bluuebunny/crossref_metadata_2025 huggingface dataset:
SIGNAL FUNCTIONS IN DELAYED REINFORCEMENT
Authors: Lattal Kennon A.
Published: March 2006

Three experiments were conducted with pigeons to examine the role of the signal in delay‐of‐reinforcement procedures. In the first, a blackout accompanying a period of nonrein‐forcement increased key‐peck response rates maintained by immediate reinforcement. The effects of dissociating the blackout from the delay interval were examined in the second experiment. In three conditions, blackouts and unsignaled delays were negatively correlated or occurred randomly with respect to one another. A signaled delay and an unsignaled delay that omitted the blackouts were studied in two other conditions. All delay‐of‐reinforcement conditions generally produced response rates lower than those produced by immediate reinforcement. Signaled delays maintained higher response rates than did any of the various unsignaled‐delay conditions, with or without dissociated blackouts. The effects of these latter conditions did not differ systematically from one another. The final experiment showed that response rates varied as a function of the frequency with which a blackout accompanied delay intervals. By eliminating a number of methodological difficulties present in previous delay‐of‐reinforcement experiments, these results suggest the importance of the signal in maintaining responding during delay‐of‐reinforcement procedures and, conversely, the importance of the delay interval in decreasing responding.
EXPERIMENTAL ANALYSIS OF INDIVIDUAL DIFFERENCES AND PERSONALITY
Authors: Harzem Peter
Published: March 2006

In psychological studies individual differences that result in variability in data and thus mask the effects under investigation have been reduced or eliminated in two ways: (1) through the use of large numbers of subjects and statistical manipulations, or (2) through extensive and controlled studies of individual subjects. The latter, behavior‐analytic, method is scientifically better because it permits identification of the variables that result in individual differences. This paper advocates the direct study of individual differences and personality rather than indirect study through experimental control procedures. Some data are presented showing that individual differences in response patterns have orderly characteristics. Extension of the experimental analysis of behavior to the study of individual differences and personality is likely to be important both scientifically and for the future growth of behavior analysis.
STIMULUS CONTROL AND ASSOCIATIVE LEARNING
Authors: Williams Ben A.
Published: March 2006

Interest in operant research on stimulus control has declined at the same time that much interest has burgeoned in nonoperant areas. Several examples of this shift toward traditional learning theory are considered, all of which have sponsored theoretical approaches that attempt to characterize the underlying associative units. These theoretical approaches are defended on the grounds that they have generated a deeper understanding of a variety of often puzzling phenomena. My projection is that future research will be determined even more strongly by theories about the structure of associations. Particular issues for which such discussion will have major impact include (1) whether conditional stimulus control is qualitatively different than simpler forms of stimulus control, (2) whether stimulus control is organized hierarchically, and (3) the origin of categories of stimulus equivalence.
AVERSIVE CONTROL: A SEPARATE DOMAIN?
Authors: Hineline Philip N.
Published: March 2006

Traditionally, aversive control has been viewed as a separate domain within behavior theory. Sometimes this separateness has been based upon a distinction between reinforcement and punishment, and sometimes upon a distinction between positive and negative reinforcement. The latter is regarded here as the more compelling basis, due to some inherent procedural asymmetries. An approach to the interpretation of negative reinforcement is presented, with indication of types of experiments that support it and that also point to promising directions for further work. However, most of the interpretive issues that arise here are relevant to positively reinforced behavior as well. These include: possible reformulation of the operant/respondent distinction; the place of emotional concepts in behavior analysis; the need for simultaneous, complementary analysis on differing time scales; the understanding of behavioral situations with rewarding or aversive properties that depend as much upon the contingencies that the situations involve as upon the primary rewarding or aversive stimuli that they include. Thus, an adequate understanding of this domain, which has been traditionally viewed as distinct, has implications for all domains of behavior‐analytic theory.
CONFIRMATION OF LINEAR SYSTEM THEORY PREDICTION: RATE OF CHANGE OF HERRNSTEIN'S k AS A FUNCTION OF RESPONSE‐FORCE REQUIREMENT
Authors: McDowell J. J. , Wood Helena M.
Published: March 2006

Four human subjects worked on all combinations of five variable‐interval schedules and five reinforcer magnitudes (¢/reinforcer) in each of two phases of the experiment. In one phase the force requirement on the operandum was low (1 or 11 N) and in the other it was high (25 or 146 N). Estimates of Herrnstein's k were obtained at each reinforcer magnitude. The results were: (1) response rate was more sensitive to changes in reinforcement rate at the high than at the low force requirement, (2) k increased from the beginning to the end of the magnitude range for all subjects at both force requirements, (3) the reciprocal of k was a linear function of the reciprocal of reinforcer magnitude for seven of the eight data sets, and (4) the rate of change of k was greater at the high than at the low force requirement by an order of magnitude or more. The second and third findings confirm predictions made by linear system theory, and replicate the results of an earlier experiment (McDowell & Wood, 1984). The fourth finding confirms a further prediction of the theory and supports the theory's interpretation of conflicting data on the constancy of Herrnstein's k.
REPEATED ACQUISITION IN THE ANALYSIS OF RULE‐GOVERNED BEHAVIOR
Authors: Vaughan Margaret E.
Published: March 2006

