bluuebunny/crossref_metadata_2025 huggingface dataset:
CONCURRENT RATIO SCHEDULES: FIXED vs. VARIABLE RESPONSE REQUIREMENTS1
Authors: Rider David P.
Published: March 2006

Rats were trained on concurrent fixed‐ratio variable‐ratio or concurrent fixed‐ratio mixed‐ratio schedules of food reinforcement. The variable‐ratio schedule was composed of an arithmetic sequence of 11 ratios that averaged 50; the mixed‐ratio schedule consisted of equiprobable ratios of 1 and 99. Fixed‐ratio values, varied over experimental conditions, included 25, 35, 50, 60, and 99. The proportion of responses and time allocated to the variable‐ or mixed‐ratio schedule increased as the size of the fixed ratio increased. For most subjects, higher proportions of responses and time were maintained on the fixed‐ratio schedule at fixed‐ratio values of 25 and 35; higher proportions of responses and time were maintained on the variable‐ or mixed‐ratio schedule at fixed‐ratio values of 50 or higher. On concurrent variable‐ratio fixed‐ratio schedules, the tendency for responding to be maintained exclusively by one schedule was related to the difference in local reinforcement rates obtained from those schedules. Exclusive responding was approximated when the difference in local reinforcement rates obtained from those schedules was large; responding was more evenly distributed between the schedules as the difference in the rates at which reinforcement was obtained from each decreased.
CHANGEOVER RATIO EFFECTS ON CONCURRENT VARIABLE‐INTERVAL PERFORMANCE1
Authors: White Jason M.
Published: March 2006

Rats' bar‐pressing was maintained by concurrent variable‐interval schedules of reinforcement. A fixed‐ratio of pulls on a chain (the changeover ratio) was required for switching between schedules. The first experiment employed equal variable‐interval schedules and symmetrical changeover ratios. Increasing these ratios resulted in a decrease in the rate of switching between schedules and an increase in local response rate. In the second experiment, a range of asymmetrical changeover ratios was used with equal variable‐interval schedules, and a preference was found for the schedule associated with the larger switching‐into ratio. Both the distributions of responses and time between the two schedules deviated from those expected on the basis of obtained reinforcers. In the third experiment, the switching‐out‐of ratio was dependent on the amount of time spent in a variable‐interval 2‐minute schedule; a constant ratio permitted switching out of the alternative variable‐interval 1‐minute schedule. A strong preference was shown for the variable‐interval 2‐minute schedule. The fourth experiment used equal variable‐interval schedules; one changeover ratio was varied while the second remained constant. The results failed to show systematic differences in local response rates immediately after a changeover.
A MULTIVARIATE RATE EQUATION FOR VARIABLE‐INTERVAL PERFORMANCE
Authors: McDowell J. J. , Kessel Robert
Published: March 2006

A value‐like parameter is introduced into a rate equation for describing variable‐interval performance. The equation, derived solely from formal considerations, expresses rate of responding as a joint function of rate of reinforcement and “reinforcer power.” Preliminary tests of the rate equation show that it handles univariate data as well as Herrnstein's hyperbola. In addition, a form of Herrnstein's hyperbola can be derived from the equation, and it predicts forms of matching in concurrent situations. For the multivariate case, reinforcer values scaled in concurrent situations where matching is assumed to hold are taken as determinations of reinforcer power. The multivariate rate equation is fitted to an appropriate set of data and found to provide a good description of variable‐interval performance when both rate and power of reinforcement are varied. Rate and power measures completely describe reinforcement. The effects of their joint variation are not predicted and cannot be described by Herrnstein's equation.
RAT DEFENSIVE BEHAVIOR: BURYING NOXIOUS FOOD1
Authors: Wilkie Donald M. , MacLennan A. John , Pinel John P. J.
Published: March 2006

In Experiment 1, rats living in chambers containing bedding material were injected with a toxicosis‐producing dose of lithium chloride shortly after their initial taste of sweetened condensed milk. They consumed no additional milk and used the bedding to bury the spout through which the milk had been delivered, although they did not bury a concurrently available water spout. In another control condition, rats did not bury a spout containing a novel solution (saccharin) not paired with toxicosis. In Experiment 2, rats did not bury a milk spout until milk consumption was followed by toxicosis. In Experiment 3, rats buried a spout containing Tabasco pepper sauce but not a concurrently available water spout. Thus, burying the food source appears to be an integral component of the rat's defensive reaction to noxious food.
REINFORCING THE ABSENCE OF FIXED‐RATIO PERFORMANCE1
Authors: Zeiler Michael D.
Published: March 2006

Pigeons received food for key pecking according to a fixed‐ratio schedule, while, at the same time, food also was available for not pecking for a specified time. With a fixed ratio of 60, responding was not affected by not‐pecking times of 80 or 40 seconds, and was eliminated completely at 10 seconds. With ratios of 180, pecking stopped with not‐pecking times of 80 seconds or less; with ratios of 300, it stopped at 120 seconds or less. Not‐responding schedules produced steady‐state performance immediately following contact with the schedule. With return to the fixed‐ratio schedule alone, response rate sometimes was elevated temporarily. When response‐independent food presentations replaced the not‐pecking schedule, response rate often was enhanced, and the ratio pattern was lost. Only the highest densities of food delivery eliminated responding, even with a fixed ratio of 300. In general, the effects corresponded to those of punishment, except that contrast had appeared both during and after punishment, and now appeared only after the response elimination procedure was suspended.
TEMPORAL CONTROL OF BEHAVIOR AND THE POWER LAW1
Authors: Lowe C. Fergus , Harzem Peter , Spencer Peter T.
Published: March 2006

