bluuebunny/crossref_metadata_2025 huggingface dataset:
SELECTIVE PUNISHMENT OF INTERRESPONSE TIMES: THE ROLES OF SHOCK INTENSITY AND SCHEDULING
Authors: Sizemore O. J. , Maxwell F. R.
Published: March 2006

Two experiments investigated the roles of shock intensity and scheduling in selective punishment of interresponse times. In each experiment the punishment contingencies were imposed on a background of rats' responding maintained by a variable‐interval schedule of food presentation. In Experiment 1 all interresponse times greater than 8 seconds produced shock. In Experiment 2 all interresponse times greater than 8 seconds but less than 12 seconds produced shock. In each experiment shock intensity was initially 0.3 milliamperes (mA) and then was varied through an ascending sequence ranging from 0.1 mA to 0.4 mA, in 0.1‐mA increments. Experiment 1 produced response‐rate increases at low intensities (0.1 and 0.2 mA) but eliminated responding at the remaining intensities. Experiment 2 produced response‐rate increases only with 0.1‐mA shock, although responding was maintained at all shock parameters investigated. Analysis of the interresponse times per opportunity showed differential suppression of the targeted responses in all cases except the high‐intensity shock phases of Experiment 1. The current data support and extend previous studies of selective interresponse‐time‐dependent shock schedules but suggest that response‐rate increases are not a necessary outcome of this type of procedure. The view that variable‐interval schedules of shock presentation selectively target long interresponse times was also supported.
ORAL DRUG SELF‐ADMINISTRATION IN RHESUS MONKEYS: INTERACTIONS BETWEEN DRUG AMOUNT AND FIXED‐RATIO SIZE
Authors: Lemaire Gregory A. , Meisch Richard A.
Published: March 2006

During daily 3‐hr sessions, 5 rhesus monkeys drank drug solutions and water that were concurrently available. The drug solutions were: 1 milligram per milliliter (mg/mL) pentobarbital (2 monkeys), 1 mg/mL pentobarbital plus 0.5% ethanol (1 monkey), 1 mg/mL pentobarbital plus 1% ethanol (1 monkey), and 8% ethanol (1 monkey). The drug solution and water were available under identical two‐component tandem fixed‐ratio continuous‐reinforcement N schedules. Two variables were manipulated: the size of the fixed‐ratio component and the number of liquid deliveries (N) in the second component. Deliveries of the drug solution maintained higher rates of responding than did deliveries of the drug vehicle, water. The number of drug deliveries per session increased with increases in the number of deliveries per fixed ratio and decreased with increases in fixed‐ratio size. Analysis of the results in terms of the proportion of deliveries to responses showed that the number of drug deliveries per session was directly related to the size of this quotient. Finally, when fixed‐ratio size was repeatedly doubled, the following orderly relationship emerged: The greater the number of available drug deliveries per fixed ratio, the less was the percent decrease in the number of fixed ratios completed per session. It was concluded that increases in the number of liquid deliveries per fixed ratio resulted in increases in reinforcing efficacy.
CONJOINT CONTROL OF PERFORMANCE IN CONDITIONAL DISCRIMINATIONS BY SUCCESSIVE AND SIMULTANEOUS STIMULI
Authors: White K. Geoffrey
Published: March 2006

In a conditional discrimination, reinforcement of pigeons' responses to pairs of simultaneously presented wavelength stimuli depended on the orientation of white lines superimposed on the wavelengths. Over different conditions in Experiment 1, three wavelength differences were combined with two differences between successively presented line orientations. Measures of stimulus discriminability increased with increases in the difference between both orientation and wavelength stimuli. Conditional‐discrimination performance was thus conjointly determined by stimulus disparity in the successive and simultaneous discriminations. In Experiment 2, ratios of rates of reinforcement contingent upon the two categories of correct responses were varied over several conditions for difficult and easy discriminations. Ratios of responses to wavelength pairs were sensitive to variations in the reinforcement ratio to a greater extent for the more difficult orientation discrimination than for the easier orientation discrimination. Performance in the conditional discrimination was therefore determined by the interacting effects of stimulus disparity and the relative rates of reinforcement contingent upon the two correct choices. It was concluded that the effect of temporally distant reinforcement on behavior in a prevailing schedule component is attenuated to an extent that depends on similarity of stimuli that delineate the successive components.
DOES EFFORT PLAY A ROLE IN THE EFFECT OF RESPONSE REQUIREMENTS ON DELAYED MATCHING TO SAMPLE?
Authors: Spetch Marcia L. , Treit Dallas
Published: March 2006

