bluuebunny/crossref_metadata_2025 huggingface dataset:
THE ROLE OF VERBAL BEHAVIOR IN HUMAN LEARNING: III. INSTRUCTIONAL EFFECTS IN CHILDREN
Authors: Bentall R. P. , Lowe C. F.
Published: March 2006

Lever pressing of children from three age groups (2½ to 4, 5 to 6½, and 7½ to 9 years) could produce reinforcers according to a fixed‐interval 40‐s schedule: (1) Some were instructed to respond at a high rate, others at a low rate, and (2) they were subsequently taught to provide their own spoken self‐instructions consonant with the earlier, experimenter‐supplied instructions. All subjects who received high‐rate instructions responded at a steady, high rate, which was maintained following self‐instructional training. The effects of low‐rate instructions were directly related to the age of the children. The two older groups produced low‐rate patterns, with the oldest children responding at very low rates; effects were least noticeable in the youngest age group. Following self‐instructional training, all three groups showed adult‐like low‐rate behavior and the oldest children showed an improved ability to estimate the interval length. The results provide further evidence of the importance of language as a determinant of human behavior.
DISCRIMINATIVE STIMULUS CONTROL AND THE EFFECTS OF CONCURRENT OPERANTS
Authors: Leigland Sam
Published: March 2006

Discriminative‐stimulus‐control functions were investigated in a concurrent operant context. Variable‐interval reinforcement schedules were arranged for pigeons on two response keys. One key, illuminated with a white vertical line on green background (position irrelevant), was programmed with a given schedule value across groups. For different groups of pigeons, the alternative key, illuminated with green alone, was programmed with twice, the same, or half the reinforcement frequency of the other key. Stimulus‐control gradients were collected from both keys as line orientation was varied. On the green‐plus‐line alternative, flattest gradients were observed when twice the reinforcement frequency was concurrently programmed and the steepest were observed when equal values were concurrently programmed. Also examined were the effects of a programmed changeover delay, important in maintaining the independence of concurrent operants. The changeover delay was found to have relatively minor effects upon stimulus control, despite its typical and marked effects upon steady‐state responding.
THE OPERANT CONDITIONING OF RESPONSE VARIABILITY: FREE‐OPERANT VERSUS DISCRETE‐RESPONSE PROCEDURES
Authors: Morris Charles J.
Published: March 2006

The operant conditioning of response variability under free‐operant and discrete‐response procedures was investigated. Two pigeons received food only if their pattern of four pecks on two response keys differed from the patterns emitted on the two immediately preceding trials. Under the free‐operant procedure, the keys remained illuminated and operative throughout each trial. There was little variability in the response patterns that resulted, and the pigeons received fewer than one third of the available reinforcers. Under the discrete‐response procedure, a brief timeout period followed each response. Variability increased under this procedure, and the pigeons obtained three fourths of the available reinforcers. Previous successes and failures to produce response variability may have been due to the use or failure to use, respectively, a discrete‐response procedure. Respondent effects inherent in the free‐operant procedure may encourage the development of response stereotypy and, in turn, prevent the development of response variability.
CONDITIONAL RELATIONS BY MONKEYS: REFLEXIVITY, SYMMETRY, AND TRANSITIVITY
Authors: McIntire Kenneth D. , Cleary James , Thompson Travis
Published: March 2006

Two cynomolgous macaques categorized six colors into two groups of three after conditional discrimination training (zero‐delay symbolic match‐to‐sample). The procedures resulted in the establishment of relations among the elements of each set—relations that were not specifically trained and that can be characterized by the properties of reflexivity, symmetry, and transitivity. Each set of colors was related to a characteristic pattern of responding: One response pattern involved temporal duration (press and hold the response keys); the second response pattern entailed repeated pressing and releasing of the response keys (fixed ratio 8). Six combinations of two colors were trained, three combinations from each set. After discriminative performance stabilized for each monkey, they were tested with 10 additional color combinations, all of which differed from the training combinations. The conditional relations established between test combinations can be characterized as stimulus equivalence. The training procedures were analogous to the procedure of using category names, and have implications for understanding the function of language in the formation of equivalence classes.
EFFECTS OF RESPONSE‐ALLOCATION CONSTRAINTS ON MULTIPLE‐SCHEDULE PERFORMANCE
Authors: Davison Michael , Charman Lesle
Published: March 2006

Four pigeons were trained on multiple variable‐interval schedules in which components alternated after a fixed number of responses had been emitted. In Part 1, each component change occurred after 20 responses; in Part 2, the number was 40; and in Part 3, the number of responses before change was 10. Component reinforcer rates were varied over five experimental conditions in each of Parts 1 to 3. Component response rates decreased as the specified number of responses per component was increased. However, the relation between component response‐rate ratios and component reinforcer‐rate ratios was independent of the specified number of responses per component, and was similar to that found when components alternate after fixed time periods. In the fourth part of the experiment, the results from Parts 1 to 3 were systematically replicated by keeping the component reinforcer rates constant, but different, while the number of responses that produced component alternation was varied from 5 to 60 responses. The results showed that multiple‐schedule performance under component‐response‐number constraint is similar to that under conventional component‐duration constraint. They further suggest that multiple‐schedule response rates are controlled by component reinforcer rates and not by principles of maximizing overall reinforcer rates or meliorating component reinforcer rates.
ANALYSIS OF A GUIDED‐RESPONSE PROCEDURE IN VISUAL DISCRIMINATIONS BY RATS
Authors: Aronsohn Susana , Pinto‐Hamuy Teresa , Toledo Patricio , Asenjo Patricio
Published: March 2006