Five children, ranging in age from 3½ years to 5½ years, were taught various four‐response chains using conditioned reinforcement. Experiment 1 investigated the effects of presenting “instruction” stimuli — a sequence of lights over the correct response buttons — to assess their role in facilitating the acquisition of a chain of responses. Without the “instruction” stimuli, children made many errors before responses were brought under the control of the programmed contingencies. When confronted with the same contingencies later in the day, these subjects made fewer errors. In contrast, in the presence of the “instruction” stimuli, subjects made virtually no errors. However, when the “instruction” stimuli were discontinued in the subsequent session, all 5 subjects made errors. In Experiment 2, the subjects were taught to verbalize the contingencies during the phase without the “instruction” stimuli. This resulted in errorless performance during the subsequent exposure to the same procedure, but errors nevertheless occurred again during reexposure to the procedure with the “instruction” stimuli discontinued.
HOMOGENEOUS CHAINS, HETEROGENEOUS CHAINS, AND DELAY OF REINFORCEMENT
Authors: Lattal Kennon A. , Crawford‐Godbey Cynthia L.
Published: March 2006

Three pigeons responded on two‐component chain schedules in which the required response topography in the initial and terminal links was similar (a homogeneous chain) or dissimilar (a heterogeneous chain). Key‐peck responding in the initial link under a variable‐interval 60‐second (VI 60) schedule produced a terminal link in which, in different conditions, either key pecking or foot treadling was reinforced according to a VI 60 schedule. Multiple VI 60 VI 60 schedules, in which the responses required in the chain schedules were maintained by primary reinforcement in the two components, preceded and followed each type of chain. These multiple schedules were used to ensure that both responses occurred reliably prior to introducing the chain schedule. Key‐peck response rates in the initial link of the chain consistently were higher during the homogeneous chain than during the heterogeneous chain. These results illustrate that intervening events during a period separating an operant response from primary reinforcement influence that operant, independently of the delay between the response and reinforcement.
COMPARISON OF DRUG EFFECTS ON FIXED‐RATIO PERFORMANCE AND CHAIN PERFORMANCE MAINTAINED UNDER A SECOND‐ORDER FIXED‐RATIO SCHEDULE
Authors: Winsauer Peter J. , Thompson Donald M. , Moerschbaecher Joseph M.
Published: March 2006

In one component of a multiple schedule, pigeons were required to complete the same four‐response chain each session by responding sequentially on three identically lighted keys in the presence of four successively presented colors (chain performance). Food presentation occurred after five completions of the chain (i.e., after 20 correct responses). Errors, such as responding on the center or right key when the left was designated correct, produced a brief timeout but did not reset the chain. In the other component, responding on a single key (lighted white) was maintained by food presentation under a fixed‐ratio 20 schedule. In general, phencyclidine and d‐amphetamine produced dose‐dependent decreases in the overall response rates in both components. With pentobarbital, overall rate in each component generally increased at intermediate doses and decreased at higher doses. All three drugs produced dose‐dependent disruptive effects on chain‐performance accuracy. Phencyclidine and pentobarbital increased percent errors at doses that had little or no rate‐decreasing effects, whereas d‐amphetamine generally increased percent errors only at doses that substantially decreased overall rate. At high doses, all three drugs produced greater disruption of chain performance than of fixedratio performance, as indicated by a slower return to control responding, although the effects of d‐amphetamine were less selective than those of phencyclidine or pentobarbital.
PREFERENCE FOR UNSEGMENTED INTERREINFORCEMENT INTERVALS IN CONCURRENT CHAINS
Authors: Leung Jin‐Pang , Winton Alan S. W.
Published: March 2006

Five pigeons were trained under concurrent‐chain schedules in which a pair of independent, concurrent variable‐interval 60‐s schedules were presented in the initial link and either both variable‐interval or both fixed‐interval schedules were presented in the terminal link. Except for the baseline, one of the terminal‐link schedules was always a two‐component chained schedule and the other was either a simple or a tandem schedule of equal mean interreinforcement interval. The values of the fixed‐interval schedules were either 15 s or 60 s; that of the variable‐interval schedules was always 60 s. A 1.5‐s changeover delay operated during the initial link in some conditions. The pigeons preferred a simple or a tandem schedule to a chain. For the fixed‐interval schedules, this preference was greater when the fixed interval was 60 s than when it was 15 s. For the variable‐interval schedules, the preferences were less pronounced and occurred only when the changeover delay was in effect. For a given type of schedule and interreinforcement interval, similar preferences were obtained whether the nonchained schedule was a tandem or simple schedule. The changeover delay generally inflated preference and lowered the changeover rate, especially when the terminal‐link schedules were either short (15 s) or aperiodic (variable‐interval). The results were consistent with the notion that segmenting the interreinforcement interval of a schedule into a chain lowers the preference for it.
AUDITORY WORD DISCRIMINATIONS IN THE PIGEON
Authors: Pisacreta Richard , Gough David , Redwood Edward , Goodfellow Lee
Published: March 2006