The possible role of “effort” in the accuracy of pigeons' performance on a delayed matching‐to‐sample procedure was investigated by examining the effects of response requirements that accompanied a trial‐initiating stimulus and that accompanied a sample stimulus. In the first experiment, the effect of varying the size of a fixed‐ratio requirement for responses during an initiating stimulus was compared to that of varying a similar requirement for responses during the sample stimulus. Accuracy increased reliably with increases in the ratio scheduled during the sample stimulus, but was not significantly affected by increases in the ratio scheduled on the key during the initiating stimulus. In another phase of Experiment 1, sample duration was held constant while the ratio requirement was varied during the initiating stimulus. Again, accuracy of matching to sample was not significantly affected by the size of the ratio scheduled during the initiating stimulus. Experiment 2 provided a systematic replication of these results in another group of pigeons and included a more detailed analysis of responding. These results support the view that increases in sample‐response requirement facilitate accuracy of delayed matching by increasing the durations of exposure to the sample stimuli, and do not support a role of effort in the sample‐response effect. In Experiment 3, the facilitative effect of responses on the sample but not of those on the initiating stimulus was replicated using a simultaneous matching‐to‐sample procedure. This finding provides further evidence against an interpretation of response‐requirement effects that appeals to effort; the finding also suggests that sample exposure might affect initial discrimination of the sample rather than remembering the sample.
EFFECTS OF CHLORPROMAZINE ON FIXED‐RATIO RESPONDING: MODIFICATION BY FIXED‐INTERVAL DISCRIMINATIVE STIMULI
Authors: Witkin Jeffrey M.
Published: March 2006

Effects of chlorpromazine (1 to 100 mg/kg) were assessed on two pigeons' responding under various modifications of a multiple schedule of food delivery. During a fixed‐interval component, the first response after 5 min produced food; during the subsequent, fixed‐ratio component, the 30th response produced food. Modifications of the schedule entailed changes in stimulus conditions imposed during the fixed‐ratio component that did not systematically alter characteristics of performance under non‐drug conditions. In the first phase of the experiment, distinctive visual stimuli were correlated with each schedule component (conventional multiple schedule); chlorpromazine produced small decreases in fixed‐ratio responding (20% at 30 mg/kg). When each response during the fixed‐ratio component produced the stimulus correlated with the fixed‐interval schedule (fixed‐interval discriminative stimulus) for 1.2 s, effects of chlorpromazine were not different from those under the conventional multiple schedule. Chlorpromazine produced greater decreases in fixed‐ratio responding (55% at 30 mg/kg) when either the first response of each fixed ratio changed the stimulus correlated with the fixed‐ratio schedule to the fixed‐interval discriminative stimulus for the remainder of the fixed‐ratio component, or when the fixed‐interval discriminative stimulus was presented independently of responding according to a matched temporal sequence. When the fixed‐interval discriminative stimulus was present continuously during the fixed‐ratio component (mixed schedule), chlorpromazine produced even more substantial decreases in fixed‐ratio responding (greater than 80% at 30 mg/kg). Effects of chlorpromazine on fixed‐interval responding were also modified by the schedules of fixed‐interval discriminative stimulus presentation. The effects of chlorpromazine were a joint function of the stimuli prevailing during the multiple schedule and the degree to which responding influenced these stimuli.
HUMAN CONCURRENT PERFORMANCES: THE EFFECTS OF EXPERIENCE, INSTRUCTIONS, AND SCHEDULE‐CORRELATED STIMULI
Authors: Takahashi Masaharu , Iwamoto Takashige
Published: March 2006

In order to investigate the effects of separate exposures to single schedules, of unique schedule‐correlated stimuli, and of independency‐informing instructions upon choice under concurrent variable‐interval schedules, 28 human subjects were divided into eight groups. Each subject was exposed to a baseline procedure, an experimental procedure, and a return to the baseline procedure. Different combinations of these three manipulations were applied to the different groups only during the experimental phase (except for the independency‐informing instructions, which were given to half of the groups at the start of training). For the group of subjects exposed to the combination of all three manipulations, the logarithms of the ratios of response frequencies tended to be linearly related to the logarithms of the ratios of reinforcement frequencies during the experimental phase. These orderly effects were not obtained with subjects in the other groups. The results suggest that human choice was well described by the generalized matching law when the three manipulations were simultaneously in effect, and that unreported differences in the use of these three procedural variables might partly account for contradictions between results in previous studies of human concurrent performance.
STIMULUS DEFINITION IN CONDITIONAL DISCRIMINATIONS
Authors: Iversen Iver H. , Sidman Murray , Carrigan Philip
Published: March 2006

With a customary arrangement of three horizontally aligned stimulus/response keys, two rhesus monkeys learned conditional hue and line discriminations—an “identity‐matching” procedure. First, sample stimuli were always presented on the center key, and comparison stimuli were presented on the two side keys. Next, the sample was allowed to appear on any one of the three keys, with the comparisons on the remaining two. The change from fixed to variable sample and comparison locations caused the horizontal and vertical lines to lose control over the animals' responses; the conditional line discrimination deteriorated. This was not true for the red and green hues; the conditional hue discrimination remained intact. Accurate description of controlling stimuli in a matching‐to‐sample procedure may therefore require that their spatial location be specified.
A COMPARISON OF DELAYS AND RATIO REQUIREMENTS IN SELF‐CONTROL CHOICE
Authors: Grossbard Caren L. , Mazur James E.
Published: March 2006

