bluuebunny/crossref_metadata_2025 huggingface dataset:
A RE‐EXAMINATION OF LOCAL CONTRAST IN MULTIPLE SCHEDULES1
Authors: Buck Steven L. , Rothstein Barry , Williams Ben A.
Published: March 2006

Pigeons were presented with multiple schedules of alternating 90‐sec components. When components in which grain was never presented alternated with components in which grain was presented on a variable‐interval schedule, the average rate of responding in the variable‐interval components increased, showing overall positive behavioral contrast. Unlike previous reports, this study found that the response rates for all birds increased toward the end of the variable‐interval components as training proceeded. This increase in local response rate disappeared when the multiple schedule was composed solely of variable‐interval components and reappeared when the variable‐interval components were again alternated with extinction. This finding cannot be predicted or explained by recent theories of behavioral contrast based on autoshaping, and thus questions their sufficiency. We suggest that this local response‐rate increase results from the predictable change from high to low density of reinforcement at the end of the fixed‐duration component. Thus, the present effect apparently illustrates a different type of interaction between components of a multiple schedule than that described by previous theories of contrast. In a given procedure, either or both types of interaction may occur; neither provides a complete account of behavioral contrast.
PEAK SHIFT FOLLOWING SIMULTANEOUS DISCRIMINATIONS1
Authors: Winton A. S. W.
Published: March 2006

Pigeons were exposed to stimuli presented on two keys. For some birds, the stimuli varied in a dimension of visual flicker‐rate, and for others they varied in visual intensity. During differential training, concurrent schedules operated, with one stimulus correlated with one schedule and another stimulus correlated with a second schedule that arranged a lower, or zero, rate of reinforcement. The stimuli were alternated randomly on the two keys. Generalization tests were given in which the original two, and seven other stimuli lying in the same dimension, were presented in pairs on the two keys in various combinations. In the generalization test given after differential training, each bird showed peak shift. The data did not support explanation for peak shift that gave critical emphasis to whether stimuli were presented simultaneously or successively during differential training.
ENHANCEMENT OF CONDITIONED REINFORCEMENT BY UNCERTAINTY1
Authors: Kendall Stephen B.
Published: March 2006

Pigeons were trained in three conditions. In the baseline condition, the birds responded on a fixed‐interval schedule with the response key white. When the interval was completed, the key turned either red or green for a delay interval that was terminated by a grain presentation dependent on no key pecks during the final 2 sec. In the uncertainty condition, no grain was presented at the end of the delay periods when the key was red. In the certainty condition, the white light appeared only on occasions when pecking would turn the key green and produce food. Otherwise, the key was illuminated red throughout the total time period. The highest response rate in white occurred in the uncertainty condition, the next highest in the certainty condition, and the lowest in baseline. The results suggest that uncertainty facilitated responding, although uncertainty is not a necessary condition for conditioned reinforcement.
RESPONSE‐SHOCK DELAY AS A REINFORCER IN AVOIDANCE BEHAVIOR1
Authors: Benedict James O.
Published: March 2006

After rats received preliminary training to avoid shock on a discrete‐trial retractable‐bar avoidance procedure, the procedure was changed such that responses retracted the lever but did not affect the rate of shock. Responses only delayed the onset of shock. About half of the animals under these procedures responded consistently on almost 100% of the discrete‐trial cycles over days. When short latencies maximized the response‐shock delay, animals tended to make short‐latency responses. When long latencies maximized the response‐shock delay, animals tended to make long‐latency responses. When all response latencies produced the same response‐shock delay, animals made differing average‐latency responses. And, when responses did not delay shock, most of the animals primarily engaged in shock‐elicited responding while the other animals engaged in preshock responding.
TWO‐COMPONENT SCHEDULES OF DIFFERENTIAL‐REINFORCEMENT‐OF‐LOW‐RATE1
Authors: Harzem Peter , Lowe C. Fergus , Davey Graham C. L.
Published: March 2006

Two‐component schedules of differential‐reinforcement‐of‐low‐rate were presented, where the contingencies specified separately two minimum interresponse times, t1 and t2, required for reinforcement, depending on whether the interresponse time was initiated by, in one case, a reinforced response (t1) or, in the other, a nonreinforced response (t2). A distinctive pattern of responding developed on each of the two contingencies. Duration of an interresponse time approximated t1 when the t1 contingency was in effect, and t2 when the t2 contingency was in effect. This relationship persisted even when t2 was shorter than t1, and responding at a higher rate on the t1 contingency would have greatly increased the rate of reinforcement. Increasing the value of t2 resulted in both longer interresponse times on the t1 contingency, and a higher probability of a response‐burst on those occasions when the contingency switched from t1 to t2. The results indicated that both reinforced and nonreinforced responses functioned as discriminative events in determining the duration of following interresponse times.
SWITCHING FROM COMPETITION TO SHARING OR COOPERATION AT LARGE RESPONSE REQUIREMENTS: COMPETITION REQUIRES MORE RESPONDING1
Authors: Hake Don F. , Olvera Dennis , Bell James C.
Published: March 2006