The performance of rats and pigeons under fixed‐interval schedules was studied in two experiments. The duration of postreinforcement pause was a declining proportion of fixed‐interval duration. For pigeons this was true both when the duration of the reinforcer was fixed and when it was increased in direct proportion to increases in fixed‐interval duration; the longer reinforcer durations did, however, lengthen the postreinforcement pause at higher schedule values. A quantitative analysis of data from Experiments 1 and 2 and from other studies showed that fractional exponent power functions described the relationship between postreinforcement pause and fixed‐interval value; similar functions have previously been observed in studies of temporal differentiation. It was concluded that power functions reflect a direct causal, rather than artifactual, relationship between performance and the temporal requirements of reinforcement schedules.
BAR PRESS AND BAR RELEASE AS AVOIDANCE RESPONSES
Authors: Meltzer Donald , Tiller James E.
Published: March 2006

Two experiments were performed in which rats had to avoid shock by both pressing and releasing a bar within specified intervals. When the release‐shock interval was held constant and the press‐shock interval was increased, response rate decreased and bar holding increased. When the press‐shock interval was held constant and the release‐shock interval was increased, both response rate and bar holding decreased.
CONDITIONAL DISCRIMINATION AFTER ERRORLESS AND TRIAL‐AND‐ERROR TRAINING1
Authors: Schilmoeller Gary L. , Schilmoeller Kathryn J. , Etzel Barbara C. , Leblanc Judith M.
Published: March 2006

Children were trained on a visual discrimination by stimulus shaping, stimulus fading, or trial‐and‐error. Those who did not acquire the conditional discrimination received a second, different training. More children initially trained by stimulus shaping acquired the conditional discrimination than did those initially trained with stimulus fading or trial‐and‐error. After a history of fading or trial‐and‐error training, children were less likely to acquire the conditional discrimination even after the more successful procedure of shaping was later used.
A MARKOV MODEL DESCRIPTION OF CHANGEOVER PROBABILITIES ON CONCURRENT VARIABLE‐INTERVAL SCHEDULES1
Authors: Heyman Gene M.
Published: March 2006

The primary data were peck‐by‐peck sequential records of four pigeons responding on several different concurrent variable‐interval schedules. According to the hypothesis that the subject chooses the alternative with the highest probability of reinforcement at the moment, response‐by‐response performance in concurrent schedules should show sequential dependencies. However, such dependencies were not found, and it was possible to describe molecular‐level performance with simple Markov chain models. The Markov model description implies that the momentary changeover probabilities were proportional to the overall relative reinforcement frequencies, and that changeover probabilities did not change as a function of previous responding. A second finding was that although a changeover‐delay procedure was omitted, relative response frequencies closely approximated relative reinforcement frequencies.
CONTINGENCY‐SHAPED AND RULE‐GOVERNED BEHAVIOR: INSTRUCTIONAL CONTROL OF HUMAN LOSS AVOIDANCE
Authors: Galizio Mark
Published: March 2006

Instructions can override the influence of programmed schedules of reinforcement. Although this finding has been interpreted as a limitation of reinforcement schedule control in humans, an alternative approach considers instructional control, itself, as a phenomenon determined by subjects' reinforcement histories. This approach was supported in a series of experiments that studied instructional and schedule control when instructions either did or did not accord with the schedule of reinforcement. Experiment I demonstrated that accurate instructions control discriminative performances on multiple avoidance schedules, and that such control persists in a novel discrimination. Experiments II and III showed that elimination of instruction‐following occurs when inaccurate instructions cause subjects to contact a monetary loss contingency. Experiment IV demonstrated the reinforcing properties of accurate instructions. Skinner's view of rule‐governed behavior is consistent with these findings, and can be extended to account for many aspects of instructional control of human operant behavior.
THE EFFECT OF PUNISHMENT ON FREE‐OPERANT CHOICE BEHAVIOR IN HUMANS
Authors: Bradshaw C. M. , Szabadi E. , Bevan P.
Published: March 2006

