bluuebunny/crossref_metadata_2025 huggingface dataset:
NATURAL CONCEPTS IN A JUVENILE GORILLA (GORILLA GORILLA GORILLA) AT THREE LEVELS OF ABSTRACTION
Authors: Vonk Jennifer , MacDonald Suzanne E.
Published: March 2006

The extent to which nonhumans are able to form conceptual versus perceptual discriminations remains a matter of debate. Among the great apes, only chimpanzees have been tested for conceptual understanding, defined as the ability to form discriminations not based solely on simple perceptual features of stimuli, and to transfer this learning to novel stimuli. In the present investigation, a young captive female gorilla was trained at three levels of abstraction (concrete, intermediate, and abstract) involving sets of photographs representing natural categories (e.g., orangutans vs. humans, primates vs. nonprimate animals, animals vs. foods). Within each level of abstraction, when the gorilla had learned to discriminate positive from negative exemplars in one set of photographs, a novel set was introduced. Transfer was defined in terms of high accuracy during the first two sessions with the new stimuli. The gorilla acquired discriminations at all three levels of abstraction but showed unambiguous transfer only with the concrete and abstract stimulus sets. Detailed analyses of response patterns revealed little evidence of control by simple stimulus features. Acquisition and transfer involving abstract stimulus sets suggest a conceptual basis for gorilla categorization. The gorilla's relatively poor performance with intermediate‐level discriminations parallels findings with pigeons, and suggests a need to reconsider the role of perceptual information in discriminations thought to indicate conceptual behavior in nonhumans.
THE STRUCTURE OF PIGEON MULTIPLE‐CLASS SAME—DIFFERENT LEARNING
Authors: Cook Robert G.
Published: March 2006

Three experiments examined the structure of the decision framework used by pigeons in learning a multiple‐class same—different task. Using a same—different choice task requiring the discrimination of odd‐item different displays (one or more of the display's component elements differed) from same displays (all display components identical), pigeons were concurrently trained with sets of four discriminable display types. In each experiment, the consistent group was tested such that the same and different displays of four display types were consistently mapped onto their choice alternatives. The inconsistent group received a conflicting mapping of the same and different displays and the choice alternatives that differed across the four display types but were consistent within a display type. Experiment 1 tested experienced pigeons, and Experiment 2 tested naive pigeons. In both experiments, the consistent group learned their discrimination faster and to a higher level of choice accuracy than did the inconsistent group, which performed poorly in general. Only in the consistent group was the discrimination transferred to novel stimuli, indicative of concept formation in that group. A third experiment documented that the different display classes were discriminable from one another. These results suggest that pigeons attempt to generate a single discriminative rule when learning this type of task, and that this general rule can cover a large variety of stimulus elements and organizations, consistent with previous evidence suggesting that pigeons may be capable of learning relatively unbounded relational same—different concepts.
A FUNCTIONAL‐ANALYTIC MODEL OF ANALOGY: A RELATIONAL FRAME ANALYSIS
Authors: Stewart Ian , Barnes‐Holmes Dermot , Roche Bryan , Smeets Paul M.
Published: March 2006

The aim of this study was to explore a behavior‐analytic model of analogical reasoning, defined as the discrimination of formal similarity via equivalence—equivalence responding. In Experiment 1, adult humans were trained and tested for the formation of four three‐member equivalence relations: A1‐B1‐C1, A2‐B2‐C2, A3‐B3‐C3, and A4‐B4‐C4. The B and C stimuli were three‐letter nonsense syllables, and the A stimulus was a colored shape. Subjects were then successfully tested for equivalence– equivalence responding (e.g., matching B1/C1 to B2/C2 rather than B3/C4). These tasks were designed such that equivalence—equivalence responding might allow subjects to discriminate a physical similarity between the relations involved. Some participants (color subjects) received only equivalence– equivalence tasks in which they might discriminate a color relation, whereas others (shape subjects) were given tasks in which they might discriminate a shape relation. A control group received both types of task. In a subsequent test for the discrimination of formal similarity, color subjects matched according to color, shape subjects matched according to shape, and the control group showed no consistent matching pattern. In Experiment 2, adult humans showed a transformation of the functions of a block‐sorting task via this basic model of analogy. Empirical and conceptual issues related to these results are discussed.
THE DEVELOPMENT OF EMERGENT DIFFERENTIAL SAMPLE BEHAVIOR IN PIGEONS
Authors: Urcuioli Peter J. , Pierce Jada N. , Lionello‐DeNolf Karen M. , Friedrich Andrea , Fetterman J. Gregor , Green Courtney
Published: March 2006