Two pairs of high‐school students matched‐to‐sample for money. On each trial, a subject could either respond on one lever to take the matching‐to‐sample problem himself (taking response) or respond on a second lever to give the problem to his coactor (giving response). The first subject to complete the response requirement determined the distribution of the problem. Competition maximizes the amount of responding over trials, i.e., both subjects make taking responses on each trial. Sharing and cooperation minimize responding: only one subject makes a taking response (sharing) or a giving response (cooperation) on each trial, and the subjects alternate responding such that there is an equitable distribution of responses and reinforcers over trials. Large increases in the fixed‐ratio response requirement to distribute problems produced: (1) a switch from competition to sharing or cooperation, (2) the expected concomitant change from inequitable to equitable distributions of reinforcers, and (3) a reduction in the amount of responding for three of the four subjects. Previous animal research has shown that large response requirements may have aversive properties. Switching from competition to sharing or cooperation at large response requirements allows a reduction in responding and, at the same time, a moderate number of reinforcers for each subject.
STIMULUS PROPERTIES OF FIXED‐INTERVAL RESPONSES1
Authors: Buchman Irvin B. , Zeiler Michael D.
Published: March 2006

Responses in the first component of a chained schedule produced a change to the terminal component according to a fixed‐interval schedule. The number of responses emitted in the fixed interval determined whether a variable‐interval schedule of food presentation or extinction prevailed in the terminal component. In one condition, the variable‐interval schedule was in effect only if the number of responses during the fixed interval was less than that specified; in another condition, the number of responses had to exceed that specified. The number of responses emitted in the fixed interval did not shift markedly in the direction required for food presentation. Instead, responding often tended to change in the opposite direction. Such an effect indicated that differential food presentation did not modify the reference behavior in accord with the requirement, but it was consistent with other data on fixed‐interval schedule performance. Behavior in the terminal component, however, did reveal sensitivity to the relation between total responses emitted in the fixed interval and the availability of food. Response rate in the terminal component was a function of the proximity of the response number emitted in the fixed interval to that required for food presentation. Thus, response number served as a discriminative stimulus controlling subsequent performance.
RESPONSE‐RATE INVARIANCE IN CONCURRENT SCHEDULES: EFFECTS OF DIFFERENT CHANGEOVER CONTINGENCIES1
Authors: Guilkey Marilyn , Shull Richard L. , Brownstein Aaron J.
Published: March 2006

In a two‐key chamber, one key (the food key) was either red or green with different variable‐interval schedules operating concurrently in each color and a second key (the changeover key) served to change the food‐key color. Three pigeons were trained with either a 2‐sec changeover delay or a 0‐sec changeover delay and three birds with a fixed‐ratio 2 on the changeover key instead of a changeover delay. The proportion of time spent in red approximated the proportion of reinforcers delivered in red for all birds. When the procedure was changed so that reinforcers were signalled in the green schedule, rates of reinforcement were unaltered, but the pigeons spent virtually the whole session in red. Changeovers to green were allowed only when a reinforcer was assigned by the schedule associated with green. For all pigeons with the fixed—ratio requirement on the changeover key or with a 0‐sec changeover delay, the overall rate of red‐key responses was higher during the signalling condition than during unsignalled, or baseline, condition. The present data question the generality of previous reports that the rate of one response is independent of the amount of time allocated to the alternative response.
PREFERENCE AND DISCRIMINATION BETWEEN RESPONSE‐DEPENDENT AND RESPONSE‐INDEPENDENT SCHEDULES OF REINFORCEMENT1
Authors: Brinker Richard P. , Treadway Jerry T.
Published: March 2006

Four Asian quail (Coturnix coturnix japonica) were exposed to concurrent‐chain schedules, the terminal links of which were either variable‐interval 30 sec and variable‐time 30 sec, or fixed‐interval 30 sec and fixed‐time 30 sec. Except for one bird that exhibited a preference for the variable‐interval schedule over the variable‐time schedule, no consistent preferences were demonstrated for response‐dependent or response‐independent schedules. However, response rates were three times greater on response‐dependent than on response‐independent schedules. The discrimination between terminal‐link schedules was rapidly recovered after the schedule positions were reversed. Casual observations revealed that the birds engaged in stereotypic circling and pecking while the response‐independent schedules were operative.
FREEDOM AND KNOWLEDGE: AN EXPERIMENTAL ANALYSIS OF PREFERENCE IN PIGEONS1
Authors: Catania A. Charles
Published: March 2006

Relative responding in initial links of concurrent‐chain schedules showed that pigeons preferred free to forced choices and informative to uninformative stimuli. Variable‐interval initial links on two lower keys (white) of a six‐key chamber produced terminal links on either two upper‐left keys (blue and/or amber) or two upper‐right keys (green and/or red). Terminal links in which pecks on either of two lit keys produced fixed‐interval reinforcement (free choice) were preferred to links with only one lit fixed‐interval key available (forced choice). Terminal links with different key colors correlated with concurrent fixed‐interval reinforcement and extinction (informative stimuli) were preferred to links with these schedules operating on same‐color keys (uninformative stimuli). Scheduling extinction for one of the two free‐choice keys assessed preference for two lit keys over one lit key, but confounded number with whether stimuli were informative. Fixed‐interval reinforcement for both keys in each terminal link, but with different‐color keys in one link and same‐color keys in the other, showed that preference for informative stimuli did not depend on stimulus variety. Preferences were independent of relative responses per reinforcement and other properties of terminal‐link performance.
BEHAVIORAL CONTROL OF VISUAL FIXATION OF THE RHESUS MONKEY1
Authors: Crawford M. L. J.
Published: March 2006