During Phase I, three female human subjects pressed a button for monetary reinforcement in five variable‐interval schedules specifying different frequencies of reinforcement. On alternate days, responding was also punished (by subtracting money) according to a variable‐ratio 34 schedule. In the absence of punishment, response rates conformed to Herrnstein's equation for single variable‐interval schedules. Punishment suppressed responding at all frequencies of reinforcement. This was reflected in a change in the values of both constants in Herrnstein's equation: the value of the theoretical maximum response‐rate parameter was reduced, and the parameter describing the reinforcement frequency corresponding to the half‐maximal response rate was elevated. During Phase II, the same five schedules (A) were in operation (without punishment), but in addition, a concurrent variable‐interval schedule (B) of standard reinforcement frequency was introduced. On alternate days, responding in Component B was punished according to a variable‐ratio 34 schedule. In the absence of punishment, absolute response rates conformed to equations proposed by Herrnstein to describe performance in concurrent schedules; the ratios of the response rates in the two components and the ratios of the times spent in the two components conformed to the Matching Law. When responding in Component B was punished, response rates in Component B were reduced and those in Component A were elevated, these changes being reflected in distortions of the matching relationship.
SCHEDULE‐INDUCED LOCOMOTOR ACTIVITY IN HUMANS1
Authors: Muller Philip G. , Crow Robert E. , Cheney Carl D.
Published: March 2006

In two experiments, humans received tokens either on a fixed‐interval schedule for plunger pulling or various response‐nondependent fixed‐time schedules ranging from 16 to 140 seconds. Locomotor activity such as walking, shifting weight, or pacing was recorded in quarters of the interreinforcement interval to examine the induced characteristics of that behavior in humans. While performance was variable, several characteristics were present that have counterparts in experiments with nonhumans during periodic schedules of food reinforcement: (a) first quarter rates, and sometimes overall rates, of locomotor activity were greater during intervals that terminated in a visual stimulus and token delivery than those without; (b) overall rates of locomotor activity were greater during fixed‐time 16‐second schedules than during fixed‐time 80‐ or 140‐second schedules; (c) rates of locomotor activity decreased during the interreinforcement intervals; (d) locomotor activity was induced by response‐dependent and response‐nondependent token delivery. These results showed that the rate and temporal pattern of locomotor activity can be schedule‐induced in humans.
ASSESSMENT OF ATTACK AND DRINKING IN WHITE KING PIGEONS ON RESPONSE‐INDEPENDENT FOOD SCHEDULES1
Authors: Yoburn Byron C. , Cohen Perrin S.
Published: March 2006

Four White King pigeons in Experiment I were exposed to a fixed‐time 90‐second food schedule with successive access to water and a conspecific target. Drinking per session was sporadic and minimal, while attack per session occurred during most interfood intervals for all animals. Analysis of the temporal distribution of attack showed that the typical postreinforcement pattern of attack developed over the course of the experiment. In Experiment II, the same animals were exposed to a series of fixed‐time schedules ranging from 30 to 360 seconds with successive access to water and target. Time engaged in drinking and the number of interfood intervals with drinking were less than that of attack. Food and no‐food baselines, which have been typically used to assess schedule‐induced drinking and attack, respectively, were used to evaluate the effect of the schedule on attack and water ingestion. Relative to the no‐food baseline, both attack and drinking were enhanced by the schedule in all birds. Relative to the food baseline, drinking was slightly suppressed in three birds and attack was enhanced in all. For all animals, the food baseline resulted in more attack and drinking than the no‐food baseline.
DECISION RULES AND SIGNAL DETECT ABILITY IN A REINFORCEMENT‐DENSITY DISCRIMINATION
Authors: Commons Michael L.
Published: March 2006

Two probabilistic schedules of reinforcement, one richer in reinforcement, the other leaner, were overlapping stimuli to be discriminated in a choice situation. One of two schedules was in effect for 12 seconds. Then, during a 6‐second choice period, the first left‐key peck was reinforced if the richer schedule had been in effect, and the first right‐key peck was reinforced if the leaner schedule had been in effect. The two schedule stimuli may be viewed as two binomial distributions of the number of reinforcement opportunities. Each schedule yielded different frequencies of 16 substimuli. Each substimulus had a particular type of outcome pattern for the 12 seconds during which a schedule was in effect, and consisted of four consecutive light‐cued 3‐second T‐cycles, each having 0 or 1 reinforced center‐key pecks. Substimuli therefore contained 0 to 4 reinforcers. On any 3‐second cycle, the first center‐key peck darkened that key and was reinforced with probability .75 or .25 in the richer or leaner schedules, respectively. In terms of the theory of signal detection, detectability neared the maximum possible d′ for all four pigeons. Left‐key peck probability increased when number of reinforcers in a substimulus increased, when these occurred closer to choice, or when pellets were larger for correct left‐key pecks than for correct right‐key pecks. Averaged over different temporal patterns of reinforcement in a substimulus, substimuli with the same number of reinforcers produced choice probabilities that matched relative expected payoff rather than maximized one alternative.
ACQUISITION OF STIMULUS CONTROL WHILE INTRODUCING NEW STIMULI IN FADING
Authors: Fields Lanny
Published: March 2006

After establishing a discrimination between a red positive stimulus and a green negative stimulus, the lowest intensity colors that restricted all responding to the positive stimulus were determined. Then, two new white lines differing in terms of line orientation were each superimposed on one of the colors and were increased in intensity. Thereafter, the intensity of the colors was decreased and eventually eliminated. Probe stimuli consisting of the lines presented against dark backgrounds were presented before each change of stimulus intensity, and probe responding was used to assess the control acquired by various dimensions of the new stimuli during the course of fading. The lines acquired control of responding while they were being introduced, and control was strengthened as the colors were attenuated. Such a locus of acquisition was attributed to the starting intensity of the original controlling stimuli and was explained in terms of stimulus blocking. Finally, using probes while introducing the new stimuli enhanced the acquisition of control by the new stimuli.
SEPARATING THE REINFORCING AND DISCRIMINATIVE PROPERTIES OF BRIEF‐STIMULUS PRESENTATIONS IN SECOND‐ORDER SCHEDULES
Authors: Cohen Steven L. , Calisto George , Lentz Barry E.
Published: March 2006