A guided‐response procedure was used to train a visual pattern discrimination by rats in a modified Sutherland box. The method consisted of guiding the animal to the correct choice by means of a retractable bridge that led to reinforcers, followed by gradually removing this prompt. This method was compared to a stimulus‐fading procedure, in which the initial differences betwen discriminative stimuli were gradually faded until they differed only with respect to the critical dimension for discrimination, and to a trial‐and‐error procedure. Both gradual procedures resulted in fewer errors compared to the trial‐and‐error procedure. The higher efficiency of the fading procedures was attributed to less aversiveness derived from performance with few errors and to the use of step‐by‐step requirements relative to the criterion performance.
COCAINE TOLERANCE: ACUTE VERSUS CHRONIC EFFECTS AS DEPENDENT UPON FIXED‐RATIO SIZE
Authors: Hoffman Sandra H. , Branch Marc N. , Sizemore Glen M.
Published: March 2006

The effects of cocaine on operant behavior were studied by examining fixed‐ratio value as a factor in the development of tolerance. Pigeons pecked a response key under a three‐component multiple schedule, with each bird being exposed to fixed‐ratio values that were categorized as small, medium, or large. Administered acutely, cocaine (1.0 to 10.0 mg/kg) produced dose‐related decreases in overall rate of responding. Responding maintained by the largest ratio was decreased by lower doses than those required to reduce rates of responding maintained by the other two ratio schedules. Following repeated daily administration of 5.6 mg/kg of cocaine, dose‐effect functions (obtained from sessions during the chronic regimen by making substitutions for the daily dose) indicated tolerance under the smaller ratios, but no tolerance or less tolerance under the largest ratio. Thus, whether tolerance developed, and the degree to which it developed, depended on the ratio value. The results are partially consistent with the notion that tolerance to drug effects on schedule‐controlled behavior will develop if drug administration initially reduces reinforcement frequency, but they indicate that reinforcement loss alone is not a sufficient condition for the generation of tolerance under such conditions. The findings suggest that amount of responding required for reinforcement, or “effort,” may contribute to the development of tolerance to effects of cocaine.
CHOICE BETWEEN RELIABLE AND UNRELIABLE OUTCOMES: MIXED PERCENTAGE‐REINFORCEMENT IN CONCURRENT CHAINS
Authors: Spetch Marcia L. , Dunn Roger
Published: March 2006

Pigeons' choices between alternatives that provided different percentages of reinforcement in mixed schedules were studied using the concurrent‐chains procedure. In Experiment 1, the alternatives were terminal‐link schedules that were equal in delay and magnitude of reinforcement, but that provided different percentages of reinforcement, with one schedule providing reinforcement twice as reliably as the other. All pigeons preferred the more reliable schedule, and their level of preference was not systematically affected by variation in the absolute percentage values, or in the magnitude of reinforcement. In Experiment 2, preference for a schedule providing 100% reinforcement over one providing 33% reinforcement increased systematically with increases in the duration of the terminal links. In contrast, preference decreased systematically with increases in the duration of the initial links. Experiment 3 examined choice with equal percentages of reinforcement but unequal delays to reinforcement. Preference for the shorter delay to reinforcement was not systematically affected by variation in the absolute percentage of reinforcement. The overall pattern of results supported predictions based on an extension of the delay‐reduction hypothesis to choice procedures involving mixed schedules of percentage reinforcement.
SEQUENTIAL EFFECTS OF INTERVAL DURATION ON FIXED‐INTERVAL PERFORMANCE
Authors: Meltzer Donald
Published: March 2006

The bar pressing of rats was reinforced on a multiple fixed‐interval schedule. The schedule intervals were 1 and 5 min long, and the sequence was such that intervals of either duration were equally likely to be followed by intervals of the same or of the other duration. Rates were higher during 1‐min and after 5‐min intervals. Best fit equations for cumulative responses during the 5‐min intervals produced very similar exponents regardless of preceding duration. It was concluded that preceding duration may have affected the subjects' performances through direct effects on temporal discrimination.
INTERMITTENT REINFORCEMENT OF A CONTINUOUS RESPONSE
Authors: Rider David P. , Kametani Nora N.
Published: March 2006