A paradigm for the control of visual fixation of the macaque monkey in vision experiments was described. Using a Maxwellian view, the procedure permits the placement of discrete test‐light stimuli in a specific area of the retina as the monkey fixates a primary target. This procedure holds foveal fixation as other behaviorally significant visual stimuli are presented to the visual field. By a methods‐of‐limits procedure, the sensitivity of the monkey eye was measured at different retinal locations under both photopic and scotopic visual adaptation.
DETECTION OF THE VELOCITY OF MOVEMENT OF VISUAL STIMULI BY PIGEONS
Authors: Hodos William , Smith Lars , Bonbright James C.
Published: March 2006

Nine pigeons were trained to discriminate a moving stimulus from a stationary stimulus. In one experiment, the stimulus was a rotating disc with radial stripes. In a second experiment, the stimulus was a vertically moving film strip with horizontal bars. Several psychophysical procedures were used to determine the minimal detectable velocity of movement. The detection thresholds for most of the pigeons fell in the range of 4.4 to 6.5 millimeters per second, corresponding to a retinal velocity of 4.1 to 6.01 degrees per second. a signal‐detection analysis of the psychophysical data indicated systematic changes in response bias that were related to the ordinal position of the stimulus velocity in the sequence.
BEHAVIORAL CONTRAST OF TIME ALLOCATION1
Authors: Bouzas Arturo , Baum William M.
Published: March 2006

Pigeons' standing on a platform produced food reinforcement according to two‐component multiple schedules in which either both components consisted of the same variable‐interval schedule or one of these was replaced with a component without reinforcement (extinction). The components of the multiple schedule alternated every 30 sec, and were signalled by changes in the color of diffuse overhead illumination. Changing the schedule of one of the components to extinction increased the percentage of time spent on the platform during the unchanged component (behavioral contrast). This result casts doubt on accounts that attribute behavioral contrast to variations in the rate of noninstrumental elicited responses.
CONTRAST, INDUCTION, FACILITATION, SUPPRESSION, AND CONSERVATION1
Authors: Allison James
Published: March 2006

Ten rats received all of their water in daily 1‐hr sessions. Following a baseline phase in which lever and water spout were freely available throughout each session, subjects were trained to press the lever for water on mixed schedules composed of two alternating components. Each component gave access to water for a fixed cumulation of drinking time every time the rat cumulated a fixed amount of lever‐pressing time. Changes in one component produced contrast and induction effects, both positive and negative, with respect to both lever pressing and drinking in the unchanged component. All schedules facilitated lever pressing relative to baseline. All schedules suppressed drinking relative to baseline, even though contingency sessions allowed ample time to perform the baseline amount of drinking. The entire pattern of results was predicted in quantitative detail by assuming that the total amount of a dimension apportioned to lever pressing and drinking is conserved between baseline and contingency sessions. Conservation theory was shown to predict several effects produced by simple fixed‐ratio schedules, and was compared favorably with probability‐differential (Premack, 1971) and response‐deprivation (Timberlake and Allison, 1974) theory.
STIMULUS CONTROL OF DIFFERENTIAL‐REINFORCEMENT‐OF‐LOW‐RATE RESPONDING1
Authors: Gray Vicky A.
Published: March 2006

Five pigeons were given single‐stimulus training on an 8‐sec differential‐reinforcement‐of‐low‐rate schedule followed by steady‐state generalization training using 12 wavelength stimuli. Three birds had a high percentage of reinforced responses on the training schedule and flat generalization gradients of total responses. The birds with fewer reinforced responses had much steeper generalization gradients. Generalization gradients plotted as a function of both stimulus wavelength and interresponse time showed that for most birds, stimulus control was restricted to responses with long interresponse times. Responses with very short interresponse times were not under stimulus control and there was some evidence of inhibitory control of short interresponse times. Interresponse‐times‐per‐opportunity functions, plotted as a function of stimulus wavelength, showed that stimulus wavelength controlled the temporal distribution of responses, rather than the overall rate of response. The data indicate that the differential‐reinforcement‐of‐low‐rate schedule generates several response categories that are controlled in different ways by wavelength and time‐correlated stimuli, and that averaging responses regardless of interresponse‐time length obscures this control.
STIMULUS DURATION AS A MEASURE OF STIMULUS GENERALIZATION1
Authors: Honig W. K. , Beale I. L.
Published: March 2006