Four pigeons were trained on a multiple variable‐interval 30‐s extinction schedule with various pairs of spoken English words presented as the discriminative stimuli. The birds typically produced discrimination indices of 70% to 90% accuracy. Discrimination accuracy was improved by shortening the interval between auditory stimulus presentations, and by increasing the number of syllables in the words.
AN ASSESSMENT OF THE ROLE OF HANDLING CUES IN “SPONTANEOUS RECOVERY” AFTER EXTINCTION
Authors: Thomas David R. , Sherman Leslie
Published: March 2006

Three experiments examined the assertion that presession handling cues that accompany training with reinforcement might account for spontaneous recovery when they reoccur following extinction. In Experiment 1, after extensive training on a variable‐interval schedule, key pecking in pigeons was extinguished following either normal or distinctively different handling and transportational cues. Those cues resulted in enhanced spontaneous recovery 24 hr later when normal cues were reinstated. In Experiment 2, however, subjects tested following the normal handling cues showed no more spontaneous recovery than did subjects that spent the entire extinction‐test interval in the experimental chambers and thus were tested without handling cues altogether. In Experiment 3, a group whose test for recovery began 10 min after being placed in the chambers yielded as much spontaneous recovery as did a group tested normally. Furthermore, a group for which extinction began at mid‐session and for which handling therefore could not be a discriminative cue for extinction showed no more spontaneous recovery than did the other two groups. Handling cues thus contributed to spontaneous recovery only after explicit discrimination training, as provided in Experiment 1.
MORE ON CONCURRENT INTERVAL‐RATIO SCHEDULES: A REPLICATION AND REVIEW
Authors: Heyman Gene M. , Herrnstein R. J.
Published: March 2006

It has been suggested that the failure to maximize reinforcement on concurrent variable‐interval, variable‐ratio schedules may be misleading. Inasmuch as response costs are not directly measured, it is possible that subjects are optimally balancing the benefits of reinforcement against the costs of responding. To evaluate this hypothesis, pigeons were tested in a procedure in which interval and ratio schedules had equal response costs. On a concurrent variable time (VT), variable ratio‐time (VRT) schedule, the VT schedule runs throughout the session and the VRT schedule is controlled by responses to a changeover key that switches from one schedule to the other. Reinforcement is presented independent of response. This schedule retains the essential features of concurrent VI VR, but eliminates differential response costs for the two alternatives. It therefore also eliminates at least one significant ambiguity about the reinforcement maximizing performance. Pigeons did not maximize rate of reinforcement on this procedure. Instead, their times spent on the alternative schedules matched the relative rates of reinforcement, even when schedule parameters were such that matching earned the lowest possible overall rate of reinforcement. It was further shown that the observed matching was not a procedural artifact arising from the constraints built into the schedule.
EFFECTS OF BODY WEIGHT ON DISCRIMINATIVE‐STIMULUS CONTROL BY PHENCYCLIDINE IN THE PIGEON
Authors: Massey B. W. , McMillan D. E.
Published: March 2006

Using a color‐tracking procedure with responses reinforced under a second‐order schedule, the discriminative‐stimulus properties of phencyclidine were studied in pigeons maintained at 70%, 80%, or 90% of their free‐feeding weights. The generalization curves for phencyclidine were similar at all three body weights. Generalization curves for pentobarbital, d‐amphetamine, and saline were also unrelated to body weight. These data suggest that food deprivation may not influence the discriminative‐stimulus properties of drugs in the way that it influences the reinforcing‐stimulus properties of drugs. The reason may be that during discrimination training interoceptive stimuli resulting from food deprivation do not become conditioned to the stimulus properties of the drug, because the food‐deprivation stimuli are paired equally often with the presence and absence of drug stimuli.
SHAPING BY AUTOMATED TRACKING OF AN ARBITRARY OPERANT RESPONSE
Authors: Pear Joseph J. , Legris Joseph A.
Published: March 2006

Although shaping is a widely accepted operant‐conditioning procedure for establishing new responses, technological problems involved in specifying and recording precise approximations to the target response have hindered experimental analysis of the shaping process. The present study used a computer‐controlled system that allows relatively precise procedural specification by continuous tracking of a pigeon's head and reinforcing successively closer approximations to contact of the head with an arbitrary fixed spherical region of 3‐cm diameter. The procedure was demonstrated to be effective, in that shaping of the target response occurred rapidly for each of the 3 birds in the study.
EFFECTS OF DELAYED CONDITIONED REINFORCEMENT IN CHAIN SCHEDULES
Authors: Royalty Paul , Williams Ben A. , Fantino Edmund
Published: March 2006

The contingency between responding and stimulus change on a chain variable‐interval 33‐s, variable‐interval 33‐s, variable‐interval 33‐s schedule was weakened by interposing 3‐s delays between either the first and second or the second and third links. No stimulus change signaled the delay interval and responses could occur during it, so the obtained delays were often shorter than the scheduled delay. When the delay occurred after the initial link, initial‐link response rates decreased by an average of 77% with no systematic change in response rates in the second or third links. Response rates in the second link decreased an average of 59% when the delay followed that link, again with little effect on response rates in the first or third links. Because the effect of delaying stimulus change was comparable to the effect of delaying primary reinforcement in a simple variable‐interval schedule, and the effect of the unsignaled delay was specific to the link in which the delay occurred, the results provide strong evidence for the concept of conditioned reinforcement.
WITHIN‐SESSION MEAL‐SIZE EFFECTS ON INDUCED DRINKING
Authors: Reid Alliston K. , Staddon J. E. R.
Published: March 2006

