bluuebunny/crossref_metadata_2025 huggingface dataset:
WARMUP IN AVOIDANCE AS A FUNCTION OF TIME SINCE PRIOR TRAINING1
Authors: Hineline Philip N.
Published: March 2006

On avoidance procedures, rats and pigeons typically show warmup effects, characterized by improving performance within sessions and loss of the improvement (“warmup decrement”) between sessions. Between‐session losses were examined by varying the time between periods of avoidance training. In one experiment, rats lived fulltime in conditioning chambers while intermission intervals were varied. In a second experiment, the animals lived in home cages between sessions; timeout intervals were introduced at midsession, producing recurrence of warmup in the second half‐session. In both experiments, the warmup decrements increased substantially as the timeout or intersession intervals were increased from zero to 30 minutes. With intervals of 60 or 120 minutes, the decrements approached or exceeded those obtained with intervals of a day or more. When avoidance was interposed between appetitive sessions, the appetitive responding was disrupted, but this seemed unrelated to the warmup or to the proficiency of avoidance. The warmup in avoidance shares characteristics with transient punishment effects, with the Kamin effect, and with habituation phenomena, but it is premature to assume that they reflect common processes.
CHOICE IN A “SELF‐CONTROL” PARADIGM: EFFECTS OF A FADING PROCEDURE
Authors: Mazur James E. , Logue A. W.
Published: March 2006

Pigeons chose between an immediate 2‐second reinforcer (access to grain) and a 6‐second reinforcer delayed 6 seconds. The four pigeons in the control group were exposed to this condition initially. The four experimental subjects first received a condition where both reinforcers were delayed 6 seconds. The small reinforcer delay was then gradually reduced to zero over more than 11,000 trials. Control subjects almost never chose the large delayed reinforcer. Experimental subjects chose the large delayed reinforcer significantly more often. Two experimental subjects showed preference for the large reinforcer even when the consequences for pecking the two keys were switched. The results indicate that fading procedures can lead to increased “self‐control” in pigeons in a choice between a large delayed reinforcer and a small immediate reinforcer.
REACTION TIMES OF PIGEONS ON A WAVELENGTH DISCRIMINATION TASK
Authors: Blough Donald S.
Published: March 2006

After extensive pretraining, three pigeons were exposed in 2‐second trials to a random series of 14 light wavelengths, ranging in one nanometer (nm) steps from 575 nanometers to 589 nanometers. Responses to one of the wavelengths, 582 nanometers, were intermittently reinforced. The relative frequency of response approached 1.0 at 582 nanometers, and decreased with progressively higher and lower wavelengths. Reaction times shorter than about 0.2 second occurred with a low frequency that was largely independent of wavelength. Wavelength controlled the frequency of longer reaction times, but did not affect the distribution of these reaction times. Consequently, receiver‐operating characteristic curves constructed by using reaction time as a rating measure did not conform to the signal‐detection model, in contrast to such conformity when response rate is used in a similar way. The data suggest that stimulus onset as such triggers early response emission with some small probability; the probability of responses with longer latency is controlled by wavelength, but their time of emission is controlled by some independent process.
DRUG EFFECTS ON RESPONDING MAINTAINED BY STIMULUS‐REINFORCER AND RESPONSE‐REINFORCER CONTINGENCIES
Authors: Spealman Roger D. , Katz Jonathan L. , Witkin Jeffrey M.
Published: March 2006

The effects of pentobarbital and d‐amphetamine were assessed on key pecking by pigeons under conventional single‐key multiple schedules and under two‐key multiple schedules in which discriminative stimuli appeared on one key (stimulus key) while pecks on a second key (constant key) produced food. Pecks on the stimulus key had no scheduled consequences. A 60‐second variable‐interval schedule operated in one component of each multiple schedule; either extinction or a 60‐second variable‐time schedule operated in the alternate component. When the alternate‐component schedule was extinction, a high rate of responding was maintained in the variable‐interval component of the single‐key schedule; responding on both keys was maintained in the variable‐interval component of the two‐key schedule. Pentobarbital increased responding in the variable‐interval component of the single‐key schedule and increased stimulus‐key, but not constant‐key responding in that component of the two‐key schedule. When the alternate‐component schedule was changed to variable time, responding declined in the variable‐interval component of the single‐key schedule; stimulus‐key responding was no longer maintained under the two‐key schedule. Pentobarbital decreased responding in the variable‐interval component of both schedules. With an exception, d‐amphetamine only decreased responding in the variable‐interval component of the single‐ and two‐key schedules both when the alternate‐component schedule was extinction and when it was variable time. The results suggest that the effects of pentobarbital, but not d‐amphetamine, depend on the nature of the contingency (stimulus‐reinforcer, response‐reinforcer) that maintains responding.
A PROCEDURE FOR STUDYING ECHOIC CONTROL IN VERBAL BEHAVIOR1
Authors: Boe Rodlyn , Winokur Stephen
Published: March 2006