Six rats were trained with food deliveries contingent upon their pressing a lever and holding it down for either fixed or variable cumulative durations. Fixed‐hold requirements ranged from 15 s to 90 s over experimental conditions; variable‐hold requirements ranged from 15 s to 120 s. At most long and intermediate values, variable‐hold requirements maintained more lever holding than fixed requirements. At the longest hold requirements studied, more lever holding was maintained by variable requirements than by fixed requirements of equivalent mean length for each rat. Postreinforcement‐pause duration increased with lever‐holding time for both fixed‐ and variable‐hold requirements. At comparable lever‐holding times per reinforcer, longer pauses typically were produced by fixed requirements than by variable requirements. Data from this study on the maintenance of responding, temporal response patterns, and postreinforcement pausing are comparable to those obtained with intermittent reinforcement of discrete responses. These findings suggest that the response—reinforcer relation specified by a reinforcement schedule is a fundamental determinant of responding, whether responding consists of discrete units or of continuous activity.
VARIABLE‐INTERVAL SCHEDULES OF TIMEOUT FROM AVOIDANCE
Authors: Perone Michael , Galizio Mark
Published: March 2006

Rats were trained on concurrent schedules in which pressing one lever postponed shock and pressing the other occasionally produced a 2‐min timeout during which the shock‐postponement schedule was suspended and its correlated stimuli were removed. Throughout, the shock‐postponement schedule maintained proficient levels of avoidance. Nevertheless, in Experiment 1 responding on the timeout lever was established rapidly, was maintained at stable levels on variable‐interval schedules, was extinguished by withholding timeout, was reestablished when timeout was reintroduced, and was brought under discriminative control with a multiple variable‐interval extinction schedule of timeout. These results are in contrast with Verhave's (1962) conclusion that timeout is an ineffective reinforcer when presented to rats on intermittent schedules. In Experiment 2 the consequence of responding on the timeout lever was altered so that the shock‐postponement schedule remained in effect even though the stimulus conditions associated with timeout were produced for 2 min. Responding extinguished, indicating that suspension of the shock‐postponement schedule, not stimulus change, was the source of reinforcement. By establishing the reinforcing efficacy of timeout with standard variable‐interval schedules, these experiments illustrate a procedure for studying negative reinforcement in the same way as positive reinforcement.
THE MAXIMIZATION OF OVERALL REINFORCEMENT RATE ON CONCURRENT CHAINS
Authors: Houston Alasdair I. , Sumida Brian H. , Mcnamara John M.
Published: March 2006

We model behavioral allocation on concurrent chains in which the initial links are independent variable‐interval schedules. We also quantify the relationship between behavior during the initial links and the probability of entering a terminal link. The behavior that maximizes overall reinforcement rate is then considered and compared with published experimental data. Although all the trends in the data are predicted by rate maximization, there are considerable deviations from the predictions of rate maximization when reward magnitudes are unequal. We argue from our results that optimal allocation on concurrent chains, and prey choice as used in the theory of optimal diets, are distinct concepts. We show that the maximization of overall rate can lead to apparent violations of stochastic transitivity.
INTERPERSONAL CONTINGENCIES: PERFORMANCE DIFFERENCES AND COST‐EFFECTIVENESS
Authors: Schmitt David R.
Published: March 2006

Three reinforcement contingencies were compared with regard to performance differences and cost‐effectiveness (i.e., responses per unit reinforcer). Pairs of college students were studied under individual, cooperative, or competitive contingencies using a concurrent setting that included one of these three contingencies as one alternative and a lower paying individual contingency as the other alternative. With the individual and the cooperative contingencies, overall response rates were typically high; under competitive contingencies the overall response rates were substantially lower. Subjects responded at very high rates when competing, but chose not to compete most of the time. Competition and cooperation produced the most cost‐effective responding, assessed as the number of responses made per $.01 of reinforcer. High overall rates of competitive responding were obtained when the contests were longer and the lower paying alternative contingency was not available.
FACTORS AFFECTING CONDITIONAL DISCRIMINATION LEARNING BY PIGEONS
Authors: Thomas David R. , Stengel Todd , Sherman Leslie , Woodford Margaret
Published: March 2006

In Experiment 1 (within subjects) and Experiment 2 (between subjects) it was shown that the sequential training of pigeons on a color discrimination and then on its reversal, each in a different floor‐tilt/texture context, failed to produce conditional control of discriminative performance by those contexts. Daily alternation between the two problems (with correlated contexts) was successful, however. In each of these experiments conditional control was better reflected in generalization test performance in extinction than during sessions of training with reinforcement.
INTERACTION OF METHADONE, REINFORCEMENT HISTORY, AND VARIABLE‐INTERVAL PERFORMANCE
Authors: Nader Michael A. , Thompson Travis
Published: March 2006