In a discrete‐trial procedure, pigeons could choose between 2‐s and 6‐s access to grain by making a single key peck. In Phase 1, the pigeons obtained both reinforcers by responding on fixed‐ratio schedules. In Phase 2, they received both reinforcers after simple delays, arranged by fixed‐time schedules, during which no responses were required. In Phase 3, the 2‐s reinforcer was available through a fixed‐time schedule and the 6‐s reinforcer was available through a fixed‐ratio schedule. In all conditions, the size of the delay or ratio leading to the 6‐s reinforcer was systematically increased or decreased several times each session, permitting estimation of an “indifference point,” the schedule size at which a subject chose each alternative equally often. By varying the size of the schedule for the 2‐s reinforcer across conditions, several such indifference points were obtained from both fixed‐time conditions and fixed‐ratio conditions. The resulting “indifference curves” from fixed‐time conditions and from fixed‐ratio conditions were similar in shape, and they suggested that a hyperbolic equation describes the relation between ratio size and reinforcement value as well as the relation between reinforcer delay and its reinforcement value. The results from Phase 3 showed that subjects chose fixed‐time schedules over fixed‐ratio schedules that generated the same average times between a choice response and reinforcement.
PREFERENCE FOR MULTIPLE VERSUS MIXED SCHEDULES OF REINFORCEMENT
Authors: Alsop Brent , Davison Michael
Published: March 2006

Five pigeons were trained in a concurrent‐chain procedure. In the initial links, equal nonindependent variable‐interval schedules were available concurrently on two keys. Completing the schedule on either key led to exclusive presentation of one of two further variable‐interval schedules for a fixed period of time. During these terminal links, as many reinforcers as were scheduled could be obtained. If the response producing this terminal link occurred on one key, differential stimuli signaled which variable‐interval schedule had been produced. If the response producing the terminal link occurred on the other key, no such differential stimuli were available. Once the fixed period of time elapsed, the initial links were reinstated. In Experiment 1, the period of time for which the terminal links were available was always 10 s and the absolute duration of the initial links was varied. Subjects preferred the alternative leading to the multiple schedule when the initial‐link duration was short, but preferred the alternative leading to the mixed schedule when the initial‐link durations were longer. In Experiment 2, both the initial‐link duration and the duration of the terminal links were varied. The effect of initial‐link duration was identical to that in Experiment 1 and there was no systematic effect of varying the terminal‐link duration.
SUPERIMPOSITION OF RESPONSE‐INDEPENDENT REINFORCEMENT
Authors: Burgess I. S. , Wearden J. H.
Published: March 2006

Studies that have superimposed response‐independent reinforcement (or reinforcers scheduled by contingencies placed on the absence of responding) upon conventional response‐dependent schedules are reviewed. In general, providing alternative sources of reinforcement reduced response rates below the levels observed when alternative reinforcement was absent. However, response‐rate elevation was sometimes found, particularly when rates of superimposed response‐independent reinforcement were low. Superimposition of schedules providing reinforcers contingent on the absence of responding usually produced more severe response‐rate decrements than superimposition of response‐independent reinforcement. A variant of Herrnstein's equation, which assumes that some of the alternative reinforcers function as if they were delivered by baseline response‐dependent source of reinforcement, is in qualitative agreement with the overall body of results obtained, and can predict both increases and decreases in response rate as resulting from superimposed reinforcers.
THE GENERALIZED MATCHING LAW AS A DESCRIPTION OF MULTIPLE‐SCHEDULE RESPONDING
Authors: McSweeney Frances K. , Farmer Valeri A. , Dougan James D. , Whipple J. E.
Published: March 2006

The literature was examined to determine how well the generalized matching law (Baum, 1974) describes multiple‐schedule responding. In general, it describes the data well, accounting for a median of 91% of the variance. The median size of the undermatching parameter was 0.46; the median bias parameter was 1.00. The size of the undermatching parameter, and the proportion of the variance accounted for by the equation, varied inversely with the number of schedules conducted, with the number of sessions conducted per schedule, and with the time within a component. The undermatching parameter also varied with the operanda used to produce reinforcers and with the reinforcer used. The undermatching parameter did not vary consistently with component duration or with several other variables. Bias was greater when fewer rather than more schedules were conducted, when two rather than one operanda were used, and when White Carneaux rather than homing pigeons served as subjects. These results imply that the generalized matching law may describe both concurrent and multiple‐schedule responding, but that the same variables do not always influence the bias and undermatching parameters in the same way for the two types of schedules.
INSTRUCTIONS, MULTIPLE SCHEDULES, AND EXTINCTION: DISTINGUISHING RULE‐GOVERNED FROM SCHEDULE‐CONTROLLED BEHAVIOR
Authors: Hayes Steven C. , Brownstein Aaron J. , Haas Joseph R. , Greenway David E.
Published: March 2006

Schedule sensitivity has usually been examined either through a multiple schedule or through changes in schedules after steady‐state responding has been established. This study compared the effects of these two procedures when various instructions were given. Fifty‐five college students responded in two 32‐min sessions under a multiple fixed‐ratio 18/differential‐reinforcement‐of‐low‐rate 6‐s schedule, followed by one session of extinction. Some subjects received no instructions regarding the appropriate rates of responding, whereas others received instructions to respond slowly, rapidly, or both. Relative to the schedule in operation, the instructions were minimal, partially inaccurate, or accurate. When there was little schedule sensitivity in the multiple schedule, there was little in extinction. When apparently schedule‐sensitive responding occurred in the multiple schedule, however, sensitivity in extinction occurred only if differential responding in the multiple schedule could not be due to rules supplied by the experimenter. This evidence shows that rule‐governed behavior that occurs in the form of schedule‐sensitive behavior may not in fact become schedule‐sensitive even though it makes contact with the scheduled reinforcers.
SELF‐CONTROL IN ADULT HUMANS: VARIATION IN POSITIVE REINFORCER AMOUNT AND DELAY
Authors: Logue A. W. , Peña‐Correal Telmo E. , Rodriguez Monica L. , Kabela Elise
Published: March 2006