Male and female college students answered standard questions about the women's liberation movement on three occasions. A set of target words was embedded in the questions, with one set used in Sessions 1 and 3, and a synonymous, but different set used in Session 2. The relative frequencies of usage of a given target word were directly related to whether the questions for that session contained the word. The results supported the hypothesis of echoics as proposed in Skinner's theory of verbal behavior.
SECOND‐ORDER SCHEDULES OF TOKEN REINFORCEMENT: COMPARISONS OF PERFORMANCE UNDER FIXED‐RATIO AND VARIABLE‐RATIO EXCHANGE SCHEDULES1
Authors: Webbe Frank M. , Malagodi E. F.
Published: March 2006

Rats' lever pressing produced tokens according to a 20‐response fixed‐ratio schedule. Sequences of token schedules were reinforced under a second‐order schedule by presentation of periods when tokens could be exchanged for food pellets. When the exchange period schedule was a six‐response fixed ratio, patterns of completing the component token schedules were bivalued, with relatively long and frequent pauses marking the initiation of each new sequence. Altering the exchange period schedule to a six‐response variable ratio resulted in sharp reductions in the frequency and duration of these initial pauses, and increases in overall rates of lever pressing. These results are comparable to those ordinarily obtained under simple fixed‐ratio and variable‐ratio schedules.
DELAYED REINFORCEMENT OF FIXED‐RATIO PERFORMANCE WITHOUT MEDIATING EXTEROCEPTIVE CONDITIONED REINFORCEMENT
Authors: Kendall Stephen B. , Newby William
Published: March 2006

The performance of pigeons was studied under conditions in which the completion of a fixed‐ratio requirement was not contiguous with the presentation of a reinforcer. Timein and timeout periods alternated throughout the experimental sessions. Responses made by an experimental bird during the timein period were accumulated, and when a fixed‐ratio requirement had been met, grain was presented to the experimental bird and a yoked control following their first response in the next timein period. Across most manipulations of the fixed‐ratio requirement and of the duration of the timeout period, the response rates of the experimental birds were considerably higher than those of their controls, suggesting that the response‐reinforcer dependency controlled the behavior of the experimental bird in the absence of a close temporal association between responding on the ratio schedule and reinforcer presentations.
WARMUP IN FREE‐OPERANT AVOIDANCE AS A FUNCTION OF THE RESPONSE‐SHOCK = SHOCK‐SHOCK INTERVAL
Authors: Hineline Philip N.
Published: March 2006

Warmup effects, the repeated within‐session transitions from ineffective to effective avoidance, were examined with rats on free‐operant shock‐delay procedures. The shock‐shock and response‐shock intervals were kept equal as they were varied. As measured by both response rates and shock rates, the magnitude of within‐session change in performance was inversely related to the size of the manipulated intervals. The duration of warmup tended to decrease as the intervals were increased. This finding, that increased shock frequencies do not shorten the warmup, appears to be inconsistent with all interpretations of the warmup that have been offered to date. Late‐session performances replicated general features of prior experiments, but differed with respect to details of secondary conclusions in previous reports. These differences may stem from the selection of especially proficient avoiders for previous experiments.
A MOLAR THEORY OF REINFORCEMENT SCHEDULES
Authors: Rachlin Howard
Published: March 2006

Behavior of subjects exposed to concurrent and individual interval and ratio schedules of reinforcement may be described in terms of a set of expressions relating the value of responses to their durations, a feedback equation relating reinforcement to response duration, and the assumption that subjects allocate their time among various responses so as to maximize value.
DISCRIMINABILITY OF FIXED‐RATIO SCHEDULES FOR PIGEONS: EFFECTS OF PAYOFF VALUES
Authors: Hobson Sally L.
Published: March 2006

Three pigeons, previously trained to discriminate different numbers of responses (fixed ratios), were tested under different reinforcement contingencies (payoff matrices) at two levels of sensitivity. For one subject, relative reinforcement magnitude was varied—at first, across sessions and then, at midsession by reversing values—without exteroceptive cues. For another, relative reinforcement magnitude and/or probability was varied every 50 trials with cues by correlating different payoff matrices with different key colors. For the third subject, relative reinforcement probability was varied more frequently with cues—in the limit, at random—to demonstrate stimulus control of response bias on a trial‐by‐trial basis. A signal‐detection analysis showed that bias changed with payoffs, for as many as seven different matrices, while sensitivity remained unchanged. The obtained functions (receiver operating characteristics) were similar under different payoff conditions, which suggests that a single mechanism controls bias. However, they differed enough in slope to require a relatively complex account (e.g., the general Gaussian model of detection theory).
THE CONTROL OF RESPONDING BY AUDITORY STIMULI: INTERACTIONS BETWEEN DIFFERENT DIMENSIONS OF THE STIMULI1
Authors: Segal Marvin , Harrison J. M.
Published: March 2006