Pigeons' responses were maintained under multiple schedules to study properties of briefly presented stimuli. Responses in one component produced food according to a second‐order schedule with fixed‐interval components in which food or a brief stimulus occurred with equal probability. In the second component responses produced only the brief stimulus under a fixed‐ratio schedule. Under various conditions the brief stimulus in the first component was (a) paired with food, (b) not paired with food, (c) partially omitted, or (d) scheduled simultaneously with the second‐order schedule under an independent variable‐interval schedule. Paired and nonpaired brief stimuli maintained similar response patterning in the second‐order schedule. However, only paired stimuli maintained responses in the second component. The data suggest that nonpaired brief stimuli engender response patterning in second‐order schedules as a result of their discriminative properties. When the stimulus is paired with food, these discriminative properties sometime mask a reinforcement effect, and no change in response patterning is observed. When the discriminative properties of the brief stimulus are absent, the reinforcing effects of pairing the brief stimulus with food may be observed.
POSITIVE BEHAVIORAL CONTRAST IN 3‐MONTH‐OLD INFANTS ON MULTIPLE CONJUGATE REINFORCEMENT SCHEDULES
Authors: Rovee‐Collier Carolyn Kent , Capatides Joanne Bitetti
Published: March 2006

Positive behavioral contrast was assessed in two experiments with young infants using multiple conjugate reinforcement schedules. Reinforcement was produced by footkicks which activated the objects of an overhead crib mobile in a manner proportional to the vigor and rate of responding. Distinctive color/pattern cues on the sides of the objects served as discriminative stimuli for components of the multiple schedule. In Experiment 1, infants were trained with one cue (S+) only before insertion of S+ into a multiple schedule with an extinction component. A control group received S+ throughout all sessions. In Experiment 2, a multiple schedule was introduced at the outset, and responses in both components were reinforced before the introduction of extinction in the second component. In a final phase, reinforcement was reintroduced into the second component. Positive behavioral contrast occurred in both experiments. Response reduction in the extinction component was seen only in individual relative response curves. In both experiments, negative emotional behaviors accompanied the extinction component, and in Experiment 1, cooing accompanied presentations of S+.
MATCHING‐TO‐SAMPLE ACCURACY ON FIXED‐RATIO SCHEDULES
Authors: Thomas John R.
Published: March 2006

Pigeons performing on a matching‐to‐sample procedure were exposed to six fixed‐ratio (FR) schedules (FR 1, 5, 10, 20, 40, and 60) of food reinforcement for correct matching responses. During both a correction and a noncorrection procedure without an intertrial interval (ITI), matching accuracy was lower on FR 1 and FR 60 than at intermediate ratios. With the FR 1 schedule, both a 5‐sec and a 25‐sec ITI resulted in higher matching accuracy than without an ITI; accuracy, with an ITI, was fairly constant for ratios of 1 to 20 but declined at higher ratios. The results suggest that the presence or absence of an ITI in matching to sample may account for inconsistencies obtained in earlier studies of the relationship of matching accuracy to ratio size.
STIMULUS GENERALIZATION ALONG A DIMENSION BASED ON A VERBAL CONCEPT
Authors: Howard Robert W.
Published: March 2006

The present study examined generalization along a dimension based on a verbal concept of occupational status. The status dimension was scaled by students who placed occupation names into five status categories, Category 1 representing highest status and Category 5 the lowest status. In two experiments, key presses by students were occasionally reinforced when a slide showing an occupation name from Status Category 3 was present. For half the subjects, key presses were not reinforced during a name from Category 1; for the other half, presses were not reinforced during a name from Category 5. Occupation names from all status categories were later singly presented. In this generalization test, subjects typically divided the dimension into two parts, responding alike to all names within each part. The results suggest that generalization along a dimension in humans is mediated by a subject's verbal classifications of stimuli.
CONSTITUENTS OF RESPONSE RATE
Authors: Pear Joseph J. , Rector Brian L.
Published: March 2006

Response rate and the proportion of time pigeons allocated to a key‐pecking activity were measured on several basic types of reinforcement schedules. Reinforcement frequency was varied within each type of basic schedule, and the effects on two constituents of response rate were noted. Propensity, the proportion of time the birds spent on a platform in front of the key, showed very consistent effects as reinforcement frequency varied: in general, it decreased when reinforcement frequency markedly decreased and it increased when reinforcement frequency increased. Speed, key pecks per unit of time spent on the platform, showed inconsistent effects when reinforcement frequency varied. Consequently, response rate showed less consistent effects than did propensity. Cumulative response records demonstrated the existence of several different types of transitions or boundary states between the key‐pecking activity and other activities. The types of transitions that occurred between activities depended on both the type of reinforcement schedule and the frequency of reinforcement. The propensity data support the position that general laws of behavior can be based on temporal measures of behavior. The speed data suggest that, if a complete assessment of the dynamic properties of behavior is to be achieved, measures of behavior must incorporate the structural variations in the operant unit.
COMPARISON OF YES‐NO AND LATENCY MEASURES OF AUDITORY INTENSITY DISCRIMINATION
Authors: Green Marc , Terman Michael , Terman Jiuan S.
Published: March 2006