In five experiments, choice responding of female human adults was examined, as a function of variations in reinforcer amount and reinforcer delay. Experiment 1 used a discrete‐trials procedure, and Experiments 2, 3, 4, and 5 used a concurrent variable‐interval variable‐interval schedule. Reinforcer amount and reinforcer delay were varied both separately and together. In contrast to results previously reported with pigeons, the subjects in the present experiments usually chose the larger reinforcers even when those reinforcers were delayed. Together, the results from all the experiments suggest that the subjects followed a maximization strategy in choosing reinforcers. Such behavior makes it easy to observe self‐control and difficult to observe impulsiveness in traditional laboratory experiments that use adult human subjects.
DEPRIVATION AND SATIATION: THE INTERRELATIONS BETWEEN FOOD AND WHEEL RUNNING
Authors: Pierce W. David , Epling W. Frank , Boer Douglas P.
Published: March 2006

Two experiments were designed to assess whether depriving rats of food would increase the reinforcement effectiveness of wheel running (Experiment 1) and whether satiation for wheel running would decrease the reinforcement effectiveness of food (Experiment 2). In Experiment 1, a progressive‐ratio schedule was used to measure the reinforcement effectiveness of wheel running when rats were deprived or not deprived of food. Completion of a fixed number of lever presses released a brake on a running wheel for 60 s, and the response requirement was systematically increased until the rat stopped pressing or until 8 hr had elapsed. The ratio value reached (and the total number of lever presses) was an inverted‐U function of food deprivation (percentage body weight). In Experiment 2, when wheel running preceded test sessions, fewer food‐reinforced lever presses were maintained by the progressive‐ratio schedule, and responding occurred at a lower rate on a variable‐interval schedule. An interpretation of these results is that deprivation or satiation with respect to one event (such as food) alters the reinforcement effectiveness of a different event (such as access to wheel running).
RAPID DETERMINATIONS OF PREFERENCE IN MULTIPLE CONCURRENT‐CHAIN SCHEDULES
Authors: Cerutti Daniel T. , Catania A. Charles
Published: March 2006

With concurrent chains arranged for a pigeon's key pecks, pecks on two concurrently available initial‐link keys (left and right) respectively produce separately operating terminal links (A and B). Preferences for terminal link A over terminal link B are usually calculated as deviations of relative initial‐link response rates (left divided by total pecks) from those during baseline conditions, when A equals B. Baseline preferences, however, are often variable and typically are determined indirectly (e.g., with unequal A and B, reversing left‐right assignments of A and B over sessions and estimating the baseline from differences between the relative rates generated). Multiple concurrent‐chain schedules, with components each consisting of a pair of concurrent chains, speed the determination of preferences by arranging A and B and their reversal within sessions. In two experiments illustrating the feasibility of this procedure, one component operated with circles projected on initial‐link keys and the other with pluses; when left and right initial‐link pecks respectively produced terminal links A and B in one component, they produced B and A in the other. Even as the baselines fluctuated, preference was observable within sessions as the difference between relative initial‐link response rates in the two components. The first experiment demonstrated the rapid development of preferences when terminal links A and B consisted of fixed‐interval 15‐s and 30‐s schedules. The second demonstrated the sensitivity of the procedure to preference for a fixed‐interval 30‐s schedule operating for pecks on either of two keys (free choice) over its operating for pecks on only a single key (forced choice).
VARIABLE‐RATIO SCHEDULES AS VARIABLE‐INTERVAL SCHEDULES WITH LINEAR FEEDBACK LOOPS
Authors: McDowell J. J , Wixted John T.
Published: March 2006

The mathematical theory of linear systems has been used successfully to describe responding on variable‐interval (VI) schedules. In the simplest extension of the theory to the variable‐ratio (VR) case, VR schedules are treated as if they were VI schedules with linear feedback loops. The assumption entailed by this approach, namely, that VR and VI‐plus‐linear‐feedback schedules are equivalent, was tested by comparing responding on the two types of schedule. Four human subjects' lever pressing produced monetary reinforcers on five VR schedules, and on five VI schedules with linear feedback loops that reproduced the feedback properties of the VR schedules. Pressing was initiated by instructions in 2 subjects, and was shaped by successive approximation in the other 2. The different methods of response initiation did not have differential effects on behavior. For each of the 4 subjects, the VR and the comparable VI‐plus‐linear‐feedback schedules generated similar average response rates and similar response patterns. The subjects' behavior on both types of schedule was similar to that of avian and rodent species on VR schedules. These results indicate that the assumption entailed by the VI‐plus‐linear‐feedback approach to the VR case is valid and, consequently, that the approach is worth pursuing. The results also confute interresponse‐time theories of schedule performance, which require interval and ratio contingencies to produce different response rates.
RELATIVE DURATIONS OF CONDITIONED STIMULUS AND INTERTRIAL INTERVAL IN CONDITIONED SUPPRESSION
Authors: Coleman David A. , Hemmes Nancy S. , Brown Bruce L.
Published: March 2006