Four pigeons in the line‐positive group were trained with a vertical line on a green background that signalled intermittent reinforcement while a plain green field signalled extinction. Four pigeons in the line‐negative group were trained with the opposite discrimination. Response to a control key terminated any trial and initiated the next trial. The birds also used the control key during generalization tests to control the durations of trials in which various line orientations were presented. These durations were summed to provide generalization gradients of stimulus duration that were positive or negative in accordance with the trained discriminations. In Experiment 2, birds from the line‐positive group were tested with a procedure in which the control key was not available on some trials. This provided an independent assessment of response rates to the test stimuli. These rates were used to predict the stimulus durations obtained when the control key was available. The findings supported a general model for the prediction of response distributions among concurrent stimuli from rates observed with single stimuli.
A COMPARISON OF PECKING GENERATED BY SERIAL, DELAY, AND TRACE AUTOSHAPING PROCEDURES1
Authors: Newlin Robert J. , LoLordo Vincent M.
Published: March 2006

Pigeons were exposed to serial, delay, and trace autoshaping procedures. In Experiment I, all conditioned stimuli (CSs) were changes in illumination of the response key. The number of trials to acquisition of the keypeck increased from serial, to 4‐sec delay, 8‐sec delay, and 8‐sec trace procedures, in that order. In Experiment II, which used a longer intertrial interval, trials to criterion increased from 8‐sec delay, to 28‐sec delay, 8‐sec trace, and 28‐sec trace procedures, in that order. In Experiment III, two groups received serial procedures in which the first CS was either a tone or a houselight, and the second was a keylight. The tone group acquired the key peck more rapidly than the houselight group. Early in conditioning in these experiments, and when the conditioned stimulus was a change in the keylight, there was a short latency to the onset of pecking and pecking was directed at the CS. After extensive conditioning, or when the CS was relatively diffuse, pecking still occurred, but had a longer latency and was not reliably directed toward the conditioned stimulus.
RESPONSE BIAS AND THE DISCRIMINATION OF STIMULUS DURATION1
Authors: Stubbs D. Alan
Published: March 2006

Pigeons discriminated stimulus duration in a psychophysical choice situation. Following presentation of any duration from a set of short durations (11 to 15 sec), responses on a red key were reinforced intermittently. Following presentation of any duration from a set of long durations (16 to 22 sec), responses on a green key were reinforced intermittently. Relative reinforcement rates were manipulated for choice responses across conditions. As relative reinforcement rates were varied, psychometric functions showed shifts in green‐key responses at all durations. A signal‐detection analysis showed that sensitivity remained roughly constant across conditions while response bias changed as a function of changes in relative reinforcement rate. Relative error rates tended to match relative reinforcement rates.
CONTROL BY THE AUDITORY OR THE VISUAL ELEMENT OF A COMPOUND DISCRIMINATIVE STIMULUS: EFFECTS OF FEEDBACK1
Authors: Lolordo Vincent M. , Furrow David R.
Published: March 2006

Groups of pigeons were trained to depress a treadle in the presence of a compound stimulus consisting of a tone and a red houselight (a) to avoid electric shock, or (b) to obtain grain. Immediate, exteroceptive feedback was equated for avoidance and appetitive groups within an experiment, but varied across experiments from elevation of a nonilluminated feeder to darkening of the chamber, termination of the tone, and elevation of an illuminated feeder. Responding in the absence of the compound stimulus postponed its next occurrence. After performance had stabilized, the degree to which each element controlled treadle pressing was determined. Generally, in the appetitive tests, the red light controlled much more responding than did the tone, but in the avoidance tests, the tone controlled more responding than did the red light.
PREFERENCE FOR MIXED VERSUS CONSTANT DELAY OF REINFORCEMENT1
Authors: Cicerone Robert A.
Published: March 2006

Preference for constant and mixed delay of reinforcement was studied using concurrent equal variable‐interval schedules. For four pigeons, pecking one key was reinforced following constant delays of 8 sec and mixed delays of 6 or 10 and 2 or 14 sec. Pecking a second key was reinforced following constant delays of 0, 8, 16, and 32 sec. For two additional pigeons, pecking one key was reinforced following delays of 30, 15 or 45, 5 or 55, and 0 or 60 sec. Reinforcements on the other key were delayed 30 sec. It was found that (a) pigeons preferred mixed relative to constant delay of reinforcement, and (b) preference for mixed delay of reinforcement increased as the range of delay interval variability increased.
FACILITATION OF HUMAN TOBACCO SELF‐ADMINISTRATION BY ETHANOL: A BEHAVIORAL ANALYSIS1
Authors: Griffiths Roland R. , Bigelow George E. , Liebson Ira
Published: March 2006

The effect of ethanol on the cigarette smoking of alcoholic subjects was studied in a residential laboratory. During daily 6‐hr sessions, cigarettes were obtained either by request to the ward staff or by operation of a lever (fixed‐ratio 5 or 10). In a mixed sequence across days, sessions involved ingestion of either vehicle (orange juice) alone or vehicle plus ethanol (133.7 g). During ethanol sessions, the rate of cigarette smoking increased from 26% to 117% of vehicle levels. A series of control studies eliminated a number of potential behavioral mechanisms for the observed effect and indicated that the ethanol‐induced increase in cigarette smoking occurred under a variety of experimental conditions: (1) when smoking could not occur concurrently with ethanol or vehicle consumption; (2) when subjects were not allowed to socialize; (3) when ingestion of ethanol or vehicle was scheduled for a number of consecutive days; (4) when various doses of ethanol were administered under blind conditions. In control experiments, weighing unsmoked tobacco and counting the number of puffs per cigarette indicated the effect was not due to smoking less of each cigarette. The effect was not limited to the experimental sessions alone, since total daily smoking was higher on ethanol days than vehicle days.
NEGATIVE REINFORCEMENT WITH SHOCK‐FREQUENCY INCREASE1
Authors: Gardner Edward T. , Lewis Paul
Published: March 2006