Three experiments attempted to replicate Manabe, Kawashima, and Staddon's (1995) finding of emergent differential sample behavior in budgerigars that has been interpreted as evidence of functional equivalence class formation. In Experiments 1 and 2, pigeons initially learned two‐sample/two‐alternative matching to sample in which comparison presentation was contingent on pecking one sample on a differential‐reinforcement‐of‐low‐rate (DRL) schedule and the other on a fixed‐ratio (FR) schedule. Later, two new samples were added to the task. Comparison presentation on these trials occurred after the first sample peck following a predetermined interval (Experiment 1) or after completion of either the DRL or FR requirement, whichever occurred first (Experiment 2). Experiment 1 found no evidence for emergent spaced versus rapid responding to the new samples as they established conditional control over the familiar choices. By contrast, differential responding did emerge for some pigeons in Experiment 2, with responding to each new sample coinciding with the pattern explicitly conditioned to the original sample occasioning the same comparison choice. This emergent effect, however, disappeared for most pigeons with continued training. Experiment 3 systematically replicated Experiment 2 using differential peck location as the sample behavior. Differential location pecking emerged to the new samples for most pigeons and remained intact throughout training. Our findings demonstrate a viable pigeon analogue to the budgerigar emergent calling paradigm and are discussed in terms of equivalence‐ and non‐equivalence‐based processes.
CONTEXTUAL CONTROL OF STIMULUS GENERALIZATION AND STIMULUS EQUIVALENCE IN HIERARCHICAL CATEGORIZATION
Authors: Griffee Karen , Dougher Michael J.
Published: March 2006

The purpose of this study was to determine whether hierarchical categorization would result from a combination of contextually controlled conditional discrimination training, stimulus generalization, and stimulus equivalence. First, differential selection responses to a specific stimulus feature were brought under contextual control. This contextual control was hierarchical in that stimuli at the top of the hierarchy all evoked one response, whereas those at the bottom each evoked different responses. The evocative functions of these stimuli generalized in predictable ways along a dimension of physical similarity. Then, these functions were indirectly acquired by a set of nonsense syllables that were related via transitivity relations to the originally trained stimuli. These nonsense syllables effectively served as names for the different stimulus classes within each level of the hierarchy.
CHIMPANZEE RESPONDING DURING MATCHING TO SAMPLE: CONTROL BY EXCLUSION
Authors: Beran Michael J. , Washburn David A.
Published: March 2006

Three chimpanzees performed a computerized matching‐to‐sample task in which samples were photographs of items and comparison stimuli were geometric symbols called lexigrams. In Experiment 1, samples were either defined (i.e., they represented items that were associated already with a specific lexigram label by the chimpanzees) or undefined (i.e., they did not have an already learned association with a specific lexigram). On each trial, the foil (incorrect) comparison could be either a defined or an undefined lexigram. All 3 chimpanzees selected the correct comparison for undefined samples at a level significantly better than chance only when the foil comparison was defined. In Experiment 2, three comparisons were presented on each trial, and in Experiment 3, four comparisons were presented on each trial. For Experiments 2 and 3, the foil comparisons consisted of either defined or undefined comparisons or a mixture of both. For these two experiments, when the chimpanzees were presented with an undefined sample, they typically made selections of only undefined comparisons. These data indicate that the chimpanzees responded through use of exclusion. A final experiment, however, indicated that, despite the use of exclusion to complete trials with undefined samples correctly, the chimpanzees did not learn new associations between undefined samples and comparisons.
ON THE ROLE OF COVARYING FUNCTIONS IN STIMULUS CLASS FORMATION AND TRANSFER OF FUNCTION
Authors: Markham Rebecca G. , Markham Michael R.
Published: March 2006

This experiment investigated whether directly trained covarying functions are necessary for stimulus class formation and transfer of function in humans. Initial class training was designed to establish two respondent‐based stimulus classes by pairing two visual stimuli with shock and two other visual stimuli with no shock. Next, two operant discrimination functions were trained to one stimulus of each putative class. The no‐shock group received the same training and testing in all phases, except no stimuli were ever paired with shock. The data indicated that skin conductance response conditioning did not occur for the shock groups or for the no‐shock group. Tests showed transfer of the established discriminative functions, however, only for the shock groups, indicating the formation of two stimulus classes only for those participants who received respondent class training. The results suggest that transfer of function does not depend on first covarying the stimulus class functions.
TOWARD A UNIFIED THEORY OF DECISION CRITERION LEARNING IN PERCEPTUAL CATEGORIZATION
Authors: Maddox W. Todd
Published: March 2006

Optimal decision criterion placement maximizes expected reward and requires sensitivity to the category base rates (prior probabilities) and payoffs (costs and benefits of incorrect and correct responding). When base rates are unequal, human decision criterion is nearly optimal, but when payoffs are unequal, suboptimal decision criterion placement is observed, even when the optimal decision criterion is identical in both cases. A series of studies are reviewed that examine the generality of this finding, and a unified theory of decision criterion learning is described (Maddox & Dodd, 2001). The theory assumes that two critical mechanisms operate in decision criterion learning. One mechanism involves competition between reward and accuracy maximization: The observer attempts to maximize reward, as instructed, but also places some importance on accuracy maximization. The second mechanism involves a flat‐maxima hypothesis that assumes that the observer's estimate of the reward‐maximizing decision criterion is determined from the steepness of the objective reward function that relates expected reward to decision criterion placement. Experiments used to develop and test the theory require each observer to complete a large number of trials and to participate in all conditions of the experiment. This provides maximal control over the reinforcement history of the observer and allows a focus on individual behavioral profiles. The theory is applied to decision criterion learning problems that examine category discriminability, payoff matrix multiplication and addition effects, the optimal classifier's independence assumption, and different types of trial‐by‐trial feedback. In every case the theory provides a good account of the data, and, most important, provides useful insights into the psychological processes involved in decision criterion learning.
CONTEXTUAL CONTROL OF EQUIVALENCE‐BASED TRANSFORMATION OF FUNCTIONS
Authors: Dougher Michael , Perkins David R. , Greenway David , Koons Ashton , Chiasson Carmenne
Published: March 2006