Sounds have position in addition to other dimensions, such as intensity and frequency. Position rapidly gains control of spatially contiguous responses and this may interfere with control of responding by other acoustic dimensions. These experiments investigated interference of a tone‐noise discrimination by the discrimination of acoustic position. Squirrel monkeys were studied when responding was differentially reinforced in the presence of both spectral content (tone‐noise) and positional differences between the stimuli, and when responding was differentially reinforced only in the presence of spectral differences. Under the first condition, responding rapidly came under the control of the position of the noise in the two monkeys tested. The position of the tone controlled responding in one monkey; in the second monkey, responding came under the control of the spectral content of the tone. Under the second condition, responding was initially under the control of the noise in all three monkeys tested. This persisted for the duration of the condition for two of the monkeys; in one monkey, responding came under the control of the spectral content of the noise. Under the second condition, responding was also initially under the control of the position of the tone for all monkeys, but control by spectral content of the tone relatively rapidly developed in two of three monkeys.
FOOD DELIVERY AS A CONDITIONAL STIMULUS: FEATURE‐LEARNING AND MEMORY IN PIGEONS1
Authors: Bottjer Sarah W. , Hearst Eliot
Published: March 2006

Three experiments investigated the learning and memory of discriminations based on presence versus absence of a pre‐trial food delivery. In Experiment 1 half the illuminations of a response key were followed by food regardless of the subject's behavior. In one group an extra food delivery preceded only reinforced trials (feature‐positive condition), whereas in a second group it preceded only nonreinforced trials (feature‐negative condition). Key pecks and approaches revealed more rapid and superior discrimination learning in the first group. Experiment 2 replicated the results of Experiment 1 but yielded no evidence that greater “unexpectedness” of pretrial food conditions facilitates discriminative performance. In Experiment 3, individual pigeons trained on a conditional discrimination exhibited a within‐subject feature‐positive superiority. Delay between pretrial and trial stimuli interacted with feature‐positive versus feature‐negative training in both the between‐group (Experiment 2) and within‐subject (Experiment 3) procedures: performance was decremented at both short and long delays in the feature‐positive condition but was decremented only at longer delays in the feature‐negative condition. The feature‐positive superiority obtained here is incompatible with explanations based on either the general concept of “perceptual organization” or on the conditional nature of feature‐negative discriminations.
PERIODICITIES WITHIN A FIXED‐INTERVAL SESSION1
Authors: Wearden J. H.
Published: March 2006

Within‐session periodicities in number of responses per interval and postreinforcement pauses were investigated on fixed‐interval schedules of 1, 2, and 3 minutes with rats. Post‐reinforcement pause values and the number of responses in successive intervals were not systematically related. The direction of change of these variables from one pair of intervals to the next revealed periodicities in that the direction of change varied more than would be expected by chance. A response prevention technique used to manipulate the length of time spent responding in an interval had little effect on the postreinforcement pause value of the next interval except when only a single response was permitted in an interval. This procedure tended to reduce the postreinforcement pause value of the next interval to an abnormally low level.
AUTOSHAPING WITH COMMON AND DISTINCTIVE STIMULUS ELEMENTS, COMPACT AND DISPERSED ARRAYS1
Authors: Sperling Sally E. , Perkins Mark E.
Published: March 2006

Four groups of pigeons were trained with a standard autoshaping procedure in which a brief fixed‐duration interval always followed by a grain delivery alternated with a longer variable‐duration interval never associated with grain delivery. One of two stimuli was always presented during each interval. One of them contained three black dots and a black star on a green background; the other contained four black dots on a green background. The four elements of each stimulus were arranged in a more compact array for two groups and in a more dispersed array for the other two groups. Which of the two stimuli preceded grain delivery was counterbalanced within each pair of groups. The speed of occurrence of the first autoshaped peck was not affected by whether the stimulus containing the distinctive star element preceded grain delivery, but autoshaping was faster when the stimulus arrays were compact than when they were dispersed. During 560 response‐independent training trials that followed the first autoshaped peck, this pattern reversed; both discriminative control over responding and the relative frequency of pecking the stimulus that preceded grain delivery were greater for the two groups where this stimulus contained the discriminative element than for the two groups where it contained only common elements. During subsequent testing with stimuli containing only a single element each, the distinctive feature was responded to proportionately more often by the two groups for which it had been an element of the stimulus preceding grain delivery than by the two groups for which it had been an element of the stimulus complex that never was associated with grain delivery. These data add further support to the hypothesis that the initial occurrence of autoshaped responding and its subsequent maintenance are not affected by the same variables. They also suggest that automaintenance is as sensitive as response‐dependent training to the presence or absence of a distinctive stimulus element among several common elements and that this sensitivity appears to be independent of the specific method used for presenting the stimuli during automaintenance.
ATTENTION IN THE PIGEON: TESTING FOR EXCITATORY AND INHIBITORY CONTROL BY THE WEAK ELEMENTS1
Authors: Kendall Stephen B. , Mills William A.
Published: March 2006

