bluuebunny/crossref_metadata_2025 huggingface dataset:
SIMPLE AND CONDITIONAL VISUAL DISCRIMINATION WITH WHEEL RUNNING AS REINFORCEMENT IN RATS
Authors: Iversen Iver H.
Published: March 2006

Three experiments explored whether access to wheel running is sufficient as reinforcement to establish and maintain simple and conditional visual discriminations in nondeprived rats. In Experiment 1, 2 rats learned to press a lit key to produce access to running; responding was virtually absent when the key was dark, but latencies to respond were longer than for customary food and water reinforcers. Increases in the intertrial interval did not improve the discrimination performance. In Experiment 2, 3 rats acquired a go‐left/go‐right discrimination with a trial‐initiating response and reached an accuracy that exceeded 80%; when two keys showed a steady light, pressing the left key produced access to running whereas pressing the right key produced access to running when both keys showed blinking light. Latencies to respond to the lights shortened when the trial‐initiation response was introduced and became much shorter than in Experiment 1. In Experiment 3, 1 rat acquired a conditional discrimination task (matching to sample) with steady versus blinking lights at an accuracy exceeding 80%. A trial‐initiation response allowed self‐paced trials as in Experiment 2. When the rat was exposed to the task for 19 successive 24‐hr periods with access to food and water, the discrimination performance settled in a typical circadian pattern and peak accuracy exceeded 90%. When the trial‐initiation response was under extinction, without access to running, the circadian activity pattern determined the time of spontaneous recovery. The experiments demonstrate that wheel‐running reinforcement can be used to establish and maintain simple and conditional visual discriminations in nondeprived rats.
EFFECTS OF VARIABLE‐INTERVAL VALUE AND AMOUNT OF TRAINING ON STIMULUS GENERALIZATION
Authors: Walker Diana J. , Branch Marc N.
Published: March 2006

In Experiment 1 pigeons pecked a key that was illuminated with a 501‐nm light and obtained food by doing so according to a variable‐interval (VI) schedule of reinforcement, the mean value of which differed across groups: either 30 s, 120 s, or 240 s. The pigeons in all three groups were trained for 10 50‐min sessions. Generalization testing was conducted in extinction with different wavelengths of light. Absolute and relative generalization gradients were similar in shape for the three groups. Experiment 2 was a systematic replication of Experiment 1 using line orientation as the stimulus dimension and a mean VI value of either 30 s or 240 s. Again, gradients of generalization were similar for the two groups. In Experiment 3 pigeons pecked a key that was illuminated with a 501‐nm light and obtained food reinforcers according to either a VI 30‐s or a 240‐s schedule. Training continued until response rates stabilized (>30 sessions). For subjects trained with the 30‐s schedule, generalization gradients were virtually identical regardless of whether training was for 10 sessions (Experiment 1) or until response rates stabilized. For subjects trained with the VI 240‐s schedule, absolute generalization gradients for subjects trained to stability were displaced upward relative to gradients for subjects trained for only 10 sessions (Experiment 1), and relative generalization gradients were slightly flatter. These results indicate that the shape of a generalization gradient does not necessarily depend on the rate of reinforcement during 10‐session single‐stimulus training but that the effects of prolonged training on stimulus generalization may be schedule dependent.
RESPONSE PERSISTENCE UNDER RATIO AND INTERVAL REINFORCEMENT SCHEDULES
Authors: Lattal Kennon A. , Reilly Mark P. , Kohn James P.
Published: March 2006

In Experiment 1, rats were exposed to progressive‐ratio schedules of food reinforcement while other rats were exposed simultaneously to yoked‐interval schedules that arranged equivalent interreinforcer intervals but required only a single response at the end of the interval for food delivery. In Experiment 2, a within‐subject yoked‐control procedure was employed in which pigeons were exposed to alternating sessions (one per day) of progressive‐ratio schedules and yoked‐interval schedules as described above. In both experiments, responding under the yoked‐interval schedule persisted beyond the point at which responding under the progressive‐ratio schedule had ceased. The progressive‐ratio schedules controlled break‐and‐run distributions, and the yoked‐interval schedules controlled more even distributions of responses in time. Response rates decreased and postreinforcement pauses increased over time within individual sessions under both schedules. The results suggest that responding maintained by interval schedules is more persistent than that maintained by ratio schedules. The limitations and implications of this conclusion are discussed in the context of other investigations of response strength and behavioral momentum.
RATIO SIZE AND COCAINE CONCENTRATION EFFECTS ON ORAL COCAINE‐REINFORCED BEHAVIOR
Authors: Macenski Mitchell J. , Meisch Richard A.
Published: March 2006

