bluuebunny/crossref_metadata_2025 huggingface dataset:
DISSECTING THE CONDITIONED PECKING RESPONSE: AN INTEGRATED SYSTEM FOR THE ANALYSIS OF PECKING RESPONSE PARAMETERS
Authors: Bermejo Roberto , Houben Dirk , Zeigler H. Philip
Published: March 2006

The conventional pecking response key, although an excellent transducer of response rate, can provide minimal information on the topography, coordination, or localization of conditioned pecking. We describe the hardware and software components of a system that, in addition to recording response rates, permits simultaneous “on‐line” monitoring of head acceleration, jaw movement, terminal peck location, and duration of pecking response. Head movements are monitored with a miniature accelerometer, jaw movements with a magnetosensitive transducer, and peck location with modified touch screen technology. Initial experiments with the system suggest that it will be useful in studies of response differentiation, acquisition and maintenance of complex discriminations, and interaction of conditioned and unconditioned stimuli in the control of pecking response probability and response topography.
DRINKING IN A PATCHY ENVIRONMENT: THE EFFECT OF THE PRICE OF WATER
Authors: Collier George , Johnson Deanne F. , Borin Gabrielle , Mathis Carl E.
Published: March 2006

Rats in a laboratory foraging paradigm searched for sequential opportunities to drink in two water patches that differed in the bar‐press price of each “sip” (20 licks) of water within a bout of drinking (Experiment 1) or the price and size (10, 20, or 40 licks) of each sip (Experiment 2). Total daily water intake was not affected by these variables. The rats responded faster at the patch where water was more costly. However, they accepted fewer opportunities to drink, and thus had fewer drinking bouts, and drinking bouts were smaller at the more costly patch than at the other patch. This resulted in the rats consuming a smaller proportion of their daily water from the more costly patch. The size of the differences in bout frequency and size between the patches appears to be based on the relative cost of water at the patches. The profitability of each patch was calculated in terms of the return (in milliliters) on either effort (bar presses) or time spent there. Although both measures were correlated with the relative total intake, bout size, and acceptance of opportunities at each patch, the time‐based profitability was the better predictor of these intake measures. The rats did not minimize bar‐press output; however, their choice between the patches and their bout sizes within patches varied in a way that reduced costs compared to what would have been expended drinking randomly. These data accord well with similar findings for choices among patches of food, suggesting that foraging for water and food occurs on the basis of comparable benefit‐cost functions: In each case, the amount consumed is related to the time spent consuming.
LEAVING PATCHES: EFFECTS OF TRAVEL REQUIREMENTS
Authors: McCarthy Dianne , Voss Philip , Davison Michael
Published: March 2006

Five pigeons were trained in an analogue foraging procedure in which, by completing a travel requirement, they entered a “patch” in which a reinforcer might be available after an unpredictable time. They also had the opportunity, by emitting a defined response, to exit the patch and travel to another patch. Prey availability in a patch was not signaled. Data were collected on the length of time that subjects stayed in patches before exiting (residence times) as a function of various travel requirements: travel for a fixed time in blackout, fixed‐interval schedule traveling, fixed‐time traveling with an added response required to terminate traveling, and fixed‐ratio traveling. For each of these conditions, the required amount of travel (time or responses) was varied over a wide range. As previously reported, residence times increased with increases in fixed‐time traveling, as they did with increasing fixed‐interval or fixed‐ratio traveling. There was no evidence that adding response or work requirements systematically affected residence time except via increased travel time, although 3 of the 5 birds stayed longer in a patch under higher fixed‐ratio values. A “threshold‐maximization” model described the data well with a single parameter that was consistent across subjects, procedures, and experiments.
EXCHANGE DELAYS AND IMPULSIVE CHOICE IN ADULT HUMANS
Authors: Hyten Cloyd , Madden Gregory J. , Field Douglas P.
Published: March 2006

Choice responding by adult humans in a discrete‐trial task was examined as a function of conditions that manipulated either the delay to point delivery or the delay between points and their exchange for money. In point‐delay conditions, subjects chose between an “impulsive” alternative that provided a small amount of points immediately and a “self‐control” alternative that provided a larger amount of points delayed by 15, 30, or 60 s. Points were exchanged for money immediately following the session. Subjects preferred the self‐control alternative. In exchange‐delay conditions, subjects chose between a small amount of points exchangeable for money immediately following the session and a larger amount of points exchangeable for money after 1 day, 3 weeks, or 6 weeks. A self‐control preference observed for all subjects in the 1‐day exchange‐delay condition reversed to exclusive impulsive preference for 4 of the 6 subjects when choice conditions involved exchange delays of 3 or 6 weeks. These results show that human choice is sensitive to the manipulation of exchange delays and that impulsive preference can be obtained with exchange delays on the order of weeks.
EFFECTS OF DIFFERENT ACCESSIBILITY OF REINFORCEMENT SCHEDULES ON CHOICE IN HUMANS
Authors: Stockhorst Ursula
Published: March 2006