In the present study, we examined how a reinforcement schedule history that generated high or low rates of responding influenced the effects of acute (Experiment 1) and chronic (Experiment 2) methadone administration. Initially, key‐peck responses of pigeons were maintained under a variable‐interval 90‐s schedule of food presentation, and a methadone dose‐response curve was determined with doses of 0.6, 1.2, and 2.4 mg/kg. The pigeons were then exposed, for at least 40 sessions, to either a fixed‐ratio 50 schedule or a differential‐reinforcement‐of‐low‐rate 10‐s schedule, or were given continued exposure to the variable‐interval schedule. The methadone dose—response curve was redetermined after all pigeons again were responding under the variable‐interval schedule. The effects of two different daily methadone doses (9.0 and 12.0 mg/kg/day) and withdrawal precipitated by naloxone also were assessed. Experience with a fixed‐ratio or differential reinforcement of low rate schedule did not result in significantly different response rates under the variable‐interval schedule and, in general, the acute effects of methadone did not have differential effects correlated with schedule history. However, for 2 of 4 subjects the rate‐decreasing effects of methadone on rates of key pecking were greater following a history of low‐rate responding, suggesting a possible interaction between schedule history and effects of methadone. Daily methadone administration under the variable‐interval schedule revealed that pigeons with experience under the differential reinforcement of low rate schedule developed more rapid and complete tolerance to the rate‐decreasing effects of methadone. Three of the 4 subjects in this group showed rate increases above drug‐free baselines during chronic methadone dosing. Pigeons with a history of fixed‐ratio responding also developed tolerance to the rate‐decreasing effects of methadone but without the subsequent rate increases seen by subjects with low‐rate histories. No subjects with variable‐interval histories showed complete recovery of drug‐free baselines, suggesting that interpolated training under other schedules may attenuate the rate‐altering effects of chronically administered drugs. Naloxone (1.0 mg/kg), administered during the chronic methadone phase, resulted in greater disruption of responding by pigeons with a history of low‐rate responding, as compared to subjects in the other two groups. These experiments reveal that although acute doses of methadone did not differentiate performances based on prior reinforcement schedule history, recovery of drug‐free baselines during chronic drug administration was more rapid and complete in subjects with low‐rate histories. It appears that reinforcement schedule histories can influence the behavioral effects of chronically administered methadone even when no current differences in baseline rates or in the effects of acute administration of methadone are apparent.
REPLY TO SILBERBERG AND ZIRIAX
Authors: Vaughan William
Published: March 2006

Silberberg and Ziriax (1985) report that a modification of Vaughan's (1981) procedure produces results inconsistent with melioration (the position advocated by Vaughan) but consistent with a process they term molecular maximizing. Here it is argued that the theory of molecular maximization is not sufficiently unambiguous that researchers other than the developers can test its predictions, and that in any case none of the data presented by Silberberg and Ziriax are both clearly consistent with molecular maximization and inconsistent with melioration.
PROBABILITY AND DELAY IN COMMITMENT
Authors: Rachlin Howard , Castrogiovanni Anthony , Cross David
Published: March 2006

In the first stage of a two‐stage choice, human subjects chose between probabilistic access to a second choice (between a small high‐probability reward and a large low‐probability reward) and commitment to the large low‐probability reward. When confronted with the second‐stage choice, subjects strongly preferred the small high‐probability reward. When the first‐stage probability (of access to the second stage) was high, subjects strongly preferred the path leading to the choice in the second stage. But when the first‐stage probability was low, subjects committed themselves to the large low‐probability reward. These results parallel those obtained by Rachlin and Green (1972) with pigeons and constitute some evidence that probabilities may be interpreted as delays.
ON THE DISTINCTION BETWEEN OPEN AND CLOSED ECONOMIES
Authors: Timberlake> William , Peden Blaine F.
Published: March 2006

Open and closed economies have been assumed to produce opposite relations between responding and the programmed density of reward (the amount of reward divided by its cost). Experimental procedures that are treated as open economies typically dissociate responding and total reward by providing supplemental income outside the experimental session; procedures construed as closed economies do not. In an open economy responding is assumed to be directly related to reward density, whereas in a closed economy responding is assumed to be inversely related to reward density. In contrast to this predicted correlation between response—reward relations and type of economy, behavior regulation theory predicts both direct and inverse relations in both open and closed economies. Specifically, responding should be a bitonic function of reward density regardless of the type of economy and is dependent only on the ratio of the schedule terms rather than on their absolute size. These predictions were tested by four experiments in which pigeons' key pecking produced food on fixed‐ratio and variable‐interval schedules over a range of reward magnitudes and under several open‐ and closed‐economy procedures. The results better supported the behavior regulation view by showing a general bitonic function between key pecking and food density in all conditions. In most cases, the absolute size of the schedule requirement and the magnitude of reward had no effect; equal ratios of these terms produced approximately equal responding.
OBSERVING RESPONSES MAINTAINED BY CONDITIONAL DISCRIMINATIVE STIMULI
Authors: Ohta Akira
Published: March 2006

In a conditional discrimination procedure, pigeons' observing responses were analyzed to examine whether two color stimuli (blue or red), conditionally related to whether each of two line stimuli (vertical or horizontal) accompanied reinforcement or nonreinforcement, functioned as conditioned reinforcers. If a variable‐interval (VI) 10‐s requirement was fulfilled, an observing response produced onset of a color stimulus. A little later, a line stimulus was presented independently of responding, added to the color stimulus to form a compound stimulus. If 55 s elapsed with a response not having occurred either through 55 s or after the variable‐interval 10‐s had timed out, one of the color—line compound stimuli was presented independently of responding. To control for sensory reinforcement effects and for earlier entrance to the later link, a simple discrimination procedure also was conducted in which reinforcement was not correlated with the color stimuli but with the line stimuli only. As in the conditional discrimination, the observing response also could produce earlier presentation of blue or red. The observing response occurred more frequently during the conditional discrimination than during the simple discrimination. The results were related to different theoretical accounts of conditioned reinforcement, particularly the information hypothesis.
DISSOCIATION OF VALUE AND RESPONSE STRENGTH
Authors: Vaughan William
Published: March 2006