Rats discriminated auditory intensity differences of sinusoids at 3.0 kilohertz in a go/no‐go signal detection procedure. Responses to the signal (hits) were reinforced with electrical brain stimulation, and misses produced a brief timeout. On intermixed noise trials, withholding of responses (correct rejections) was reinforced, and false alarms produced the timeout. In two test conditions, the signal was either the louder (100 decibels) or softer (90, 93, 96, or 99 decibels) of the pair of intensities presented within a set of trials. Each animal was first trained with signal value louder or softer, and reversed for the second condition so that the former noise value served as signal. Hits showed shorter latencies than false alarms, regardless of the relative intensity of signal and noise, and the magnitude of differentiation was proportional to signal‐noise separation. Both hits and false alarms showed longer latencies as the discrimination became more difficult. Isosensitivity contours derived from the latencies showed close similarity across conditions; in comparison, the yes‐no measure of detectability, d′, showed greater variability. The similarity of latency differentiation across louder and softer signal conditions supports a detection model in which the observer's judgment is controlled by the distance of sensory effect from criterion on each trial, as opposed to the loudness of the tones per se.
EFFECTS OF d‐AMPHETAMINE AND CAFFEINE ON SCHEDULE‐CONTROLLED AND SCHEDULE‐INDUCED RESPONDING
Authors: McMillan D. E.
Published: March 2006

The effects of d‐amphetamine and caffeine were studied on rates and patterns of lever pressing and schedule‐induced licking under fixed‐interval schedules of food pellet presentation. In addition, the effects of caffeine were studied on lever pressing and licking under a multiple fixed‐ratio fixed‐interval schedule. Caffeine reduced mean overall rates of licking at lower doses than it reduced mean overall rates of pressing under the fixed‐interval schedules, but the effects of caffeine on both licking and lever pressing depended largely on the control rate of responding. d‐Amphetamine reduced mean overall rates of lever pressing and licking at about the same dose, but the effects of d‐amphetamine also were a function of the control rate of responding.
I. V. ZAVADSKII AND THE BEGINNINGS OF BEHAVIORAL PHARMACOLOGY: AN HISTORICAL NOTE AND TRANSLATION
Authors: Laties Victor G.
Published: March 2006

I. V. Zavadskii, who worked in Pavlov's laboratory between 1907 and 1909, performed a study that has many of the characteristics of modern behavioral pharmacology. He studied the effects of alcohol, morphine, cocaine and caffeine on the conditioned salivary reflex. A translation of his paper and some brief comments on his life are presented.
THE EFFECT OF SIGNALED REINFORCEMENT AVAILABILITY ON CONCURRENT PERFORMANCES IN HUMANS
Authors: Bradshaw C. M. , Szabadi E. , Bevan P. , Ruddle H. V.
Published: March 2006

During Phase I, three female human subjects pressed a button for monetary reinforcement in two‐component concurrent variable‐interval schedules. Five different reinforcement frequencies were used in component A, whereas the reinforcement frequency in component B was held constant. Absolute rates of responding conformed to equations proposed by Herrnstein to describe concurent performances, and the ratios of the response rates and the times spent in the two components conformed to the matching law. During Phase II, the availability of reinforcement in component A was signaled by the illumination of a lamp. This resulted in suppression of response rates in component A and elevation of response rates in component B, these changes being reflected in a distortion of the matching relationship which took the form of a bias in favor of component B.
EFFECTS OF d‐AMPHETAMINE AND COCAINE ON STRAINED RATIO BEHAVIOR IN A REPEATED‐ACQUISITION TASK
Authors: Thompson Donald M. , Moerschbaecher Joseph M.
Published: March 2006

Pigeons acquired a different four‐response chain each session by responding sequentially on three keys in the presence of four colors. When the fixed‐ratio requirement for food presentation was five completions of the chain, d‐amphetamine and cocaine disrupted the behavior. As the dose of each drug was increased, the overall response rate decreased, the overall accuracy was impaired (i.e., percent errors increased), and there was less within‐session error reduction (acquisition). In contrast, when the fixed‐ratio requirement was either 20 or 50 completions of the chain, certain doses of both drugs produced large increases in the overall response rate by eliminating the extended pausing (ratio strain) that was characteristic of the control sessions. These rate‐increasing effects were accompanied by error‐decreasing effects, both during acquisition and after the response chain had been acquired. Taken together, the results show that the effects of d‐amphetamine and cocaine on behavior in a repeated‐acquisition task can be modulated by manipulating the value of the fixed‐ratio schedule maintaining the behavior.
CONTINGENCY AND STIMULUS CHANGE IN CHAINED SCHEDULES OF REINFORCEMENT
Authors: Catania A. Charles , Yohalem Rona , Silverman Philip J.
Published: March 2006