Based on the delay‐reduction hypothesis, a less profitable schedule should be rejected if its duration exceeds the mean delay to reinforcement. It should be accepted if its duration is shorter than the mean delay. This was tested for humans, using a successive‐choice schedule. The accessibility of the less profitable (variable‐interval 18 s) schedule was varied by changing the duration (in terms of a fixed interval) of the waiting‐time component preceding its presentation. Forty‐eight students were randomly assigned to three groups. In Phase 1, the duration of the less profitable schedule equaled the mean delay to reinforcement in all groups. In Phase 2, waiting time preceding the less profitable schedule was reduced in Group 1 and increased in Group 2. Thus, the schedule was correlated either with a relative delay increase (Group 1) or a delay reduction (Group 2). In Group 3, conditions remained unchanged. As predicted, acceptance of the less profitable schedule decreased in Group 1 and increased in Group 2. The increased acceptance in Group 2 was accompanied by a decreased acceptance of the more profitable (variable‐interval 3 s) schedule, resembling a pattern of negative contrast. Response rates were higher under the component preceding (a) the more profitable schedule in Group 1 and (b) the less profitable schedule in Group 2. Implications for the modification of human choice behavior are discussed.
DOES PACKAGE SIZE MATTER? A UNIT‐PRICE ANALYSIS OF “DEMAND” FOR FOOD IN BABOONS
Authors: Foltin Richard W.
Published: March 2006

In a study examining “demand” for food, responding of 8 adult male baboons (Papio c. anubis) was maintained under a fixed‐ratio schedule of food reinforcement during daily 23‐hr experimental sessions. Completion of the ratio requirement resulted in the delivery of one, five, or 10 1‐g food pellets. Supplemental feeding was limited to fruit and a dog biscuit daily. Responding increased as “cost” was increased across a wide range of fixed‐ratio values before reaching a maximum and then decreasing. Increasing the number of food pellets per delivery decreased total responding and the number of reinforcements per day. A unit‐price analysis, in which intake was converted to grams per day and fixed‐ratio values were converted to responses per gram, yielded demand functions that overlapped at lower unit prices. Under one or more multiple‐pellet conditions, however, intake decreased more quickly than under the one‐pellet condition as the fixed‐ratio value was increased in all but 1 baboon. This indicates that even when using unit‐price conversions, there was variability in total intake. Although unit‐price conversions yielded intake data that were more consistent across conditions, conditions differed in response topography even at the same unit prices: Under the multiple‐pellet conditions there were longer pauses in responding, running response rate was slower, and the first eating bout (i.e., “meal”) of the session was smaller than under the one‐pellet condition. These findings (a) support the heuristic value of a unit‐price analysis for studying responding for and consumption of commodities that have similar attributes, and (b) indicate that different response topographies may result in similar intakes of a commodity.
THE TRANSFER OF RESPONDENT ELICITING AND EXTINCTION FUNCTIONS THROUGH STIMULUS EQUIVALENCE CLASSES
Authors: Dougher Michael J. , Augustson Erik , Markham Michael R. , Greenway David E. , Wulfert Edelgard
Published: March 2006

Two studies investigated the transfer of respondent elicitation through equivalence classes. In Experiment 1, match‐to‐sample procedures were used to teach 8 subjects two four‐member equivalence classes. One member of one class was then paired with electric shock, and one member of the other class was presented without shock. All remaining stimuli were then presented. Using skin conductance as the measure of conditioning, transfer of conditioning was demonstrated in 6 of the 8 subjects. In Experiment 2, similar procedures were used to replicate the results of Experiment 1 and investigate the transfer of extinction. Following equivalence training and conditioning to all members of one class, one member was then presented in extinction. When the remaining stimuli from this class were then presented, they failed to elicit skin conductance. In the final phase of the experiment, the stimulus that was previously presented in extinction was reconditioned. Test trials with other members of the class revealed that they regained elicitation function. These results demonstrate that both respondent elicitation and extinction can transfer through stimulus classes. The clinical and applied significance of the results is discussed.
FORMATION OF TRANSITIVITY IN CONDITIONAL MATCHING TO SAMPLE BY PIGEONS
Authors: Kuno Hiromichi , Kitadate Tsutomu , Iwamoto Takashige
Published: March 2006

Four homing pigeons were trained over 5 months in a zero‐delay, “arbitrary” matching‐to‐sample procedure with sample and comparison stimuli presented on any of three response keys. Birds were also required to complete a fixed‐ratio 10 requirement on both sample and comparison stimuli to terminate their presentation. The procedure resulted in the establishment of relations that were not specifically trained and that can be characterized by the property of transitivity in a stimulus equivalence context. This result was in contrast with the findings obtained from most previous research with nonhuman subjects.
REVERSAL OF BASELINE RELATIONS AND STIMULUS EQUIVALENCE: II. CHILDREN
Authors: Pilgrim Carol , Chambers Lori , Galizio Mark
Published: March 2006