Four pigeons were exposed to multiple schedules and later to concurrent‐chains schedules, with terminal links that had previously been multiple‐schedule components. For 2 birds, the terminal‐link schedules arranged an inverse relationship between response rate and reinforcement rate; for the other 2 birds a direct corresponding relationship was arranged. Those response rates were further modified by differentially reinforcing either longer or shorter interresponse times, relative to the current means. Although the birds' initial‐link responses indicated preferences for terminal links with higher rates of reinforcement, in half the cases the birds responded during the terminal links in such a way as to produce lower rates of reinforcement, rates their initial‐link behavior indicated they did not prefer. That outcome is inconsistent with maximization theory, but consistent with a strengthening analysis of behavior on single‐key schedules.
A COMPARISON OF RESPONSE PATTERNS ON FIXED‐, VARIABLE‐, AND RANDOM‐RATIO SCHEDULES
Authors: Crossman Edward K. , Bonem Elliott J. , Phelps Brady J.
Published: March 2006

The behavior of individual pigeons on fixed‐ratio, variable‐ratio, and random‐ratio schedules was examined. Within each type of ratio schedule the size of the ratio was varied in an irregular sequence. At various ratio sizes (5, 10, 40, 80) no differences were found among overall response rates (post‐reinforcement pause plus running response rate) as a function of ratio type. This similarity in overall response rates held despite noticeable differences in the microstructure of performance both within and across subjects; the primary performance difference on the three types of ratio schedules was the relatively longer postreinforcement pause duration on the fixed‐ratio schedule. We concluded that the gross temporal characteristics of performance determined by the relative weightings of the postreinforcement pause and running response rate were primarily controlled by the type of ratio schedule (fixed, variable, or random), whereas the overall rate of responding was controlled by the size of the ratio.
AN AUTOMATIC PELLET DISPENSER FOR PRECISE CONTROL OF FEEDING TOPOGRAPHY IN GRANIVOROUS BIRDS
Authors: Berkhoudt H. , van der Reijden D. , Heijmans M.
Published: March 2006

Design and construction of an automatic pellet dispenser for granivorous birds are described. The dispenser permits rapid pneumatic delivery of pellets (five pellets per second maximum) to one controlled position and does not interfere with simultaneous electrophysiological recording. In addition, the device continuously indicates presence or absence of a pellet in the delivery position. This automatic dispenser proved very effective in our studies of stereotyped topographies of feeding in granivorous birds, such as pigeons and chickens.
CONCURRENT‐SCHEDULE PERFORMANCE: EFFECTS OF RELATIVE AND OVERALL REINFORCER RATE
Authors: Alsop Brent , Elliffe Douglas
Published: March 2006

Six pigeons were trained to respond on two keys, each of which provided reinforcers on an arithmetic variable‐interval schedule. These concurrent schedules ran nonindependently with a 2‐s changeover delay. Six sets of conditions were conducted. Within each set of conditions the ratio of reinforcers available on the two alternatives was varied, but the arranged overall reinforcer rate remained constant. Each set of conditions used a different overall reinforcer rate, ranging from 0.22 reinforcers per minute to 10 reinforcers per minute. The generalized matching law fit the data from each set of conditions, but sensitivity to reinforcer frequency (a) decreased as the overall reinforcer rate decreased for both time allocation and response allocation based analyses of the data. Overall response rates did not vary with changes in relative reinforcer rate, but decreased with decreases in overall reinforcer rate. Changeover rates varied as a function of both relative and overall reinforcer rates. However, as explanations based on changeover rate seem unable to deal with the changes in generalized matching sensitivity, discrimination accounts of choice may offer a more promising interpretation.
CONTROL OF BEHAVIOR BY AN ESTABLISHING STIMULUS
Authors: McPherson Adair , Osborne J. Grayson
Published: March 2006

Seventeen pigeons were exposed to a three‐key discrete‐trial procedure in which a peck on the lit center key produced food if, and only if, the left keylight was lit. The center key was illuminated by a peck on the lit right key. Of interest was whether subjects pecked the right key before or after the response‐independent onset of the left keylight. Pecks on the right key after left‐keylight onset suggest control of behavior by the left keylight—an establishing stimulus. In three experiments, the strength of center‐keylight onset as conditioned reinforcer for a response on the right key was manipulated by altering the size of the reduction in time to food delivery correlated with its onset. Control of pigeons' key pecks by onset of the left keylight occurred on more trials per session when the center keylight was a relatively weak conditioned reinforcer and on fewer trials per session when the center keylight was a relatively strong conditioned reinforcer. Differences across conditions in the degree of control by onset of the establishing stimulus were greatest when changes in conditioned reinforcer strength occurred relatively frequently and were signaled. The results provide evidence of the function of an establishing stimulus.
INFORMATION ON RESPONSE REQUIREMENTS COMPARED WITH INFORMATION ON FOOD DENSITY AS A REIN FORCER OF OBSERVING IN PIGEONS
Authors: Dinsmoor James A. , Bowe Craig A. , Green Leonard , Hanson John
Published: March 2006

