bluuebunny/crossref_metadata_2025 huggingface dataset:
GENERALIZATION AND DISCRIMINATION OF SHAPE ORIENTATION IN THE PIGEON1
Authors: Vetter Günter H. , Hearst Eliot
Published: March 2006

Pigeons learned to peck a green key on which parallelogram‐shapes were projected; they then received generalization tests in which the orientation of the parallelogram was varied. Nondifferential training produced very little eventual stimulus control along the orientation dimension, but when training included S– trials (absence of the parallelogram) subjects responded consistently more to certain orientations than to others. Unlike typical results for visual generalization (e.g., line‐tilt), the tilt gradients obtained for this complex stimulus were bimodal, supporting predictions on the basis of human perceptual data. However, unimodal gradients could be produced by specific discrimination training along the orientation dimension. Other forms of intradimensional training also produced relatively steep gradients, often characterized by unexpected but consistent secondary peaks. An attempt to obtain inhibitory gradients (S+: green key; S–: parallelogram on a green background) resulted in virtually zero responding all along the shape‐orientation dimension; therefore, specific inhibitory control could not be evaluated. All these experiments suggest that definition of this complex stimulus dimension in terms of mere “angular orientation” is inappropriate, and alternative interpretations are discussed.
PUNISHMENT: THE INTERACTIVE EFFECTS OF DELAY AND INTENSITY OF SHOCK1
Authors: Cohen Perrin S.
Published: March 2006

A discrete‐trial punishment procedure, with rats, was used to examine how delay‐of‐shock intervals of 0 to 28 sec and shock intensity interact to decrease the frequency and increase the latency of a positively reinforced response. For delay‐of‐shock intervals of 0, 7, 14, and 28 sec, there was a range of shock intensities, for some subjects, over which the punishing effect of shock was an increasing, monotonic function of shock intensity. For other subjects this transition was abrupt. Functions relating response frequency and latency measures to shock intensity were displaced toward higher values on the shock intensity axis with an increase in delay‐of‐shock interval. The effects of “gradual” and “abrupt” introduction to “severe” shock, as well as re‐exposure to previously used shock intensities, were examined under both the immediate and delay‐of‐shock conditions. With delay‐of‐shock intervals of 7, 14, or 28 sec, shock intensities of approximately 0.50 milliamperes or greater were necessary to decrease substantially the number and increase the latency of the lever‐pressing response. For the immediate punishment group this intensity was approximately 0.20 ma. These facts were related to Annau and Kamin's (1961) conditioned emotional response experiment in which a shock intensity of 0.49 ma or greater was required to suppress the rate of a positively reinforced response.
FIXED‐INTERVAL PUNISHMENT1
Authors: Appel James B.
Published: March 2006

The average rate of bar‐pressing maintained by a variable‐interval schedule of milk reinforcement in 33 rats was found to be a decreasing function of intensity of concurrent punishment and, over a wide range of shock intensities, was inversely related to punishment frequency. Cumulative records were, however, negatively accelerated during 30‐min punishment sessions with complete suppression occurring earlier and earlier (after fewer and fewer shocks) as intensity increased. In addition, acceleration was often observed between successive fixed‐interval shock presentations and, at low and moderate intensities, bursts of responding occurred after each shock. The time to recover between punishment sessions (post‐punishment recovery) was an increasing monotonic function of punishment intensity.
SCHEDULES USING NOXIOUS STIMULI. III. RESPONDING MAINTAINED WITH RESPONSE‐PRODUCED ELECTRIC SHOCKS1
Authors: Kelleher R. T. , Morse W. H.
Published: March 2006

Responding was maintained in two squirrel monkeys under several variations of a 10‐min fixed‐interval schedule of electric shock presentation. The monkeys were first trained under a 2‐min variable‐interval schedule of food presentation, and then under a concurrent schedule of food presentation and shock presentation. In one monkey, when shocks (12.6 ma) followed each response during the last minute of an 11‐min cycle ending with a timeout period, responding was increased during the first 10 min and suppressed during the last minute of each cycle. When the shock schedule was eliminated, both the enhancement and suppression disappeared, and a steady rate of responding was maintained under the variable‐interval schedule. When the food schedule was eliminated, the shock schedule maintained a characteristic fixed‐interval pattern of responding during the first 10 min, but suppressed responding during the last minute of each cycle. The fixed‐interval pattern of responding was maintained when the timeout period was eliminated and when only one shock could occur at the end of the cycle. In the second monkey, responding under the concurrent food and shock schedule was suppressed when responses produced shocks after 3‐min. Under an 11‐min cycle, responding continued to be maintained at increasing shock intensities. When the food schedule was eliminated, a fixed‐interval pattern of responding was maintained under a 10‐min schedule of shock presentation (12.6 ma). Whether response‐produced electric shocks suppressed responding or maintained responding depended on the schedule of shock presentation.
STIMULUS GENERALIZATION AS A FUNCTION OF THE DELAY BETWEEN TRAINING AND TESTING PROCEDURES: A REEVALUATION1
Authors: Thomas David R. , Burr D. E. Scott
Published: March 2006