In a systematic replication of a study using college‐student subjects (Pilgrim & Galizio, 1990), 5‐ to 7‐year‐old children learned two conditional discriminations (i.e., A1B1, A2B2, A1C1, and A2C2) in a two‐choice arbitrary match‐to‐sample task and showed the emergence of two three‐member equivalence classes (A1B1C1 and A2B2C2). Baseline conditional discrimination performances were quickly controlled by reversals of the AC reinforcement contingencies (i.e., choosing Comparison Stimulus C2 was reinforced given Sample A1, and choosing C1 was reinforced given Sample A2) when the reversals were introduced in restricted baselines. On reflexivity, symmetry, and transitivity/equivalence probes following the reversal, there was some limited indication of equivalence‐class reorganization (i.e., A1B1C2 and A2B2C1) in keeping with the concurrently performed baseline relations for 2 of 5 subjects, but the predominant pattern across probe trials was one of inconsistent conditional control. These findings suggest that, given similar challenges, equivalence‐class performances may be more easily disrupted in young children than in adults.
INDEPENDENCE OF REINFORCEMENT DELAY AND MAGNITUDE IN CONCURRENT CHAINS
Authors: Grace Randolph C.
Published: March 2006

A three‐component concurrent‐chains procedure was used to investigate preference between terminal‐link schedules that differed in delay and magnitude of reinforcement. Response and time allocation data were well described by a generalized matching model. Sensitivity to delay appeared to be lower when reinforcement magnitudes were unequal than when they were equal, but when obtained rather than programmed time spent responding in the initial links was used in the model, the difference vanished. The results support independence of delay and magnitude as separate dimensions of reinforcement value, as required by the matching law, and the assumption of the contextual choice model (Grace, 1994) that sensitivities to delay and magnitude are affected similarly by temporal context. Although there was statistical evidence for interaction between successive components, the effects were small and transient. The multiple‐component concurrent‐chains procedure should prove useful in future research on multidimensional preference, although it may be necessary to control obtained initial‐link time more precisely.
PREFERENCES FOR FIXED AND VARIABLE FOOD SOURCES: VARIABILITY IN AMOUNT AND DELAY
Authors: Bateson Melissa , Kacelnik Alex
Published: March 2006

Much research has focused on the effects of environmental variability on foraging decisions. However, the general pattern of preference for variability in delay to reward and aversion to variability in amount of reward remains unexplained at either a mechanistic or a functional level. Starlings' preferences between a fixed and a variable option were studied in two treatments, A and D. The fixed option was the same in both treatments (20‐s fixed‐interval delay, five units food). In Treatment A the variable option gave two equiprobable amounts of food (20‐s delay, three or seven units) and in D it gave two equiprobable delays to food (2.5‐s or 60.5‐s delays, five units). In both treatments the programmed ratio [amount/(intertrial interval + latency + delay)] in the fixed option equaled the arithmetic mean of the two possible ratios in the variable option (ITI = 40 s, latency = 1 s). The variable option was strongly preferred in Treatment D and was weakly avoided in Treatment A. These results are discussed in the light of two theoretical models, a form of constrained rate maximization and a version of scalar expectancy theory. The latter accommodates more of the data and is based on independently verifiable assumptions, including Weber's law.
SOFT COMMITMENT: SELF‐CONTROL ACHIEVED BY RESPONSE PERSISTENCE
Authors: Siegel Eric , Rachlin Howard
Published: March 2006

With reinforcement contingent on a single peck on either of two available keys (concurrent continuous reinforcement schedules) 4 pigeons, at 80% of free‐feeding weights, preferred a smaller‐sooner reinforcer (2.5 s of mixed grain preceded by a 0.5‐s delay) to a larger‐later reinforcer (4.5 s of mixed grain preceded by a 3.5‐s delay). However, when the smaller‐sooner and larger‐later reinforcers were contingent on a concurrent fixed‐ratio 31 schedule (the first 30 pecks distributed in any way on the two keys), all pigeons obtained the larger‐later reinforcer much more often than they did when only a single peck was required. This “self‐control” was achieved by beginning to peck the key leading to the larger‐later reinforcer and persisting on that key until reinforcement occurred. We call this persistence “soft commitment” to distinguish it from strict commitment, in which self‐control is achieved by preventing changeovers. Soft commitment also effectively achieved self‐control when a brief (1‐s) signal was inserted between the 30th and 31st response of the ratio and with concurrent fixed‐interval 30‐s schedules (rather than ratio schedules) of reinforcement. In a second experiment with the same subjects, the fixed ratio was interrupted by darkening both keys and lighting a third (center) key on which pecking was required for various fractions of the fixed‐ratio count. The interruption significantly reduced self‐control. When interruption was complete (30 responses on the center key followed by a single choice response), pigeons chose the smaller‐sooner reinforcer as frequently as they did when only a single choice response was required.
MAINTAINED NODAL‐DISTANCE EFFECTS IN EQUIVALENCE CLASSES
Authors: Fields Lanny , Landon‐Jimenez Donna V. , Buffington Dawn M. , Adams Barbara J.
Published: March 2006