In two experiments, pigeons were trained on a successive discrimination between a color and either a compound S+ or a compound S— consisting of a form superimposed on a second color. Two stimulus control tests followed discrimination training: an attention test in which the form and colors used in training were presented singly and in combination, and then a resistance‐to‐reinforcement test using the form element of S+ or S— and a novel form. In the attention test, the birds trained with a compound S+ responded most to the S+ compound, less to the S+ color alone, and still less to the S+ form on a dark key. Few responses were made to the negative stimulus, either alone or with the S+ form added. The birds trained with a compound S— pecked most at the S+ color and to a compound of the S+ color with the S— form added. The resistance‐to‐reinforcement test showed that the birds trained with a compound S+ responded more to the S+ form than to a novel form. However, the birds trained with a compound S— did not reliably respond more to a novel form than to the S— form. These findings suggested that the form element of a compound S+ gains some excitatory control, but the form element of a compound S— does not acquire inhibitory control. The possibility existed that low levels of responding to the S+ form on a dark background in the first experiment were due to use of a darkened key to separate S+ and S— periods during discrimination training. However, the essential findings were the same in a second experiment in which darkening of the chamber separated S+ and S— periods.
AUDITORY DISCRIMINATION: ROLE OF TIME AND INTENSITY IN THE PRECEDENCE EFFECT
Authors: Hoeffding V. , Harrison J. M.
Published: March 2006

Rats were trained to respond on a lever adjacent to a sounding speaker (the sound source) when a single click was emitted. A second click (the artificial echo) was presented through a second speaker on the opposite side. In Condition I, the echo (equal in intensity to the source) was delayed from .015 to 32 milliseconds; greater than 75% correct responses were given for delay times between about .040 milliseconds (lower threshold) and 8 milliseconds (upper threshold). In Condition II, the echo (simultaneous with the source) was reduced in intensity relative to the source over a range from 2.5 decibels to 40 decibels; greater than 75% correct responses occurred for intensity reductions greater than 5 decibels. In Condition III, both the intensity and the delay time of the echo were manipulated in a manner analogous to that which would occur under natural conditions; greater than 95% correct responses were given for delay times from 1 to 32 milliseconds. These data indicate that both time and intensity differences are necessary for localization of primary sources, with delay time contributing more at short echo path distances, and intensity differences at long distances.
THE ALLOCATION OF TIME TO TEMPORALLY DEFINED BEHAVIORS: RESPONDING DURING STIMULUS GENERALIZATION
Authors: Crowley Michael A.
Published: March 2006

In one stimulus condition, reinforcement depended on rats holding a lever for a duration having both minimum and maximum boundaries. During a second light intensity, reinforcement was not available for some rats; for others, reinforcement depended on a second response duration requirement. Generalization test stimuli controlled the same response durations found during training, and the amount of time allocated to a given response duration depended on the proximity of the test stimulus to the training stimulus which controlled that particular duration. The results indicated that a gradient of stimulus control does not reflect an underlying continuous change in responding, but is a result of the mixing of responses previously controlled by stimuli present during conditioning.
CONCURRENT SCHEDULE ASSESSMENT OF FOOD PREFERENCE IN COWS
Authors: Matthews L. R. , Temple W.
Published: March 2006

Six dairy cows (Bos taurus) were trained on several pairs of concurrent variable‐interval schedules with different types of food available on each alternative. The required response was a plate press made by the animal's muzzle. Performance generally replicated that found with other species. The generalized matching law accounted for the preference data, showing that food preference could be quantitatively analyzed as a special case of response bias. The preference functions showed that the response‐ and time‐allocation ratios were not as extreme as obtained reinforcement rate ratios (undermatching).
EFFECTS OF METHAMPHETAMINE AND SCOPOLAMINE ON VARIABILITY OF RESPONSE LOCATION
Authors: Moerschbaecher Joseph M. , Thompson Donald M. , Thomas John R.
Published: March 2006

Methamphetamine and scopolamine were studied in monkeys responding under a multiple fixed‐ratio fixed‐interval schedule of reinforcement. A response on any one of six levers could satisfy the schedule requirements. Variability of response location was evaluated in terms of switches, where a switch was defined as a response on one lever followed by a response on a different lever. Under baseline conditions the fixed‐ratio schedule generated a high rate of responding and a low level of variability, while the fixed‐interval schedule generated a low rate of responding and a high level of variability. Both methamphetamine (0.1 to 0.5 mg/kg) and scopolamine (2.4 to 240 μg/kg) decreased overall response rate and increased variability of response location in each component of the multiple schedule with increasing doses of drug. At lower doses both drugs were found to decrease rate without affecting response variability.
REINFORCEMENT MAGNITUDE AND THE INHIBITING EFFECT OF REINFORCEMENT
Authors: Michael Jack L.
Published: March 2006

In a two‐key concurrent variable‐interval schedule (using pigeons), if the reinforcement frequency for one response is held constant while that for the other is increased, the rate of response on the constant key decreases. The immediate reinforcement for key pecking can usually be conceptualized as the change from a condition in which the key light is on and the food hopper light is off to one in which the key light is off and the hopper light is on. The prechange condition is associated with a delay to food of one‐half the average interreinforcement interval in effect during this condition. The postchange condition is associated with a delay to food of about .5 seconds. The programming of additional reinforcement results in a decrease in the delay to food associated with the prechange stimulus condition, and thus a decrease in the value of the improvement that results from the change. This would appear to be analogous to a decrease in the amount of reinforcement, and thus sufficient explanation for the decrease in the rate of the response.
SHOCK AS A SIGNAL FOR SHOCK OR NO‐SHOCK: A FEATURE‐NEGATIVE EFFECT IN CONDITIONED SUPPRESSION
Authors: Reberg Douglas , Memmott John
Published: March 2006