Higher rates of pecking were maintained by pigeons in the middle component of three‐component chained fixed‐interval schedules than in that component of corresponding multiple schedules (two extinction components followed by a fixed‐interval component). This rate difference did not occur in equivalent tandem and mixed schedules, in which a single stimulus was correlated with the three components. The higher rates in components of chained schedules demonstrate a reinforcing effect of the stimulus correlated with the next component; the acquired functions of this stimulus make the vocabulary of conditioned reinforcement appropriate. Problems in defining conditioned reinforcement arise not from difficulties in demonstrating reinforcing effects but from disagreements about which experimental operations allow such reinforcing effects to be called conditioned.
A NOTE ON THE MEASUREMENT OF CONDITIONAL DISCRIMINATION
Authors: Sidman Murray
Published: March 2006

An analysis of some extreme forms of stimulus control that a simple conditional‐discrimination procedure can generate leads to the conclusion that accuracy does not provide an orderly scale of measurement. Dependence on accuracy to evaluate a conditional discrimination, particularly at intermediate levels of accuracy, can generate erroneous conclusions about the extent to which the controlling relations are those specified by the experimenter.
UNCERTAINTY REDUCTION, CONDITIONED REINFORCEMENT, AND OBSERVING
Authors: Fantino Edmund , Moore Jay
Published: March 2006

In a concurrent‐chains procedure, pigeons chose between equivalent mixed and multiple fixed‐interval schedules of reinforcement. In the first experiment, preference for the multiple schedule was higher when the probability of the shorter fixed interval was less than .50 than for complementary points, an outcome consistent with the delay‐reduction hypothesis of conditioned reinforcement and observing, but inconsistent with the uncertainty‐reduction hypothesis which requires symmetrical preferences with a maximum when the two intervals are equiprobable. A second experiment assessed preference for equivalent mixed and multiple schedules when each choice outcome resulted in two reinforcements, one on the longer and one on the shorter fixed interval. The order of the two fixed intervals was determined probabilistically. Pigeons again preferred multiple to mixed schedules, although multiple‐schedule preference did not vary systematically with the likelihood of the shorter fixed interval occurring first. The results from these choice procedures are consistent with those from the observing‐response literature in suggesting that the strength of a stimulus cannot be well described as a function of the degree of uncertainty reduction the stimulus provides about reinforcement.
BEHAVIORAL AND DIMENSIONAL CONTRAST IN RATS
Authors: Blough Patricia M.
Published: March 2006

Rats pressed a nose key for brain stimulation reinforcement presented on a fixed‐interval schedule. Stimuli were drawn at random from a continuum of 12 white noise intensities in the range 62–95 decibels, spaced in 3 decibel steps. Experiment 1 varied the number of stimuli and the reinforcement contingencies associated with them. In Condition I (baseline) all stimuli signaled reinforcement; in Conditions II and III stimuli from one half of the continuum signaled reinforcement and those from the other half, extinction. However, in Condition II the 6 stimuli from the middle of the continuum were omitted. Experiment 2 held constant the number of stimuli and varied their spacing. In Condition I, each of 6 sounds signaled reinforcement. In Conditions II and II, three stimuli from one half of the continuum signaled reinforcement and three from the other half, extinction. However, in Condition II the stimuli were near the extremes of the continuum (Stimuli 1, 3, 4, 9, 10, 12). Condition III replaced Stimulus 3 with Stimulus 6 and Stimulus 10 with Stimulus 7. Behavioral contrast was seen in an increase over baseline in response rate to the stimuli associated with the constant schedule component when the variable component was changed to extinction. Dimensional contrast was seen in a further elevation of rate to intermediate positive stimulus values when stimuli were added to the border region between positive and negative values.
POSITIVE CONDITIONED SUPPRESSION: TRANSFER OF PERFORMANCE BETWEEN CONTINGENT AND NON‐CONTINGENT REINFORCEMENT SITUATIONS
Authors: Davison Michael , Sheldon Linda , Lobb Brenda
Published: March 2006

Five homing pigeons were trained on concurrent variable‐interval schedules. A fixed‐duration stimulus was occasionally presented on one key; and, in various conditions, this stimulus terminated (a) without reinforcement, (b) in noncontingent reinforcement, (c) with reinforcement contingent on a response on the key on which the stimulus was presented, and (d) with reinforcement contingent on a response on the key on which the stimulus was not presented. Initially, a stimulus terminating in noncontingent reinforcement generally produced decreased response rates on both keys during the stimulus. Contingencies, however, reliably produced increased rates during the stimulus on the key on which the contingency was arranged, relative to the rate on the concurrently available key. Contingency conditions were followed by noncontingency conditions in which the separation of rates caused by contingencies was maintained. When rates during the stimulus were compared with response rates on the same keys in the absence of the stimulus, contingency‐caused rate increases and decreases were again found, but only the rate decreases were maintained in subsequent noncontingency conditions. Further data suggested that the contingency‐caused rate changes were not maintained when the stimulus terminated without reinforcement, and that they were unaffected by a threefold decrease in the reinforcement rate provided by the baseline schedules. The results support the suggestion that performance in the positive conditioned suppression procedure results from concurrent and multiple schedule interactions. They further suggest that the production of either acceleration or suppression is dependent on adventitious and historical contingencies.
CHOICE OF TIMEOUT DURING RESPONSE INDEPENDENT FOOD SCHEDULES
Authors: Lydersen Tore , Perkins David , Thome Stan , Lowman Edgar
Published: March 2006