As a control for the effects of session duration and hunger on the relation between food magnitude and induced drinking, four food‐deprived rats were exposed to a variable‐time 50‐s schedule of food delivery in which the size of each food delivery varied randomly within sessions. Food‐related behavior and schedule‐induced drinking per opportunity were examined as functions of meal size and postfood time. All rats showed an inverted‐U‐shaped relation between drinking per opportunity and meal size. This relation was caused by variation in the percentage of intervals that contained drinking and by variation in the number of drinking bouts per interval, rather than by bout duration or by the amount of drinking within those intervals that actually contained drinking. Head‐in‐feeder time increased linearly with meal size. Schedule‐induced drinking was entrained by food delivery in 3 of 4 subjects; the entrainment was due to regulation of the starting time of each drinking bout rather than to regulation of bout duration.
COLOR PREFERENCE IN PIGEONS: STIMULUS INTENSITY AND REINFORCEMENT CONTINGENCY EFFECTS IN THE AVOIDANCE OF BLUE STIMULI
Authors: Biederman G. B. , McDonald K. G. , Heighington G. A. , Vanayan M.
Published: March 2006

In a procedure intended to determine color preference in pigeons (which partially replicated Catania, Owens, & von Lossberg, 1983), two keys were illuminated by different colors drawn from a set of amber, red, green, or blue stimuli; this was followed by the presentation of grain when either of the two colors was pecked. The grain was illuminated alternately across trials with the colors presented on the keys. In Experiment 1 the intensity of the color stimuli used was not equalized, whereas in Experiment 2 the intensity of the colors was equalized. The low preference for blue found in Experiment 1, as measured by differential key pecking, was not found in Experiment 2. The discriminability of the intensity‐equalized colors was confirmed in Experiment 2a, in which equal‐intensity color discrimination problems were presented. In Experiment 3, as in Catania et al. (1983), a response‐independent reinforcement schedule was used, but with intensity‐equalized colors. In contrast to Experiment 2, very low preference for blue was found here and in Experiment 4, which used a within‐subject procedure. These findings suggest that pigeon color preference may be a function of intensity, but all controlling variables have not as yet been identified.
IS THERE A DECISIVE TEST BETWEEN MATCHING AND MAXIMIZING?
Authors: Rachlin Howard , Green Leonard , Tormey Barbara
Published: March 2006

Reinforcers under typical concurrent variable‐interval, variable‐ratio schedules may be (a) earned and obtained during the variable‐interval component, (b) earned and obtained during the variable‐ratio component, or (c) earned during the variable‐ratio component and obtained during the variable‐interval component. Categories a and b, which have no bearing on matching versus maximizing accounts of choice, were set at zero. The rate of Category c reinforcers and the duration of a changeover delay were varied. Simple matching, which predicts exclusive choice of the variable‐interval component, and strict maximizing of overall reinforcement rate, which predicts a bias towards the variable‐ratio component, were both disconfirmed: Subjects spent approximately 25% of their time in the variable‐ratio component, contrary to the matching prediction, but earned only about one third of the reinforcers predicted by strict maximizing. However, maximizing describes the findings functionally in terms of discounting of delayed reinforcers; matching may describe the data in terms of a restructuring of the alternatives. Matching and maximizing are not competing theories about the fundamental nature of choice, but compatible points of view that may reveal environmental function and behavioral structure.
ABSOLUTE AND RELATIVE MEASURES OF DIMENSIONAL CONTRAST
Authors: Hinson John M.
Published: March 2006

Two sets of experiments examined the discriminative performance of pigeons on a visual flicker‐rate continuum using a maintained generalization procedure. In the first experiment, responses during the intermediate stimulus value were not reinforced, whereas responses during all other stimuli were reinforced periodically. In the second experiment, training was similar to the first, with the exception of one condition in which stimuli adjacent to the negative stimulus border were eliminated from the discrimination set. Results from both experiments show that positive dimensional contrast seems to represent a relative enhancement of discrimination gradient form, rather than an absolute increase in responding with respect to prior baseline. Further, the form and magnitude of positive dimensional contrast are not predictable from the form and magnitude of baseline response rates. Results from the second experiment indicate that eliminating border stimuli increased response‐rate differences between positive and negative stimuli, but did not necessarily diminish the magnitude of positive dimensional contrast.
REVIEW OF B. F. SKINNER'S THE BEHAVIOR OF ORGANISMS1
Authors: Hilgard Ernest R.
Published: March 2006

As I reread my review nearly 50 years later, I think of the circumstances. I had heard a paper by Fred at the Ithaca meeting of the APA in 1932, and recall the praise by Edna Heidbreder, who was sitting next to me, whose remark was that “He has a clean mind.” The year before his book appeared, I had already cited eight of his published papers in a review of the conditioned response in relation to conventional learning experiments that appeared in the Psychological Bulletin (1937, 34, 61–102). It may be because of that the editor sent me Fred's book to review.