Rats were trained in conditioned suppression discriminations where shock at the beginning of a trial signaled either shock or no‐shock at the end of the trial. In the shock‐positive condition, shock at the beginning of a presentation of white noise signaled that noise would end with shock; noise that did not begin with shock did not end with shock. In the shock‐negative discrimination, shock at the beginning of noise signaled that noise would not end with shock; presentations of noise that did not begin with shock ended with shock. In shock‐random training, shock at the beginning of noise did not reliably signal whether the noise presentation would or would not end with shock. Most subjects in shock‐negative training quickly developed a differential pattern of suppression on positive (shock reinforced) trials and no suppression on negative (nonreinforced) trials. The shock‐positive discrimination was much more difficult to establish and was not acquired by the majority of the rats. This “feature‐negative” effect is a clear exception to the general superiority of feature‐positive learning commonly observed in discriminations based on a single distinguishing feature. The results are discussed in terms of Pavlovian stimulus‐shock contingencies in the shock‐positive and shock‐negative paradigms, which appear to favor rapid development of the shock‐negative discrimination.
A COMPARISON OF RESPONDING MAINTAINED UNDER SECOND‐ORDER SCHEDULES OF INTRAMUSCULAR COCAINE INJECTION OR FOOD PRESENTATION IN SQUIRREL MONKEYS
Authors: Katz Jonathan L.
Published: March 2006

Key pressing by squirrel monkeys was maintained under second‐order schedules of either intramuscular cocaine injection or food presentation. Under one schedule, each completion of a 10‐response fixed‐ratio unit produced a brief visual stimulus; the first fixed‐ratio unit completed after 30 minutes elapsed produced the stimulus paired with either cocaine injection or food presentation. Generally, short pauses followed by high rates of responding were maintained within the fixed‐ratio units, and responding was positively accelerated over the 30‐minute interval. Under another schedule, each completion of a 3‐minute fixed‐interval unit produced the brief stimulus; completion of the 10th fixed‐interval unit produced the stimulus paired with either cocaine injection or food presentation. Rates of responding increased within the fixed‐interval units, and to a greater extent over the entire 10 fixed‐interval units. Patterns of responding depended more on the schedule of reinforcement than on whether cocaine or food maintained responding. Omitting the brief stimuli following all but the last fixed‐ratio or fixed‐interval units decreased average rates and altered the patterns of responding. Substituting a visual stimulus that was never paired with cocaine or food following all but the last fixed‐ratio or fixed‐interval units decreased response rates to a lesser extent and did not substantially alter patterns of responding. When the duration of the paired stimulus was varied from .3 to 30.0 seconds, the highest response rates occurred at intermediate durations (1.0 to 10.0 seconds). The manner in which the stimulus changes affected performances depended more on the schedule of reinforcement than on whether cocaine injection or food presentation maintained responding.
AN INVESTIGATION OF PEAK SHIFT AND BEHAVIORAL CONTRAST FOR AUTOSHAPED AND OPERANT BEHAVIOR
Authors: Bushnell M. Catherine , Weiss Stanley J.
Published: March 2006

Instrumental treadle press and nonreinforced key peck responses were monitored during discrimination training and generalization testing in pigeons on positive and negative reinforcement schedules. In Experiment 1, six pigeons pressed a treadle for food on a multiple variable‐interval extinction schedule. In Experiment 2, three pigeons pressed a treadle to avoid shock on a multiple free‐operant avoidance extinction schedule. Different color keylights signaled the S+ and S— components. Some positive behavioral contrast occurred during discrimination training, but the effect was small. Pecking occurred to the S+ keylight in Experiment 1 but not in Experiment 2. On stimulus generalization tests, all subjects displayed a positive peak shift when pressing the treadle for food or to avoid shock. However, peak shift was not found for nonreinforced “autopecks” on the stimulus key, although an area shift was observed in Experiment 1. This is the first demonstration of peak shift for pigeons pressing treadles and the only reliable demonstration of peak shift when negative reinforcement maintained responding. These results, in combination with previous demonstrations of peak shift for rats pressing levers and pigeons pecking keys, indicate that peak shift is a general by‐product of operant discrimination learning, since it occurs across a variety of the organisms, responses, and reinforcers.
MAGNITUDE AND DURATION OF THE EFFECTS OF COCAINE ON CONDITIONED AND ADJUNCTIVE BEHAVIORS IN THE CHIMPANZEE
Authors: Byrd L. D.
Published: March 2006