Twelve subjects were trained to select one of two stimuli from a pair (the B pair) when presented with one of two stimuli from another pair (the A pair), thus establishing two AB relations, A1‐B1 and A2‐B2. In a similar fashion, additional stimuli were used to establish BC, CD, and DE relations. Trials used to train all relations occurred in each session. Once performances were established, probe trials were introduced that tested for the emergence of untrained relations (e.g., B1‐D1 or A1‐E1). These emergent relations were categorized according to nodal distance (i.e., the number of stimuli across which transitivity would have to hold in order for the relation to emerge). For example, a test for A2‐C2 crosses one node (B2), whereas a test for A1‐E1 crosses three nodes (B1, C1, and D1). Only 2 of the subjects formed equivalence classes. The evocation of class‐appropriate responding by each emergent‐relation probe was an inverse function of nodal distance for all 12 subjects. In addition, performance on the originally trained relations was disrupted by the introduction of probes. The 2 subjects who exhibited equivalence classes were then trained to make different numbers of key presses in the presence of each of the four A and E stimuli. In a response‐transfer test, the B, C, and D stimuli evoked the responses trained to the A and E stimuli in the same equivalence class. Likelihood of class‐appropriate responses was an inverse function of nodal distance, and this pattern persisted across testing. Reaction times in the transfer test were an inverted U‐shaped function of nodal distance. Because training of the baseline relations occurred concurrently and the B, C, and D stimuli were presented an equal number of times before the transfer test, the test performances illustrate effects of nodal distance that were not confounded by order or amount of experience with the stimuli. The results imply that ordered, sequential exposure to individual stimulus relations may facilitate the development of equivalence classes and that the relatedness of stimuli within an equivalence class is a relatively permanent inverse function of nodal distance.
BIASING THE PACEMAKER IN THE BEHAVIORAL THEORY OF TIMING
Authors: Bizo Lewis A. , White K. Geoffrey
Published: March 2006

In the behavioral theory of timing, pacemaker rate is determined by overall rate of reinforcement. A two‐alternative free‐operant psychophysical procedure was employed to investigate whether pacemaker period was also sensitive to the differential rate of reinforcement. Responding on a left key during the first 25 s and on a right key during the second 25 s of a 50‐s trial was reinforced at variable intervals, and variable‐interval schedule values during the two halves of the trials were varied systematically. Responding on the right key during the first 25 s and on the left key during the second 25 s was not reinforced. Estimates of pacemaker period were derived from fits of a function predicted by the behavioral theory of timing to right‐key response proportions in consecutive 5‐s bins of the 50‐s trial. Estimates of pacemaker period were shortest when the differential reinforcer rate most strongly favored right‐key responses, and were longest when the differential reinforcer rate most strongly favored left‐key responses. The results were consistent with the conclusion that pacemaker rate is influenced by relative reinforcer rate.
DISCOUNTING OF DELAYED REWARDS: MODELS OF INDIVIDUAL CHOICE
Authors: Myerson Joel , Green Leonard
Published: March 2006

The present paper addresses the question of the form of the mathematical relation between the time until a delayed reward and its present value. Data are presented from an experiment in which subjects chose between hypothetical amounts of money available either immediately or after a delay (Green, Fry, & Myerson, 1994). Analyses of the behavior of individual young adults demonstrated that temporal discounting is better described by hyperbola‐like functions than by exponential decay functions. For most individuals, the parameter that determines the rate of discounting varied inversely with amount. Raising the denominator of the discounting function to a power resulted in better descriptions of the data from most subjects. Two possible derivations of the temporal discounting function are proposed, a repeated choice model and an expected value model. These provide theoretical interpretations for amount‐dependent discounting but amount‐independent exponent parameters.
SELF‐CONTROL AND IMPULSIVENESS IN CHILDREN AND ADULTS: EFFECTS OF FOOD PREFERENCES
Authors: Forzano L. B. , Logue A. W.
Published: March 2006

Experiment 1 used 6 preschool boys and Experiment 2 used 6 adult women to explore the effects of food preference on humans' choice in self‐control paradigms. The boys showed a higher proportion of responses for more delayed, larger reinforcers (a measure of self‐control) when those choices resulted in receipt of the most preferred food compared to when those choices resulted in the least preferred food. Further, the boys chose the less delayed, smaller reinforcers significantly more often when only those choices, as opposed to both choices, resulted in the most preferred food. Conversely, they chose the more delayed, larger reinforcers significantly more often when only those choices, as opposed to both choices, resulted in the most preferred food. Finally, the women demonstrated significantly less sensitivity to reinforcer amount relative to sensitivity to reinforcer delay (another measure of self‐control) when they had a higher preference for the juice received as the less delayed, smaller reinforcer than for the juice received as the more delayed, larger reinforcer. Together, the results show that subjects' food preferences can influence self‐control for food reinforcers.
BEHAVIORAL ECONOMICS AND BEHAVIORAL MOMENTUM
Authors: Nevin John A.
Published: March 2006