Rats' lever pressing terminated visual or auditory stimuli associated with fixed‐time or variable‐time schedules of food delivery and produced a timeout period during which food delivery could not occur. Lever pressing during a timeout period reinstated the food‐associated stimuli and again permitted food delivery according to the fixed‐time or variable‐time schedules. The mean interfood interval ranged from 1 minute to 16 minutes (variable‐time schedules) or 32 minutes (fixed‐time schedules); the timer controlling schedule intervals did not stop during timeout periods. The percentage of session time spent in timeout increased when the mean interfood intervals were lengthened and decreased when the mean interfood intervals were shortened. Timeouts were initiated most frequently about half way between successive food deliveries (fixed‐time schedules) or after 15 seconds or more had lapsed since the last food delivery (variable‐time schedules). Elimination of food delivery increased the percentage of session time spent in timeout, and elimination of the timeout contingency decreased lever press rates. When timeout was produced only when the lever was held in the depressed position, little time was spent in timeout. The main determinants of timeout initiation and termination appeared to be the rate of food delivery, freedom of movement during timeout, and the stimulus change associated with initiation and termination of timeout.
EFFECTS OF d‐AMPHETAMINE AND PENTOBARBITAL UNDER CONCURRENT FIXED‐RATIO SCHEDULES
Authors: Louie Alan K.
Published: March 2006

Pigeons were studied under a two‐key concurrent fixed‐ratio schedule of food presentation. During the first five sessions, the fixed‐ratio requirements were 30 responses on one key (major key) and 120 responses on the other key (minor key): responding occurred almost exclusively on the major key. When the fixed‐ratio requirements were then made equal at 30 responses on both keys, responding continued to predominate on the major key. The asymmetric distribution of responses persisted when the concurrent fixed‐ratio fixed‐ratio schedule was interrupted with periods during which the major key was associated with extinction while the other key remained associated with a fixed‐ratio schedule. Additionally, in some subjects the fixed‐ratio requirements were increased. These schedule modifications decreased the asymmetry in responding but did not eliminate it. d‐Amphetamine decreased rates on both keys and slightly increased the asymmetric distribution of responses, while pentobarbital reversed the distribution of responses by increasing low rates and decreasing high rates. The pigeons maintained their original asymmetric distribution of responses during the 1 1/2‐year‐long study, despite schedule alterations and drug administrations.
SOME RELATIONS BETWEEN CLASSICALLY CONDITIONED AGGRESSION AND CONDITIONED SUPPRESSION IN SQUIRREL MONKEYS
Authors: Hake Don F. , Campbell Robert L.
Published: March 2006

During three experiments with squirrel monkeys, stimulus and shock pairings were given in the presence of a bite tube. Experiments 1 and 2 used a conditioned‐suppression procedure in which bar pressing was reinforced with food. A transparent shield prevented biting of the bar. When the stimulus was paired with shock, bar pressing decreased (conditioned suppression) and tube biting increased during the stimulus (classically conditioned aggression). When the bite tube was removed on alternate sessions in Experiment 2, there was more suppression when the tube was present, thus suggesting that biting competed with bar pressing. However, this simple competing‐response interpretation was complicated by the findings of Experiment 3 where, with naive monkeys, bar pressing was never reinforced with food, yet bar pressing was induced during the stimulus and was highest when the bite tube was absent. The fact that stimulus‐induced bar pressing developed indicates that bar pressing in conditioned‐suppression procedures, suppressed or not, may be maintained by two types of control—the food reinforcer and induced CS control. The higher rate of induced bar pressing during the stimulus with the bite tube absent confounds a simple competing response interpretation of conditioned suppression. It suggests that shock‐induced responses during conditioned suppression could be both contributing to and competing with responding maintained by food, with the net effect depending on specific but ill‐defined features of the situation.
SHORT‐TERM REMEMBERING OF DISCRIMINATIVE STIMULI IN PIGEONS
Authors: Jans James E. , Catania A. Charles
Published: March 2006

Pigeons learned to peck the left or right of two white keys depending on whether a red or a green stimulus was displayed on a third key. The opportunity to peck the white keys was then delayed for zero to six seconds after the red or green (to‐be‐remembered) stimulus. On half the trials, the feeder operated during the delay to interrupt behavior that might mediate discriminated responding. No events were scheduled on the remaining trials. In a later condition, the pigeons had the opportunity to peck the white keys during the delay. In general, accuracy decreased as delay increased in all conditions, but performance was least accurate following feeder operations and most accurate when pecking was allowed during the delay. The procedures may be analogous to varying the opportunity for rehearsal in studies of human short‐term memory.
PSYCHOPHYSICS OF KEY‐PECK DURATION IN THE PIGEON
Authors: Zeiler Michael D. , Davis Eric R. , DeCasper A. J.
Published: March 2006