Three groups of 12 pigeons each were trained to discriminate between lights of 550 mμ (SD), correlated with 1‐min variable‐interval reinforcement and 570 mμ (SΔ), correlated with extinction. Group A was tested for wavelength generalization in extinction 1 min after meeting the discrimination criterion; Group B was tested 24 hr later; Group C was tested 24 hr later after a 3‐min (reinforced) warm‐up with the SD. The post‐discrimination gradient of Group B was significantly flatter and showed significantly greater area shift than that of Groups A and C. The gradient of Group C was similar to that of Group A, indicating that the warm‐up eliminated the effect of the delay period.
SCHEDULES USING NOXIOUS STIMULI. VI: AN INTERLOCKING SHOCK‐POSTPONEMENT SCHEDULE IN THE SQUIRREL MONKEY1
Authors: Kelleher R. T. , Morse W. H.
Published: March 2006

Responding was studied under various schedules of electric shock postponement and presentatation in the squirrel monkey. Under an interlocking shock‐postponement schedule, successive responses decreased the time by which a response postponed the next scheduled shock until a shock immediately followed the nth response. Some parameters of this schedule, which can be formally related to fixed‐interval schedules, engendered a pattern of positively accelerated responding between shocks. This pattern did not occur under comparable parameter values of an alternative fixed‐ratio, avoidance schedule under which each response postponed shock by a fixed duration and every nth response produced shock. Subsequently, performances were studied under schedules of shock presentation. Responding was never maintained under fixed‐ratio schedules of shock presentation, but was maintained with a pattern of positive acceleration under an alternative fixed‐ratio, fixed‐interval schedule and under a fixed‐interval schedule.
STIMULUS GENERALIZATION OF GRAVITY1
Authors: McCoy D. F. , Lange K. O.
Published: March 2006

In two experiments, squirrel monkeys were exposed to centrifugally generated, artificial gravity and trained to respond for food reinforcement at selected gravity (g) levels. Experiment I involved a single g value; in Exp. II, subjects were trained to discriminate among two or three g values. After training, generalization tests were administered over a 1.1‐g to 2.1‐g range. The major findings were as follows: (a) single‐stimulus training yielded a linear relationship between percentage of responding and magnitude of gravity. (b) Two‐valued discrimination training produced gradient peaks which were shifted from SD in a direction away from SΔ. This effect was cancelled when SD was located equidistant between two SΔ stimuli, (c) Gradient form was independent of the SD‐SΔ difference, but related to continuum location and/or intensity of discriminative stimuli.
INTERMITTENT PUNISHMENT OF HUMAN RESPONDING MAINTAINED BY INTERMITTENT REINFORCEMENT1
Authors: Scobie Stanley R. , Kaufman Arnold
Published: March 2006

To determine the effects of variable‐interval shock punishment on behavior maintained by variable‐interval and variable‐ratio reinforcement, human subjects' key‐pressing behavior was reinforced with money on a four‐component multiple schedule. Components 1 and 2 were variable‐interval 30‐sec, and Components 3 and 4 were variable‐ratio 210. After responding was stabilized, response‐contingent electric shock was scheduled on a variable‐interval 10‐sec schedule during the second and fourth components of each cycle. Subjects instructed as to the reinforcement contingencies showed gradually increasing suppression of variable‐interval responding at increasing shock intensities and either very high or very low rates of variable‐ratio responding at higher intensities. Minimally instructed subjects showed suppression at higher shock intensities, but no clear differential suppression as a function of reinforcement schedule. Recovery from initial suppression was observed within sessions.
POSITIVE CONDITIONED SUPPRESSION: CONDITIONED SUPPRESSION USING POSITIVE REINFORCERS AS THE UNCONDITIONED STIMULI1
Authors: Azrin N. H. , Hake D. F.
Published: March 2006

Research has revealed the phenomenon of conditioned suppression in which the rate of responding is reduced during a stimulus that is paired with noncontingent shock. The present study replicated this procedure, but used noncontingent positive reinforcers instead of the aversive shock. The lever‐pressing responses of rats were reinforced with food or water. While the rats were responding, a stimulus was occasionally presented and paired with the delivery of a noncontingent positive reinforcer, which was either food, water, or brain stimulation for different rats. The result was a reduction in the rate of responding during the conditioned stimulus. This finding shows that conditioned suppression occurs during a signal for reinforcing as well as aversive stimuli.
A RESPONSE‐SPACING EFFECT: AN ABSENCE OF RESPONDING DURING RESPONSE‐FEEDBACK STIMULI1
Authors: Hake D. F. , Azrin N. H.
Published: March 2006