Some relations between elasticity of demand and the conditions of reinforcement are reanalyzed in terms of resistance to change, in ways suggested by the metaphor of behavioral momentum; some relations between resistance to change and the conditions of reinforcement are reanalyzed in terms of elasticity of demand, in ways suggested by behavioral economics. In addition, some data on labor supply in relation to variable‐ratio schedules and alternative reinforcement are reanalyzed in terms of resistance to change and compared with steady‐state resistance data for performance on multiple and concurrent interval schedules. The results of these studies can be summarized by two functions based on the behavioral momentum approach, relating relative behavioral mass to relative reinforcement per response or per unit time. The former is a relation between relative unit price and relative behavioral mass, suggesting the possibility of convergent measurement of a theoretical construct common to both approaches. However, the momentum and economic approaches differ fundamentally on whether it is preferable to construe discriminated operant behavior as selected and strengthened by its consequences or as part of a behavior‐consequence bundle that maximizes utility.
ECONOMICS, ECOLOGICS, AND MECHANICS: THE DYNAMICS OF RESPONDING UNDER CONDITIONS OF VARYING MOTIVATION
Authors: Killeen Peter R.
Published: March 2006

The mechanics of behavior developed by Killeen (1994) is extended to deal with deprivation and satiation and with recovery of arousal at the beginning of sessions. The extended theory is validated against satiation curves and within‐session changes in response rates. Anomalies, such as (a) the positive correlation between magnitude of an incentive and response rates in some contexts and a negative correlation in other contexts and (b) the greater prominence of incentive effects when magnitude is varied within the session rather than between sessions, are explained in terms of the basic interplay of drive and incentive motivation. The models are applied to data from closed economies in which changes of satiation levels play a key role in determining the changes in behavior. Relaxation of various assumptions leads to closed‐form models for response rates and demand functions in these contexts, ones that show reasonable accord with the data and reinforce arguments for unit price as a controlling variable. The central role of deprivation level in this treatment distinguishes it from economic models. It is argued that traditional experiments should be redesigned to reveal basic principles, that ecologic experiments should be redesigned to test the applicability of those principles in more natural contexts, and that behavioral economics should consist of the applications of these principles to economic contexts, not the adoption of economic models as alternatives to behavioral analysis.
COCAINE AND FOOD DEPRIVATION: EFFECTS ON FOOD‐REINFORCED FIXED‐RATIO PERFORMANCE IN PIGEONS
Authors: Hughes Christine E. , Pitts Raymond C. , Branch Marc N.
Published: March 2006

Key pecking by 6 pigeons was maintained by a fixed‐ratio 30 schedule of food presentation while body weights were 80% of free‐feeding weights. Acute administration of cocaine (0.3 to 13.0 mg/kg, i.m.) dose‐dependently decreased response rates. Dose‐effect curves were shifted to the right when 3 of the 6 pigeons were maintained at 70% of free‐feeding weights and were shifted to the left when the other 3 pigeons were maintained at 90% of free‐feeding weights. Then a dose of cocaine that initially decreased response rates by more than 95% of control rates was administered before each daily session. Comparable degrees of tolerance to these rate‐decreasing effects developed in the two groups. The rate at which responding recovered was relatively rapid for pigeons in the 70% free‐feeding‐weight group and was slower for 2 of the 3 pigeons in the 90% free‐feeding‐weight group. When body weights were then increased from 70% to 80% or were decreased from 90% to 80% of free‐feeding weight, performance was disrupted initially only for pigeons whose weight went from 70% to 80% of free feeding. In the present experiment the degree of deprivation may have indirectly influenced the degree of tolerance that developed to cocaine's response rate‐decreasing effects because it directly influenced the dose chosen to be administered chronically. The degree of deprivation appeared to have a more direct influence on the rate at which tolerance developed.
PROCRASTINATION BY PIGEONS: PREFERENCE FOR LARGER, MORE DELAYED WORK REQUIREMENTS
Authors: Mazur James E.
Published: March 2006

In three experiments, pigeons chose between alternatives that required the completion of a small ratio schedule early in the trial or a larger ratio schedule later in the trial. Completion of the ratio requirement did not lead to an immediate reinforcer, but simply allowed the events of the trial to continue. In Experiment 1, the ratio requirements interrupted periods in which food was delivered on a variable‐time schedule. In Experiments 2 and 3, each ratio requirement was preceded and followed by a delay, and only one reinforcer was delivered, at the end of each trial. Two of the experiments used an adjusting‐ratio procedure in which the ratio requirement was increased and decreased over trials so as to estimate an indifference point—a ratio size at which the two alternatives were chosen about equally often. These experiments found clear evidence for “procrastination”—the choice of a larger but more delayed response requirement. In some cases, subjects chose the more delayed ratio schedule even when it was larger than the more immediate alternative by a factor of four or more. The results suggest that as the delay to the start of a ratio requirement is increased, it has progressively less effect on choice behavior, in much the same way that delaying a positive reinforcer reduces it effect on choice.
VERBAL SELF‐REPORTS OF EMERGENT RELATIONS IN A STIMULUS EQUIVALENCE PROCEDURE
Authors: Lane Scott D. , Critchfield Thomas S.
Published: March 2006

