bluuebunny/crossref_metadata_2025 huggingface dataset:
CONTROL OF HUMAN VIGILANCE BY CONCURRENT SCHEDULES
Authors: Frazier Thomas W. , Bitetto Vincent E.
Published: March 2006

Twenty four subjects were studied for ten 1‐hr sessions to determine whether the human observer's visual monitoring of individual meters in a complex display can be differentially controlled by concurrent scheduling of signals. Subjects were divided into two main groups of 12 each. One group was given fixed‐interval, variable‐interval, and differential‐reinforcement‐of‐low‐rates schedules. The second group was given fixed‐interval, fixed‐ratio, and differential‐reinforcement‐of‐low‐rates schedules. Test subjects were instructed only to detect as many signals as possible. Results indicated that observing responses to the individual meters corresponded to the temporal patterns known to be associated with the schedules for the group given fixed‐ratio instead of variable‐interval as a component schedule. The group given the variable‐interval schedule in the three‐schedule combination tended to exhibit the same pattern of viewing across each of the three meters during any given session. However, subsequent testing was performed on two more subjects over 64 sessions, by adding initial feedback of signal detection results, and instructions concerning schedule construction. These results indicated that with knowledge of schedule construction and initial feedback of detection data, differentiated responding can be maintained efficiently over long periods of time by the combination including fixed‐interval, variable‐interval, and differential‐reinforcement‐of‐low‐rates schedules.
CONCURRENT FIXED‐RATIO FIXED‐INTERVAL PERFORMANCES IN ADULT HUMAN SUBJECTS1
Authors: Sanders Richard M.
Published: March 2006

Two undergraduate males worked for money on a button‐pressing task associated with concurrent fixed‐ratio fixed‐interval schedules of reinforcement. Manipulations of the fixed‐ratio requirement produced an interaction between the various fixed‐ratio and fixed‐interval performances. When the fixed ratio was small, more fixed‐interval responding occurred per interval than when the fixed ratio was large. In general, the data were similar to those obtained with lower organisms except that no post‐reinforcement pause or ratio strain was seen.
DISCRETE‐TRIAL ALTERNATION IN THE RAT1,2
Authors: Heise George A. , Keller Connie , Khavari Khalil , Laughlin Nell
Published: March 2006

The acquisition and maintenance by rats of single alternation, double alternation, and four other repeating patterns of reinforced and non‐reinforced trials was studied in a discrete‐trial lever‐pressing situation. The rats learned all these patterns in a small number of experimental sessions. Single alternation was learned more rapidly than the more complex patterns. Rate of learning single and double alternation decreased moderately as inter‐trial interval increased. Abrupt changes in the scheduling of trials, either by doubling the inter‐trial interval or by shifting from fixed to variable trial spacing, temporarily disrupted the patterned performance. Two hypotheses concerned with the means by which the rats could have learned to conform to the pattern were examined: (1) “timing” of the interval between successive reinforcements; and (2) control of responding on a trial by the outcome of preceding trials, depending on the consistency with which these outcomes were associated with reinforced or non‐reinforced trials in the pattern and on how many trials back these outcomes occurred. The second hypothesis accounted for the relative frequency of errors on trials at various locations in the sequences, and predicted most of the changes in error frequency observed in experiments in which “inter‐trial stimuli” were added to the sequences.
THE RELEASE OF CATECHOLAMINES BY SHOCKS AND STIMULI PAIRED WITH SHOCKS1
Authors: Ferreira S. H. , Gollub L. R. , Vane J. R.
Published: March 2006

One monkey and five baboons were surgically prepared so that heart rate and blood pressure could be monitored continuously, and an extra‐corporeal blood path was established to detect the secretion of epinephrine (adrenaline) and norepinephrine (noradrenaline). A respondent conditioning procedure was used in which a tone was paired with electric shocks. Epinephrine, but not norepinephrine was released by shocks, and a corresponding release was demonstrated by the tone alone. Heart rate and blood pressure changes were also elicited by shocks and by the tone.
CONDITIONED SUPPRESSION UNDER POSITIVE, NEGATIVE, AND NO CONTINGENCY BETWEEN CONDITIONED AND UNCONDITIONED STIMULI1
Authors: Davis Hank , McIntire Roger W.
Published: March 2006

Using a conditioned suppression procedure, the effects of three contingent relationships between conditioned (CS) and unconditioned (US) stimuli were investigated. A traditional positive (if CS—then US) contingency suppressed response rate during the CS relative to responding during stimulus‐free minutes of the session. A negative (if CS—then no US) contingency resulted in suppressed responding during CS‐off minutes, and rate increases during the CS. A no‐contingency control procedure, during which CS and US were randomly related, almost totally suppressed responding throughout the session and showed no differential effects of the CS on response rate. An analysis of changes in response rate during the minute after US‐offset revealed acceleration under the no‐contingency condition and, to a somewhat lesser degree, under the negative contingency. Both conditioned suppression and non‐suppression are analyzed in terms of the temporal relationship between CS and US.
THE CREATIVE PORPOISE: TRAINING FOR NOVEL BEHAVIOR1
Authors: Pryor Karen W. , Haag Richard , O'Reilly Joseph
Published: March 2006