Monkeys were given a choice between cocaine solutions and water under concurrent fixed‐ratio reinforcement schedules. The operant response was spout contact. Six rhesus monkeys served as subjects. The cocaine concentration was varied from 0.0125 to 0.8 mg/ml, and the fixed‐ratio value was varied from 8 to 128. Cocaine maintained higher response rates than did water over a wide range of conditions. Response rate and number of cocaine deliveries per session were inverted U‐shaped functions of concentration. These functions were shifted to the right as the fixed ratio was increased. The number of cocaine deliveries was more persistent as fixed‐ratio value was increased when the unit dose was larger rather than smaller. Cocaine consumption was analyzed as a function of unit price (fixed‐ratio value divided by cocaine concentration), and unit price accounted for between 77% and 92% of the variance in cocaine consumption for individual monkeys. The current data support the claim that a drug's reinforcing effects increase directly with dose and underscore the need to gather parametric data when examining the effects of experimental manipulations on a drug‐reinforced baseline.
GREATNESS AND MISERY IN THE TEACHING OF THE PSYCHOLOGY OF LEARNING
Authors: Machado Armando , Silva Francisco J.
Published: March 2006

Overshadowed by more popular disciplines, the study of learning seems to have lost its prominent place in the undergraduate psychology curriculum. In the first part of this essay, we argue that one reason for this state of affairs is the current content of psychology of learning courses, namely, its disproportionate emphasis on facts, procedures, and everyday examples at the expense of functional and conceptual investigations. In the second part of the essay, we outline an alternative approach to the teaching of learning, one that emphasizes basic contents such as the conceptualization of learning as a biological adaptation or the study of temporal regulation, critical methodological issues such as the logic of experimental designs or the difficulties of measuring behavior, and broad epistemological problems such as the role of hypothetical constructs, the advantages of quantitative reasoning, or the origins of knowledge and its integration. By using learning as a means towards more fundamental ends, the splendor of the discipline and its prominent place in the undergraduate curriculum may be restored.
CHOICE WITH DELAYED AND PROBABILISTIC REINFORCERS: EFFECTS OF PREREINFORCER AND POSTREINFORCER STIMULI
Authors: Mazur James E.
Published: March 2006

In Experiment 1, pigeons' pecks on a green key led to a 5‐s delay with green houselights, and then food was delivered on 20% (or, in other conditions, 50%) of the trials. Pecks on a red key led to an adjusting delay with red houselights, and then food was delivered on every trial. The adjusting delay was used to estimate indifference points: delays at which the two alternatives were chosen about equally often. Varying the presence or absence of green houselights during the delays that preceded possible food deliveries had large effects on choice. In contrast, varying the presence of the green or red houselights in the intertrial intervals had no effects on choice. In Experiment 2, pecks on the green key led to delays of either 5 s or 30 s with green houselights, and then food was delivered on 20% of the trials. Varying the duration of the green houselights on nonreinforced trials had no effect on choice. The results suggest that the green houselights served as a conditioned reinforcer at some times but not at others, depending on whether or not there was a possibility that a primary reinforcer might be delivered. Given this interpretation of what constitutes a conditioned reinforcer, most of the results were consistent with the view that the strength of a conditioned reinforcer is inversely related to its duration.
GENERALIZATION OF CROSS‐MODAL STIMULUS EQUIVALENCE CLASSES: OPERANT PROCESSES AS COMPONENTS IN HUMAN CATEGORY FORMATION
Authors: Lane Scott D. , Clow Julie K. , Innis Andrew , Critchfield Thomas S.
Published: March 2006

This study employed a stimulus‐class rating procedure to explore whether stimulus equivalence and stimulus generalization can combine to promote the formation of open‐ended categories incorporating cross‐modal stimuli. A pretest of simple auditory discrimination indicated that subjects (college students) could discriminate among a range of tones used in the main study. Before beginning the main study, 10 subjects learned to use a rating procedure for categorizing sets of stimuli as class consistent or class inconsistent. After completing conditional discrimination training with new stimuli (shapes and tones), the subjects demonstrated the formation of cross‐modal equivalence classes. Subsequently, the class‐inclusion rating procedure was reinstituted, this time with cross‐modal sets of stimuli drawn from the equivalence classes. On some occasions, the tones of the equivalence classes were replaced by novel tones. The probability that these novel sets would be rated as class consistent was generally a function of the auditory distance between the novel tone and the tone that was explicitly included in the equivalence class. These data extend prior work on generalization of equivalence classes, and support the role of operant processes in human category formation.
DO PARAKEETS EXHIBIT DERIVED STIMULUS CONTROL? SOME THOUGHTS ON EXPERIMENTAL CONTROL PROCEDURES
Authors: Saunders Kathryn J. , Williams Dean C.
Published: March 2006

Breaking new ground in the study of emergent stimulus control in nonverbal subjects may require innovation in procedures. A recent study of parakeets is exemplary. This study used intricate procedures for maintaining test‐trial performance without differential reinforcement of the target emergent performance. Also, it used successive simple discrimination procedures, which are rare in such studies. Given the importance of these innovations and the outcomes that they produced, we suggest additional control procedures that would rule out the possibility of adventitious reinforcement of the test‐trial performances.
TEMPORAL CONTROL IN RATS: ANALYSIS OF NONLOCALIZED EFFECTS FROM SHORT INTERFOOD INTERVALS
Authors: Higa Jennifer J. , Pierson Douglas
Published: March 2006