On a variable‐interval schedule, pecking the key to the pigeon's right (observing response) produced red or green displays relating to the delivery of grain and its dependence on pecking the key to the left (food key). During various blocks of sessions, mixed (no stimulus change) schedules including the following pairs of components were temporarily converted by the observing response to their corresponding multiple (correlated stimuli) schedules: variable‐interval 60‐s, extinction; variable‐interval 60‐s, variable‐time (response‐independent) 60‐s; extinction, variable‐time 60‐s. Differences in food delivery maintained substantial rates of responding on the observing key, without regard to pecking requirements on the food key. Although stimuli correlated with differences in the response requirement on the food key maintained higher observing rates than those maintained by uncorrelated stimuli, they were much lower than those based on food. The value of predictive stimuli as reinforcers is determined by the value of the events predicted. In particular, the cost of pecking appears to be low, and this may place limitations on the applicability of energy‐based and economic models of behavior.
CONDITIONED REINFORCEMENT BY CONDITIONAL DISCRIMINATIVE STIMULI
Authors: Ohta Akira
Published: March 2006

A concurrent‐chains schedule was used to examine how a delay to conditional discriminative stimuli affects conditioned reinforcement strength. Pigeons' key‐peck responses in the initial link produced either of two terminal links according to independent variable‐interval 30‐s schedules. Each terminal link involved an identical successive conditional discrimination and was segmented into three links: a delay interval (green), a color conditional discriminative stimulus (blue or red), and a line conditional discriminative stimulus (vertical or horizontal lines). Food delivery occurred 45 s after entering the terminal link with a probability of .5, but its conditional probability (1.0 or 0) depended on the combination of the color and the line stimuli. One of the color stimuli occurred independently of further responding, 5 s after entry into the right terminal link, but it occurred 35 s after entry into the left terminal link. One of the line stimuli occurred independently of responding 40 s after entry into either terminal link, synchronized with the offset of the color stimulus. The initial‐link relative response rate for the right was consistently higher in comparison with a control condition in which the color stimuli occurred 20 s after entry into either terminal link. The preference for the short delay to the color conditional discriminative stimuli suggests the possibility of conditioned reinforcement by information about the relation between the line conditional discriminative stimuli and the outcomes.
CHANGES IN FUNCTIONAL RESPONSE UNITS WITH BRIEFLY DELAYED REINFORCEMENT
Authors: Arbuckle Jeffery L. , Lattal Kennon A.
Published: March 2006

In two experiments, key‐peck responding of pigeons was compared under variable‐interval schedules that arranged immediate reinforcement and ones that arranged unsignaled delays of reinforcement. Responses during the nominal unsignaled delay periods had no effect on the reinforcer presentations. In Experiment 1, the unsignaled delays were studied using variable‐interval schedules as baselines. Relative to the immediate reinforcement condition, 0.5‐s unsignaled delays decreased the duration of the reinforced interresponse times and increased the overall frequency of short (<0.5‐s) interresponse times. Longer, 5.0‐s unsignaled delays increased the duration of the reinforced interresponse times and decreased the overall frequency of the short interresponse times. In Experiment 2, similar effects to those of Experiment 1 were obtained when the 0.5‐s unsignaled delays were imposed upon a baseline schedule that explicitly arranged reinforcement of short interresponse times and therefore already generated a large number of short interresponse times. The results support earlier suggestions that the unsignaled 0.5‐s delays change the functional response unit from a single key peck to a multiple key‐peck unit. These findings are discussed in terms of the mechanisms by which contingencies control response structure in the absence of specific structural requirements.
QUASI‐DYNAMIC CHOICE MODELS: MELIORATION AND RATIO IN VARIANCE
Authors: Staddon J. E. R.
Published: March 2006