The transformation of functions refers to the untrained acquisition of stimulus functions among members of stimulus equivalence classes or relational frames. Although it is widely assumed that contextual control over the transformation of functions must exist, this has not yet been conclusively demonstrated in laboratory studies. Four experiments are reported in which (a) stimulus equivalence classes were established, (b) a conditional stimulus function was trained for one member of each of the classes, and (c) multiple‐exemplar procedures were used to train and test for contextual control over the transformation of the stimulus function within the classes and to assess whether it generalized to new equivalence classes. Although a significant amount of training was required, the procedures ultimately resulted in the contextual control of function transformation for 9 of 10 participants and generalized contextual control for 4 of 5 participants.
DYNAMICAL CONCURRENT SCHEDULES
Authors: Palya William L. , Allan Robert W.
Published: March 2006

Previous work on the matching law has predominantly focused on the molar effects of the contingency by examining only one reinforcer ratio for extended periods. Responses are distributed as a function of reinforcer ratios under these static conditions. But the outcome under a dynamic condition in which reinforcer ratios change continuously has not been determined. The present study implemented concurrent variable‐interval schedules that changed continuously across a fixed 5‐min trial. The schedules were reciprocally interlocked. The variable interval for one key changed continuously from a variable‐interval 15‐s to a variable‐interval 480‐s, while the schedule for the other key changed from a variable‐interval 480‐s to a variable‐interval 15‐s. This dynamical concurrent schedule shifted behavior in the direction of matching response ratios to reinforcer ratios. Sensitivities derived from the generalized matching law were approximately 0.62, the mean absolute bias was approximately 0.11, and r2s were approximately 0.86. It was concluded that choice behavior can come to adapt to reinforcer ratios that change continuously over a relatively short time and that this change does not require extensive experience with a fixed reinforcer ratio. The results were seen as supportive of the view that all behavior constitutes choice.
STIMULUS CONTROL OF COCAINE SELF‐ADMINISTRATION
Authors: Weiss Stanley J. , Kearns David N. , Cohn Scott I. , Schindler Charles W. , Panlilio Leigh V.
Published: March 2006

Environmental stimuli that set the occasion wherein drugs are acquired can “trigger” drug‐related behavior. Investigating the stimulus control of drug self‐administration in laboratory animals should help us better understand this aspect of human drug abuse. Stimulus control of cocaine self‐administration was generated here for the first time using multiple and chained schedules with short, frequently‐alternating components—like those typically used to study food‐maintained responding. The procedures and results are presented along with case histories to illustrate the strategies used to produce this stimulus control. All these multicomponent schedules contained variable‐interval (VI) components as well as differential‐reinforcement‐of‐other‐behavior (DRO) or extinction components. Schedule parameters and unit dose were adjusted for each rat to produce stable, moderate rates in VI components, with minimal postreinforcement (infusion) pausing, and response cessation in extinction and DRO components. Whole‐body drug levels on terminal baselines calculated retrospectively revealed that all rats maintained fairly stable drug levels (mean, 2.3 to 3.4 mg/kg) and molar rates of intake (approximately 6.0 mg/kg/hr). Within this range, no relation between local VI response rates and drug level was found. The stimulus control revealed in cumulative records was indistinguishable from that achieved with food under these schedules, suggesting that common mechanisms may underlie the control of cocaine‐ and food‐maintained behavior.
SOCIAL INFLUENCE IN PIGEONS (COLUMBA LIVIA): THE ROLE OF DIFFERENTIAL REINFORCEMENT
Authors: Howard Maureen L. , White K. Geoffrey
Published: March 2006

Socially‐influenced learning was studied in observer pigeons that observed a demonstrator in an adjacent chamber performing a target response comprising standing on a box and pecking a key 10 times. In Experiment 1 there was no evidence for social learning in the absence of reinforcement of the observer's behavior. When the target response was already established in the observer's repertoire, but was not differentially reinforced in relation to the demonstrator's behavior, rates of extinction were not influenced by the demonstrator's behavior (Experiment 2). Reinforcement of the observer's target response in the presence of the modeled target response, and not in its absence, resulted in control of the observer's responding by the behavior of the demonstrator (Experiments 3 and 4). This control was extended in Experiment 5 to deferred responses that occurred following a delay since the demonstrator's target responses. The acquisition of social influence depended on differential reinforcement of the observer's target response, with the demonstrator's target behavior serving as the explicit discriminative stimulus.
EFFECTS OF ALTERNATIVE REINFORCEMENT ON HUMAN BEHAVIOR: THE SOURCE DOES MATTER
Authors: Madden Gregory J. , Perone Michael
Published: March 2006