Characteristic patterns of conditioned key‐pressing were maintained in the chimpanzee under a multiple 30‐response fixed‐ratio, 10‐minute fixed‐interval schedule of food presentation. Adjunctive drinking occurred with regularity during the fixed‐interval schedule and, with less frequency, during 1‐minute timeout periods that followed each food presentation; drinking seldom occurred during the fixed‐ratio schedule. Cocaine increased key pressing under the fixed‐interval schedule at doses between .1 and 3.0 mg/kg, but adjunctive drinking and key pressing under the fixed‐ratio schedule did not increase at any dose. Conditioned and adjunctive behaviors were disrupted and suppressed for different durations at 10.0 mg/kg, a dose which induced convulsive seizures within 10 minutes after intramuscular injection. A time‐course analysis showed the magnitude and duration of the effects of cocaine on key pressing under the fixed‐interval schedule and on adjunctive drinking to be dose‐related. Moreover, a given dose of cocaine had diverse effects, depending on the behavior and the time since drug administration.
ON THE DISCRIMINABILITY OF STIMULUS DURATION
Authors: McCarthy Dianne , Davison Michael
Published: March 2006

The performance of pigeons trained to detect differences in the duration of stimuli was analysed using a matching model of signal detection. Two white stimuli, S1 and S2, differing in duration, were arranged with equal probability on the center key of a three‐key chamber. S1 was systematically varied from 5 seconds to 25 seconds while S2 remained constant at 30 seconds. On completion of the center‐key stimulus, a peck on the center key turned on the two red side keys. A left‐key response was “correct” when S1 had been in effect on the center key and a right‐key response was “correct” on S2 trials. A correct response produced a 3‐second magazine light accompanied intermittently by food. Incorrect responses produced 3‐second blackouts. Detection performance was measured under two procedures. In the first, the obtained reinforcement ratio was uncontrolled by allowing the number of food reinforcements obtained for correct left‐ and right‐key responses to vary as the stimuli were changed. In the second procedure, the presentation of food reinforcement was controlled by holding the obtained reinforcement ratio constant. Discriminability changed as a function of stimulus differences under both procedures. No such trend was found in response bias.
ENHANCEMENT OF CONDITIONED AUTONOMIC RESPONSES IN MONKEYS WHEN PRESHOCK SIGNALS OCCASION OPERANT SUPPRESSION
Authors: Kelly Dennis D.
Published: March 2006

Classical pairings of a sound stimulus with shock elicited larger magnitude and more rapidly conditioned autonomic responses when subjects were responding on variable‐interval schedules for food than when they were eating freely available food. The difference was not attributable to changes in control values of heart rate and blood pressure, or to alterations in motor activity, but appeared related to operant suppression.
POLYDIPSIA INDUCED BY INTERMITTENT DELIVERY OF SALTED LIQUID FOODS
Authors: Poling Alan , Krafft Kathy , Chapman Linda , Lyon David
Published: March 2006

Food‐deprived rats given constant access to water were exposed to fixed‐time presentations of soybean milk and diluted sweetened condensed cows' milk. In some conditions these liquid foods were adulterated with varying amounts of sodium chloride. Under a fixed‐time 30‐sec schedule of food delivery, little water was consumed when the food was soybean milk alone, or soybean milk with sodium chloride added in concentrations of .9, 1.8, or 3.6%. However, schedule‐induced polydipsia appeared when soybean milk adulterated with 7.2 or 14.4% sodium chloride was delivered under this schedule. When soybean milk containing 7.2% sodium chloride was presented under fixed‐time 15‐, 30‐, 60‐, 120‐, and 240‐sec schedules, schedule‐induced drinking increased with the fixed‐time value from 15 to 120 seconds, and decreased at 240 seconds. Like soybean milk, diluted sweetened condensed milk delivered under fixed‐time schedules of 30, 60, and 120 seconds failed to evoke schedule‐induced polydipsia, but did so when adulterated with 7.2% sodium chloride. Drinking induced by salted liquid foods resembled the polydipsia engendered by spaced dry‐food presentations in several ways, including temporal relation to food delivery, persistence within and across sections, sensitivity to interfood interval, and magnitude relative to intake evoked by bulk‐food presentation.
EFFECTS OF d‐AMPHETAMINE, COCAINE, AND PHENCYCLIDINE ON THE ACQUISITION OF RESPONSE SEQUENCES WITH AND WITHOUT STIMULUS FADING
Authors: Moerschbaecher Joseph M. , Thompson Donald M.
Published: March 2006

In each of three components of a multiple schedule, monkeys were required to emit a different sequence of four responses in a predetermined order on four levers. Sequence completions produced food on a fixed‐ratio schedule. Errors produced a brief timeout. One component of the multiple schedule was a repeated‐acquisition task where the four‐response sequence changed each session (learning). The second component of the multiple schedule was also a repeated‐acquisition task, but acquisition was supported through the use of a stimulus‐fading procedure (faded learning). In a third component of the multiple schedule, the sequence of responses remained the same from session to session (performance). At higher doses, d‐amphetamine, cocaine, and phencyclidine decreased the overall rate of responding and increased the percent errors in all three components. At lower doses, however, the three drugs produced selective effects on errors. Errors were increased in the learning component at lower doses than those required to disrupt the behavior in the faded‐learning component. The performance component tended to be the least sensitive to disruptive drug effects. The data are consistent with the view that stimulus fading can modulate the effects of drugs on acquisition.
LONG‐TERM POTENTIAL FOR IMPRINTING IN DUCKS AND CHICKENS
Authors: Eiserer Leonard A.
Published: March 2006