When I received the copy of his new book to review, I read it carefully, and soon reported on it orally before Lewis Terman's weekly seminar to get comments and questions before revising my review. I was pleased by Terman's excitement over the originality of Fred's approach.
CHANGES IN FEEDING AND FORAGING PATTERNS AS AN ANTIPREDATOR DEFENSIVE STRATEGY: A LABORATORY SIMULATION USING AVERSIVE STIMULATION IN A CLOSED ECONOMY
Authors: Fanselow Michael S. , Lester Laurie S. , Helmstetter Fred J.
Published: March 2006

The effects of the risk of electric shock on the meal patterns of rats living in an operant chamber were investigated. Rats could obtain food by working on a response lever that provided reinforcement according to chained fixed‐ratio continuous reinforcement schedules that allowed the animals control over meal size. Using a two‐compartment operant chamber with a safe nesting area and manipulanda area with a grid floor, shock could be correlated with responding on the schedule. Shocks (≥1.25 per hour) were scheduled to occur randomly throughout the day, independent of the rat's behavior. Shock caused a reorganization of meal patterns such that the animals took less frequent but larger meals. This pattern reduced the time the animals spent at risk without compromising caloric balance. Similar changes in feeding pattern were obtained in both hooded and albino rats. Exposure to shock in a separate chamber did not produce these behavioral modifications. The magnitude of shock‐induced alterations of meal patterns was greater with chained fixed‐ratio 90 continuous reinforcement than with chained fixed‐ratio 10 continuous reinforcement. Additionally, the rats seemed to be able to reduce food intake but increase caloric efficiency, such that the reduced food intake did not have deleterious effects on maintenance of body weight. These behavioral modifications reduced the number of shocks received from that which would have been expected if meal pattern changes had not occurred. We suggest that this technique may provide a useful laboratory simulation of the impact that the risk of predation has on foraging behavior.
A COST‐BENEFIT ANALYSIS OF DEMAND FOR FOOD
Authors: Hursh Steven R. , Raslear Thomas G. , Shurtleff David , Bauman Richard , Simmons Laurence
Published: March 2006

Laboratory studies of consumer demand theory require assumptions regarding the definition of price in the absence of a medium of exchange (money). In this study we test the proposition that the fundamental dimension of price is a cost‐benefit ratio expressed as the effort expended per unit of food value consumed. Using rats as subjects, we tested the generality of this “unit price” concept by varying four dimensions of price: fixed‐ratio schedule, number of food pellets per fixed‐ratio completion, probability of reinforcement, and response lever weight or effort. Two levels of the last three factors were combined in a 2 × 2 × 2 design giving eight groups. Each group was studied under a series of six FR schedules. Using the nominal values of all factors to determine unit price, we found that grams of food consumed plotted as a function of unit price followed a single demand curve. Similarly, total work output (responses × effort) conformed to a single function when plotted in terms of unit price. These observations provided a template for interpreting the effects of biological factors, such as brain lesions or drugs, that might alter the cost‐benefit ratio.
DETERMINANTS OF PAUSING UNDER VARIABLE‐RATIO SCHEDULES: REINFORCER MAGNITUDE, RATIO SIZE, AND SCHEDULE CONFIGURATION
Authors: Blakely Elbert , Schlinger Henry
Published: March 2006

Pigeons pecked a key under two‐component multiple variable‐ratio schedules that offered 8‐s or 2‐s access to grain. Phase 1 assessed the effects of differences in reinforcer magnitude on postreinforcement pausing, as a function of ratio size. In Phase 2, postreinforcement pausing and the first five interresponse times in each ratio were measured as a function of differences in reinforcer magnitude under equal variable‐ratio schedules consisting of different configurations of individual ratios. Rates were also calculated exclusive of postreinforcement pause times in both phases. The results from Phase 1 showed that as ratio size increased, the differences in pausing educed by unequal reinforcer magnitudes also increased. The results of Phase 2 showed that the effects of reinforcer magnitude on pausing and IRT durations were a function of schedule configuration. Under one configuration, in which the smallest ratio was a fixed‐ratio 1, pauses were unaffected by magnitude but the first five interresponse times were affected. Under the other configuration, in which the smallest ratio was a fixed‐ratio 7, pauses were affected by reinforcer magnitude but the first five interresponse times were not. The effect of each configuration seemed to be determined by the value of the smallest individual ratio. Rates calculated exclusive of postreinforcement pause times were, in general, directly related to reinforcer magnitude, and the relation was shown to be a function of schedule configuration.
PSYCHOLOGICAL DISTANCE TO REWARD: A HUMAN REPLICATION
Authors: Leung Jin‐Pang
Published: March 2006