The present experiment analyzed temporal control of postreinforcement pause duration during within‐session changes in the criterion for reinforcement (interfood interval, IFI). Analysis of interval‐by‐interval changes in the pause revealed localized and nonlocalized effects from short intervals that caused specific changes in performance. In Phase 1, rats were presented with five consecutive 15‐s IFIs intercalated into a series of 60‐s IFIs. The 15‐s set decreased the pause in adjacent and more remote 60‐s intervals. In Phase 2, two sets of 15‐s intervals were intercalated. The spacing between the two sets varied so that 0, 5, 10, or 15 60‐s IFIs separated the sets. The postreinforcement pause tracked all changes in the IFI duration, and the localized effect from a short set extended beyond the next interval to the next few 60‐s IFIs. Effects from one set, however, did not combine with a second set: Changes in the pause after two sets were the same regardless of the spacing between sets.
EFFECTS OF FIXED‐INTERVAL SCHEDULE AND REINFORCER DURATION ON RESPONDING REINFORCED BY THE OPPORTUNITY TO RUN
Authors: Belke T. W. , Dunbar M.
Published: March 2006

Two experiments investigated the effects of schedule value and reinforcer duration on responding for the opportunity to run on fixed‐interval (FI) schedules in rats. In the first experiment, 8 male Wistar rats were exposed to FI 15‐s, 30‐s, and 60‐s schedules of wheel‐running reinforcement. The operant was lever pressing, and the consequence was the opportunity to run for 60 s. In the second experiment, 8 male Long‐Evans rats were exposed to reinforcer durations of 15 s, 30 s, and 90 s. The schedule of reinforcement was an FI 60‐s schedule. Results showed that postreinforcement pause and wheel‐running rates varied systematically with reinforcer duration but not schedule value. Local lever‐pressing rates decreased with reinforcer duration. Overall lever‐pressing rates decreased with reinforcer duration but increased with schedule value. Although the reinforcer‐duration effect is consistent with previous research, the lack a schedule effect appears to be the result of long post‐reinforcement pauses following wheel‐running reinforcement that render the manipulation of the interval requirement ineffective.
AVOIDANCE OF 20% CARBON DIOXIDE—ENRICHED AIR WITH HUMANS
Authors: Lejuez C. W. , O'Donnell Jennifer , Wirth Oliver , Zvolensky Michael J. , Eifert Georg H.
Published: March 2006

Four college students were exposed to a Sidman avoidance procedure to determine if an avoidance contingency involving 20% carbon dioxide—enriched air (CO2) would produce and maintain responding. In Phase 1, two conditions (contingent and noncontingent) were conducted each day. These conditions were distinguished by the presence or absence of a blue or green box on a computer screen. In the contingent condition, CO2 presentations were delivered every 3 s unless a subject pulled a plunger. Each plunger pull postponed CO2 presentations for 10 s. In the noncontingent condition, CO2 presentations occurred on the average of every 5 min independent of responding. Following stable responding in Phase 1, condition‐correlated stimuli were reversed. In both conditions, plunger response rate was high during the contingent condition and low or zero during the noncontingent condition. Furthermore, subjects avoided most CO2 presentations. However, CO2 presentations did not increase verbal reports of fear. Overall, the results from the present study suggest that CO2 can be used effectively in basic studies of aversive control and in laboratory analogues of response patterns commonly referred to as anxiety.
EXTINCTION OF RESPONDING MAINTAINED BY TIMEOUT FROM AVOIDANCE
Authors: Galizio Mark
Published: March 2006

The resistance to extinction of lever pressing maintained by timeout from avoidance was examined. Rats were trained under a concurrent schedule in which responses on one lever postponed shock on a free‐operant avoidance (Sidman) schedule (response—shock interval = 30 s) and responses on another lever produced 2 min of signaled timeout from avoidance on a variable‐ratio 15 schedule. Following extended training (106 to 363 2‐hr sessions), two experiments were conducted. In Experiment 1 two different methods of extinction were compared. In one session, all shocks were omitted, and there was some weakening of avoidance but little change in timeout responding. In another session, responding on the timeout lever was ineffective, and under these conditions timeout responding showed rapid extinction. The within‐session patterns produced by extinction manipulations were different than the effects of drugs such as morphine, which also reduces timeout responding. In Experiment 2 shock was omitted for many consecutive sessions. Response rates on the avoidance lever declined relatively rapidly, with noticeable reductions within 5 to 10 sessions. Extinction of the timeout lever response was much slower than extinction of avoidance in all 4 rats, and 2 rats continued responding at baseline levels for more than 20 extinction sessions. These results show that lever pressing maintained by negative reinforcement can be highly resistant to extinction. The persistence of responding on the timeout lever after avoidance extinction is not readily explained by current theories.
BLOCKING A SELECTIVE ASSOCIATION IN PIGEONS
Authors: Weiss Stanley J. , Panlilio Leigh V.
Published: March 2006