During a preliminary training phase, college students were taught to categorize each of their responses accurately in a conditional discrimination task as either correct or incorrect. Next, in the absence of self‐reports, subjects acquired conditional discriminations (involving novel stimuli) prerequisite to the formation of two four‐member equivalence classes. The self‐report procedure was reinstated during probe sessions that tested for untrained relations indicative of equivalence class formation. Interspersed trials involving trained relations provided a positive control, and trials with no class‐consistent comparison provided a negative control. Eight of 10 subjects demonstrated equivalence class formation; all accurately reported their performance on trained relations and on trials with no class‐consistent comparison. Subjects also reported their performance on most untrained (emergent) relations accurately, but in several instances self‐reports indicated failure or uncertainty despite nearly perfect emergent‐relations performance. These inconsistencies add to a growing body of literature that suggests there are differences between individual types of emergent relations. We sugggest that the present procedure may be helpful in understanding these differences and other equivalence‐related effects.
EFFECTS OF COCAINE ON BRIEFLY SIGNALED VERSUS COMPLETELY SIGNALED DELAYS TO REINFORCEMENT
Authors: Walker Diana J. , Branch Marc N.
Published: March 2006

Key pecking by 4 pigeons was maintained by a multiple schedule consisting of two variable‐interval 60‐s schedules wherein each food presentation followed a nonresetting 27‐s delay that was either briefly signaled at its outset or completely signaled. Brief‐signal duration was adjusted so that response rates maintained by the briefly and completely signaled delays of reinforcement were similar. In general, acute administration of small to intermediate doses (0.3 to 3.0 mg/kg) of cocaine produced either small increases in response rates in both components or no change, and larger doses (5.6 to 13.0 mg/kg) decreased response rates. Chronic (i.e., daily) cocaine administration (10.0 mg/kg) resulted in tolerance to the rate‐decreasing effects in both components. Cocaine's effects were generally similar whether delays were completely or briefly signaled. Discontinuation of cocaine administration and subsequent removal of the delay signals also had similar effects in both components of the multiple schedule. Taken together, these results are consistent with the view that the two types of delay signals were equally effective in maintaining responding during the variable‐interval schedules.
DIFFERENCES IN THE EFFECT OF PAVLOVIAN CONTINGENCIES UPON BEHAVIORAL MOMENTUM USING AUDITORY VERSUS VISUAL STIMULI
Authors: Mauro Benjamin C. , Mace F. Charles
Published: March 2006

We examined the role of Pavlovian and operant relations in behavioral momentum by arranging response‐contingent alternative reinforcement in one component of a three‐component multiple concurrent schedule with rats. This permitted the simultaneous arranging of different response—reinforcer (operant) and stimulus—reinforcer (Pavlovian) contingencies during three baseline conditions. Auditory or visual stimuli were used as discriminative stimuli within the multiple concurrent schedules. Resistance to change of a target response was assessed during a single session of extinction following each baseline condition. The rate of the target response during baseline varied inversely with the rate of response‐contingent reinforcement derived from a concurrent source, regardless of whether the discriminative stimuli were auditory or visual. Resistance to change of the target response, however, did depend on the discriminative‐stimulus modality. Resistance to change in the presence of visual stimuli was a positive function of the Pavlovian contingencies, whereas resistance to change was unrelated to either the operant or Pavlovian contingencies when the discriminative stimuli were auditory. Stimulus salience may be a factor in determining the differences in resistance to change across sensory modalities.
SUBSTITUTION AND CALORIC REGULATION IN A CLOSED ECONOMY
Authors: Bauman Richard A. , Raslear Thomas G. , Hursh Steven R. , Shurtleff David , Simmons Laurence
Published: March 2006

Three experiments were conducted to study the effect of an imperfect substitute for food on demand for food in a closed economy. In Experiments 1 and 2, rats pressed a lever for their entire daily food ration, and a fixed ratio of presses was required for each food pellet. In both experiments, the fixed ratio was held constant during a daily session but was increased between sessions. The fixed ratio was increased over a series of daily sessions once in the absence of concurrently available sucrose and again when sucrose pellets were freely available. For both series, increases in the fixed ratio reduced food intake, but body weight was reduced only in the no‐sucrose condition. In the sucrose condition, body weight and total caloric intake (sucrose plus food) were relatively unaffected by increases in the fixed ratio. At all fixed ratios, food intake was proportionally reduced by the intake of sucrose. In Experiment 3, monkeys obtained food or saccharin by pressing keys; the fixed ratio of presses per food pellet was increased once when tap water was each monkey's only source of fluid, again when each monkey's water was sweetened with saccharin, and a third time when each monkey had concurrent access to the saccharin solution and plain water. Increases in the fixed ratio, but not the intake of the saccharin solution, reduced each monkey's food intake. Because neither rats' sucrose nor monkeys' saccharin intakes affected the slope of the respective demand curves for food, monkeys and rats increased their daily output of presses and thereby defended their daily intake of those complementary elements of food. However, sucrose reduced rats' food intake. The relative constancy of body weight and total caloric intake in the sucrose condition is consistent with the possibility that rats tended to regulate caloric intake.
CONCURRENT CHOICE: EFFECTS OF OVERALL REINFORCER RATE AND THE TEMPORAL DISTRIBUTION OF REINFORCERS
Authors: Elliffe Douglas , Alsop Brent
Published: March 2006