Two rough‐toothed porpoises (Steno bredanensis) were individually trained to emit novel responses, which were not developed by shaping and which were not previously known to occur in the species, by reinforcing a different response to the same set of stimuli in each of a series of training sessions. A technique was developed for transcribing a complex series of behaviors on to a single cumulative record so that the training sessions of the second animal could be fully recorded. Cumulative records are presented for a session in which the criterion that only novel behaviors would be reinforced was abruptly met with four new types of responses, and for typical preceding and subsequent sessions. Some analogous techniques in the training of pigeons, horses, and humans are discussed.
REINFORCEMENT OMISSION ON FIXED‐INTERVAL SCHEDULES1
Authors: Staddon J. E. R. , Innis Nancy K.
Published: March 2006

Experiments with pigeons and rats showed that: (1) When a brief blackout was presented in lieu of reinforcement at the end of 25% of intervals on a fixed‐interval 2‐min schedule, response rate was reliably and persistently higher during the following 2‐min intervals (omission effect). This effect was largely due to a decrease in time to first response after reinforcement omission. (2) When blackout duration was varied, within sessions, over the range 2 to 32 sec, time to first response was inversely related to the duration of the preceding blackout, for pigeons, and for rats during the first few sessions after the transition from FI 2‐min to FI 2‐min with reinforcement omission. Post‐blackout pause was independent of blackout duration for rats at asymptote. These results were interpreted in terms of differential depressive effects of reinforcement and blackout on subsequent responding.
CHOICE AND RATE OF REINFORCEMENT1,2
Authors: Fantino Edmund
Published: March 2006

Pigeons' responses in the presence of two concurrently available (initial‐link) stimuli produced one of two different (terminal‐link) stimuli. The rate of reinforcement in the presence of one terminal‐link stimulus was three times that of the other. Three different pairs of identical but independent variable‐interval schedules controlled entry into the terminal links. When the intermediate pair was in effect, the pigeons distributed their (choice) responses in the presence of the concurrently available stimuli of the initial links in the same proportion as reinforcements were distributed in the mutually exclusive terminal links. This finding was consistent with those of earlier studies. When either the pair of larger or smaller variable‐interval schedules was in effect, however, proportions of choice responses did not match proportions of reinforcements. In addition, matching was not obtained when entry into the terminal links was controlled by unequal variable‐interval schedules. A formulation consistent with extant data states that choice behavior is dependent upon the amount of reduction in the expected time to primary reinforcement, as signified by entry into one terminal link, relative to the amount of reduction in expected time to reinforcement signified by entry into the other terminal link.
VARIABILITY OF RESPONSE LOCATION FOR PIGEONS RESPONDING UNDER CONTINUOUS REINFORCEMENT, INTERMITTENT REINFORCEMENT, AND EXTINCTION1
Authors: Eckerman David A. , Lanson Robert N.
Published: March 2006

The effect of several reinforcement schedules on the variability in topography of a pigeon's key‐peck response was determined. The measure of topography was the location of a key peck within a 10‐in. wide by 0.75‐in. high response key. Food reinforcement was presented from a magazine located below the center of the response key. Variability in response locus decreased to a low value during training in which each response produced reinforcement. Variability increased when fixed intervals, variable intervals, random intervals, or extinction were scheduled.
BLOCKING THE DEVELOPMENT OF STIMULUS CONTROL WHEN STIMULI INDICATE PERIODS OF NONREINFORCEMENT1
Authors: Seraganian Peter , vom Saal Walter
Published: March 2006

To learn whether prior discrimination training based on one stimulus would block learning about a subsequently added stimulus, rats were first trained to press a bar on a variable‐interval schedule of food reinforcement. Occasional stimuli were presented during which no reinforcement was available. Responding became suppressed in the presence of these stimuli. Stimuli could be noise, light, or a compound of noise plus light. A group trained with noise in Phase 1, then trained with the compound in Phase 2, showed less suppression to light in a subsequent test than a group that had the same compound training in Phase 2 but only variable‐interval training in Phase 1. This showed that prior training with noise blocked the development of control by light during compound training. Two further groups showed that noise training following compound training did not have the same effect on control by light.
ACQUIRED STIMULUS CONTROL OF DRUG‐INDUCED CHANGES IN AGGRESSIVE DISPLAY IN BETTA SPLENDENS
Authors: Braud William G. , Weibel Jorge Erik
Published: March 2006

Male Siamese fighting fish exhibit stereotyped aggression reactions to their mirror reflections. When distinctive neutral stimuli (flickering colored lights) were repeatedly associated with drug‐potentiated aggression (morphine sulfate) and drug‐depressed aggression (phenergan), the stimuli came to exert specific stimulus control over aggressive display even after the drugs were discontinued.
GENERALIZATION OF CONDITIONED SUPPRESSION AFTER DIFFERENTIAL TRAINING1
Authors: Hendry Derek P. , Switalski Richard , Yarczower Matthew
Published: March 2006