Competing theories regarding the effects of delivering periodic response‐independent reinforcement (more accurately, response‐independent points exchanged for money) on a baseline rate of behavior were evaluated in human subjects. Contiguity theory holds that these events decrease target responding because incompatible behavior is adventitiously strengthened when the point deliveries follow target behavior closely in time. Matching theory holds that response‐independent points, like any other alternative reinforcer, should reduce target responding. On this view, temporal contiguity between target responding and response‐independent point delivery is unimportant. In our experiment, four different responses (moving a joystick in four different directions) were reinforced with points exchangeable for money according to four independent variable‐interval schedules. Different schedules of point delivery were then superimposed on these baselines. When all superimposed point deliveries occurred immediately after one of the four responses (the target response), time allocated to target responding increased. When the superimposed point deliveries could be delivered at any time, time allocated to target responding declined and other behavior increased. When superimposed points could never immediately follow target responses, time allocated to target responding decreased further and other behavior or pausing predominated. The findings underscore the contribution of temporal contiguity in the effects of response‐independent deliveries of food, money, points, etc.
REINFORCING STAYING AND SWITCHING WHILE USING A CHANGEOVER DELAY
Authors: MacDonall James S.
Published: March 2006

Performance on concurrent schedules can be decomposed to run lengths (the number of responses before switching alternatives), or visit durations (time at an alternative before switching alternatives), that are a function of the ratio of the rates of reinforcement for staying and switching. From this analysis, a model of concurrent performance was developed and examined in two experiments. The first exposed rats to variable‐interval schedules for staying and for switching, which included a changeover delay for reinforcers following a switch. With the changeover delay, run lengths and visit durations were functions of the ratios of the rates of reinforcement for staying and for switching, as found by previous research not using a changeover delay. The second directly assessed the effect of a changeover delay on run lengths and visit durations. Each component of a multiple schedule consisted of equivalent stay and switch schedules but only one component included a changeover delay. Run lengths and visit durations were longer when a changeover delay was used. Because visit duration is the reciprocal of changeover rate, these results are consistent with the established finding that a changeover delay reduces the frequency of switching. Together these results support the local model of concurrent performance as an alternative to the generalized matching law as a model of concurrent performance. The local model may be preferred when accounting for more molecular aspects of concurrent performance.
QUANTITATIVE ANALYSES OF MATCHING‐TO‐SAMPLE PERFORMANCE
Authors: Jones B. M.
Published: March 2006

Six pigeons performed a simultaneous matching‐to‐sample (MTS) task involving patterns of dots on a liquid‐crystal display. Two samples and two comparisons differed in terms of the density of pixels visible through pecking keys mounted in front of the display. Selections of Comparison 1 after Sample 1, and of Comparison 2 after Sample 2, produced intermittent access to food, and errors always produced a time‐out. The disparity between the samples and between the comparisons varied across sets of conditions. The ratio of food deliveries for the two correct responses varied over a wide range within each set of conditions, and one condition arranged extinction for correct responses following Sample 1. The quantitative models proposed by Davison and Tustin (1978), Alsop (1991), and Davison (1991) failed to predict performance in some extreme reinforcer‐ratio conditions because comparison choice approached indifference (and strong position biases emerged) when the sample clearly signaled a low (or zero) rate of reinforcement. An alternative conceptualization of the reinforcement contingencies operating in MTS tasks is advanced and was supported by further analyses of the data. This model relates the differential responding between the comparisons following each sample to the differential reinforcement for correct responses following that sample.
CONCURRENT SCHEDULES: REINFORCER MAGNITUDE EFFECTS
Authors: Landon Jason , Davison Michael , Elliffe Douglas
Published: March 2006

Five pigeons were trained on pairs of concurrent variable‐interval schedules in a switching‐key procedure. The arranged overall rate of reinforcement was constant in all conditions, and the reinforcer‐magnitude ratios obtained from the two alternatives were varied over five levels. Each condition remained in effect for 65 sessions and the last 50 sessions of data from each condition were analyzed. At a molar level of analysis, preference was described well by a version of the generalized matching law, consistent with previous reports. More local analyses showed that recently obtained reinforcers had small measurable effects on current preference, with the most recently obtained reinforcer having a substantially larger effect. Larger reinforcers resulted in larger and longer preference pulses, and a small preference was maintained for the larger‐magnitude alternative even after long interreinforcer intervals. These results are consistent with the notion that the variables controlling choice have both short‐ and long‐term effects. Moreover, they suggest that control by reinforcer magnitude is exerted in a manner similar to control by reinforcer frequency. Lower sensitivities when reinforcer magnitude is varied are likely to be due to equal frequencies of different sized preference pulses, whereas higher sensitivities when reinforcer rates are varied might result from changes in the frequencies of different sized preference pulses.
EFFECTS OF DIFFERENCES IN INTERREINFORCER INTERVALS BETWEEN PAST AND CURRENT SCHEDULES ON FIXED‐INTERVAL RESPONDING
Authors: Okouchi Hiroto
Published: March 2006