In the first of five experiments, three of four adult ducks who had been reared in visual isolation gradually developed strong approach responses towards a moving panel of colored lights. Experiment 2 provided evidence that the ducks' approach response reflected the same sort of social attachment that is typically formed to moving objects by newly hatched ducklings. Experiment 3 revealed that the fourth duck would not approach the moving stimulus even after additional exposure to it, but would approach a conspecific after group housing had been enforced for seven days. In Experiment 4, none of five adult chickens who had been reared in visual isolation developed approach responses towards the moving stimulus, even though in Experiment 5, newly hatched chicks approached the stimulus quite readily. Taken together, these findings (a) indicate that ducks retain the ability to form filial‐type attachments to novel objects throughout their lives, and (b) offer preliminary evidence that chickens do not retain this ability into adulthood.
BRIGHTNESS CONTRAST: A REINTERPRETATION OF COMPOUND CUE AND COMBINED CUE EXPERIMENTS WITH PIGEONS
Authors: Santiago Héctor C. , Wright Anthony A.
Published: March 2006

A group of three pigeons was trained on a 4‐ply multiple schedule: a green color and a vertical line superimposed upon an achromatic background as positive stimuli, and a red color and a horizontal line on an achromatic background as negative stimuli. The pigeons were tested with the vertical line superimposed upon different achromatic background intensities, then with the vertical line superimposed upon different green background intensities, and finally with the vertical line and its training achromatic background attenuated (and unattenuated) by a neutral density filter. The gradients peaked at the luminance of the achromatic background used during training and at the equivalent luminance for the green background when it was substituted for the achromatic background. The brightness contrast, not the background luminance, was the critical variable as the neutral density filter attenuated both the line and the background equally, leaving brightness contrast unchanged; there was no response decrement to this attenuated stimulus. Two other groups of three pigeons showed that they attended to line orientation as well as to brightness contrast. The brightness contrast hypothesis was extended to explain results of attention experiments and combined cue experiments which have used line stimuli in combinations with different backgrounds.
THE ROLE OF CONTINGENCIES AND “PRINCIPLES OF BEHAVIORAL VARIATION” IN PIGEONS' PECKING
Authors: Fenner Douglas
Published: March 2006

Staddon and Simmelhag's proposal that behavior is produced by “principles of behavioral variation” instead of contingencies of reinforcement was tested in two experiments. In the first experiment pigeons were exposed to either a fixed‐interval schedule of response‐contingent reinforcement, an autoshaping schedule of stimulus‐contingent reinforcement, or a fixed‐time schedule of noncontingent reinforcement. Pigeons exposed to contingent reinforcement came to peck more rapidly than those exposed to noncontingent reinforcement. Staddon and Simmelhag's “principles of behavioral variation” included the proposal that patterns (interim and terminal) were a function of momentary probability of reinforcement. In the second experiment pigeons were exposed to either a fixed‐time or a random‐time schedule of noncontingent reinforcement. Pecking showed a constant frequency of occurrence over postfood time on the random‐time schedule. Most behavior showed patterns on the fixed‐time schedule that differed in overall shape (i.e., interim versus terminal) from those shown on the random‐time schedule. It was concluded that both the momentary probability of reinforcement and postfood time can affect patterning.
EFFECTS OF ETHANOL ON MULTIPLE FIXED‐INTERVAL FIXED‐RATIO SCHEDULE PERFORMANCES: DYNAMIC INTERACTIONS AT DIFFERENT FIXED‐RATIO VALUES
Authors: Barrett James E. , Stanley Jennifer A.
Published: March 2006

Key pecking by three pigeons was maintained under a multiple fixed‐interval fixed‐ratio schedule of food presentation. The fixed‐interval value remained at 3 minutes, while the fixed‐ratio size was increased systematically in 30‐response increments from 30 to either 120 (two pigeons) or 150 (one pigeon). At least two lower fixed‐ratio values were also redetermined. The effects of ethanol (.5 to 2.5 g/kg) were assessed at each of the different schedule parameters. Both overall and running response rates under the fixed‐ratio schedule decreased with increases in the size of the fixed‐ratio schedule; pause duration under the fixed‐ratio schedule was directly related to increases in fixed‐ratio size. Overall and running rates of responding under the fixed‐interval schedule changed little with increases in the size of the fixed‐ratio schedule. Despite the relative invariance of fixed‐interval responding across the different fixed‐ratio values, the effects of ethanol on responding under the fixed‐interval schedule differed depending on the size of the fixed‐ratio schedule. Greater increases occurred in both overall and in lower local rates of responding under the fixed‐interval schedule when the fixed‐ratio value was 120 or 150. The effects of ethanol on responding under the fixed‐ratio schedule also depended on the size of the fixed ratio. Increases in responding under the fixed‐ratio schedule were typically greater at the higher fixed‐ratio values where response rates were lower. When the effects of ethanol were redetermined at the lower fixed‐ratio parameter values, rates and patterns of responding were comparable to those obtained initially. However, the dose‐effect curves for responding under both fixed‐ratio and fixed‐interval schedules were shifted up and to the right of those determined during the ascending series. The effects of ethanol can depend on rate of responding, behavioral history, and the context in which behavior occurs.
FEEDBACK FUNCTIONS FOR VARIABLE‐INTERVAL REINFORCEMENT
Authors: Nevin John A. , Baum William M.
Published: March 2006