In a modified conditioned suppression procedure, clicks at one frequency (danger signal) preceded shocks, while no shocks followed clicks at a different frequency (safe signal). During generalization tests, the maximal response rate was frequently shifted from the safe signal in the direction away from the danger signal, and the minimal response rate was frequently shifted in the opposite direction, away from the safe signal. There was considerable variability in the results from one animal to another. The generalization tests also suggested different generalization functions according to whether the danger signal was a lower or a higher frequency than the safe signal. The results also showed the development of systematic differences in response rate during and after the safe and danger signals, notably a relatively high rate at the beginning of the safe signal and after the danger signal.
CONDITIONED SUPPRESSION AS A SENSITIVE BASELINE FOR SOCIAL FACILITATION1
Authors: Hake D. F. , Powell J. , Olsen R.
Published: March 2006

The key pecking of pigeons maintained on a variable‐interval schedule of food reinforcement was suppressed during occasional presentations of a warning stimulus paired with electric shock. On alternate sessions, a co‐actor pigeon was visible in an adjoining chamber where it emitted the same food‐reinforced key peck during the warning stimulus that signalled shock for the subject. With no shock and at low shock intensities, where the subject's responding was not suppressed or suppressed only slightly, the co‐actor had little effect. At the higher shock intensities, where the subject's responding was reduced by at least 40%, the response rate during the warning stimulus was consistently higher when the co‐actor was present. One explanation of these results assumes a special relationship between social stimuli and aversive stimuli in which the presence of another animal reduces emotional reactions and thereby allows operant responses to increase. This was not the case here because the mere presence of the co‐actor did not maintain social facilitation. Rather, the present results, taken in conjunction with previous findings, suggest that changes in social and non‐social variables which affect the rate of food‐reinforced responding may produce proportionately larger changes in responding when that responding is suppressed by aversive stimulation than when it is not.
ATTACK BEHAVIOR AS A FUNCTION OF MINIMUM INTER‐FOOD INTERVAL1
Authors: Flory Randall
Published: March 2006

Pigeons were exposed to a procedure in which food was presented after a fixed period of time had elapsed, provided no attack against a nearby stuffed pigeon had occurred during the last 15 sec of the period. As the minimum inter‐food interval was increased logarithmically through seven values from 15 sec to 960 sec, attack increased to a maximum and then decreased. For both pigeons, attack predominantly occurred after, rather than shortly before, food deliveries.
INTERVAL REINFORCEMENT OF CHOICE BEHAVIOR IN DISCRETE TRIALS1
Authors: Nevin John A.
Published: March 2006

Pigeons were trained to peck at red or green keys presented simultaneously in discrete trials. In one experiment, reinforcements were arranged by concurrent variable‐interval schedules. The proportion of responses to green approximately matched the proportion of reinforcements produced by pecking green. Detailed analysis of responding revealed a systematic decrease in the probability of switching from green to red within sequences of trials after reinforcement. This trend corresponded to sequential changes in the relative frequency of reinforcement, and not to sequential changes in probability of reinforcement. In a second experiment, reinforcements were scheduled probabilistically every seventh trial. Even though there were no contingencies on pecking during the first six post‐reinforcement trials, choices of green on the first response after reinforcement matched the proportion of reinforcements for pecking green. These results extend the generality of overall matching under concurrent reinforcement.
CONCURRENT RESPONDING WITH FIXED RELATIVE RATE OF REINFORCEMENT1
Authors: Stubbs D. Alan , Pliskoff Stanley S.
Published: March 2006

Responding by pigeons on one key of a two‐key chamber alternated the color of the second key, on which responding produced food according to a variable‐interval schedule of reinforcement. From time to time, reinforcement would be available for a response, but in the presence of a particular stimulus, either red or green light on the key. Red or green was chosen irregularly from reinforcement to reinforcement, so that a proportion of the total number of reinforcements could be specified for each color. Experimental manipulations involved variations of (1) the proportions for each color, (2) changeover delay, or, alternatively, (3) a fixed‐ratio changeover requirement. The main findings were: (1) relative overall rates of responding and relative times in the presence of a key color approximated the proportions of reinforcements obtained in the presence of that color, while relative local rates of responding changed little; (2) changeover rate decreased as the proportions diverged from 0.50; (3) relative overall rate of responding and relative time remained constant as the changeover delay was increased from 2 to 32 sec, with reinforcement proportions for red and green of 0.75 and 0.25, but they increased above 0.90 when a fixed‐ratio changeover of 20 responses replaced the changeover delay; (4) changeover rate decreased as the delay or fixed‐ratio was increased.
REINFORCEMENT OF EYE MOVEMENT WITH CONCURRENT SCHEDULES1
Authors: Schroeder Stephen R. , Holland James G.
Published: March 2006

Human macrosaccadic eye movements to two areas of a four‐dial display were conditioned by concurrent variable‐interval schedules of signals. Reinforcers (signals) were delivered to the two right‐hand dials on one schedule and to the two left‐hand dials on another, independent schedule. The use of a changeover delay between crossover eye movements and reinforcement had the effect of changing the pattern of scanning from fixating four dials in succession or in a Z‐shaped pattern to scanning vertically the dials on either side with fewer crossovers. In the presence of a changeover delay, subjects matched relative eye‐movement rates and relative reinforcement rates on each schedule. Rate of crossover eye movements, with a changeover delay in effect, was also inversely related to the difference in reinforcements arranged by the concurrent schedules. The results suggest that for stimuli whose critical components are arranged spatially, conditioned eye movements play an important part in selective stimulus control.
GENERALIZATION GRADIENT SHAPE AND SUMMATION IN STEADY‐STATE TESTS1
Authors: Blough Donald S.
Published: March 2006