Undergraduates were exposed to a mixed fixed‐ratio differential‐reinforcement‐of‐low‐rate schedule. Values of the schedule components were adjusted so that interreinforcer intervals in one component were longer than those in another component. Following this, a mixed fixed‐interval 5‐s fixed‐interval 20‐s schedule (Experiment 1) or six fixed‐interval schedules in which the values ranged from 5 to 40 s (Experiment 2) were in effect. In both experiments, response rates under the fixed‐interval schedules were higher when the interreinforcer intervals approximated those produced under the fixed‐ratio schedule, whereas the rates were lower when the interreinforcer intervals approximated those produced under the different‐reinforcement‐of‐low‐rate schedule. The present results demonstrate that the effects of behavioral history were under control of the interreinforcer intervals as discriminative stimuli.
STRICT AND RANDOM ALTERNATION IN CONCURRENT VARIABLE‐INTERVAL SCHEDULES
Authors: Elliffe Douglas , Davison Michael
Published: March 2006

Six pigeons responded on pairs of concurrent variable‐interval schedules with, in different parts, four different arrangements of alternation between schedules. Following a single switching‐key response, alternation was either strict or random, and the alternative presented after a switch (the postswitch alternative) was either signaled by the location of the switching key or unsignaled. Generalized‐matching analyses showed little difference in behavior among the different alternation arrangements, except the usual finding of lower sensitivity of response allocation than time allocation was eliminated by arranging random alternation. Patterns of interchangeover times were similar for all arrangements except signaled random alternation. Differences in behavior preceding the different postswitch alternatives were found in the signaled random alternation procedure. Preference was biased towards the color of the signaled postswitch alternative and showed increased sensitivity when the postswitch alternative was to be the one with the higher reinforcer rate. Interchangeover times were substantially shorter when the postswitch alternative was signaled to be different from the current alternative than when it was signaled to be the same. However, when separate reinforcer ratios were calculated for the different postswitch alternatives, those effects were eliminated or greatly reduced. We suggest that, although behavior is indeed influenced by the postswitch alternative, the mechanism is indirect. That is, the distributions of reinforcers between alternatives obtained before each postswitch alternative differ when those alternatives are signaled, and those distributions are discriminated, but the same relations between choice and relative reinforcement hold irrespective of which postswitch alternative is signaled.
PUNISHMENT IN HUMAN CHOICE: DIRECT OR COMPETITIVE SUPPRESSION?
Authors: Critchfield Thomas S. , Paletz Elliott M. , MacAleese Kenneth R. , Newland M. Christopher
Published: March 2006

This investigation compared the predictions of two models describing the integration of reinforcement and punishment effects in operant choice. Deluty's (1976) competitive‐suppression model (conceptually related to two‐factor punishment theories) and de Villiers' (1980) direct‐suppression model (conceptually related to one‐factor punishment theories) have been tested previously in nonhumans but not at the individual level in humans. Mouse clicking by college students was maintained in a two‐alternative concurrent schedule of variable‐interval money reinforcement. Punishment consisted of variable‐interval money losses. Experiment 1 verified that money loss was an effective punisher in this context. Experiment 2 consisted of qualitative model comparisons similar to those used in previous studies involving nonhumans. Following a no‐punishment baseline, punishment was superimposed upon both response alternatives. Under schedule values for which the direct‐suppression model, but not the competitive‐suppression model, predicted distinct shifts from baseline performance, or vice versa, 12 of 14 individual‐subject functions, generated by 7 subjects, supported the direct‐suppression model. When the punishment models were converted to the form of the generalized matching law, least‐squares linear regression fits for a direct‐suppression model were superior to those of a competitive‐suppression model for 6 of 7 subjects. In Experiment 3, a more thorough quantitative test of the modified models, fits for a direct‐suppression model were superior in 11 of 13 cases. These results correspond well to those of investigations conducted with nonhumans and provide the first individual‐subject evidence that a direct‐suppression model, evaluated both qualitatively and quantitatively, describes human punishment better than a competitive‐suppression model. We discuss implications for developing better punishment models and future investigations of punishment in human choice.
EQUIVALENCE RELATIONS IN INDIVIDUALS WITH LANGUAGE LIMITATIONS AND MENTAL RETARDATION
Authors: O'Donnell Jennifer , Saunders Kathryn J.
Published: March 2006