Choice behavior in college students was examined in two experiments using the concurrent‐chains procedure. In both experiments, the concurrent chains were presented on a microcomputer in the form of an air‐defense game in which subjects used two radar systems to detect and subsequently destroy enemy aircraft. Access to one of two radar systems was controlled by a pair of independent concurrent variable‐interval 60‐s schedules with a 4‐s changeover delay always in effect. In the terminal link, the appearance of an enemy aircraft was determined by a pair of differentially segmented fixed‐time schedules (Experiment 1) or fixed‐interval schedules (Experiment 2) of equal overall duration. In Experiment 1, the terminal‐link duration was either 20 s or 40 s, and subjects preferred the unsegmented to the segmented intervals. In Experiment 2, the duration was either 10 s or 60 s, and the reinforcement contingencies required responding during the terminal link. Prior to the reinstatement of the initial link, subjects estimated the duration of the terminal‐link schedule. Segmentation affected choice in the 60‐s conditions but not in the 10‐s ones. Preference for the unsegmented schedule was correlated with an overestimation of the durations for the segmented schedules. These results replicated those found in animal experiments and support the notion of increasing the psychological distance to reward by segmenting a time‐based schedule of reinforcement.
REINFORCING EFFECTS OF CAFFEINE IN COFFEE AND CAPSULES
Authors: Griffiths Roland R. , Bigelow George E. , Liebson Ira A.
Published: March 2006

In a residential research ward the reinforcing and subjective effects of caffeine were studied under double‐blind conditions in volunteer subjects with histories of heavy coffee drinking. In Experiment 1, 6 subjects had 13 opportunities each day to self‐administer either a caffeine (100 mg) or a placebo capsule for periods of 14 to 61 days. All subjects developed a clear preference for caffeine, with intake of caffeine becoming relatively stable after preference had been attained. Preference for caffeine was demonstrated whether or not preference testing was preceded by a period of 10 to 37 days of caffeine abstinence, suggesting that a recent history of heavy caffeine intake (tolerance/dependence) was not a necessary condition for caffeine to function as a reinforcer. In Experiment 2, 6 subjects had 10 opportunities each day to self‐administer a cup of coffee or (on different days) a capsule, dependent upon completing a work requirement that progressively increased and then decreased over days. Each day, one of four conditions was studied: caffeinated coffee (100 mg/cup), decaffeinated coffee, caffeine capsules (100 mg/capsule), or placebo capsules. Caffeinated coffee maintained the most self‐administration, significantly higher than decaffeinated coffee and placebo capsules but not different from caffeine capsules. Both decaffeinated coffee and caffeine capsules were significantly higher than placebo capsules but not different from each other. In both experiments, subject ratings of “liking” of coffee or capsules covaried with the self‐administration measures. These experiments provide the clearest demonstrations to date of the reinforcing effects of caffeine in capsules and in coffee.
AN ECOLOGICAL ANALYSIS OF KNOWING BY WIELDING
Authors: Turvey M. T. , Solomon H. Yosef , Burton Gregory
Published: March 2006

The ecological approach to perception, as developed by James Gibson, is described and applied to how one knows, by means of the haptic perceptual system, various properties of hand‐held objects. Four sets of experiments are reviewed in which subjects reported on the extent, orientation, shape, and fractional components of unseen objects wielded freely. For each task, an invariant specific to the object property in question is identified in the structured arrays of rotational moments and strains produced by the act of wielding. Results are discussed in relation to the concepts of attention and stimulation, as reformulated by the ecological approach, and the general theory of perception as information pickup.
RESPONDING OF PIGEONS UNDER VARIABLE‐INTERVAL SCHEDULES OF SIGNALED‐DELAYED REINFORCEMENT: EFFECTS OF DELAY‐SIGNAL DURATION
Authors: Schaal David W. , Branch Marc N.
Published: March 2006

Two experiments with pigeons examined the relation of the duration of a signal for delay (“delay signal”) to rates of key pecking. The first employed a multiple schedule comprised of two components with equal variable‐interval 60‐s schedules of 27‐s delayed food reinforcement. In one component, a short (0.5‐s) delay signal, presented immediately following the key peck that began the delay, was increased in duration across phases; in the second component the delay signal initially was equal to the length of the programmed delay (27 s) and was decreased across phases. Response rates prior to delays were an increasing function of delay‐signal duration. As the delay signal was decreased in duration, response rates were generally higher than those obtained under identical delay‐signal durations as the signal was increased in duration. In Experiment 2 a single variable‐interval 60‐s schedule of 27‐s delayed reinforcement was used. Delay‐signal durations were again increased gradually across phases. As in Experiment 1, response rates increased as the delay‐signal duration was increased. Following the phase during which the signal lasted the entire delay, shorter delay‐signal‐duration conditions were introduced abruptly, rather than gradually as in Experiment 1, to determine whether the gradual shortening of the delay signal accounted for the differences observed in response rates under identical delay‐signal conditions in Experiment 1. Response rates obtained during the second exposures to the conditions with shorter signals were higher than those observed under identical conditions as the signal duration was increased, as in Experiment 1. In both experiments, rates and patterns of responding during delays varied greatly across subjects and were not systematically related to delay‐signal durations. The effects of the delay signal may be related to the signal's role as a discriminative stimulus for adventitiously reinforced intradelay behavior, or the delay signal may have served as a conditioned reinforcer by virtue of the temporal relation between it and presentation of food.
CHOICE BETWEEN DELAYED REINFORCERS AND FIXED‐RATIO SCHEDULES REQUIRING FORCEFUL RESPONDING
Authors: Mazur James E. , Kralik J. Daniel
Published: March 2006