Pigeons' pecks at one or two wavelengths were reinforced intermittently. Random series of adjacent wavelengths appeared without reinforcement. Gradients of responding around the reinforced wavelengths were allowed to stabilize over a number of sessions. The single (one reinforced stimulus) and summation (two reinforced stimuli) gradients were consistent with a statistical decision account of the generalization process.
AVERSIVE PROPERTIES OF THE NEGATIVE STIMULUS IN A SUCCESSIVE DISCRIMINATION1
Authors: Rilling Mark , Askew Henry R. , Ahlskog J. Eric , Kramer Thomas J.
Published: March 2006

Experiment I sought to determine if the stimulus correlated with extinction in a successive discrimination was an aversive stimulus. An escape response provided an index of aversive control. Two groups of pigeons were exposed to a multiple variable‐interval 30‐sec extinction schedule. For the experimental group, a single peck on a second key produced a timeout during which all lights in the chamber were dark. For the control group, pecks on the second key had no contingency. The rate of responding on the timeout key during extinction for the experimental group was higher than that of the control group during all sessions of discrimination training except the first. In Exp. II, green was correlated with variable interval 30‐sec and red was correlated with variable‐interval 5‐min. Timeouts were obtained from variable‐interval 5‐min. There were more timeouts from extinction in Exp. I than from variable‐interval 5‐min in Exp. II. Experiment III showed that not presenting the positive stimulus reduced the number of timeouts from the negative stimulus for the two birds from Exp. I that had the highest rate of timeouts from extinction, but had little effect on the two birds that had the lowest rate of timeouts. These results suggest that in a multiple schedule, the stimulus correlated with extinction, or the lower response rate, functions as a conditioned aversive stimulus. Explanations of the timeout response in terms of extinction produced variability, displaced aggression, and stimulus change, were considered but found inadequate.
BEHAVIORAL DISCRIMINATION OF CLICK INTENSITY IN CAT1
Authors: Saunders James C.
Published: March 2006

Avoidance conditioning procedures were used to train cats to discriminate intensity differences between successive clicks. The discriminative behavior was applied in a modified method of adjustment to determine a difference limen (DL) for click intensity. The obtained DLs were consistent within and between subjects, and averaged 4.4 db. This value is greater than previously reported intensity DLs for pure tones in cats.
SOME VARIABLES AFFECTING THE SUPERSTITIOUS CHAINING OF RESPONSES1,2
Authors: Boren John J.
Published: March 2006

This study was based upon a repeated acquisition technique that systematically generated superstitious chains of responses. Several procedures were investigated in an effort to modify the amount of superstitious chaining. The effects of a large work requirement, a stimulus correlated with non‐reinforcement after inappropriate responses, an equivalent time delay after inappropriate responses, and extensive training were examined. The presentation of a stimulus correlated with non‐reinforcement was found to be the most effective technique for reducing superstitious chaining; the time delay was the least effective.
COLLATERAL RESPONDING DURING DIFFERENTIAL REINFORCEMENT OF LOW RATES1
Authors: Zuriff G. E.
Published: March 2006

Two pigeons were trained to peck either of two response keys for food, under two different variable‐interval schedules. When responding stabilized, the schedule on the left key (reinforcement‐key) was changed to a differential‐reinforcement‐of‐low‐rates schedule, and responses on the right key (extinction‐key) were no longer reinforced. The mean interresponse time of responses on the reinforcement‐key approximated the temporal requirement of the reinforcement schedule on that key. Collateral responding on the extinction‐key was maintained by one of the birds. A “run” of these collateral responses was defined as a sequence of responses on the extinction‐key occurring between two responses on the reinforcement‐key. For this one bird, collateral behavior, measured by mean time per run and mean number of responses per run, was an increasing function of the temporal requirements of the reinforcement schedule on the reinforcement key, and it was strongly positively correlated with the mean interresponse time of responses on the reinforcement‐key. However, from an analysis of the results, the collateral behavior did not appear to have mediated the temporal spacing of responses on the reinforcement‐key.
COMBINED ACTION OF DIAZEPAM AND d‐AMPHETAMINE ON FIXED‐INTERVAL PERFORMANCE IN CATS1
Authors: Richelle Marc
Published: March 2006