Two avoidance‐conditioning experiments in which responding delayed shocks are reported. Rats receiving an average of two shocks per minute (imposed condition) could produce, by pressing a bar, a 3‐min alternate condition. Six (Experiment I) or more (Experiment II) shocks occurred in the alternate condition. All shocks in the alternate condition were delayed and delivered at 1‐sec intervals. With long delays, all subjects produced the alternate condition and spent a large percentage of each session in the alternate condition. The first experiment demonstrated that the longer the delay from onset of the alternate condition to onset of the shocks, the more session time spent in the alternate condition. The second experiment indicated that despite increased shock frequency, behavior is acquired and maintained when responding leads to sufficient delay. Individual subjects produced the alternate condition by bar pressing in essentially one of two patterns. One pattern, termed postshock, involved bar pressing immediately after shock; the other, termed posttransition, involved responding immediately after the transition from the alternate to the imposed condition. These results indicate that shock‐frequency reduction is not necessary for avoidance conditioning; delay to shock onset is sufficient.
SEQUENTIAL REACQUISITION AS A FUNCTION OF TIMEOUT FROM AVOIDANCE1
Authors: Schrot John , Boren John J. , Moerschbaecher Joseph M.
Published: March 2006

Rats learned to reacquire four similar three‐member response sequences. Each sequence member was associated with a different response lever, and the correct sequence of levers (i.e., 3‐1‐2, 2‐1‐3, 1‐3‐2, and 2‐3‐1) changed each session. The first two correct responses of each sequence postponed shock for a fixed period of time. The third correct response initiated a signalled timeout from avoidance. Incorrect responses did not affect the shock interval or reset the sequence. The effects of manipulating timeout duration on the sequential reacquisition baseline were investigated. All subjects displayed biphasic reacquisition performances similar to those controlled by food. The phases were characterized by an initial increase in accuracy, which reached a stable level during the latter portion of each session. Timeout duration affected rate of sequence completion and shock density, but not percentage of errors. Rate of sequence completion was fastest with intermediate timeouts (15 to 60 sec), and slowest with extreme durations (1 or 120 sec). Shock densities peaked with extreme durations and were at minimum with intermediate timeout values. The percentage of errors was the same across timeout durations. These data extend the generality of sequential reacquisition as a procedure for studying learning, and demonstrate timeout from avoidance to be a controlling variable.
ALTERNATIVE RESPONSE TRAINING, DIFFERENTIAL REINFORCEMENT OF OTHER BEHAVIOR, AND EXTINCTION IN SQUIRREL MONKEYS (SAIMIRI SCIUREUS)1
Authors: Mulick J. A. , Leitenberg H. , Rawson R. A.
Published: March 2006

In Experiment I, (a) extinction, (b) extinction plus reinforcement of a discrete alternative response, and (c) differential reinforcement of other behavior were each correlated with a different stimulus in a three‐component multiple schedule. The alternative‐response procedure more rapidly and completely suppressed behavior than did differential reinforcement of other behavior. Differential reinforcement of other behavior was slightly more effective than extinction alone. In Experiment II, reinforcement of specific alternative behavior during extinction and differential reinforcement of other behavior were used in two components, while one component continued to provide reinforcement for the original response. Once again, the alternative‐response procedure was most effective in reducing responding as long as it remained in effect. However, the responding partially recovered when reinforcement for competing behavior was discontinued. In general, responding was less readily reduced by differential reinforcement of other behavior than by the specific alternative‐response procedure.
PERFORMANCE ON VARIABLE‐INTERVAL SCHEDULES ARRANGED SINGLY AND CONCURRENTLY1
Authors: Davison M. C. , Hunter I. W.
Published: March 2006

Extensive parametric data were obtained from pigeons responding on variable‐interval schedules arranged on three, two, and one response keys. Number of responses on the keys, the time spent responding on the keys, and the number of reinforcements obtained on the keys were measured. Response rates on each key were an increasing function of the reinforcement rate on that key, and an inverse function of the reinforcement rate on the other keys. In terms of preference, both response and time‐allocation ratios undermatched ratios of obtained reinforcements, and the degree of undermatching was consistent both within, and between, two‐ and three‐schedule data. When absolute response‐rate data were analyzed according to Herrnstein's (1970) quantitative account, obtained values of assumed constants were not consistent either within or between conditions. However, a power‐function modification of Herrnstein's account fitted the data well and provided similar exponent values to those obtained for the undermatching of preference ratios.
AFTEREFFECTS OF REINFORCEMENT ON VARIABLE‐RATIO SCHEDULES1
Authors: Priddle‐Higson Peter J. , Lowe C. Fergus , Harzem Peter
Published: March 2006