Experiment 1 demonstrated for the first time a stimulus—reinforcer interaction in pigeons trained with free‐operant multiple schedules of reinforcement. Pigeons that treadle pressed in the presence of a tone‐light (TL) compound for food exhibited primarily visual stimulus control on a stimulus‐element test, whereas pigeons that avoided shock in TL exhibited auditory control. In Experiment 2, this selective association was blocked in pigeons pretrained with the biologically contingency‐disadvantaged element of the compound (i.e., tone‐food or light‐shock) before TL training. When this pretraining preceded compound‐stimulus training, control was now auditory in pigeons that treadle pressed for food and was visual in pigeons that avoided shock. Previous attempts at blocking this selective association were unsuccessful in pigeons (LoLordo, Jacobs, & Foree, 1982) but were successful in rats (Schindler & Weiss, 1985). Experiment 2 established that selective associations can be blocked in pigeons when the procedures that were effective with rats were systematically replicated. These results further demonstrate the cross‐species generality of an associative attentional mechanism involving a biological constraint on learning in species with different dominant sensory systems.
BASE RATES VERSUS SAMPLE ACCURACY: COMPETITION FOR CONTROL IN HUMAN MATCHING TO SAMPLE
Authors: Goodie Adam S. , Fantino Edmund
Published: March 2006

People often place undue weight on specific sources of information (case cues) and insufficient weight on more global sources (base rates) even when the latter are highly predictive, a phenomenon termed base‐rate neglect. This phenomenon was first demonstrated with paper‐and‐pencil tasks, and also occurs in a matching‐to‐sample procedure in which subjects directly experience case sample (cue) accuracy and base rates, and in which discrete, nonverbal choices are made. In two nonverbal experiments, subjects were exposed to hundreds of trials in which they chose between two response options that were both probabilistically reinforced. In Experiment 1, following one of two possible samples (the unpredictive sample), either response was reinforced with a .5 probability. The other sample (predictive) provided reinforcement for matching on 80% of the trials in one condition but in only 20% of the trials in another condition. Subjects' choices following the unpredictive sample were determined primarily by the contingencies in effect for the predictive sample: If matching was reinforced following the predictive sample, subjects tended to match the unpredictive sample as well; if countermatching the predictive sample was generally reinforced, subjects tended to countermatch the unpredictive sample. These results demonstrate only weak control by base rates. In Experiment 2, base rates and sample accuracy were simultaneously varied in opposite directions to keep one set of conditional probabilities constant. Subjects' choices were determined primarily by the overall accuracy of the sample, again demonstrating only weak control by base rates. The same pattern of choice occurred whether this pattern increased or decreased rate of reinforcement. Together, the results of the two experiments provide a clear empirical demonstration of base‐rate neglect.
THE ROLE OF THE RESPONSE—REINFORCER RELATION IN DELAY‐OF‐REINFORCEMENT EFFECTS
Authors: Williams April Michele , Lattal Kennon A.
Published: March 2006

The role of the response—reinforcer relation in maintaining operant behavior under conditions of delayed reinforcement was investigated by using a two‐operandum (i.e., two‐key) procedure with pigeons. Responding on one key was reinforced under a tandem variable‐interval differential‐reinforcement‐of‐other‐behavior (tandem VI DRO) schedule. The schedule defined a resetting unsignaled delay‐of‐reinforcement procedure in that a response was required when the interfood interval of the VI schedule lapsed, but further responding during the DRO component on either key reset the time interval. This ensured a fixed delay duration between any response and reinforcement. Responding on another key, physically identical to the first one except for spatial location, otherwise was without consequence. The location of the key correlated with the delay‐of‐reinforcement procedure varied between sessions according to a semirandom sequence. Differences in response rates between the two keys were greater, with proportionally higher rates on the key correlated with the delay‐of‐reinforcement procedure, the longer the delay‐of‐reinforcement procedure remained correlated with the same key. Differences in responding on the two keys also increased within individual sessions. These results suggest that the response—reinforcer relation is the primary determinant of responding when responding is acquired and maintained with delayed reinforcement.
TIMING WITHOUT A TIMER
Authors: Donahoe John W. , Burgos José E.
Published: March 2006

Inferred‐process theories propose various internal timing mechanisms to provide discriminative stimuli for temporal control of behavior. Biobehaviorally informed computer simulations indicate that timing may emerge from the action of reinforcement on neural circuits without the need to postulate timers of any sort.
THE MATCHING LAW AND AMOUNT‐DEPENDENT EXPONENTIAL DISCOUNTING AS ACCOUNTS OF SELF‐CONTROL CHOICE
Authors: Grace Randolph C.
Published: March 2006