The duration of the pigeon's key peck was differentially reinforced in either a trials or a free‐operant procedure. Mean emitted peck duration was a power function of the duration required for food delivery to occur. The exponents of the power function differed considerably from those observed in earlier research involving longer duration responses in pigeons and other species. The coefficients of variation also did not correspond with those of the earlier research on other responses, nor did consideration of the durations actually reinforced resolve the differences. Duration was neither a function of response rate nor of intermittency of reinforcement. Key‐peck duration was changed in an orderly way by differential reinforcement. However, it appeared to be more strongly determined by its duration in the absence of differential reinforcement than were longer duration responses.
LOCAL CONTRAST AND MAINTAINED GENERALIZATION
Authors: Hinson John M. , Malone John C.
Published: March 2006

Pigeons received variable‐interval reinforcement for key pecking during presentations of horizontal and vertical line‐orientation stimuli, while pecks during five intermediate orientations were extinguished. Lowest peck rates were observed during presentations of negative stimuli adjacent to the positive orientations while peck rate during 45 degrees (the intermediate negative orientation) was relatively high, i.e., there were negative contrast shoulders. When peck rates were manipulated in the positive orientations, peck rate in neighboring orientations changed in the opposite direction. Contrast shoulders faded after prolonged training. A second type of contrast, local contrast, was correlated with similarity of preceding stimulus and different average peck rates during different stages of the discrimination process. The data suggest that sequential local contrast accompanying the formation of a discrimination contributes to the form of generalization gradients. Blough's model of stimulus control predicts the changes in gradient form described here, but may not accurately depict the underlying processes responsible for gradient form.
INDEPENDENCE OF SENSITIVITY TO RELATIVE REINFORCEMENT RATE AND DISCRIMINABILITY IN SIGNAL DETECTION
Authors: McCarthy Dianne , Davison Michael
Published: March 2006

Six pigeons were trained to detect differences between two white stimuli, S1 and S2 differing in duration and arranged probabilistically on the center key of a three‐key chamber. Detection performance was measured at two levels of discriminability. At one level, S1 was five seconds and S2 was thirty seconds. At the other level, S1 was twenty seconds and S2 was thirty seconds. The procedure was a standard signal‐detection yes‐no design in which stimulus‐presentation probability was varied from .1 to .9 at both discriminability levels. On completion of the center‐key stimulus, a peck on the center key darkened the center‐key light and turned on the two red side keys. A left‐key response was “correct” on S1 trials, and a right‐key response was “correct” on S2 trials. Correct responses produced food reinforcement on a variable‐ratio 1.3 schedule. Incorrect responses produced three second blackout. Discriminability was higher for the five‐second versus thirty‐second conditions than for the twenty‐second versus thirty‐second conditions, but there were no differences in sensitivity of behavior to reinforcement variation for the two stimulus pairs. Response bias was a function of the relative reinforcement rate for correct choice responses.
THE EFFECT OF CONTINGENCY UPON THE APPETITIVE CONDITIONING OF FREE‐OPERANT BEHAVIOR
Authors: Hammond Lynn J.
Published: March 2006

The problem of maintaining independence between response rates and reinforcement probabilities when determining the effect of varying the response‐reinforcement contingency upon free‐operant behavior was solved by programming local reinforcement probabilities for response and no response on a second‐by‐second basis. Fifty‐seven rats were trained to lever‐press on schedules of water reinforcement involving different values of contingency. All rats were first trained on a high positive contingency and then shifted to less positive, zero, or negative contingencies. Under these conditions, rate of lever‐pressing declined appropriately when the contingency between response and reinforcement decreased or was made negative. The decline in rate produced by a zero contingency cannot be attributed to extinction, since the probability of reinforcement given the occurrence of a response was the same as for the positive contingency from which the shift to zero was made. That is, there was no change in the opportunity for response‐reinforcement contiguity. It was concluded that the technique of programming local reinforcement probabilities offers promise for more critical examinations of the effects of contingency upon free‐operant behavior.
REINFORCEMENT FOR ERRORS IN A SIGNAL‐DETECTION PROCEDURE
Authors: Davison Michael , McCarthy Dianne
Published: March 2006

Six pigeons were trained on a signal‐detection procedure. They were required to peck the left key when a 5‐second white light had been presented, and the right key when a 10‐second light had been presented. These two correct responses were followed by food reinforcement with a probability of .7. Errors, left responses after the 10‐second stimulus or right responses after the 5‐second stimulus, were initially followed by a 3‐second blackout of the chamber. In nine subsequent experimental conditions, errors were followed by food reinforcement with increasing probability while the probability of reinforcement for correct responses was kept constant. The percentage of correct responses decreased as error reinforcement probability increased. A matching model of detection performance, in which discrimination is a joint function of stimulus discriminability and stimulus‐reinforcement association, provided a convincing fit to the data and to two sets of published data. The model also fitted published data on multiple and multiple‐concurrent free‐operant performance. This description of detection performance in terms of matching offers both accurate prediction of complex behavior and measures of discriminability with wide generality.