On a given variable‐interval schedule, the average obtained rate of reinforcement depends on the average rate of responding. An expression for this feedback effect is derived from the assumptions that free‐operant responding occurs in bursts with a constant tempo, alternating with periods of engagement in other activities; that the durations of bursts and other activities are exponentially distributed; and that the rates of initiating and terminating bursts are inversely related. The expression provides a satisfactory account of the data of three experiments.
ECONOMIC CONCEPTS FOR THE ANALYSIS OF BEHAVIOR
Authors: Hursh Steven R.
Published: March 2006

A review of the relationship between schedule of reinforcement, response rate, and choice suggests that certain unifying concepts from economics can contribute to a more complete science of behavior. Four points are made: 1) a behavioral experiment is an economic system and its characteristics—open or closed—can strongly determine the results; 2) reinforcers can be distinguished by a functional property called elasticity; 3) reinforcers may interact as complements as well as substitutes; 4) no simple choice rule, such as strict matching, can account for all choice behavior.
CONCURRENT AVOIDANCE OF SHOCKS BY PIGEONS PECKING A KEY
Authors: Ferrari Elenice A. de Moraes , Todorov João Claudio
Published: March 2006

Three pigeons were studied on concurrent, unsignaled, avoidance schedules in a two‐key procedure. Shock‐shock intervals were two seconds in both schedules. The response‐shock interval on one key was always 22 seconds, while the response‐shock interval associated with the other key was varied from 7 to 52 seconds in different experimental conditions. Response rates on the key associated with the varied schedule tended to decrease when the response‐shock interval length was increased. Responding on the key associated with the constant schedule was not systematically affected.
A COMPARISON OF SIGNALED AND UNSIGNALED DELAY OF REINFORCEMENT
Authors: Richards Ralph W.
Published: March 2006

Pigeons were trained on either a variable‐interval 60‐second schedule, or on a schedule that differentially reinforced responses that were spaced at least 20 seconds apart. The birds were then exposed to several durations of reinforcement delay, with comparisons between signaled and unsignaled delays. Although unsignaled delays of 5 and 10 seconds produced large decreases in response rate, signaled delays of up to 10 seconds produced only moderate decreases in response rates. In addition, some subjects responded more rapidly with a .5 or 1.0 second duration of unsignaled delay than with immediate reinforcement. These response rate changes occurred regardless of whether the rate of reinforcement concomitantly decreased or increased.
COMPARATIVE PSYCHOLOGY RETURNS: A REVIEW OF HULSE, FOWLER, AND HONIG'S COGNITIVE PROCESSES IN ANIMAL BEHAVIOR1
Authors: Wasserman Edward A.
Published: March 2006

Especially remarkable seems the rarity of efforts to trace the evolution of the human intellect from that of the lower animals. Since Darwin's discovery, the beasts of the field, the fowl of the air and the fish of the sea have been examined with infinite pains by hundreds of workers in the effort to trace our physical genealogy, and with consummate success; yet few and far between have been the efforts to find the origins of intellect and trace its progress up to human faculty. And none of them has achieved any sure success. (Thorndike, 1911, p. 282)
HOW TO MAXIMIZE REWARD RATE ON TWO VARIABLE‐INTERVAL PARADIGMS
Authors: Houston Alasdair I. , McNamara John
Published: March 2006

Without assuming any constraints on behavior, we derive the policy that maximizes overall reward rate on two variable‐interval paradigms. The first paradigm is concurrent variable time‐variable time with changeover delay. It is shown that for nearly all parameter values, a switch to the schedule with the longer interval should be followed immediately by a switch back to the schedule with the shorter interval. The matching law does not hold at the optimum and does not uniquely specify the obtained reward rate. The second paradigm is discrete trial concurrent variable interval‐variable interval. For given schedule parameters, the optimal policy involves a cycle of a fixed number of choices of the schedule with the shorter interval followed by one choice of the schedule with the longer interval. Molecular maximization sometimes results in optimal behavior.
OPTIMAL CHOICE
Authors: Staddon J. E. R. , Hinson John M. , Kram Richard
Published: March 2006

We present a classification and theoretical analysis of discrete‐trial and free‐operant choice procedures in which reinforcement is assigned to one alternative only, or independently to both, is either always available or conditionally available, and is either “held” or not from trial to trial. Momentary‐maximizing and (globally) optimal choice sequences are defined in terms of initializing and marker events. Free‐operant choice is analyzed in terms of a clock space whose axes are the times since the last A and B choices. The analysis shows that most molar matching data are derivable from momentary maximizing, and that the momentary‐maximizing hypothesis has not been adequately tested in either discrete‐trial or free‐operant situations.