The study of equivalence relations exhibited by individuals with mental retardation and language limitations holds the promise of providing information of both theoretical and practical significance. We reviewed the equivalence literature with this population, defined in terms of subjects having moderate, severe, or profound mental retardation. The literature includes 55 such individuals, most of whom showed positive outcomes on equivalence tests. The results to date suggest that naming skills are not necessary for positive equivalence test outcomes. Thus far, however, relatively few subjects with minimal language have been studied. Moreover, we suggest that the scientific contributions of studies in this area would be enhanced with better documentation of language skills and other subject characteristics. With recent advances in laboratory procedures for establishing the baseline performances necessary for equivalence tests, this research area is poised for rapid growth.
STIMULUS GENERALIZATION OF BEHAVIORAL HISTORY
Authors: Okouchi Hiroto
Published: March 2006

Undergraduates responded under a variable‐ratio 30 schedule in the presence of a 25‐mm long line and on a differential‐reinforcement‐of‐low‐rate 6‐s schedule when a 13‐mm long line was present. Following this, a line‐length continuum generalization test was administered under a fixed‐interval 6‐s schedule (Experiment 1) or extinction (Experiment 2). In both experiments, obtained generalization gradients conformed to typical postdiscrimination gradients. Responses were frequent under stimuli physically similar to the 25‐mm line and infrequent under stimuli physically similar to the 13‐mm line. The generalization gradients were generally asymmetric with peak response rates occurring at line lengths greater than 25 mm.
RECENCY, REPEATABILITY, AND REINFORCER RETRENCHMENT: AN EXPERIMENTAL ANALYSIS OF RESURGENCE
Authors: Lieving Gregory A. , Lattal Kennon A.
Published: March 2006

Four experiments were conducted with pigeons to assess the experimental conditions necessary for the occurrence of resurgence. The general procedure consisted of the following conditions: Condition 1—reinforcement of key pecking; Condition 2—reinforcement of treadle pressing and concurrent extinction of key pecking; and Condition 3—the resurgence condition wherein resurgence was defined as the recovery of key pecking. In Experiments 1 and 2, the resurgence condition was conventional extinction. The effect of recency on resurgence magnitude was examined in Experiment 1 by manipulating the number of sessions of Condition 2, above. Resurgence was not a function of recency with the parameters used. Repeating the three conditions revealed resurgence to be a repeatable effect in Experiment 2. In Experiment 3, a variable‐time schedule was in effect for the resurgence condition. Resurgence was not produced by response‐independent food delivery. In Experiment 4, the resurgence condition was a variable‐interval schedule for treadle pressing that arranged a lower reinforcement rate than in Condition 2 (92% reduction in reinforcers per minute). Resurgence was lower in magnitude relative to conventional extinction, although resurgence was obtained with 2 out of 3 pigeons. The results are discussed in terms of the variables controlling resurgence and the relations between behavioral history, resurgence, and other forms of response recovery.
VARIABLE‐INTERVAL REINFORCEMENT SCHEDULE VALUE INFLUENCES RESPONDING FOLLOWING REM SLEEP DEPRIVATION
Authors: Kirby Michael , Kennedy Craig H.
Published: March 2006

The effects of rapid‐eye movement sleep deprivation (REMSD) in rats were studied in relation to variable‐interval (VI) reinforcement schedule value. Initially, lever pressing was maintained on a VI 30‐s schedule of food pellet delivery. After a baseline was established, rats were repeatedly exposed to 96 hr of REMSD and control conditions of an equivalent duration. Responding decreased following REMSD but not after exposure to control conditions. Lever pressing was then maintained on a VI 15‐s schedule of food pellet delivery and exposure to the REMSD and control conditions was repeated. Under this condition following repeated REMSD exposures, rates of lever pressing became similar to baseline responding. A VI 30‐s schedule of food pellet delivery was then reinstated and REMSD and control conditions were repeated. Lever pressing following exposure to the REMSD condition decreased for 3 of 4 rats. Results suggest that VI schedule value influences the effects of REMSD on responding.
DISCRIMINATION OF DIRECTION OF MOVEMENTS IN PIGEONS FOLLOWING PREVIOUS EXPERIENCE OF MOTION/STATIC DISCRIMINATION
Authors: Goto Kazuhiro , Lea Stephen E. G.
Published: March 2006

Two experiments examined pigeons' discrimination of directional movement using pictorial images shown on computer monitors. Stimuli consisted of the movement of a bird against a stationary background or the movement of the background behind a stationary bird. In Experiment 1, pigeons were trained to discriminate either leftward or rightward motion of either the bird or the background from stationary frames drawn from the same movies. The background‐discrimination group acquired the discrimination faster than the bird‐discrimination group. In Experiment 2, transfer of the discrimination from the task of Experiment 1 to a discrimination between motion directions was examined. Most of the pigeons learned this discrimination rapidly, whereas in a pilot study in which direction discrimination was trained without previous static/movement discrimination, learning was poor. It appears that an experimental history of movement against stationary discrimination promoted the pigeons' learning of the directional motion discrimination.
ON THE FORM OF THE FORGETTING FUNCTION: THE EFFECTS OF ARITHMETIC AND LOGARITHMIC DISTRIBUTIONS OF DELAYS
Authors: Sargisson Rebecca J. , White K. Geoffrey
Published: March 2006