This experiment measured pigeons' choices between delayed reinforcers and fixed‐ratio schedules in which a force of approximately 0.48 N was needed to operate the response key. In ratio‐delay conditions, subjects chose between a fixed‐ratio schedule and an adjusting delay. The delay was increased or decreased several times a session in order to estimate an indifference point—a delay duration at which the two alternatives were chosen about equally often. Each ratio‐delay condition was followed by a delay‐delay condition in which subjects chose between the adjusting delay and a variable‐time schedule, with the components of this schedule selected to match the ratio completion times of the preceding ratio‐delay condition. The adjusting delays at the indifference point were longer when the alternative was a fixed‐ratio schedule than when it was a matched variable‐time schedule, which indicated a preference for the matched variable‐time schedules over the fixed‐ratio schedules. This preference increased in a nonlinear manner with increasing ratio size. This nonlinearity was inconsistent with a theory that states that indifference points for both time and ratio schedules can be predicted by multiplying the choice response‐reinforcer intervals of the two types of schedules by different multiplicative constants. Two other theories, which predict nonlinear increases in preference for the matched variable‐time schedules, are discussed.
UNIFICATION OF MODELS FOR CHOICE BETWEEN DELAYED REINFORCERS
Authors: Killeen Peter R. , Fantino Edmund
Published: March 2006

Two models for choice between delayed reinforcers, Fantino's delay‐reduction theory and Killeen's incentive theory, are reviewed. Incentive theory is amended to incorporate the effects of arousal on alternate types of behavior that might block the reinforcement of the target behavior. This amended version is shown to differ from the delay‐reduction theory in a term that is an exponential in incentive theory and a difference in delay‐reduction theory. A power series approximation to the exponential generates a model that is formally identical with delay‐reduction theory. Correlations between delay‐reduction theory and the amended incentive theory show excellent congruence over a range of experimental conditions. Although the assumptions that gave rise to delay‐reduction theory and incentive theory remain different and testable, the models deriving from the theories are unlikely to be discriminable by parametric experimental tests. This congruence of the models is recognized by naming the common model the delayed reinforcement model, which is then compared with other models of choice such as Killeen and Fetterman's (1988) behavioral theory of timing, Mazur's (1984) equivalence rule, and Vaughan's (1985) melioration theory.
SUBOPTIMAL CHOICE IN A PERCENTAGE‐REINFORCEMENT PROCEDURE: EFFECTS OF SIGNAL CONDITION AND TERMINAL‐LINK LENGTH
Authors: Spetch Marcia L. , Belke Terry W. , Barnet Robert C. , Dunn Roger , Pierce W. David
Published: March 2006

Pigeons' choice between reliable (100%) and unreliable (50%) reinforcement was studied using a concurrent‐chains procedure. Initial links were fixed‐ratio 1 schedules, and terminal links were equal fixed‐time schedules. The duration of the terminal links was varied across conditions. The terminal link on the reliable side always ended in food; the terminal link on the unreliable side ended with food 50% of the time and otherwise with blackout. Different stimuli present during the 50% terminal links signaled food or blackout outcomes under signaled conditions but were uncorrelated with outcomes under unsignaled conditions. In signaled conditions, most pigeons displayed a nearly exclusive preference for the 100% alternative when terminal links were short (5 or 10 s), but with terminal links of 30 s or longer, preference for the 100% alternative was sharply reduced (often to below .5). In unsignaled conditions, most pigeons showed extreme preference for the 100% alternative with either short (5 s) or longer (30 s) terminal links. Thus, pigeons' choice between reliable and unreliable reinforcement is influenced by both the signal conditions on the unreliable alternative and the duration of the terminal‐link delay. With a long delay and signaled outcomes, many pigeons display a suboptimal tendency to choose the unreliable side.
DELAY AND NUMBER OF FOOD REINFORCERS: EFFECTS ON CHOICE AND LATENCIES
Authors: Shull Richard L. , Mellon Robert C. , Sharp Jennifer A.
Published: March 2006

Pigeons were given a choice between two identical‐duration situations (terminal links of chain schedules). One terminal link of the choice pair provided two food deliveries, and the other provided five. The exact times of these food deliveries differed between the terminal links and were varied over conditions. A single response during the initial link gave immediate access to the corresponding terminal link. Forced trials, during which only one of the initial‐link keys was lighted, were interspersed with choice trials during which both initial‐link keys were lighted. Choice tended to favor whichever terminal link was correlated with the higher sum of the immediacies (i.e., the sum of the reciprocals of the delays to each of the reinforcers following the choice, with all delays measured from the choice). Latencies on forced trials and on choice trials also were related (negatively) to the sum of the immediacies. This correlation among response measures (choice and latencies) suggests that both measures are manifestations of the effect of conditioned reinforcement on response tendencies.
QUININE PELLETS AS AN INFERIOR GOOD AND A GIFFEN GOOD IN RATS
Authors: Hastjarjo Thomas , Silberberg Alan , Hursh Steven R.
Published: March 2006