Six pigeons responded on a series of concurrent exponential variable‐interval schedules, offering a within‐subject comparison with previously published data from concurrent arithmetic variable‐interval schedules. Both relative and overall reinforcer rates were varied between conditions. The generalized matching law described the data well, with undermatching much more frequent than strict matching. Time‐allocation sensitivity consistently exceeded response‐allocation sensitivity for both schedule types, and exponential‐schedule sensitivity exceeded arithmetic‐schedule sensitivity for both measures of choice. A further set of conditions using variable‐interval schedules whose shortest interval was correlated with the mean interval, like arithmetic schedules, but that provided a constant conditional probability of reinforcement, like exponential schedules, produced sensitivities between those produced by conventional arithmetic and exponential schedules. Unlike previous arithmetic‐schedule results, exponential sensitivity changed nonmonotonically with changes in overall reinforcer rate. The results clarify our knowledge of the effects of arithmetic and exponential schedules but confuse our understanding of the effects of overall reinforcer rate on concurrent choice.
TOWARD GRANTING LINGUISTIC COMPETENCE TO APES: A REVIEW OF SAVAGE‐RUMBAUGH ET AL.‘S LANGUAGE COMPREHENSION IN APE AND CHILD1
Authors: Sundberg Mark L.
Published: March 2006

Savage‐Rumbaugh et al.'s (1993) monograph describes a study that compared the language comprehension of an 8‐year‐old ape (a bonobo named Kanzi) with that of a normal 2‐year‐old human (Alia). The primary purpose of the research was to see if Kanzi could comprehend novel and compound spoken English commands without imitative prompts, contrived reinforcement contingencies, or explicit training procedures. As it turned out, Kanzi acquired a complex comprehension repertoire in a pattern similar to the human child's and even performed better than the human child in many cases. Although this review describes these empirical results favorably, it questions the authors' claim that the subjects learned the repertoire on their own, without reinforcement or training. A close examination of the subjects' histories and of the procedures, transcripts, and videos suggested that the training and testing procedures involved a number of independent variables and processes that were not discussed by the authors, including conditioned reinforcement and punishment, verbal prompts, stimulus control, establishing operations, and extinction. Nonetheless, the methodological and empirical contributions to ape and human language research are substantial and deserve behavior analysts' attention and support. Behavior analysts could contribute to this kind of research by applying the analytic and conceptual tools of behavior analysis in general and the concepts from Verbal Behavior (Skinner, 1957) in particular.
CHANGEOVER BEHAVIOR AND PREFERENCE IN CONCURRENT SCHEDULES
Authors: Williams Ben A. , Bell Matthew C.
Published: March 2006

Pigeons were trained on a multiple schedule of reinforcement in which separate concurrent schedules occurred in each of two components. Key pecking was reinforced with milo. During one component, a variable‐interval 40‐s schedule was concurrent with a variable‐interval 20‐s schedule; during the other component, a variable‐interval 40‐s schedule was concurrent with a variable‐interval 80‐s schedule. During probe tests, the stimuli correlated with the two variable‐interval 40‐s schedules were presented simultaneously to assess preference, measured by the relative response rates to the two stimuli. In Experiment 1, the concurrently available variable‐interval 20‐s schedule operated normally; that is, reinforcer availability was not signaled. Following this baseline training, relative response rate during the probes favored the variable‐interval 40‐s alternative that had been paired with the lower valued schedule (i.e., with the variable‐interval 80‐s schedule). In Experiment 2, a signal for reinforcer availability was added to the high‐value alternative (i.e., to the variable‐interval 20‐s schedule), thus reducing the rate of key pecking maintained by that schedule but leaving the reinforcement rate unchanged. Following that baseline training, relative response rates during probes favored the variable‐interval 40‐s alternative that had been paired with the higher valued schedule. The reversal in the pattern of preference implies that the pattern of changeover behavior established during training, and not reinforcement rate, determined the preference patterns obtained on the probe tests.
RESPONSE‐INDEPENDENT FOOD DELIVERY AND BEHAVIORAL RESISTANCE TO CHANGE
Authors: Harper David N.
Published: March 2006

Response‐independent food was delivered during a dark‐key phase between two multiple‐schedule components to explore its disruptive effects on responding. Responding in components was maintained by separate variable‐interval 120‐s schedules, with a 2‐s reinforcer in Component 1 and a 6‐s reinforcer in Component 2. Across conditions the rate and duration of response‐independent food presentations were manipulated. The results showed that response rates in both components decreased as a function of the duration and the rate of response‐independent food presentations; moreover, the decrease in response rate relative to the baseline level was larger in Component 1 than in Component 2. These findings were consistent with expectations from behavioral momentum theory, which predicts that if equal disruption (response‐independent food in this case) is applied to responding in two components, then the ratio of response‐rate change in Component 1 versus Component 2 should remain constant, irrespective of the magnitude of that disruption.
BLOCKING, UNBLOCKING, AND OVEREXPECTATION IN AUTOSHAPING WITH PIGEONS
Authors: Khallad Yacoub , Moore Jay
Published: March 2006