Forgetting functions with 18 delay intervals were generated for delayed matching‐to‐sample performance in pigeons. Delay interval variation was achieved by arranging five different sets of five delays across daily sessions. In different conditions, the delays were distributed in arithmetic or logarithmic series. There was no convincing evidence for different effects on discriminability of the distributions of different delays. The mean data were better fitted by some mathematical functions than by others, but the best‐fitting functions depended on the distribution of delays. In further conditions with a fixed set of five delays, discriminability was higher with a logarithmic distribution of delays than with an arithmetic distribution. This result is consistent with the treatment of the forgetting function in terms of generalization decrement.
SCIENCE AND HUMAN BEHAVIOR TRANSLATED INTO PORTUGUESE: CIÊNCIA E COMPORTAMENTO HUMANO
Authors: Todorov João Claudio
Published: March 2006

Science and Human Behavior was translated to Portuguese as part of the effort to begin a psychology course at the University of Brasília 40 years ago; one of the many results of the first visit of Fred S. Keller to Brazil. The book has been used continuously in undergraduate courses in Brazil since 1967.
ECONOMIC AND BIOLOGICAL INFLUENCES ON KEY PECKING AND TREADLE PRESSING IN PIGEONS
Authors: Green Leonard , Holt Daniel D.
Published: March 2006

Pigeons were studied on a two‐component multiple schedule in which the required operant was, in different conditions, biologically relevant (i.e., key pecking) or nonbiologically relevant (i.e., treadle pressing). Responding was reinforced on a variable‐interval (VI) 2‐min schedule in both components. In separate phases, additional food was delivered on a variable‐time (VT) 15‐s schedule (response independent) or a VI 15‐s schedule (response dependent) in one of the components. The addition of response‐independent food had different effects on responding depending on the operant response and on the frequency with which the components alternated. When components alternated frequently (every 10 s), all pigeons keypecked at a much higher rate during the component with the additional food deliveries, whether response dependent or independent. In comparison, treadle pressing was elevated only when the additional food was response dependent; rate of treadling was lower when the additional food was response independent. When components alternated infrequently (every 20 min), pigeons key pecked at high rates at points of transition into the component with the additional food deliveries. Rate of key pecking decreased with time spent in the 20‐min component when the additional food was response independent, whereas rate of pecking remained elevated in that component when the additional food was response dependent. Under otherwise identical test conditions, rate of treadle pressing varied only as a function of its relative rate of response‐dependent reinforcement. Delivery of response‐independent food thus had different, but predictable, effects on responding depending on which operant was being studied, suggesting that animal‐learning procedures can be integrated with biological considerations without the need to propose constraints that limit general laws of learning.
EVERY REINFORCER COUNTS: REINFORCER MAGNITUDE AND LOCAL PREFERENCE
Authors: Davison Michael , Baum William M.
Published: March 2006

Six pigeons were trained on concurrent variable‐interval schedules. Sessions consisted of seven components, each lasting 10 reinforcers, with the conditions of reinforcement differing between components. The component sequence was randomly selected without replacement. In Experiment 1, the concurrent‐schedule reinforcer ratios in components were all equal to 1.0, but across components reinforcer‐magnitude ratios varied from 1:7 through 7:1. Three different overall reinforcer rates were arranged across conditions. In Experiment 2, the reinforcer‐rate ratios varied across components from 27:1 to 1:27, and the reinforcer‐magnitude ratios for each alternative were changed across conditions from 1:7 to 7:1. The results of Experiment 1 replicated the results for changing reinforcer‐rate ratios across components reported by Davison and Baum (2000, 2002): Sensitivity to reinforcer‐magnitude ratios increased with increasing numbers of reinforcers in components. Sensitivity to magnitude ratio, however, fell short of sensitivity to reinforcer‐rate ratio. The degree of carryover from component to component depended on the reinforcer rate. Larger reinforcers produced larger and longer postreinforcer preference pulses than did smaller reinforcers. Similar results were found in Experiment 2, except that sensitivity to reinforcer magnitude was considerably higher and was greater for magnitudes that differed more from one another. Visit durations following reinforcers measured either as number of responses emitted or time spent responding before a changeover were longer following larger than following smaller reinforcers, and were longer following sequences of same reinforcers than following other sequences. The results add to the growing body of research that informs model building at local levels.
REPEATED POST‐ OR PRESESSION COCAINE ADMINISTRATION: ROLES OF DOSE AND FIXED‐RATIO SCHEDULE
Authors: Pinkston Jonathan W. , Branch Marc N.
Published: March 2006