In Experiment 1, 4 rats earned their daily food ration by choosing between two levers. One lever delivered two regular and one quinine‐adulterated food pellets, and the other delivered two regular and four quinine pellets. A 20‐s intertrial interval separated successive choices. Sessions began with 10 forced trials during which only one lever, selected with p = .5 and cued by a light above it, could deliver its reinforcer. Forced trials were followed by 30 or 150 trials, depending on the condition, during which choices to either lever could be reinforced. Over this range, absolute choice of the four‐quinine, two‐regular‐pellet lever was inversely related to the number of free‐choice trials, establishing this reinforcer as an inferior good. In Condition 1 of Experiment 2, the prior design was altered in two ways: (a) one lever delivered four quinine pellets, and the other lever delivered one standard pellet; and (b) sessions ended after 140 free‐choice trials. When the number of free‐choice trials was reduced to 100 (Condition 2), all 3 rats increased their preference for quinine pellets, confirming their status as an inferior good. In the next several conditions, the number of quinine pellets provided for selecting its associated lever was varied between three and four. Preference for the quinine‐pellet alternative was inversely related to the number of pellets it provided, a result defining it as a Giffen good. These findings are not accommodated readily by extant choice models and complicate the search for a unitary model of choice.
A FUNCTIONAL ANALYSIS OF ANOTHER INDIVIDUAL'S BEHAVIOR AS DISCRIMINATIVE STIMULUS FOR A MONKEY
Authors: Fushimi Takao
Published: March 2006

Key presses of 1 monkey (called the performer) became the basis upon which a 2nd monkey (called the judge) solved conditional‐discrimination tasks. First, the performer was trained to press one of two colored choice keys (red or green) depending on the location of a white light in her chamber. The performer's key‐pressing behavior was brought under the control of the experimenter by this procedure. Subsequently, the judge was trained to discriminate the performer's key‐pressing behavior. In Experiment 1, the judge had to press Key 1 when the performer pressed the red choice key and Key 2 when the performer pressed the green choice key. In Experiment 2, a sample key was introduced. The judge had to press Key 1 when the performer pressed the same colored choice key as the sample; the judge had to press Key 2 when the performer pressed the different colored choice key. In both experiments, the judge was required to attend to the behavior of the performer. It was shown that the performer's behavior served as a discriminative stimulus for the judge's responses in a conditional‐discrimination task.
HUMAN AGGRESSIVE RESPONSES MAINTAINED BY AVOIDANCE OR ESCAPE FROM POINT LOSS
Authors: Cherek Don R. , Spiga Ralph , Steinberg Joel L. , Kelly Thomas H.
Published: March 2006

During 50‐min sessions, 6 male human subjects could press either Button A or Button B available as nonreversible options. Button A presses were nonaggressive responses and earned points according to a fixed‐ratio 100 schedule. Prior to the experiment subjects were instructed that every 10 (fixed‐ratio 10) Button B presses (aggressive responses) subtracted a point from a fictitious 2nd subject. A random‐time schedule of point loss was used to engender aggressive responding. The instructions attributed these point losses to the Button B presses of the subject's fictitious partner. Aggressive responding either escaped or avoided point loss by initiating an interval free of point loss. The duration of the interval was varied systematically across sessions. Avoidance contingencies maintained a high rate of aggressive responding over 30 sessions in the absence of point loss. Escape contingencies also maintained aggressive responding across sessions, with rates of aggressive responding corresponding to rates of point loss.
MOTIVATIONAL EFFECTS OF SMOKED MARIJUANA: BEHAVIORAL CONTINGENCIES AND LOW‐PROBABILITY ACTIVITIES
Authors: Foltin Richard W. , Fischman Marian W. , Brady Joseph V. , Bernstein Daniel J. , Capriotti Richard M. , Nellis Margaret J. , Kelly Thomas H.
Published: March 2006

Six adult male research volunteers, in two groups of 3 subjects each, lived in a residential laboratory for 15 days. All contact with the experimenters was through a networked computer system, and subjects' behavior was monitored continuously and recorded. During the first part of each day, subjects remained in private rooms doing planned work activities, and during the remainder of each day, they were allowed to socialize. Two cigarettes containing active marijuana (2.7% Δ9‐THC) or placebo were smoked during the private work period and the period of access to social activities. Three‐day contingency conditions requiring subjects to engage in a low‐probability work activity (instrumental activity) in order to earn time that could be spent engaging in a high‐probability work activity (contingent activity) were programmed during periods of placebo and active‐marijuana smoking. During placebo administration, the contingency requirement reliably increased the amount of time that subjects spent engaged in the low‐probability instrumental activity and decreased the time spent engaged in the high‐probability contingent activity. During active‐marijuana administration, however, the increases in instrumental activity were consistently larger than observed under placebo conditions. The decreases in contingent activity were similar to those seen under placebo conditions. Smoking active marijuana was thus observed to produce increments in instrumental activity under motivational conditions involving contingencies for “work activities.”