Cats trained under a fixed‐interval 5‐min schedule of milk presentation were injected with diazepam, amphetamine, and combinations of amphetamine and diazepam. Diazepam increased overall response rate as a function of the dose and disrupted the temporal pattern of responding. Low doses of amphetamine (0.5 mg/kg) usually increased the response rate; higher doses (1 to 2 mg/kg) either decreased the response rate or had little effect. Amphetamine always disrupted the temporal pattern of responding, even though it did not affect the overall rate. When doses of amphetamine that increased the response rate or left it unchanged were combined with diazepam, a potentiated increase in response rate occurred. When doses of amphetamine that decreased the response rate were combined with diazepam, the amphetamine‐induced rate decreases were reversed at least partially. Less clear potentiation of disruption of the temporal pattern of responding was observed when amphetamine and diazepam were combined.
COMPARISONS BETWEEN ONE‐KEY AND TWO‐KEY VERSIONS OF THE SINEWAVE SCHEDULE FOR PIGEONS
Authors: Johnson Daniel F. , Wheeler H. P.
Published: March 2006

When the rate of reinforcement for pigeons' key pecking varied over time following a sine waveform, performances were more consistent and reliable if a constant‐rate reinforcement schedule was concurrently available on a second key than if only the sinewave‐varying reinforcement schedule was available. In the two‐key version, response rates clearly followed varying reinforcement rates with the same frequency, with no phase lag, and without breaks. In both versions, pecking rate was a power function of reinforcement rate. Sinewave‐schedule performance waveforms qualified for engineering methods of frequency analysis and met criteria for a standard measurement system.
CHOICE AND FORAGING
Authors: Abarca Nureya , Fantino Edmund
Published: March 2006

In Experiment 1, six naive pigeons were trained on a foraging schedule characterized by different states beginning with a search state in which completion of a fixed‐interval on a white key led to a choice state. In the choice state the subject could, by appropriate responding on a fixed ratio of three, either accept or reject the schedule of reinforcement that was offered (either a variable‐interval five‐second or a variable‐interval 20‐second). If the subject accepted the schedule, it entered a “handling state” in which the appropriate variable‐interval schedule was presented. Completion of the variable‐interval schedule produced food. The independent variable was the fixed‐interval value in the search state, and the dependent variable was the rate of acceptance of the long variable‐interval in the choice state. Experiment 2 was identical except that the search state required completion of a variable‐interval, instead of a fixed‐interval, schedule. The rate of acceptance of the long variable‐interval schedule in both experiments was a direct function of the length of the search state, in accordance with both optimality theory and the delay‐reduction hypothesis.
FIXED‐RATIO PERFORMANCE WITH AND WITHOUT A POSTREINFORCEMENT TIMEOUT
Authors: Mazur James E. , Hyslop Marcia E.
Published: March 2006

Pigeons pecked a key, producing food reinforcement on fixed‐ratio (FR) schedules requiring 50, 100, or 150 responses. In each session, 30‐second timeouts were inserted before a random half of the FR trials, whereas the other trials began immediately after reinforcement. In general, preratio pauses were shorter on trials preceded by timeouts. On these trials, the probability of a first response tended to be highest in the first 20 seconds of the trials, suggesting that the shorter pauses were the result of transient behavioral contrast. Direct observations and analyses of interresponse times (IRTs) after the preratio pause indicated that IRTs could be grouped into three categories: (1) IRTs of about .1 second, which were produced by small head movements in the vicinity of the key; (2) IRTs of about .3 second, which were produced by distinct pecking motions; and (3) IRTs greater than .5 second, which were accompanied by pausing or movements away from the key. At all ratio sizes, as a subject progressed through a trial, the probability of a long IRT decreased, whereas the probability of an intermediate IRT usually increased at first and then decreased. The probability of a short IRT increased monotonically across a trial. The results show that responding changes systematically as a subject progresses through a ratio on an FR schedule. Some characteristics of performance varied as functions of the absolute size of the response requirement, whereas others appeared to depend on the relative location within a ratio (i.e., the proportion of the ratio completed at a given moment).
CONDITIONAL ACCELERATION AND EXTERNAL DISINHIBITION OF OPERANT LEVER PRESSING BY PREREWARD, NEUTRAL, AND REINFORCING STIMULI
Authors: Hemmes Nancy S. , Rubinsky Hillel J.
Published: March 2006

Rats responding under a differential‐reinforcement‐of‐low‐rate schedule increased their rates of lever pressing during a 20‐second click/flash stimulus that preceded the delivery of a response‐independent food pellet. The increase could not be attributed to suppression of collateral behavior that has been said to mediate temporally‐spaced responding. We propose that the prereward stimulus functioned as an external disinhibitor of lever pressing that had been inhibited by the constraints of the operant schedule. Support is derived from the observed disinhibitory effects of a 10‐second unpaired click/flash stimulus and of unsignaled, response‐independent pellets that were presented while the animals were responding under the same schedule.
IMMEDIATE REINFORCEMENT IN DELAYED REWARD LEARNING IN PIGEONS
Authors: Winter Janet , Perkins Charles C.
Published: March 2006