The effects of the relative durations of the conditional stimulus and the intertrial interval on bar pressing during a conditioned‐suppression procedure were examined as a function of two additional variables—type of operant baseline schedule and rate of shock presentation. In Experiment 1, response suppression was compared across components of a multiple fixed‐ratio, random‐ratio, fixed‐interval, random‐interval schedule, at relative conditioned‐stimulus/intertrial‐interval durations of 1/1, 1/4, and 1/9. In Experiment 2, relative conditioned‐stimulus/intertrial‐interval duration (1/5, 3/3, or 5/1) was manipulated across groups, while shock frequency (2, 6, or 10 shocks/hr) was manipulated within groups. In both experiments, suppression during the signal was virtually complete at all relative durations. Responding was also suppressed during the intertrial interval, but that suppression varied as a function of experimental manipulations. In Experiment 1, intertrial‐interval response rates were higher when relative signal duration was 1/9 than when it was 1/1, although both relative signal duration and shock frequency, which covaried, could have contributed to the difference. In Experiment 2, the patterning of response rates between successive shocks was affected by relative duration, absolute rates during the intertrial interval varied as a function of shock frequency, and differences between suppression during the signal and suppression during the intertrial interval were affected by both relative duration and shock frequency. The data support an analysis based upon relationships between shock‐correlated and intertrial‐interval stimuli and, as assessed by the relative‐delay‐to‐reinforcement metric, are comparable to results that have been reported from experiments using similar manipulations under the autoshaping paradigm.
VARIABLE‐INTERVAL SCHEDULES OF TIMEOUT FROM AVOIDANCE: EFFECTS OF CHLORDIAZEPOXIDE, CGS 8216, MORPHINE, AND NALTREXONE
Authors: Galizio Mark , Perone Michael
Published: March 2006

Rats were trained on concurrent schedules in which pressing one lever postponed shock and pressing the other occasionally (variable‐interval schedule) produced a 2‐min timeout during which the shock‐postponement schedule was suspended and its correlated stimuli were removed. These procedures provided a baseline for studying the effects of drugs on behavior maintained by different sources of negative reinforcement (shock avoidance and timeout from avoidance). Experiment 1 studied a benzodiazepine agonist, chlordiazepoxide, and antagonist, CGS 8216. Chlordiazepoxide (2.5–30 mg/kg) had little effect on avoidance responding except at higher doses, when it reduced responding. By comparison, responding on the timeout lever was increased in 5 of 6 rats. These effects were reversed by CGS 8216 (2.5–5 mg/kg) in the 2 rats tested, but CGS 8216 had no effect by itself. Experiment 2 studied an opiate agonist, morphine, and antagonist, naltrexone, with 3 rats. Morphine's (2.5–20 mg/kg) effects were opposite those of chlordiazepoxide: At doses that either increased or had no effect on avoidance responding, morphine depressed timeout responding. Naltrexone (5 mg/kg) reversed these actions but had no effect by itself.
RELATIVE ALLOCATION ON CONCURRENT SCHEDULES CAN DEPEND ON SCHEDULE PARAMETERS WHEN BEHAVIORAL PARAMETERS ARE CONSTANT
Authors: Houston Alasdair I. , McNamara John M. , Sumida Brian H.
Published: March 2006

We develop a simple model of switching between the initial links of a concurrent‐chain procedure. Behavior is determined by four parameters μ1, μ2, q1, and q2. The first two are the basic rates of switching from Schedule 1 and Schedule 2, respectively. The second two are the probabilities of leaving Schedule 1 and Schedule 2 after the corresponding terminal link has been completed. We show that for fixed values of these four parameters, the relative allocation on the initial links may change as a result of changes in initial‐link schedules. The effect can be quite large if the switching rates are low. An implication is that relative allocation is not necessarily a good measure of behavior.
OPTIMAL TEMPORAL DIFFERENTIATION
Authors: Zeiler Michael D. , Scott Gregory K. , Hoyert Mark S.
Published: March 2006

In order to illuminate a light signaling a correct response, adult humans had to space their button presses according to a range of time requirements. In some conditions, the spacing needed only to exceed a minimum duration; in others, it had to fall between lower and upper bounds. Mean interresponse times always exceeded the lower limit, and decreased the more stringent were the upper bounds. Variability of interresponse times increased with larger lower bounds, but was unaffected by the size of the upper bound. Feedback about the direction of errors in conditions involving both upper and lower bounds did not affect the means, but it did reduce variability. Predictions were derived from optimality theory, based on the assumption that the critical factor was minimization of the time between correct responses. Without upper bounds, the theory overestimated the mean interresponse times by about 10%; with upper bounds, the theoretical predictions corresponded closely to the actual data. The results did not appear to reflect a scalar timing process. Optimality theory, in contrast to Weber's law, correctly predicted the variety of curves relating sensitivity to duration requirements.
CONTROL OF RESPONDING DURING STIMULI THAT PRECEDE TRANSITIONS IN REINFORCEMENT FREQUENCY
Authors: Ortega Maria G. , Marcucella Henry
Published: March 2006

