response location (a rectangle) appeared on the computer screen. After all stimuli for a trial were presented, subjects selected one of the response locations. Six subjects acquired the conditional discrimination baseline, 4 subjects demonstrated the formation of three‐member auditory equivalence classes resulting from sample‐S+ relations, and 1 subject demonstrated equivalence classes resulting from sample‐S— relations. Four subjects received additional training and subsequently demonstrated expansion of the three‐member classes to four members each.
REMOVAL OF AN OBSTACLE: PROBLEM‐SOLVING BEHAVIOR IN PIGEONS
Authors: Nakajima Sadahiko , Sato Masaya
Published: March 2006

The importance of a subject's personal history in the solution of an obstruction problem was demonstrated with pigeons. Four birds were trained to peck a key located outside the chamber by poking their heads through an opening in a screen. During tests, a white block was placed in front of the opening, so that it was not possible to peck the key without removing the block. All birds failed to remove the block. However, all birds that were subsequently trained to push the white block around the chamber in the absence of the key and a few of the birds trained similarly but with a black block solved the problem by pushing the block aside and pecking the key. One bird showed the abrupt descent in the learning curve that has been considered a characteristic of “insightful” problem solving. All birds maintained their successful performance after a 1‐month interval with no intervening tests.
EFFECTS OF DIFFERENCES BETWEEN STIMULI, RESPONSES, AND REINFORCER RATES ON CONDITIONAL DISCRIMINATION PERFORMANCE
Authors: Nevin John A. , Cate Heather , Alsop Brent
Published: March 2006

In a discrete‐trial conditional discrimination procedure, 4 pigeons obtained food reinforcers by pecking a key with a short latency on trials signaled by one stimulus and by pecking the same key with a long latency on trials signaled by a second stimulus. The physical difference between the two stimuli and the temporal separation between the latency values required for reinforcement were varied factorially over four sets of conditions, and the ratio of reinforcer rates for short and long latencies was varied within each set of conditions. Stimulus discrimination varied directly with both stimulus and response differences and was unaffected by the reinforcer ratio. Sensitivity to reinforcement, estimated by generalized‐matching‐law fits to the data within each set of conditions, varied directly with the response difference but inversely with the stimulus difference arranged between sets of conditions. Because variations in stimulus differences, response differences, and reinforcer differences did not have equivalent effects, these findings question the functional equivalence of the three terms of the discriminated operant: antecedent stimuli, behavior, and consequences.
THE EFFECTS OF RESPONSE COST AND RESPONSE RESTRICTION ON A MULTIPLE‐RESPONSE REPERTOIRE WITH HUMANS
Authors: Crosbie John
Published: March 2006

In two experiments a multiple‐response repertoire of four free‐operant responses was developed with university students as subjects using monetary gain as reinforcement. Following baseline, one of the responses was reduced either by making monetary loss contingent upon it (response cost) or by removing it from the repertoire (response restriction). In Experiment 1 a multielement baseline design was employed in which baseline and restriction or response‐cost contingencies alternated semirandomly every 3 minutes. In Experiment 2 a reversal design was employed (i.e., baseline, restriction or response cost, then baseline), and each response required a different amount of effort. Both experiments had the following results: (a) The target response decreased substantially; (b) most nontarget responses increased, and the rest remained near their baseline levels; and (c) no support was found for Dunham's hierarchical, most frequent follower, or greatest temporal similarity rules. For several subjects, the least probable responses during baseline increased most, and the most probable responses increased least. Furthermore, in Experiment 2, responses with the lowest frequency of reinforcement increased most (for all 7 subjects), and those with the greatest frequency of reinforcement increased least (for 5 subjects).