In most studies of operant reinforcement a response‐feedback stimulus is used which is so brief that the nature of the responding during it is virtually undetectable. The present study investigated the nature of this responding by lengthening an initially brief feedback stimulus. The key‐pecking responses of pigeons were maintained by a variable‐interval schedule of food reinforcement. Each response produced a brief stimulus light in addition to the usual auditory response feedback. When the duration of the feedback stimulus light was gradually increased, it was found to control a nearly zero rate of responding. The result was a paced, metronomic‐like performance in which the pigeon made a single response, paused until the stimulus terminated, and then responded again. As a result, the overall response rate was greatly reduced; the mean interresponse time approximated the stimulus duration. A plausible interpretation is that brief feedback stimuli acquire control over responding because they coincide with few responses and few reinforcers. These findings show that in addition to their known functions as conditioned‐reinforcing stimuli and discriminative stimuli, response‐feedback stimuli also exert direct stimulus control: responding is reduced during the feedback stimulus itself.
CONDITIONED SUPPRESSION TO ODOROUS STIMULI IN PIGEONS1,2
Authors: Henton Wendon W.
Published: March 2006

The conditioned suppression technique was employed to establish criterion discrimination of an amyl acetate concentration of 3% of vapor saturation, and to generate differential response rates in the presence of equal concentrations of amyl acetate and butyl acetate. The magnitude of suppression was also recorded as a function of amyl acetate concentration, with the concentrations presented in descending, ascending, and irregular series. The three stimulus presentation procedures generated approximately equivalent suppression versus concentration functions. Amyl acetate suppression thresholds were 0.16%, 0.50%, and 0.73% of vapor saturation for three subjects. Amyl acetate, butyl acetate, and butyric acid thresholds for two additional subjects were approximately 0.10% of vapor saturation. No suppression was recorded during control trials.
CONTROL OF RESPONDING BY THE LOCATION OF AN AUDITORY STIMULUS: ROLE OF RISE TIME OF THE STIMULUS1
Authors: Harrison J. M. , Beecher M. D.
Published: March 2006

The control of responding by the location of tone bursts of 0.2‐ or 50‐msec rise time was investigated in three albino rats. The apparatus consisted of an enclosure with two levers, two loudspeakers (in different locations), and a dipper feeder. The animal was exposed to tone bursts from either one or the other of the two speakers, and the speaker through which the tone bursts were delivered on any particular trial alternated in an irregular manner. Responses on one lever were reinforced with food in the presence of tone bursts from one speaker; responses on the second lever were reinforced with food in the presence of tone bursts from the second speaker. Responding came under the control of the location of 4‐kHz tone bursts of 0.2‐msec rise time within the first session. At this rise time, animals maintained a stable level of correct responding of greater than 95%. When the rise time was increased to 50 msec the percentage of correct responding fell to an average of 80 to 85%. It was concluded that location of an auditory stimulus is a powerful controller of responding in rats and that the degree of control is dependent upon rise time.
BEHAVIORAL CONTRAST IN ONE COMPONENT OF A MULTIPLE SCHEDULE AS A FUNCTION OF THE REINFORCEMENT CONDITIONS OPERATING IN THE FOLLOWING COMPONENT1
Authors: Wilton R. N. , Gay Robert A.
Published: March 2006

The key pecks of four pigeons were reinforced on a variable‐interval 5‐min schedule which operated in each of the four components of a multiple schedule, indicated by red, green, yellow, and blue stimuli and presented in such an order that the red stimulus always preceded the yellow and the green stimulus always preceded the blue. After establishing baseline rates, the reinforcement schedule associated with the blue and yellow components was altered so that one was now an extinction schedule and the other was a variable‐interval 1‐min schedule. In a second experimental stage, the blue stimulus was interchanged with the yellow so that the red stimulus preceded the blue and the green stimulus preceded the yellow. In both experimental stages the response rate in the variable‐interval 5‐min component that preceded the extinction component was higher than the response rate in the variable‐interval 5‐min component that preceded the variable‐interval 1‐min component. The results were discussed in relation to the importance of stimulus ordering in experiments concerned with investigating behavioral contrast.
PREFERENCE FOR MIXED‐INTERVAL VERSUS FIXED‐INTERVAL SCHEDULES1
Authors: Davison M. C.
Published: March 2006