Pigeons' responses were reinforced on a variant of a mixed variable‐interval extinction schedule of reinforcement in which the transition to the higher reinforcement rate was signaled by a trace stimulus projected on the response key prior to the onset of the component correlated with food delivery. In the first of two experiments, the duration of the trace stimulus preceding the component correlated with food delivery was varied from 1.5 to 50.0 s and in the second experiment, the reinforcement frequency in the same component was varied from 10 to 60 reinforcers per hour. Pigeons pecked at the trace stimulus preceding the onset of the component correlated with food delivery even though responding was not reinforced in its presence and only one of the changes in reinforcement rate (i.e., from extinction to reinforcement) was signaled. The rate of pecking during the trace stimulus was a function of its duration but not of the reinforcement frequency in the following component. Higher rates generally occurred at the shorter trace‐stimulus durations. Component responding following the offset of the trace stimulus was under discriminative control of the trace stimulus whether or not responding occurred in the presence of the trace stimulus.
CHOICE BETWEEN SEQUENCES OF FIXED‐RATIO SCHEDULES: EFFECTS OF RATIO VALUES AND PROBABILITY OF FOOD DELIVERY
Authors: Poling Alan , Blakely Eb , Pellettiere Victoria , Picker Mitchell
Published: March 2006

Pigeons were exposed to schedules of food delivery that consisted of two sequential fixed ratios. When alternative sequences provided two food deliveries per 50 responses, the schedule with the shorter initial fixed‐ratio value was consistently preferred. Progressively reducing from 1.0 to .25 the probability of food delivery following completion of the second fixed ratio of the sequence with the shorter initial fixed ratio did not reduce preference for this sequence. Moreover, the sequence with the shorter initial fixed ratio also was preferred when the probability of food delivery following completion of the initial ratio in that sequence was progressively reduced from 1.0 to .5, although preference shifted to the alternative when the probability was reduced to 0. These findings suggest that the length of the initial fixed ratio was a primary determinant of choice. Subsequent manipulations demonstrated, however, that when the initial fixed ratios of the two alternatives were equal, changes in the ratio value and probability of food delivery following completion of the second fixed ratio lawfully affected choice.
SUPERSTITIOUS BEHAVIOR IN HUMANS
Authors: Ono Koichi
Published: March 2006

Twenty undergraduate students were exposed to single response‐independent schedules of reinforcer presentation, fixed‐time or variable‐time, each with values of 30 and 60 s. The reinforcer was a point on a counter accompanied by a red lamp and a brief buzzer. Three color signals were presented, without consistent relation to reinforcer or to the subjects' behavior. Three large levers were available, but the subjects were not asked to perform any particular behavior. Three of the 20 subjects developed persistent superstitious behavior. One engaged in a pattern of lever‐pulling responses that consisted of long pulls after a few short pulls; the second touched many things in the experimental booth; the third showed biased responding called sensory superstition. However, most subjects did not show consistent superstitious behavior. Reinforcers can operate effectively on human behavior even in the absence of a response‐reinforcer contingency and can, in some cases, shape stable superstitious patterns. However, superstitious behavior is not a consistent outcome of exposure of human subjects to response‐independent reinforcer deliveries.
TESTS OF TRANSITIVITY IN CHOICES BETWEEN FIXED AND VARIABLE REINFORCER DELAYS
Authors: Mazur James E. , Coe David
Published: March 2006

This experiment tested for transitivity in pigeons' choices between variable‐time (VT) and fixed‐time (FT) schedules. In a discrete‐trials procedure, a subject chose between two alternatives by making a single key peck. Each choice was between a “standard alternative,” which was the same schedule throughout a condition, and an “adjusting alternative,” in which the delay to reinforcement was systematically increased or decreased many times a session. These adjustments enabled an approximate indifference point to be identified—the value of the adjusting delay at which the subject chose each alternative about equally often. Each test of transitivity involved four conditions. In one, the standard alternative was a variable‐time schedule with a 2‐s reinforcer, and the adjusting alternative also delivered a 2‐s reinforcer. A second condition was similar except that the adjusting alternative delivered a 5‐s reinforcer. The indifference point from each of these conditions was then converted to a fixed‐time schedule for subsequent comparisons in the third and fourth conditions, respectively. Each of these last two conditions compared one of the fixed‐time schedules (based upon the previous conditions and including their different reinforcer durations) with an adjusting schedule that delivered the alternative reinforcer duration, to determine whether the obtained indifference points would be those predicted from the prior alternative‐duration comparisons with the VT schedule. There was little evidence for intransitivity of choice: Averaged across subjects and replications, the obtained indifference points deviated from perfect transitivity by less than 8%, and these deviations were not statistically significant. These results contrast with those of Navarick and Fantino (1972), who found frequent violations of transitivity between periodic and aperiodic schedules using a concurrent‐chains procedure with variable‐interval schedules in the initial links.
TOPOGRAPHICAL VARIATIONS IN BEHAVIOR DURING AUTOSHAPING, AUTOMAINTENANCE, AND OMISSION TRAINING
Authors: Eldridge Gloria D. , Pear Joseph J.
Published: March 2006