Effects of repeated administration of cocaine to animals behaving under operant contingencies have depended on when the drug is given. Moderate doses given presession have generally led to a decrease in the drug's effect, an outcome usually referred to as tolerance. When these same doses have been given after sessions, the usual result has been no change or an increase in the drug's effects, with the latter usually referred to as sensitization. In the present study, repeated postsession administration of a relatively small dose of cocaine (3.0 or 5.6 mg/kg) to pigeons responding under a multiple fixed‐ratio 5, fixed‐ratio 100 schedule of food presentation generally resulted in tolerance to the rate‐decreasing effects of the drug. When the same dose was given before sessions, little additional tolerance was observed, although some subjects showed further tolerance in the small‐ratio component. A regimen of repeated postsession injection of larger (10.0–23.0 mg/kg) doses suppressed key pecking during the session; responding resumed following discontinuation of postsession administrations. Effects of postsession administration of cocaine, therefore, depended on the dose, with smaller doses leading to tolerance and larger ones to suppression of behavior during the session. Effects of postsession drug administration of either small or large doses were not related to whether effects of postsession drug were experienced mainly in the operant test chamber or in the pigeon's home cage. The results with large postsession doses are compatible with a view that the drug acted as a Pavlovian unconditional stimulus, with the session‐related stimuli acting as a long‐duration Pavlovian conditional stimulus. Tolerance following postsession administration of the smaller doses challenges the view that it depended on experiencing the drug's effects while the arranged reinforcement contingencies were in effect.
TEMPORAL CONTEXT IN CONCURRENT CHAINS: I. TERMINAL‐LINK DURATION
Authors: Grace Randolph C.
Published: March 2006

Two experiments are reported in which the ratio of the average times spent in the terminal and initial links (Tt/Ti) in concurrent chains was varied. In Experiment 1, pigeons responded in a three‐component procedure in which terminal‐link variable‐interval schedules were in constant ratio, but their average duration increased across components by a factor of two. The log initial‐link response ratio was a negatively accelerated function of Tt/Ti. Overall, the data were well described by Grace's (1994) contextual choice model (CCM) with temporal context represented as (Tt/Ti)k or 2Tt/(Tt + Ti), and by Mazur's (2001) hyperbolic value‐added model (HVA), with each model accounting for approximately 93% of the variance. In Experiment 2, fixed‐parameter predictions for each model were generated, based on the data from Experiment 1, for conditions in which Tt/Ti was varied over a more extreme range. Data were consistent with the predictions of CCM with temporal context represented as 2Tt/(Tt 1 Ti) and to a lesser extent as (Tt/Ti)k, but not with HVA. Overall, these results suggest that preference increases as a hyperbolic function of Tt/Ti when terminal‐link duration is increased relative to initial‐link duration, with the terminal‐link schedule ratio held constant.
FUNCTION TRANSFER IN HUMAN OPERANT EXPERIMENTS: THE ROLE OF STIMULUS PAIRINGS
Authors: Tonneau François , González Carmen
Published: March 2006

Although function transfer often has been studied in complex operant procedures (such as matching to sample), whether operant reinforcement actually produces function transfer in such settings has not been established. The present experiments, with high school students as subjects, suggest that stimulus pairings can promote function transfer in conditions that closely approximate those of matching to sample. In Experiment 1, the subjects showed transfer of operant responding from three geometric figures (C1, C2, C3) to three colored shapes (B1, B2, B3) when the latter were paired with the former. Experiment 2 involved two groups of subjects. In the matching group, subjects matched the colored shapes with the geometric figures; in the yoked group, the shapes were merely paired with the geometric figures, and the schedule of stimulus pairing was yoked to the performance of the subjects in the matching group. Both groups of subjects showed function transfer. Experiment 3 documented function transfer from C stimuli to B stimuli through indirect stimulus pairings (A—B, A—C). In Experiment 4, function transfer was obtained even though the subjects vocalized continuously during the pairing trials, presumably preventing covert verbalization that might mediate transfer effects. Our results are consistent with a Pavlovian account and raise difficulties for current operant theories of function transfer.
THE RELATION BETWEEN STIMULUS FUNCTION AND EQUIVALENCE CLASS FORMATION
Authors: Tyndall Ian T. , Roche Bryan , James Jack E.
Published: March 2006

Fifty participants were exposed to a simple discrimination‐training procedure during which six S+ functions were established for six arbitrary stimuli, and S2 functions were established for a further six stimuli. Following this training, each participant was exposed to one of five conditions. In the S+ condition, participants were exposed to a stimulus equivalence training and testing procedure using only the six S+ stimuli as samples and comparisons. In the S+/S‐ condition, participants were exposed to the same training and testing sequence as in the S+ condition, the difference being that three S+ and three S‐ stimuli were used as sample and comparison stimuli, with each set of three corresponding to the trained equivalence relations. In the S+/S‐ mixed condition, the S+ and S‐ stimuli were assigned to their roles as samples and comparisons in a quasi‐random order. In the S‐ condition, all six S‐ stimuli were used. The no‐function condition served as a control condition and employed stimuli for which no stimulus‐control functions had been established. The results showed that, on average, participants required more testing trials to form equivalence relations when the stimuli involved were functionally similar rather than functionally different. Moreover, participants required more test trials to form equivalence relations when novel arbitrary stimuli, rather than functionally distinct stimuli, were used as samples and comparisons. The speed of acquisition of stimulus equivalence was also related to the number of functionally similar stimuli established before training. These findings indicate a variety of ways in which the emergence of equivalence relations is affected by the functional classes in which the relevant stimuli participate.