Three experiments used pigeons in an autoshaping procedure and a single‐subject design to examine compound stimulus control in classical conditioning. Experiment 1 examined the blocking effect, and Experiment 2 examined the unblocking effect. In both experiments, response‐independent food was first delivered intermittently in the presence of one distinctively colored houselight but not another. Then, conventional autoshaping trials were carried out in the presence of each houselight. In Experiment 1, the keylight readily elicited responding in the presence of the houselight that had been negatively correlated with food, but not in the presence of the houselight that had been positively correlated with food. In Experiment 2, the keylight readily elicited responding in the presence of the houselight positively correlated with food, but only when the amount of food used on the autoshaping trials was either greater or less than that previously delivered in the presence of the houselight. Experiment 3 examined the overexpectation effect. Conventional autoshaping trials were first carried out by presenting each of two keylights individually. Then, additional autoshaping trials were carried out by presenting the two keylights as a compound, with either the same amount of food or a greater amount of food per trial. Finally, the keylights were retested by again presenting them individually. The number of responses per trial elicited by the keylights decreased when the amount of food used in compound trials was the same as that used in individual trials. However, the number of responses per trial remained approximately the same when the amount of food used in compound trials was greater than that used in individual trials. Taken together, the results of the three experiments demonstrate (a) the generality of the blocking, unblocking, and overexpectation effects by virtue of their extension to appetitive unconditioned stimuli; (b) the suitability of pigeons as subjects and autoshaping as a procedure for studying classical conditioning; and (c) the appropriateness of single‐subject designs.
COMMITMENT USING PUNISHMENT
Authors: Green Leonard , Rachlin Howard
Published: March 2006

Experimental parameters were adjusted so that pigeons' pairwise choices among three alternatives reflected the following order of preference: (a) a smaller‐sooner reinforcer, (b) a larger‐later reinforcer, and (c) the smaller‐sooner reinforcer followed by a punishment (consisting of an extended blackout period). After this order of preference was established, the pigeons were exposed to a two‐link, concurrent‐chain‐like choice procedure. One terminal link consisted of a choice between the smaller‐sooner and the larger‐later reinforcer; the other terminal link was identical to the first except that the smaller‐sooner reinforcer was followed by blackout punishment. The pigeons' preference (in their initial‐link choice) for the terminal link with the punished smaller‐sooner alternative increased as the delay between the initial and terminal links increased. By choosing this terminal link, the pigeons are said to have “committed” themselves to obtaining the larger‐later reinforcer. However, unlike prior studies of commitment (e.g., Rachlin & Green, 1972), it was still possible after making the commitment for the pigeons to choose the smaller‐sooner reinforcer and undergo the punishment. The pigeons did in fact occasionally make this highly deleterious choice.
DYNAMICS OF WAITING IN PIGEONS
Authors: Wynne C. D. L. , Staddon J. E. R. , Delius J. D.
Published: March 2006

Two experiments used response‐initiated delay schedules to test the idea that when food reinforcement is available at regular intervals, the time an animal waits before its first operant response (waiting time) is proportional to the immediately preceding interfood interval (linear waiting; Wynne & Staddon, 1988). In Experiment 1 the interfood intervals varied from cycle to cycle according to one of four sinusoidal sequences with different amounts of added noise. Waiting times tracked the input cycle in a way which showed that they were affected by interfood intervals earlier than the immediately preceding one. In Experiment 2 different patterns of long and short interfood intervals were presented, and the results implied that waiting times are disproportionately influenced by the shortest of recent interfood intervals. A model based on this idea is shown to account for a wide range of results on the dynamics of timing behavior.
DETECTING A NONEVENT: DELAYED PRESENCE‐VERSUS‐ABSENCE DISCRIMINATION IN PIGEONS
Authors: Dougherty Deirdra H. , Wixted John T.
Published: March 2006

Eight pigeons were trained on a delayed presence‐versus‐absence discrimination paradigm in which a sample stimulus was presented on some trials but not on others. If a sample was presented, then a response to one choice key produced food. If no sample was presented, a response to the other choice key produced food. The basic finding was that performance remained constant and well above 50% correct on no‐sample trials as the retention interval increased, whereas performance dropped precipitously (to below 50% correct) on sample trials. In the second phase of the experiment, all of the trials were no‐sample trials, and reinforcers were delivered probabilistically for one group of pigeons and according to time‐based schedules for the other group. The exact reinforcement probabilities used in Phase 2 were those calculated to be in effect on no‐sample trials in Phase 1 (according to a discrete‐state model of performance). Subjects did not show exclusive preference for the richer alternative on no‐sample trials in the first phase, but those in the probabilistic group developed near‐exclusive preference for the richer alternative during the second phase. These data are inconsistent with the predictions of the discrete‐state model, but are easily accommodated by an account based on signal detection theory, which also can be applied effectively to discrimination of event duration and the “subjective shortening” effect.