On each of variable‐ratio 10, 40, and 80 schedules of reinforcement, when rats' lever‐pressing rates were stable, the concentration of a liquid reinforcer was varied within sessions. The duration of the postreinforcement pause was an increasing function of the reinforcer concentration, this effect being more marked the higher the schedule parameter. The running rate, calculated by excluding the postreinforcement pause, was unaffected by concentration. The duration of the postreinforcement pause increased with the schedule parameter, but the proportion of the interreinforcement interval taken up by the pause decreased. Consequently, the overall response rate was an increasing function of the schedule parameter; i.e., it was inversely related to reinforcement frequency, contrary to the law of effect. The running rate, however, decreased with the reinforcement frequency, in accord with the law of effect. When 50% of reinforcements were randomly omitted, the postomission pause was shorter than the postreinforcement pause, but the running rate of responses was not affected.
ACQUISITION OF THE AUTOSHAPED KEY PECK AS A FUNCTION OF AMOUNT OF PRELIMINARY MAGAZINE TRAINING
Authors: Steinhauer G. D. , Davol G. H. , Lee A.
Published: March 2006

Three experiments evaluated the effect of magazine training on acquisition of the pigeon's key peck during autoshaping. In Experiment I, pigeons were exposed to two days of extended magazine training, followed on the third day by keylight‐only presentations. All pigeons pecked the keylight early in the keylight‐only session. Experiment II examined the relationship between the number of magazine‐training trials and trials to the first peck. Pigeons were given either 0, 3, 10, or 25 magazine‐training trials followed by the standard autoshaping procedure. The number of trials to the first peck was related to the number of magazine‐training trials. In Experiment III, pigeons were exposed to the standard autoshaping procedure without prior magazine training. The data from Experiment III suggested that key pecking will occur only after the response of eating from the lighted hopper has occurred. Taken together, these results suggest that initial magazine training is an important variable in autoshaping. Key pecking is discussed as a generalized consummatory response.
AN ANALYSIS OF RATS' DRINKING‐TUBE CONTACTS UNDER TANDEM AND FIXED‐INTERVAL SCHEDULES OF FOOD PRESENTATION1
Authors: McLeod Daniel R. , Gollub Lewis R.
Published: March 2006

Rats' lever presses and drinking‐tube contacts were studied under fixed‐interval schedules of food presentation and under a tandem schedule composed of three fixed intervals. One group of rats was exposed first to the tandem schedule, next to fixed‐interval schedules of comparable interpellet intervals, and once again to the tandem schedule; a second group of rats was exposed first to a fixed‐interval and then to the tandem schedule. Under the tandem schedule, lever presses occurred at a higher rate and were more uniformly distributed in time than under the fixed‐interval schedule. Tube contacts emitted by rats exposed first to a fixed‐interval schedule consisted mostly of tongue contacts, which occurred at a high rate shortly after food; tube contacts emitted by rats exposed first to the tandem schedule consisted mostly of paw contacts, which occurred at a lower rate at times other than shortly after food. Changing the schedule from fixed interval to tandem decreased the frequency of tongue contacts for all rats. Under schedules of food presentation with comparable interpellet intervals, the schedule of food presentation, rather than the rate of food delivery per se, determined the topography and temporal locus of drinking‐tube contacts.
PREFERENCE FOR FIXED‐INTERVAL SCHEDULES: EFFECTS OF UNEQUAL INITIAL LINKS
Authors: Davison M. C.
Published: March 2006

Six homing pigeons were trained on concurrent chain schedules in which the terminal links were fixed‐interval schedules of 5 sec or 15 sec. One initial‐link schedule was always VI 27‐sec; the other was varied over conditions from VI 27‐sec to VI 181‐sec. Preference measured in the initial links varied as a joint function of the initial‐ and terminal‐link schedules. When the initial links were varied with constant, but unequal, terminal links, the slope of the function relating the logarithm of the initial‐link response ratio to the logarithm of the terminal‐link entry ratio differed from that obtained with equal terminal links. This result indicates that biases attributable to the terminal‐link schedules were not constant. The rate of change of preference, or degree of undermatching, in the initial links depended on whether the shorter initial link led to the shorter or the longer terminal link. These results raise the question of whether bias and undermatching in concurrent schedule performance are independent measures.
CONCURRENT PERFORMANCES: RATE CONSTANCIES WITHOUT CHANGEOVER DELAYS1
Authors: Catania A. Charles
Published: March 2006

Pigeons' pecks on two keys were maintained, without changeover delays, by independent variable‐interval schedules of food reinforcement. Four regularly cycling 2‐min components scheduled reinforcement respectively for both keys, left key only, both keys, and right key only. Initially, reinforcement scheduled for one key alone produced more responding on that key than reinforcement scheduled concurrently for both keys. Continued sessions reduced this difference; response rate on a given key approached constancy, or invariance with respect to the performance on and schedule for the other key. When extinction replaced the reinforcement schedule on either key, responding on that key decreased more during components that scheduled reinforcement for the other key than during those that did not. This demonstration that responses on one key were not supported by reinforcers on the other key suggested that the alternation of concurrent responding and either‐key‐alone responding prevented concurrent superstitions from developing.
THE INFLUENCE OF THE VICTIM ON SHOCK‐INDUCED AGGRESSION IN RATS
Authors: Hynan Michael T.
Published: March 2006