Three pigeons were exposed to an autoshaping and automaintenance procedure while a computer‐controlled tracking system continuously recorded the position of the bird's head as it moved freely in the experimental chamber. Although only 2 birds pecked the key during the conditional stimulus (red keylight), all 3 birds exhibited stable patterns of approaching the conditional stimulus and withdrawing from the intertrial stimulus (white keylight). Subsequent exposure to an omission procedure, in which pecks on the red key cancelled the presentation of food upon the termination of the red keylight, greatly reduced key pecking, but approaching and pecking in the vicinity of the conditional stimulus were maintained at high levels. When the omission contingency was removed key pecking increased. During all phases the birds withdrew from the area of the white key and engaged in repetitive back‐and‐forth or circuiting movements during this intertrial stimulus. The data document (a) the strong control the conditional stimulus in autoshaping and automaintenance exerts over approach to the key and pecking motions whether or not the conditional stimulus elicits key pecking at a high level; and (b) withdrawal from the vicinity of the key and the occurrence of stereotypic behavior during the intertrial interval.
AN ANIMAL MODEL OF EXCESSIVE EATING: SCHEDULE‐INDUCED HYPERPHAGIA IN FOOD‐SATIATED RATS
Authors: Wilson Josephine F. , Cantor Michael B.
Published: March 2006

Nineteen rats were maintained throughout the experiment on ad libitum wet mash and water and were trained to press a lever on fixed‐interval or fixed‐ratio schedules of reinforcement with electrical brain stimulation. Fourteen rats ate at least 150% more mash during intermittent reinforcement sessions than during baseline, massed reinforcement control, and/or extinction sessions. In a 3‐hr session, 11 of those 14 consumed more than 22 g of wet mash (13 g dry weight), the equivalent of nearly half an animal's daily food intake. In subsequent control sessions, the electrodes did not support stimulus‐bound eating despite attempts to make stimulation parameters optimal. These results indicate that the eating was schedule induced or adjunctive, and suggest that the procedure may provide an animal model of excessive nonregulatory eating that contributes to obesity in humans.
CHOOSING AMONG NATURAL STIMULI
Authors: Vaughan William , Herrnstein R. J.
Published: March 2006

Pigeons worked on concurrent variable‐interval, variable‐interval schedules with the alternatives signaled by slides either containing trees or not. The schedules were designed to hold both overall and relative rates of reinforcement within narrowly constrained limits, and slides were quasi‐randomly ordered each day. Responding to the two alternatives was well described by the generalized matching equation with substantial undermatching. Using an adaptation of the matching law, we estimated that the subjects were correctly classifying 82% to 95% of exemplars. The matching performance transferred to new exemplars of trees and nontrees with only slight generalization decrement. The pigeons appeared to be discriminating among exemplars even when the alternatives provided equal rates of reinforcement and the average relative performances were close to 50%.
AN ANIMAL MODEL OF THE INTERPERSONAL COMMUNICATION OF INTEROCEPTIVE (PRIVATE) STATES
Authors: Lubinski David , Thompson Travis
Published: March 2006

Pigeons were taught to interact communicatively (i.e., exchange discriminative stimuli) based on 1 pigeon's internal state, which varied as a function of cocaine, pentobarbital, and saline administration. These performances generalized to untrained pharmacological agents (d‐amphetamine and chlordiazepoxide) and were observed in the absence of aversive stimulation, deprivation, and unconditioned reinforcement. The training procedure used in this study appears similar to that by which humans learn to report on (tact) their internal environments and may be construed as a rudimentary animal model of the interpersonal communication of private events.
DEVALUATION OF STIMULI CONTINGENT ON CHOICE: EVIDENCE FOR CONDITIONED REINFORCEMENT
Authors: Dunn Roger , Williams Ben , Royalty Paul
Published: March 2006

Pigeons were presented a concurrent‐chains schedule of reinforcement that had terminal links of equal duration. The initial links of the schedule were periodically interrupted by 15‐s periods during which an extinction schedule was in effect. The extinction periods were presented on either a response‐contingent or a noncontingent basis. Relative response rate for the left alternative decreased when the extinction periods were accompanied by the left terminal‐link stimulus. Relative response rate for the right alternative decreased when the extinction periods were accompanied by the right terminal‐link stimulus. Relative response rate varied inversely with the frequency of presentation of the extinction periods but was unaffected by presence versus absence of the response contingency in the schedule of extinction‐period presentation. Furthermore, relative response rate was unaffected by presentation of extinction periods accompanied by a novel stimulus. When the extinction periods were presented after reinforcement in the left terminal link instead of as interruptions of the initial links, relative response rate for the left alternative was reduced if the postreinforcement extinction period was accompanied by the terminal‐link stimulus for the left chain and reduced less if the extinction period was accompanied by the terminal‐link stimulus for the right chain. The results demonstrate that the correlation between the terminal‐link stimulus and extinction influenced the relative response rate in the initial link.
A MOLECULAR ANALYSIS OF CHOICE ON CONCURRENT‐CHAINS SCHEDULES
Authors: Fantino Edmund , Royalty Paul
Published: March 2006