Studies with humans have found evidence for amount‐dependent temporal discounting, that is, that the sensitivity of choice to reinforcer delay varies inversely with reinforcer magnitude. To test whether similar results could be obtained with nonhumans, pigeons were trained on a two‐component concurrent‐chains procedure in which the durations of food reinforcement in the terminal links were equal within components but unequal between components. Terminal‐link schedules were varied over four conditions to allow separate estimates of sensitivity to delay to be obtained for the large and small reinforcer‐magnitude components. Although sensitivity to delay was greater in the small‐magnitude component for all subjects, the effect was quite small. The difference in sensitivity was generally less than one standard error, and t tests on parameter differences failed to reach significance. Several models for temporal discounting, including an amount‐dependent exponential function, were fitted to the data from the first four conditions. The resulting parameter estimates were used to make predictions for a self‐control condition in which one terminal link arranged a smaller, less delayed reinforcer and the other arranged a larger, more delayed reinforcer. For all models, predictions were considerably more accurate when sensitivity to delay was the same regardless of reinforcer magnitude. The results support the independence of delay and magnitude as required by a version of the matching law, and provide strong evidence against amount‐dependent exponential discounting as an account of self‐control choice. A new two‐parameter discounting function, consistent with the matching law, is proposed that has wide empirical generality for both human and nonhuman data.
TIME WITHOUT CLOCKS
Authors: Zeiler Michael D.
Published: March 2006

Staddon and Higa show that the ability to time events derives from principles of memory rather than from an internal device for measuring the duration of events. This insightful timing theory is parsimonious, fits the data, has potential widespread generality, and is evolutionarily plausible.
HUMAN SENSITIVITY TO CONCURRENT SCHEDULES OF REINFORCEMENT: EFFECTS OF OBSERVING SCHEDULE‐CORRELATED STIMULI
Authors: Madden Gregory J. , Perone Michael
Published: March 2006

The determinants of human sensitivity to concurrent variable‐interval variable‐interval schedules of reinforcement have been difficult to identify, in part because of procedural differences separating published experiments. This experiment investigated vigilance to stimuli correlated with concurrent schedules. Across phases, 3 college students were provided with either no schedule‐correlated stimuli, an observing response that provided brief access to the stimuli, or a contingency that required the subject to identify the stimulus correlated with the source of each obtained reinforcer. Sensitivity, as quantified by the generalized matching equation, was low when no stimuli were available. When the stimuli were response contingent, 1 subject observed them, and her behavior became more sensitive to the distribution of reinforcers across the concurrent schedules. When the procedure required discrimination of the stimulus correlated with each reinforcer, the other 2 subjects also observed the stimuli, and their schedule sensitivity was increased as well. These results implicate procedural differences, rather than inherent behavioral differences, as the source of differences in sensitivity to schedules of reinforcement between humans and nonhumans.
CHOICE, CONTINGENCY DISCRIMINATION, AND FORAGING THEORY
Authors: Baum William M. , Schwendiman Jed W. , Bell Kenneth E.
Published: March 2006

Four pigeons were trained on eight or nine pairs of independent concurrent variable‐interval schedules. The range of reinforcement ratios included extreme ratios (up to 532 to 1). Large samples of stable performance were gathered. Contrary to the findings of Davison and Jones (1995), the generalized matching law described choice more accurately than a contingency‐discriminability model. Taking small samples (5 to 10 sessions) and applying a more liberal stability criterion used by Davison and Jones only increased the unsystematic variance in the data and in estimates of generalized‐matching‐law sensitivity. Because changing to dependent scheduling and inserting a changeover delay had no systematic effect, the deviations from generalized matching reported by Davison and Jones probably arose from imperfectly discriminated stimuli. Analysis of visits revealed that visits to the nonpreferred alternative were brief and approximately constant. When choice between the preferred (rich) and nonpreferred (lean) alternatives, regardless of position, was analyzed according to the generalized matching law, sensitivities approximated 1.0, with bias in favor of the lean alternative. This bias, which arose from an excessive frequency of visits to the lean alternative, explains undermatching as the result of fitting one line to a choice relation that consists of two displaced lines, both with a slope of 1.0. The pattern of deviation from the generalized matching line confirmed this account. The findings suggest an alternative analysis of choice that focuses on probability of visiting the lean alternative as the dependent variable. This probability was directly proportional to ratio of reinforcement. Matching, undermatching, and overmatching may all be explained by a view of concurrent performance based on foraging theory, in which responding occurs primarily at the rich alternative and is occasionally interrupted by brief visits to the lean alternative.
SOME EFFECTS OF INTERTRIAL‐INTERVAL DURATION ON DISCRETE‐TRIAL CHOICE
Authors: Jones J. R. , Moore J.
Published: March 2006