There is continuing controversy about the behavioral process or processes that underlie the major regularities of free‐operant choice such as molar matching and systematic deviations therefrom. A recent interchange between Vaughan and Silberberg and Ziriax concerned the relative merits of melioration, and a computer simulation of molecular maximizing. There are difficulties in evaluating theories expressed as computer programs because many arbitrary decisions must often be made in order to get the programs to operate. I therefore propose an alternative form of, model that I term quasi‐dynamic as a useful intermediate form of theory appropriate to our current state of knowledge about free‐operant choice. Quasi‐dynamic models resemble the game‐theoretic analyses now commonplace in biology in that they can predict stable and unstable equilibria but not dynamic properties such as learning curves. It is possible to interpret melioration as a quasi‐dynamic model. An alternative quasi‐dynamic model for probabilistic choice, ratio invariance, has been proposed by Horner and Staddon. The present paper compares the predictions of melioration and ratio invariance for five experimental situations: concurrent variable‐interval variable‐interval schedules, concurrent variable‐interval variable‐ratio schedules, the two‐armed bandit (concurrent random‐ratio schedules), and two types of frequency‐dependent schedule. Neither approach easily explains all the data, but ratio invariance seems to provide a better picture of pigeons' response to probabilistic choice procedures. Ratio invariance is also more adaptive (less susceptible to “traps”) and closer to the original expression of the law of effect than pure hill‐climbing processes such as momentary maximizing and melioration, although such processes may come in to play on more complex procedures that provide opportunities for temporal discrimination.
MAXIMIZING PRESENT VALUE: A MODEL TO EXPLAIN WHY MODERATE RESPONSE RATES OBTAIN ON VARIABLE‐INTERVAL SCHEDULES
Authors: Silberberg Alan , Warren‐Boulton Frederick R. , Asano Toshio
Published: March 2006

In Phases 1 and 3, two Japanese monkeys responded on a multiple variable‐ratio 80 variable‐interval X schedule, where the value of X was adjusted to ensure equal between‐schedule reinforcement rates. Components strictly alternated following the delivery of a food pellet, and each session ended following 50 components. Phase 2 differed from the others only in that the 50 pellets previously earned during the session were delivered together at session's end. Variable‐ratio response rates did not decrease across phases, but variable‐interval response rates decreased substantially during the Phase 2 procedure. This rate decrease was attributed to the food‐at‐session's‐end manipulation removing the greater immediacy of reinforcement provided by short interresponse times relative to long interresponse times. Without this time preference for short interresponse times, the variable‐interval interresponse‐time reinforcement feedback function largely controlled response emission, dictating a response‐rate reduction. This result was explained in terms of the economic notion of “maximizing present value.”
CONCURRENT‐CHAIN PERFORMANCE: EFFECTS OF ABSOLUTE AND RELATIVE TERMINAL‐LINK ENTRY FREQUENCY
Authors: Alsop Brent , Davison Michael
Published: March 2006

Six pigeons were trained in a concurrent‐chain procedure with constant variable‐interval 6‐s variable‐interval 12‐s terminal links. Five groups of conditions were arranged. Within a group of conditions, the duration of one initial‐link schedule was held constant and the duration of the other initial link was varied. The duration of the varied initial link was always longer than, or equal to, the constant initial‐link duration. The duration of the shorter initial link was varied across groups of conditions from 5 s to 70 s. The data from each group were well described by the generalized matching law. Sensitivity (a) to the terminal‐link entry ratio increased as the shorter initial‐link duration increased, but appeared to reach an asymptote at shorter initial‐link durations greater than 32 s. Terminal‐link bias did not change with changes in shorter initial‐link duration for the response‐allocation data, but showed a small increase with increasing shorter initial‐link duration for the time‐allocation data.
THE EFFECTS OF A VARIETY OF INSTRUCTIONS ON HUMAN FIXED‐INTERVAL PERFORMANCE
Authors: LeFrancois Janet R. , Chase Philip N. , Joyce James H.
Published: March 2006

College students were instructed to press a button for points under a single reinforcement schedule or under a variety of reinforcement schedules. Instructions for a single schedule were either specific or minimal. Instructions on a variety of schedules involved specific instructions on eight different schedules of reinforcement. Subsequent to the varied training, responding under a fixed‐interval schedule occurred at a low rate. Both the minimal and specific instruction training led to fixed‐interval responding that was similar to the responding exhibited during training. These findings suggest that under certain conditions instructed behavior is sensitive to changes in contingencies.
A TEST OF SYMMETRY AND TRANSITIVITY IN THE CONDITIONAL DISCRIMINATION PERFORMANCES OF PIGEONS
Authors: Lipkens Regina , Kop Pieter F. M. , Matthijs Werner
Published: March 2006

In a matching‐to‐sample context, pigeons were taught two conditional discriminations according to one of three equivalence paradigms: train if A, then select B and if B, then select C; train if B, then A and if B, then C; or train if A, then B and if C, then B. Test trials without reinforcement revealed that the conditional relations did not satisfy the symmetrical and transitive properties of an equivalence relation. Apparently, only specific if … then relations were learned. Contrary to Kendall's (1983) findings, and probably as a consequence of procedural differences, none of the pigeons in the present experiment were observed to emit mediating behavior during the transitivity probe trials. The absence of symmetry and transitivity may be related to the individual stimuli not being reflexive. Behavioral techniques other than the commonly used matching‐to‐sample technique might better succeed in avoiding unintended stimulus control in the study of the formation of stimulus classes.
DIFFERENTIAL EFFECTS OF COCAINE AND PENTOBARBITAL ON FIXED‐INTERVAL AND RANDOM‐INTERVAL PERFORMANCE
Authors: Howell Leonard L. , Byrd Larry D. , Marr M. J.
Published: March 2006