Six pigeons responded on concurrent‐chains schedules with either independent or interdependent equal variable‐interval schedules in the initial links and unequal variable‐interval schedules, always in a 2:1 ratio, in the terminal links. Relative response rates in the initial links increased across conditions as initial‐link duration was shortened and decreased across conditions as terminal‐link duration was shortened, replicating previous findings. Responses in the initial links were recorded in 5‐s bins, and local or molecular relative response rates were calculated in order to ascertain how relative response rate varied as a function of time since the onset of the initial links. Two distinct molecular patterns were found. With interdependent initial links, relative response rates for the preferred key were elevated for the first 10 or 20 s of the initial links and then declined to an asymptotic value. With independent initial links, a negative recency effect was found similar to that reported by Killeen (1970). These two molecular patterns were related to the different momentary reinforcement probabilities resulting from independent and interdependent scheduling.
REMOTE EFFECTS OF AVERSIVE CONTINGENCIES: DISRUPTION OF APPETITIVE BEHAVIOR BY ADJACENT AVOIDANCE SESSIONS
Authors: Hackenberg Timothy D. , Hineline Philip N.
Published: March 2006

Disruption of ongoing appetitive behavior before and after daily avoidance sessions was examined. After baselines of appetitive responding were established under a fixed‐interval 180‐s schedule of food presentation, 4 rats were exposed to 40‐min sessions of the appetitive schedule just prior to 100‐min sessions of electric shock postponement, while another 4 rats received the 40‐min appetitive sessions just following daily sessions of shock postponement. In all 8 subjects, fixed‐interval response rates decreased relative to baseline levels, the effect being somewhat more pronounced when the avoidance sessions immediately followed. The disruption of fixed‐interval responding was only partially reversed when avoidance sessions were discontinued. During the initial exposure to the avoidance sessions, patterns of responding under the fixed‐interval schedule were differentially sensitive to disruption, with high baseline response rates generally more disturbed than low rates. These disruptions were not systematically related to changes in reinforcement frequency, which remained fairly high and invariant across all conditions of the experiment; they were also not systematically related to the response rates or to the shock rates of the adjacent avoidance sessions. The results, while qualitatively resembling patterns of conditioned suppression as typically studied, occurred on a greatly expanded time scale. As disruption of behavior extending over time, the present data suggest that some forms of conditioned suppression are perhaps best viewed within a larger temporal context.
DOES CONTINGENT REINFORCEMENT STRENGTHEN OPERANT BEHAVIOR?
Authors: Nevin John A. , Smith Laurence D. , Roberts Jean
Published: March 2006

In Experiment 1, pigeons were trained to peck keys with equal food‐reinforcement schedules in components that ended with either noncontingent or contingent transitions to a third component with a five‐fold richer schedule. Response rates were higher in the initial component with contingent transitions, but resistance to prefeeding or extinction was not consistently greater. Experiment 2 also included noncontingent or contingent transitions to a signaled period of nonreinforcement. There was no effect of the contingency on transitions to nonreinforcement, but the difference in response rates maintained by contingent versus noncontingent transitions to the richer schedule was replicated. In addition, response rates were higher in components that preceded nonreinforcement than in components that preceded the richer schedule. However, resistance to extinction was greater for noncontingent transitions to the richer schedule than to nonreinforcement, implicating stimulus—reinforcer relations in the determination of resistance to change. Resistance to change was also somewhat greater for noncontingent than for contingent transitions to the richer schedule. The latter result, together with the results of Experiment 1 and related research, suggests that response‐contingent reinforcement does not increase resistance to change.
CONTROLLING RELATIONS IN CONDITIONAL DISCRIMINATION AND MATCHING BY EXCLUSION
Authors: McIlvane William J. , Kledaras Joanne B. , Munson Lee C. , King Katherine A. J. , Rose Julio C. de , Stoddard Lawrence T.
Published: March 2006

Normally capable adults learned two‐choice identity matching of three‐digit numerals and arbitrary matching of physically dissimilar nonsense syllables. The stimuli were displayed on a computer terminal, and responses consisted of typing on the terminal's keyboard. In Experiment 1, every trial displayed a sample numeral, a comparison numeral, and three equal signs (===). The comparison stimulus was to be selected if it was identical with the sample; otherwise the equal sign was to be selected. This “single comparison” method was then used to show that arbitrary matching could be based upon either sample‐S+ or sample‐S– relations. In Experiment 2, a series of probe trials displayed a novel sample, a comparison stimulus from the arbitrary matching baseline, and ===. Subjects typically selected ===; they apparently were excluding the baseline comparison stimulus. Experiments 3 through 5 investigated which variables in training would lead to the selection of baseline comparison stimuli in response to novel samples. Behavior was usually unchanged when baseline training included relating comparison stimuli to as many as four different samples. Punishment contingencies were effective, but performance did not generalize unless those contingencies were applied in relation to more than one baseline comparison stimulus.