Pigeons were trained in Experiment 1 on a discrete‐trial concurrent variable‐interval (VI) 1‐min VI 3‐min schedule, and in Experiment 2 on a discrete‐trial concurrent VI 1.5‐min VI 1.5‐min schedule. In each experiment, the intertrial‐interval durations (ITIs) were 0 s, 6 s, 22 s, and 120 s, and the schedules were both independent and interdependent. The purpose of the research was to determine whether lengthening the ITI would disrupt any local control that existed, measured with respect to relative response rate and changeover probability. In Experiment 1, with the independent schedules, both preference and obtained relative reinforcement rate approximated .75 at short ITIs, but then decreased toward .50 with longer ITIs. With interdependent schedules, both preference and obtained relative reinforcement rate approximated .75 at all ITIs. In both experiments, with both independent and interdependent schedules, changeover probabilities for each response in a sequence of up to five successive responses to a given schedule were variable for individual birds. The average changeover probabilities for all birds suggested perseveration rather than a systematic increase within a given ITI or a systematic trend toward chance responding as ITI duration increased. Finally, the changeover functions did not differ when a sequence of responses was calculated to begin anew after reinforcement rather than with the first response on a schedule. Taken together, the data were inconsistent with a theory holding that only local processes underlie choice in discrete‐trial procedures.
EQUIVALENCE RELATIONS BETWEEN VISUAL STIMULI: THE FUNCTIONAL ROLE OF NAMING
Authors: Randell Tom , Remington Bob
Published: March 2006

The functionality of verbal behavior in equivalence class formation was demonstrated by training 30 verbally able adults using different combinations of the same easily nameable, yet formally unrelated, pictorial stimuli. Match‐to‐sample baselines for four four‐member classes were established sequentially (i.e., AB‐BC‐CD), with participants in the rhyme condition trained to select comparisons whose normative names rhymed with those of the samples. For the orthogonal condition, class rearrangement was such that on every trial all available comparisons' names rhymed with each other, but not with the name of the sample. In the diagonal condition, stimuli were allocated pseudorandomly as samples and comparisons. Although all participants maintained baseline discriminations prior to emergent testing, equivalence was confined almost exclusively to the rhyme condition, in which it was ubiquitous. These participants also required less training than those in the control conditions, among whom effects of nodal distance were observed most strongly. Subsequent testing presented participants with no‐reinforcement trials involving novel pictorial stimuli, in which one of the available comparisons' names always rhymed with that of the sample. All rhyme participants consistently selected these comparisons. Results indicate that visual stimuli are named, that the phonological properties of those names can influence equivalence class formation, and that the emergence of untrained discriminations may, under certain circumstances, be rule governed.
COMPARING SINGLE AND CUMULATIVE DOSING PROCEDURES IN HUMAN TRIAZOLAM DISCRIMINATORS
Authors: Smith Brandi J. , Bickel Warren K.
Published: March 2006

This study evaluated a cumulative dosing procedure for drug discrimination with human participants. Four participants learned to discriminate triazolam (0.35 mg/70 kg) from placebo. A crossover design was used to compare the results under a single dosing procedure with results obtained under a cumulative dosing procedure. Under the single dosing procedure, a dose of triazolam (0, 0.05, 0.15, or 0.35 mg/70 kg) or secobarbital (0, 25, 75, or 175 mg/70 kg) was administered 45 min before assessment. Determining each dose—effect curve thus required four sessions. Under the cumulative dosing procedure, four doses of triazolam (0, 0.05, 0.10, and 0.20 mg/70 kg) or secobarbital (0, 25, 50, and 100 mg/70 kg) were administered approximately 55 min apart, producing a complete dose—effect curve in one four‐trial session. Regardless of procedure, triazolam and secobarbital produced discriminative stimulus and self‐reported effects similar to previous single dosing studies in humans. Shifts to the right in cumulative dose—effect curves compared to single dose—effect curves occurred on several self‐report measures. When qualitative stimulus functions rather than quantitative functions are of interest, application of cumulative dosing may increase efficiency in human drug discrimination.
STIMULI, REINFORCERS, AND BEHAVIOR: AN INTEGRATION
Authors: Davison Michael , Nevin John A.
Published: March 2006

We propose that a fundamental unit of behavior is the concurrent discriminated operant, and we discuss in detail a quantitative model of the concurrent three‐term contingency that is based on the notion that an animal's behavior is controlled to differing extents by both stimulus—behavior and behavior—reinforcer relations. We show how this model can describe performance in a variety of experimental procedures: conditional discrimination and matching to sample, both with and without reinforcement for responses that are traditionally identified as errors; conditional discrimination with more than two stimuli and choice alternatives; delayed matching to sample and delayed reinforcement in matching to sample; second‐order and complex conditional discrimination; and multiple and concurrent schedules. Although the model is incomplete in its coverage, and may be incorrect, we believe that this conceptual approach will bear fruit in the development of behavior theory.
OPTIMALITY AND CONCURRENT VARIABLE‐INTERVAL VARIABLE‐RATIO SCHEDULES
Authors: Baum William M. , Aparicio Carlos F.
Published: March 2006