Pigeons were trained on simultaneous red‐green discrimination procedures with delayed reward and sequences of stimuli during the delay. In Experiment 1, three stimuli appeared during the 60‐second intervals between the correct responses and reward, and the incorrect responses and nonreward. The stimulus that immediately followed a correct response also preceded nonreward, and the stimulus that followed an incorrect response preceded reward. These stimuli were 10 or .33 second in duration for different groups. Stimuli during the remainder of the delay interval differed following correct and incorrect responses. Group 10 initially persisted in the nonrewarded choice, but shifted to a preponderance of rewarded responses after further training. Group .33 rapidly acquired the correct response. Similar results were obtained in Experiment 2 where delay intervals consisted of opposite sequences of two stimuli of equal duration and total delays were 6, 20, or 60 seconds. Early in training, generalization of differential conditioned‐reinforcing properties from the conditions preceding reward and nonreward to postchoice conditions had a greater effect relative to backchaining than it did later. It was concluded that delayed‐reward learning is best analyzed in terms of the conditioned‐reinforcing value of the patterns of cues that follow immediately after rewarded and nonrewarded responses.
AUTOSHAPED KEY PECKING MAINTAINED BY ACCESS TO A SOCIAL SPACE
Authors: Peele David B. , Ferster C. B.
Published: March 2006

When four experimentally naive pigeons were exposed to occasional forward pairings of a keylight followed by a doorlight (that signaled access to a large social space), all subjects began to peck the lit key. In a second experiment, where the keylight either preceded the presentation of the doorlight or was presented independently of it, key pecking was maintained only in the former circumstance. The unconditioned stimulus in these experiments—arrival in the social space—did not elicit pecking. Hence, the conditioned response of key pecking and the unconditioned response of entering the social space differed. This demonstration of autoshaping with a social‐space unconditioned stimulus argues against a stimulus‐substitution account of the findings.
SCHEDULE‐INDUCED DEFECATION
Authors: Rayfield Frederick , Segal Marvin , Goldiamond Israel
Published: March 2006

Excessive defecation, typically considered to be a concomitant of stress, was experimentally induced or eliminated under specific schedules of positive reinforcement of lever pressing by rats. The schedules were, by and large, those under which polydipsia is typically induced. In the first of three experiments, rats under fixed‐interval 32‐second schedules and variable interval 32‐second schedules for food and water reinforcers defecated profusely, but not under fixed‐interval one‐second schedules or other small interval schedules. Somewhat higher rates of defecation were observed on variable interval 32‐second schedules than on fixed‐interval 32‐second schedules. In a second experiment, fixed‐ratio schedules were used, some of which resulted in responding such that reinforcement densities were similar to those on the interval schedules that induced defecation. Defecation was not systematically induced by these ratio schedules. In a third experiment, fixed‐time schedules of food presentations were utilized. High rates of defecation were induced comparable to those induced by interval schedules of the same time parameter. No other behavior commonly termed “emotional” was observed in any of these experiments.
PREFERENCES AMONG STIMULUS MATCHES IN THE PIGEON
Authors: Pisacreta Richard
Published: March 2006

Three pigeons were trained to peck two to five illuminated response keys. A peck to any of the keys changed the stimulus on the key. When all keys showed the same stimulus (i.e., a stimulus match), an additional key was illuminated with white light. A peck on this key produced three‐second access to grain, a three‐second intertrial interval, and the next trial. For most sessions, no particular stimulus match was required. Although there were often several stimuli available, each bird preferred a particular stimulus match. With up to 12 stimuli available, birds matched a particular stimulus 60% to 100% of the time.
“LYING” IN THE PIGEON
Authors: Lanza Robert P. , Starr James , Skinner B. F.
Published: March 2006

Two pigeons were taught to use symbols to communicate information about hidden colors to each other. When reporting red was more generously reinforced than reporting yellow or green, both birds passed through a period in which they “lied” by reporting another color as red.
THE SECOND OFFSPRING OF GENERAL PROCESS LEARNING THEORY: OVERT BEHAVIOR AS THE AMBASSADOR OF THE MIND
Authors: Malone John C.
Published: March 2006

Wasserman suggested in a recent book review that the study of intervening cognitive processes represents a current focus of interest in animal learning and that this has led to a revitalization of comparative psychology. An examination of the volume reviewed suggests that he may have overstated the case. Most of the authors to whom he refers expressed dissatisfaction with traditional stimulus‐response associationism but few argued for the extreme (information processing) sort of cognitive approach described by Wasserman.
THE ACQUISITION OF OBSERVING
Authors: Dinsmoor James A. , Mueller Kay L. , Martin Louise T. , Bowe Craig A.
Published: March 2006

Pigeons were exposed to stimuli correlated with the presence or absence of a variable‐interval 60‐second schedule of reinforcement only while they depressed a crossbar or “perch.” In the first experiment, the stimuli were different tilts of a line displayed on the key. When the difference in brightness between the line and the background (salience) was maximal, seven of eight birds acquired the discrimination, but when the difference was reduced by 50%, only one succeeded. In the second experiment, wavelength of chamber illumination served as the relevant dimension. Neither experiment showed a large effect attributable to the magnitude of the difference (disparity) between the positive and the negative stimulus. Individual differences in time spent observing were positively correlated with level of discrimination in the presence of the stimuli. All birds produced the positive stimulus for a greater proportion of the available time than they did the negative stimulus. This may be the mechanism that provides selective reinforcement of observing. Finally, the formation of a discrimination was analyzed in terms of changes in the proportion of time spent in contact with the discriminative stimuli.
ON THE FAILURE AND FACILITATION OF CONDITIONAL DISCRIMINATION
Authors: Williams Ben A.
Published: March 2006