In two studies, free‐roaming male rats (aggressors) were shocked in the presence of male target rats restrained in either an upright or a supine posture. In addition, in Experiment II, two levels of aggressor shock intensity (0.8 mA or 2.0 mA) were used while targets received one of three levels of shock (0.5 mA, 1.5 mA, or 2.5 mA). In both studies, upright targets were attacked less than supine targets. Frequency of aggression was directly related to level of aggressor shock intensity in Experiment II. Also, attack by 0.8‐mA aggressors against supine targets was inversely related to level of target shock intensity. The low level of attack against upright targets was interpreted in terms of a threat display. Similarly, it was concluded that the target shock‐intensity effect in Experiment II was due to specific threat behaviors displayed by those supine rats that received the highest‐intensity shocks.
TITRATION OF SCHEDULE PARAMETERS BY PIGEONS1
Authors: Lea S. E. G.
Published: March 2006

Pigeons were tested in a computer‐controlled two‐key chamber. A standard (nonchanging) schedule of reinforcement was in force on one key, and an adjusting schedule on the other. The schedules were available concurrently after each reinforcement, but after the first peck on either key (the choice peck), the schedule on the other key was made inoperative. The parameter of the adjusting schedule was decreased when the standard schedule was chosen and increased when the adjusting schedule was chosen. The standard schedule was changed only between sessions. Fixed intervals and fixed ratios were used as standard schedules, and intervals and ratios were used as adjusting schedules. When standard and adjusting schedules were of the same type, median parameters on the adjusting key equalled those of the standard schedules, at four values of each standard schedule. For four of five birds, and for the group median, similar curves could be plotted through the indifference points obtained from a standard ratio with an adjusting interval, and from a standard interval with an adjusting ratio. These points showed consistent individual differences, but they could be predicted by assuming that the median time from the choice peck to reinforcement should be the same on both keys. This is equivalent to treating the schedule as a concurrent chain and assuming that Herrnstein's quantitative law of effect applies.
MATCHING WITH A TRIO OF CONCURRENT VARIABLE‐INTERVAL SCHEDULES OF REINFORCEMENT
Authors: Pliskoff Stanley S. , Brown Thomas G.
Published: March 2006

A trio of concurrent variable‐interval schedules of reinforcement was arranged according to a changeover‐key procedure, including a changeover delay of 1.5 sec. The three schedules provided a combined maximum reinforcement rate of 45 reinforcements per hour. With that restriction, the nine experimental conditions included several combinations of variable‐interval schedules, sometimes including extinction. The pigeons matched relative response rate and relative time to relative reinforcement rate. Relative time appeared to match somewhat better than relative response rate. Performance adjusted rapidly from one experimental condition to the next, whether the change involved two or all three schedules of the concurrent trio.
BEHAVIOR CONTROLLED BY SCHEDULED INJECTIONS OF COCAINE IN SQUIRREL AND RHESUS MONKEYS1
Authors: Goldberg Steven R. , Kelleher R. T.
Published: March 2006

Rates and patterns of key‐press responding maintained under schedules in which responding resulted in intravenous injections of cocaine were studied in squirrel monkeys and rhesus monkeys. Each injection was followed by a 60‐ or 100‐sec timeout period. Schedule‐controlled behavior was obtained at appropriate cocaine doses in each species. Under FR 10 or FR 30 schedules, performance was characterized by high rates of responding (usually more than one response per second) in each ratio. Under FI 5‐min schedules, performance was characterized by an initial pause, followed by acceleration of responding to a final rate that was maintained until the end of the interval. Under multiple fixed‐ratio fixed‐interval schedules, rates and patterns of responding appropriate to each schedule component were maintained. Responding seldom occurred during timeout periods under any schedule studied. At doses of cocaine above or below those that maintained characteristic schedule‐controlled behavior, rates of responding were relatively low and patterns of responding were irregular. Characteristic fixed‐interval responding was maintained over a wider range of cocaine doses than characteristic fixed‐ratio responding. Complex patterns of responding controlled by discriminative stimuli under fixed‐ratio or fixed‐interval schedules can be maintained by cocaine injections in squirrel monkeys and rhesus monkeys.
ORGANIZATION IN MEMORY AND BEHAVIOR1
Authors: Shimp Charles P.
Published: March 2006

Some common reinforcement contingencies make the delivery of a reinforcer depend on the occurrence of behavior lacking significant temporal structure: a reinforcer may be contingent on nearly instantaneous responses such as a pigeon's key peck, a rat's lever press, a human's button press or brief verbal utterance, and so on. Such a reinforcement contingency conforms much more closely to the functionalist tradition in experimental psychology than to the structuralist tradition. Until recently, the functionalist tradition, in the form of a kind of associationism, typified most research on human learning and memory. Recently, however, research on human memory has focused more on structural issues: now the basic unit of analysis often involves an organized temporal pattern of behavior. A focus on the interrelations between the function and structure of behavior identifies a set of independent and dependent variables different from those identified by certain common kinds of “molar” behavioral analyses. In so doing, such a focus redefines some of the significant issues in the experimental analysis of behavior.
BEHAVIOR OF HUMANS IN VARIABLE‐INTERVAL SCHEDULES OF REINFORCEMENT
Authors: Bradshaw C. M. , Szabadi E. , Bevan P.
Published: March 2006