Despite claims to the contrary, all leading theories about operant choice may be seen as models of optimality. Although melioration is often contrasted with global maximization, both make the same core assumptions as other versions of optimality theory, including momentary maximizing, hill climbing, and the various versions of optimal foraging theory. The present experiment aimed to test melioration against more global optimality and to apply the visit‐by‐visit analysis suggested by foraging theory. Rats were exposed to concurrent schedules in which one alternative was always variable‐ratio 10 and the other alternative was a variable‐interval schedule. Although choice relations varied from rat to rat, the overall results roughly confirmed the matching law, a result often taken to support melioration. Pooling the data across sessions and across rats, however, resulted in no increment in unsystematic variance, lending support to the contention by Ziriax and Silberberg (1984) that the choice relation is partly constrained. When the data were analyzed at the level of visits, the results either disconfirmed predictions of melioration or showed regularities about which melioration is silent. Instead, performance tended toward a rough optimization, in which responding favored the variable ratio, but with relatively brief visits to the variable interval. There were no asymmetries in travel or variability that would indicate that different processes were involved in generating visits at the two different schedules. The findings point toward a more global optimality model than melioration and demonstrate the value of per‐visit analysis in the study of concurrent performances.
PSYCHOPHYSICS OF REMEMBERING
Authors: White K. Geoffrey , Wixted John T.
Published: March 2006

We present a new model of remembering in the context of conditional discrimination. For procedures such as delayed matching to sample, the effect of the sample stimuli at the time of remembering is represented by a pair of Thurstonian (normal) distributions of effective stimulus values. The critical assumption of the model is that, based on prior experience, each effective stimulus value is associated with a ratio of reinforcers obtained for previous correct choices of the comparison stimuli. That ratio determines the choice that is made on the basis of the matching law. The standard deviations of the distributions are assumed to increase with increasing retention‐interval duration, and the distance between their means is assumed to be a function of other factors that influence overall difficulty of the discrimination. It is a behavioral model in that choice is determined by its reinforcement history. The model predicts that the biasing effects of the reinforcer differential increase with decreasing discriminability and with increasing retention‐interval duration. Data from several conditions using a delayed matching‐to‐sample procedure with pigeons support the predictions.
HOW PIGEONS DISCRIMINATE THE RELATIVE FREQUENCY OF EVENTS
Authors: Keen Richard , Machado Armando
Published: March 2006

This study examined how pigeons discriminate the relative frequencies of events when the events occur serially. In a discrete‐trials procedure, 6 pigeons were shown one light nf times and then another nl times. Next, they received food for choosing the light that had occurred the least number of times during the sample. At issue were (a) how the discrimination was related to two variables, the difference between the frequencies of the two lights, D = nf — nl, and the total number of lights in the sample, T = nf + nl; and (b) whether a simple mathematical model of the discrimination process could account for the data. In contrast with models that assume that pigeons count the stimulus lights, engage in mental arithmetic on numerons, or remember the number of stimuli, the present model assumed only that the influence of a sample stimulus on choice increases linearly when the stimulus is presented, but decays exponentially when the stimulus is absent. The results showed that, overall, the pigeons discriminated the relative frequencies well. Their accuracy always increased with the absolute value of the difference D and, for D > 0, it decreased with T. Performance also showed clear recency, primacy, and contextual effects. The model accounted well for the major trends in the data.
VALUE TRANSMISSION IN DISCRIMINATION LEARNING INVOLVING STIMULUS CHAINS
Authors: Williams Ben A.
Published: March 2006

Rats learned a series of reversals of a positional discrimination in which responses to one lever led to delayed food and responses to a second lever led to no food. Interpolated within the delays leading to the different outcomes were two‐link stimulus chains. The pairing of each stimulus element with the delayed outcome of food or no food varied across reversals. Either stimulus element could have the same correlation with outcome as occurred on the preceding reversal or the opposite correlation as on the preceding reversal. New reversals were acquired more quickly when both stimulus elements had the same status as during the preceding reversal, and were acquired most slowly when both stimulus elements had the opposite status as that of the preceding reversal. The rate of learning was intermediate when only one of the stimulus elements had the same status as that during the preceding reversal. All of the data are compatible with an interpretation in terms of backward chaining of stimulus value.
INSTRUCTIONS AS DISCRIMINATIVE STIMULI
Authors: Okouchi Hiroto
Published: March 2006

Four undergraduates were exposed to a fixed‐ratio schedule under an instruction to respond slowly and to a differential‐reinforcement‐of‐low‐rate 5‐s schedule under an instruction to respond rapidly. Following this, a fixed‐interval schedule was in effect under those same two sets of instructions. For 3 of 4 subjects, response rates were higher with the instruction to respond slowly than with the instruction to respond rapidly during the fixed‐interval schedule. For the remaining subject, low‐rate responding with the instruction to respond rapidly continued during the first 17 reinforcements of the fixed‐interval schedule. Such control by instructions was not observed for other subjects exposed only to a fixed‐interval schedule, with or without instructions. The results demonstrate that the effect of instructions can be altered by contingencies and suggest that instructions can function as discriminative stimuli.
PREFERENCES FOR AND AGAINST STIMULI PAIRED WITH FOOD
Authors: Mazur James E.
Published: March 2006