Pigeons acquired a conditional discrimination in an autoshaping procedure in which certain stimulus combinations (form plus color) were followed by food, whereas others were not followed by food. Although the discrimination normally was acquired quickly, it was completely prevented when the color elements of the stimulus compounds were presented during the intertrial intervals preceding the trials in which both stimulus elements were available. This failure of discrimination was then prevented by having the colors serve as houselights rather than being localized on the response key and by pretraining procedures in which the colors were utilized in simpler discriminations. The results suggest that stimulus salience plays a critical role in determining whether conditional discriminations will be acquired, as the effects of all of the different operations could be understood in terms of increasing or decreasing the salience of the color elements, above or below some threshold value.
ACQUISITION AND MAINTENANCE OF AUTOSHAPED KEY PECKING AS A FUNCTION OF FOOD STIMULUS AND KEY STIMULUS SIMILARITY
Authors: Steinhauer G. D.
Published: March 2006

The results of a number of recent studies suggest that acquisition of autoshaped key pecking in pigeons is affected by the similarity of the grain‐hopper stimulus and response‐key stimulus. In Experiment 1 this hypothesis was tested by training independent groups of pigeons to key peck under six different hopper‐stimulus and key‐stimulus similarity conditions, and three procedures containing either immediate reinforcement, variable delay of reinforcement, or omission of reinforcement for key pecking. Number of trials to acquisition was found to be related to the similarity variable. Maintained responding was affected by the response‐reinforcer contingency. This effect was found both within and between subjects. Under two of the contingencies (automaintenance and omission), maintained responding continued to be affected by the similarity of the hopper stimulus and key stimulus. In Experiment 2 pigeons were given omission training with a hopper light on or off. Both acquisition and maintenance of key pecking were facilitated by the presence of the hopper light. The present findings suggest that much of the responding reported in various automatic shaping and training procedures may reflect the effects of key stimulus/food stimulus similarity.
CHOICE, RELATIVE REINFORCER DURATION, AND THE CHANGEOVER RATIO
Authors: Dunn Roger M.
Published: March 2006

Relative reinforcer duration was varied in concurrent schedules with a fixed‐ratio four changeover requirement. The schedule in effect after each reinforcer was randomly chosen. For all three pigeons, relative response rates overmatched relative reinforcer durations. Time allocation was less extreme and, on the average, matched relative reinforcer duration. In a subsequent manipulation, the level of preference was shown to depend on the size of the changeover requirement. These results are similar to those from related unequal reinforcement‐frequency procedures.
AN INVARIANT RELATION BETWEEN CHANGING OVER AND REINFORCEMENT
Authors: Dreyfus L. R. , Dorman L. G. , Fetterman J. G. , Stubbs D. A.
Published: March 2006

Although concurrent schedules may arrange reinforcers irregularly, relatively large numbers of reinforcers are obtained when an animal changes from one schedule to the other. This paper proposes a quantitative relation that predicts the proportion of reinforcers obtained when an animal is working on a schedule and the proportion when the animal changes over to a schedule. Basically the relation states that the number of reinforcers obtained while an animal works on a schedule varies directly with the relative amount of time spent working on that schedule; and the number of reinforcers obtained when an animal changes to a schedule varies directly with the relative amount of time spent on the alternate schedule. An important aspect of this relation is that when relative reinforcement rates are less than .50, more reinforcers are obtained just after an animal changes to a schedule than at all other times when this schedule is engaged. Data obtained both from a stat‐bird and a live pigeon were in close agreement with the quantitative predictions. The relation between changing over and reinforcement held across several procedural changes that included changes in relative reinforcement rate, changes from independent to interdependent scheduling procedures, and changes in the variable‐interval reinforcement distributions. The results are discussed in terms of the effects of the local distribution of reinforcement on responding. The local reinforcement distribution can affect local response rates and affects the resulting matching relation. This arrangement has implications for explanations of choice.
MATCHING SINCE BAUM (1979)
Authors: Wearden J. H. , Burgess I. S.
Published: March 2006

Data from recent studies employing concurrent variable‐interval schedules are reviewed. Subject species employed in different experiments have included rats, pigeons, and humans, and reinforcers have varied from food and shock avoidance to points exchangeable for money. Undermatching (a greater preference for the schedule of the concurrent pair that delivers the lower rate of reinforcement than the Matching Law predicts) has been preponderant in recent studies, irrespective of whether behavior has been measured in terms of response ratios or time allocation, with the possible exception of data produced by human subjects. Little difference in the degree of undermatching exhibited by response and time measures has been found, except in the results from a single laboratory, in which time‐allocation measures have tended to undermatch less than response measures. Procedural features, such as type of manipulandum used and changeover delay, seem to have little effect on the degree of undermatching exhibited, but asymmetrical response manipulanda (such as lever and key) for the different concurrent schedules, or other asymmetries in the experimental situation, show up clearly in bias measures, in a manner consistent with previous analyses.
PERFORMANCE OF HUMANS IN CONCURRENT AVOIDANCE/POSITIVE‐REINFORCEMENT SCHEDULES
Authors: Ruddle H. V. , Bradshaw C. M. , Szabadi E. , Foster T. M.
Published: March 2006