During Phase I, human subjects pressed a button for monetary reinforcement in five variable‐interval schedules, each of which specified a different frequency of reinforcement. The rate of responding was an increasing, negatively accelerated function of reinforcement frequency; the data conformed closely to Herrnstein's equation. During Phase II, the same five schedules were in operation, but in addition a concurrent variable‐interval schedule (B) was introduced, responses on which were always reinforced at the same frequency. Response rate in component A increased while the response rate in B decreased, as a function of the reinforcement frequency in component A. Relative response rates in the two component schedules matched the relative frequencies of reinforcement. Comparing the absolute response rates in component A during Phase I and Phase II it was found that introduction of the concurrent schedule did not affect the value of the theoretical maximum response rate, but did increase the value of the reinforcement frequency needed to obtain any particular submaximal response rate.
EFFECTS OF VARIATIONS IN THE TEMPORAL DISTRIBUTION OF REINFORCEMENTS ON INTERVAL SCHEDULE PERFORMANCE
Authors: Lund Charles A.
Published: March 2006

Pigeons were exposed to variable‐interval and fixed‐interval schedules and schedules approximating variable‐interval and fixed‐interval schedules. The probabilities of the variable‐interval and fixed‐interval components in a mixed fixed‐interval variable‐interval schedule in Experiment I and the minimum and maximum interreinforcement intervals in Experiment II in a variable‐interval schedule were manipulated to create intermediate schedule contingencies and contingencies approximating simple variable‐interval or fixed‐interval contingencies. Maximal control by time as defined by quantitative indices of the temporal pattern of response occurred as fixed‐interval contingencies were approximated and minimal control occurred as variable‐interval contingencies were approximated. Changes in the temporal pattern of response were systematically related to changes in the temporal distribution of reinforcements with both procedural definitions for manipulating the temporal distribution of reinforcements.
CLOCK CONTROL OF HUMAN PERFORMANCE ON AVOIDANCE AND FIXED‐INTERVAL SCHEDULES1
Authors: Baron Alan , Galizio Mark
Published: March 2006

The avoidance and fixed‐interval performances of human subjects were studied in two experiments. Addition of time‐correlated stimuli (added clock) improved behavioral efficiency, since response rates decreased without decreases in reinforcement rates. Response‐dependent display of the clock maintained a second, observing response and reductions in clock duration weakened such observing behavior. Generally, the reinforcing properties of the clock were more apparent with the avoidance than with the fixed‐interval schedule, a finding attributed to temporal cues already provided by delivery of the fixed‐interval reinforcers. Reduced rates of the main response when the clock was dependent on an observing response were more than offset by rates of the observing response in the majority of subjects. Thus, the results do not support an interpretation of the reinforcing properties of added clocks simply in terms of work reduction.
DIMENSIONAL STIMULUS CONTROL FOLLOWING BRIEF WAVELENGTH TRAINING1
Authors: Weisman R. G. , Thio Harriet
Published: March 2006

Pigeons with extensive training pecking a key illuminated by a white line then had brief training with the key illuminated by 555 nanometers. This was immediately followed by a wavelength generalization test in extinction. Dimensional stimulus control about the training wavelength increased with the duration and number of reinforcements given on variable‐interval 30‐sec and variable‐interval 10‐sec schedules in Experiment I. In Experiment II, dimensional stimulus control was obtained after only 4 min of wavelength training from birds with prior and independent discrimination training. Experiment III provided groups equated in number of reinforcers with groups in Experiment I and two 8‐min duration groups. Analyses, which included results from both Experiments I and III, showed that dimensional stimulus control increased: (a) more rapidly as a function of the duration of variable‐interval 10‐sec than variable‐interval 30‐sec reinforcement; (b) at the same rate across variable‐interval reinforcement schedules, as a function of the number of reinforcers available during brief wavelength training.
SIGNALLED REINFORCEMENT AND MULTIPLE SCHEDULES1
Authors: Marcucella Henry
Published: March 2006

The responses of four pigeons were first reinforced in the presence of two different wavelengths (green and red) on a two‐ply multiple schedule with identical variable‐interval 3‐min schedules of reinforcement associated with each component. While the constant‐component reinforcement schedule remained unchanged during the experiment, the schedule associated with the variable component was changed to (1) signalled variable time, (2) unsignalled variable time, or (3) signalled variable interval. The probability with which the availability of the reinforcer was signalled in the variable‐interval schedules was either 0.5 or 1.0. Positive contrast occurred in both signalled variable‐interval and variable‐time schedules, but only when the availability of all the variable‐component reinforcers was signalled. Signalling the availability of only 50% of the reinforcers in signalled variable‐interval schedules resulted in negative induction. The present data suggest that positive behavioral contrast resulting from signalled reinforcer availability is due to the presence of an extinction‐correlated stimulus.