Reports have indicated that the behavioral effects of a drug can be related to the nondrug control rate of behavior in the absence of the drug. To investigate the purported relationship between control rate and drug rate, squirrel monkeys were trained under a fixed‐interval 300‐s schedule of stimulus‐shock termination, a procedure that engendered a wide range of response rates. A light illuminated the experimental chamber during the fixed interval, and the first lever press after 300 s had elapsed terminated the light for 30 s and precluded an electrical stimulus to the tail. Following acute intra‐muscular administration of cocaine (0.03–0.56 mg/kg), overall rate increased and different control rates of responding, during different parts of the fixed interval, converged toward a common rate. Subsequently, the schedule was changed to a multiple fixed‐interval 300‐s random‐interval 300‐s schedule; performance during the random‐interval component was characterized by steady responding at a uniformly high rate. Analysis of fixed‐interval and random‐interval performances following acute cocaine administration revealed convergence of response rates toward a common, uniform rate. Pentobarbital (0.3–10.0 mg/kg) only decreased overall rate, and different control rates of responding during the fixed interval did not converge toward a common rate. The results indicate that this type of analysis can be useful in comparing pharmacological agents from different classes and that the rate at which responding becomes uniform can provide a quantitative behavioral end point for characterizing drug effects on behavior.
REINFORCEMENT SCHEDULES: RETROACTIVE AND PROACTIVE EFFECTS OF REINFORCERS INSERTED INTO FIXED‐INTERVAL PERFORMANCES
Authors: Catania A. Charles , Sagvolden Terje , Keller Kenneth J.
Published: March 2006

The responding maintained by a reinforcer depends on the relation of the reinforcer not merely to the response that produces it but also to other preceding responses. Early responses in a sequence that ends in a reinforcing consequence make smaller contributions to later response rates than more recent ones, by virtue of the longer delays that separate them from the reinforcer. This study shows that the relation between a response and a later reinforcer contributes to responding only if no other reinforcers intervene; in other words, each reinforcer blocks responses that precede it from the effects of later reinforcers. Pigeons' pecks were maintained by fixed‐interval (FI) schedules of food reinforcement. When FI 60‐s (short) and FI 75‐s (long) schedules began simultaneously within constant 150‐s cycles, long FIs did not affect short‐FI performances, but short FIs eliminated the first 60 s of long‐FI performances. Removing either short‐FI reinforcers or short‐FI stimuli showed that short‐FI reinforcers and not short‐FI stimuli blocked the first 60 s of the long‐FI performance from the retroactive effects of the long‐FI reinforcer. With FI 15‐s and FI 75‐s schedules, the short‐FI reinforcer was followed by reduced long‐FI responding, but a schedule that prevented discrimination based on time since a reinforcer eliminated this proactive effect of the short‐FI reinforcer. In other words, the retroactive effects were reinforcer effects whereas the proactive effects were discriminative effects. Quantitative descriptions of variable‐interval performances, in which reinforcer effects may operate in the absence of temporal discriminative effects, can be derived from these relations.
EFFECTS OF MAGNITUDE OF FOOD REINFORCEMENT ON FREE‐OPERANT RESPONSE RATES
Authors: Reed Phil , Wright J. E.
Published: March 2006

In Experiment 1 rats were trained to press a lever on a variable‐ratio schedule of food presentation and were then exposed to progressively increasing magnitudes of food reinforcement. Response running rates (rates exclusive of the postreinforcement pause) were found to increase as a function of increasing reinforcement magnitudes. The effect of reinforcement magnitude on response rates inclusive of the postreinforcement pause, however, was less pronounced. Increases in the magnitude of reinforcement were also found to increase the length of the postreinforcement pause. Rats in Experiment 2 were trained to respond on a chained differential‐reinforcement‐of‐low‐rate variable‐ratio schedule, and were exposed to increasing magnitudes of reinforcement as in Experiment 1. Response running rates increased in the variable‐ratio component but decreased in the other component of the schedule. The results are discussed with reference to incentive accounts of reinforcement and the action of reinforcement on the response units generated by the operative contingencies.
SOME EFFECTS OF RESPONSE‐CORRELATED INCREASES IN REINFORCER MAGNITUDE ON HUMAN BEHAVIOR
Authors: Buskist William , Oliveira‐Castro Jorge , Bennett Robert
Published: March 2006

After training under short or long fixed‐interval schedules, humans responded under a modified fixed‐interval schedule in which magnitude of reinforcement (X or 2X) was minimally correlated with response frequency. Response frequencies that equaled or exceeded a minimum response criterion were followed by the larger reinforcer at the end of the interval; otherwise, the smaller reinforcer was delivered. The modified schedule alternated with the baseline schedule across conditions. In a control condition, the reinforcer magnitudes produced by control subjects were yoked to those of experimental subjects. Experimental subjects, but not control subjects, showed increased responding. In addition to the baseline and modified fixed‐interval schedules used in Experiment 1, subjects in Experiment 2 also responded under a second modified fixed‐interval contingency in which increases in reinforcer magnitude were more highly correlated with response frequency. Experimental subjects, but not control subjects, showed increased responding under both procedures. Direct comparison of these two procedures showed that the high‐correlation procedure produced greater increases in responding than did the low‐correlation procedure.