Performance maintained under concurrent schedules consisting of a variable‐interval avoidance component and a variable‐interval positive‐reinforcement component was studied in three human subjects using points exchangeable for money as the reinforcer. The rate of responding in the avoidance component increased, and the rate of responding in the positive‐reinforcement component declined, as a function of the frequency of point‐losses avoided in the avoidance component. The performance of all three subjects conformed to equations proposed by Herrnstein to describe behavior in concurrent schedules. The logarithms of the ratios of the response rates in the two components, and the logarithms of the ratios of the times spent in the two components, were linearly related to the logarithms of the ratios of the frequency of loss avoidance in the avoidance component to the frequency of reinforcement in the positive‐reinforcement component. When a changeover delay of 5.0 sec was imposed, the slopes of the linear functions were close to 1.0 in the case of two subjects, whereas the third subject exhibited significant undermatching. For two subjects the changeover delay was then reduced to 2.0 sec; in both cases the slopes of the linear functions were lower than under the 5.0‐sec condition. One subject participated in a third phase, in which no changeover delay was imposed; there was a further reduction in the slopes of the linear functions.
MEMORY FOR RECENT BEHAVIOR IN THE PIGEON
Authors: Kramer Stephen P.
Published: March 2006

Variations of the symbolic delayed‐matching‐to‐sample procedure were used to study a pigeon's memory for a small number of pecks. In the first experiment a choice of a left or right sidekey after a delay or retention interval was reinforced if a bird had not pecked at all or had pecked exactly once, before the delay, respectively. In the second experiment a choice of a red or green sidekey, regardless of its position, was reinforced if a bird had not pecked at all or had pecked exactly twice, respectively. In the first experiment a bird could orient toward the correct choice during the delay, whereas it could not in the second experiment. In a third experiment a feature‐probing method was used to study a pigeon's memory for a number of pecks in the context of certain other pecks. The results showed that a pigeon can remember a small number of pecks for one‐half to one minute or more and that the percent correct is a decreasing function of the log retention interval. When a second number of pecks is different from the first number, memory for the first number lasts only a few seconds. When a second number is the same, memory lasts considerably longer. The more recent number of pecks is remembered better. The results are interpreted in terms of a theory which holds that a reinforcer, in general, may act on a subjects' memory for recent behavior to generate patterns of behavior.
NOTE ON AVERSION LEARNING TO THE SHAPE OF FOOD BY MONKEYS
Authors: Domjan Michael , Miller Van , Gemberling Gail A.
Published: March 2006

Vervet and grivet monkeys were repeatedly tested eating bar‐ and circle‐shaped cookies. One subject was always injected with lithium immediately after eating cookies with the circle shape and learned to avoid the circular cookies while continuing to eat the bar‐shaped cookies. Another subject received similar treatment except that lithium injections were always delayed 30 minutes after access to the circle‐shaped cookies. She also acquired a discriminative aversion. Aversion learning was not observed with 60‐minute delayed toxicosis or with lithium injections administered unpaired with access to the cookies. The two types of cookies differed only in shape, and conditioning and test sessions were conducted in total darkness to preclude the use of visual cues. Therefore, the avoidance observed in subjects conditioned with immediate and 30‐minute delayed toxicosis represents a conditioned aversion to the shape of the cookies as revealed by tactile cues. These findings illustrate that monkeys can learn to select food on the basis of tactile stimuli when such stimuli are conditioned with delayed aversive stimulation.
SIGNAL DETECTION AND MATCHING: ANALYZING CHOICE ON CONCURRENT VARIABLE‐INTERVAL SCHEDULES
Authors: Logue A. W.
Published: March 2006

Pigeons' pecks on a red key and a green key were followed by access to grain according to pairs of concurrent independent variable‐interval schedules in a combined signal detection/matching law paradigm. Pecks on the red key were reinforced by the richer variable‐interval schedule if a short‐duration tone had been presented; pecks on the green key were reinforced by the richer variable‐interval schedule if a long‐duration tone had been presented. Pecks on the green key given a short‐duration tone, or on the red key given a long‐duration tone, were reinforced by the leaner variable‐interval schedule. The data were analyzed according to both signal detection's and the matching law's separate measures of, first, the discrimination of the choices and, second, the bias to make one response or another. Increasing the difficulty of the tone‐duration discrimination decreased both methods' measures of the discrimination of the choices and did not change both methods' measures of the bias to make one response or another. Changing the leaner variable‐interval schedule so that it approached the richer variable‐interval schedule decreased signal detection's measure of discrimination but left its measure of response bias and the matching law measures unchanged. Data collected only until a subject's first changeover response following presentation of a long or a short tone showed higher values for both methods' measures of discrimination, no change in signal detection's measure of response bias, and lower values for the matching law's measure of response bias. Relationships between the matching law's and signal detection's methods of analyzing choice are discussed. It is concluded that a signal detection analysis is more efficient for examining changes in the difficulty of a discrimination, whereas a matching law analysis is more effective for examining the effects of changes in relative rein forcer frequency.