Pigeons were presented with a concurrent‐chains schedule in which terminal‐link entries were assigned to two response keys on a percentage basis. The terminal links were fixed delays that sometimes ended with food and sometimes did not. In most conditions, 80% of the terminal links were assigned to one key, but a smaller percentage of the terminal links ended with food for this key, so the number of food reinforcers delivered by the two alternatives was equal. When the same terminal‐link stimuli (orange houselights) were used for both alternatives, the pigeons showed a preference for whichever alternative delivered more frequent terminal links. When different terminal‐link stimuli (green vs. red houselights) were used for the two alternatives, the pigeons showed a preference for whichever alternative delivered fewer terminal links when terminal‐link durations were long, and no systematic preferences when terminal‐link durations were short. This pattern of results was consistent with the predictions of Grace's (1994) contextual choice model. Preference for the alternative that delivered more frequent terminal links was usually stronger in the first few sessions of a condition than at the end of a condition, suggesting that the conditioned reinforcing effect of the additional terminal‐link presentations was, in part, transitory.
THE TRANSITIVITY OF CHOICES BETWEEN DIFFERENT RESPONSE REQUIREMENTS
Authors: Sumpter Catherine E. , Temple William , Foster T. Mary
Published: March 2006

This experiment tested the transitivity of hens' choices between response requirements differing in both form and number. In a concurrent second‐order schedule procedure, 6 hens chose between two alternatives by making either key‐peck or door‐push responses. The reinforcement rates on the two alternatives remained constant and equal throughout conditions, but the number of responses (i.e., key pecks or door pushes) required on each alternative was varied by changing the second‐order (fixed‐ratio) requirements. The preferences obtained from two pairings of response requirements allowed prediction of the preferences expected in a third pairing. No intransitivities were found, implying that the response requirements lie on a common unitary scale of value. For response‐based measures, the obtained preferences varied evenly around perfect, multiplicative prediction, and all satisfied strong transitivity, implying an underlying interval scale of value. For time‐based measures, only moderate transitivity was satisfied, implying only an ordinal scale of value. Time‐based measures were confounded with the differing times taken to complete each response requirement. The existence of such scales indicates that direct comparisons of different response requirements may be possible.
PHILOSOPHICAL BEHAVIORISM: A REVIEW OF THINGS THAT HAPPEN BECAUSE THEY SHOULD: A TELEOLOGICAL APPROACH TO ACTION, BY ROWLAND STOUT
Authors: Rachlin Howard
Published: March 2006

Mentalistic terms such as belief and desire have been rejected by behavior analysts because they are traditionally held to refer to unobservable events inside the organism. Behavior analysis has consequently been viewed by philosophers to be at best irrelevant to psychology, understood as a science of the mind. In this book, the philosopher Rowland Stout argues cogently that beliefs and desires (like operants such as rats' lever presses) are best understood in terms of an interaction over time between overt behavior and its overt consequences (a viewpoint called teleological behaviorism). This book is important because it identifies the science of the mind with the science of overt behavior and implies that the psychologists best equipped to study mental life are not those who purport to do so but those who focus on the experimental analysis of behavior.
SAMPLE‐DURATION EFFECTS ON PIGEONS' DELAYED MATCHING AS A FUNCTION OF PREDICTABILITY OF DURATION
Authors: Urcuioli Peter J. , DeMarse Thomas B. , Lionello Karen M.
Published: March 2006

Three experiments assessed the impact of sample duration on pigeons' delayed matching as a function of whether or not the samples themselves signaled how long they would remain on. When duration was uncorrelated with the sample appearing on each matching trial, the typical effect of duration was observed: Choice accuracy was higher with long (15‐s) than with short (5‐s) durations. By contrast, this difference either disappeared or reversed when the 5‐ and 15‐s durations were correlated with the sample stimuli. Sample duration itself cued comparison choice by some birds in the latter (predictable) condition when duration was also correlated with the reinforced choice alternatives. However, even when duration could not provide a cue for choice, pigeons matched predictably short‐duration samples as accurately as, or more accurately than, predictably long‐duration samples. Moreover, this result was observed independently of whether the contextual conditions of the retention interval were the same as, or different from, those of the intertrial interval. These results strongly support the view that conditional stimulus control by the samples is partly a function of their conditioned reinforcing properties, as determined by the relative reduction in overall delay to reinforcement that they signal.
INTERRESPONSE‐TIME SENSITIVITY DURING DISCRETE‐TRIAL AND FREE‐OPERANT CONCURRENT VARIABLE‐INTERVAL SCHEDULES
Authors: Cleaveland J. M.
Published: March 2006

Two experiments investigated the sensitivity of pigeons' choice to elapsed time since the last response (i.e., to interresponse time [IRT]) during concurrent variable‐interval variable‐interval schedules. Experiment 1 used a two‐key discrete‐trial procedure with variable intertrial intervals. Experiment 2 employed a three‐key free‐operant procedure. In both experiments choice was found to be a function of the active‐schedule IRT, defined as the time since the most recent response. Monte Carlo simulations show how this finding permits the joining of several seemingly incompatible data sets held to both support and contradict a kind of choice strategy, termed momentary maximizing, which attempts to maximize momentary reinforcement probabilities. The studies suggest that only two variables are needed to describe the static molecular structure of concurrent variable‐interval choice: active‐schedule IRTs and “response states” consisting of the last one or two schedule choices.