Pigeons were trained on a two‐link concurrent chain schedule in which responses on two keys were reinforced according to independent variable‐interval schedules by the production of a change in key color. Further responses on the key on which the stimulus change had been produced gave a single food reinforcement and a return to concurrent variable‐interval conditions. On one key the terminal link was a two‐valued mixed‐interval schedule, while on the other, the terminal link was a fixed‐interval schedule. When the mixed‐interval values were kept constant and the fixed‐interval values varied, relative response rates in the initial concurrent links matched relative reinforcement rates in the terminal links when these were computed from cubic transformations of the reciprocals of the intervals comprising the terminal link schedules.
CONTIGUITY OF BRIEFLY PRESENTED STIMULI WITH FOOD REINFORCEMENT1
Authors: Stubbs Alan
Published: March 2006

Pigeons performed on second‐order schedules of reinforcement consisting of four fixed‐interval components. Only the terminal component ended with food. Performance was studied both when a brief stimulus followed the completion of each of the first three fixed intervals (brief‐stimulus schedule) and when the stimulus was omitted (tandem schedule). Variations in the temporal contiguity of the last presentation of the stimulus and the presentation of food indicated that the shorter the delay, the greater was the enhancement of rate of responding in comparison with tandem performance. A positively accelerated pattern of responding within fixed‐interval components was a function of the contiguity of the brief stimulus and reinforcement; this pattern was absent for all tandem‐schedule performance.
FIXED‐INTERVAL SCHEDULES OF ELECTRIC SHOCK PRESENTATION: EXTINCTION AND RECOVERY OF PERFORMANCE UNDER DIFFERENT SHOCK INTENSITIES AND FIXED‐INTERVAL DURATIONS1
Authors: McKearney James W.
Published: March 2006

In squirrel monkeys responding under a schedule in which responding postponed the delivery of electric shock, the presentation of response‐dependent shock under a fixed‐interval (FI) schedule increased the rate of responding. When the schedule of shock‐postponement was eliminated, so that the only shocks delivered were those produced by responses under the FI schedule, a pattern of positively accelerated responding developed and was maintained over an extended period. When responses did not produce shocks (extinction), responding decreased. When shocks were again presented under the FI schedule, the previous pattern of responding quickly redeveloped. In general, response rates were directly related to the intensity of the shock presented, and inversely related to the duration of the fixed‐interval. These results raise fundamental questions about the traditional classification of stimuli as reinforcers or punishers. The basic similarities among FI schedules of food presentation, shock termination, and shock presentation strengthen the conclusion that the schedule under which an event is presented and the characteristics of the behavior at the time the event is presented, are of overriding importance in determining the effect of that event on behavior.
DELAYED REINFORCEMENT VERSUS REINFORCEMENT AFTER A FIXED INTERVAL1
Authors: Neuringer Allen J.
Published: March 2006

When interreinforcement intervals were equated, pigeons demonstrated little or no preference between reinforcement after a delay interval and reinforcement presented on a fixed‐interval schedule. The small preferences sometimes found for the fixed interval (a) were considerably smaller than when the delay and fixed intervals differed in duration, and (b) were caused by the absence of light during the delay. These results suggest that the effects of delayed reinforcement on prior responding can be reproduced by imposing a temporally equal fixed‐interval schedule in place of the delay; and, therefore, that the time between a response and reinforcement controls the probability of that response, whether other responses intervene or not.
SUCCESSIVE INTERRESPONSE TIMES IN FIXED‐RATIO AND SECOND‐ORDER FIXED‐RATIO PERFORMANCE1
Authors: Davison M. C.
Published: March 2006

Three rats were trained on a schedule in which every sixth response produced a timeout of 5 sec minimum duration, and food was delivered at the onset of timeout. Successive interresponse times were measured under these conditions, and also when behavior was maintained by second‐order fixed‐ratio and fixed‐interval schedules. Under the second‐order schedules, each six‐response fixed‐ratio component was followed by a timeout, and occasionally food was delivered at the onset of a timeout. In the fixed‐ratio schedule, the successive interresponse times showed a decrease followed by an increase before food delivery, but this systematic variation in interresponse times was not found when the performance was under second‐order reinforcement. Under both second‐order schedules the latencies of successive components, and the successive interresponse times within each component, showed a decrease as food delivery was approached.
REINFORCEMENT FREQUENCY AND CONTINGENCY AS FACTORS IN FIXED‐RATIO BEHAVIOR1
Authors: Killeen Peter
Published: March 2006

Two variables often confounded in fixed‐ratio schedules are reinforcement frequency and response requirement. These variables were isolated by a technique that yoked the distributions of reinforcements in time for one group of pigeons to those of pigeons responding on various fixed‐ratio schedules. The contingencies for the yoked birds were then manipulated by adding various tandem fixed‐ratio requirements to their schedules. Post‐reinforcement pause was approximately equal for the yoked and ratio pigeons, and was relatively insensitive to changes in the tandem requirement. Terminal response rate increased with increases in the tandem requirement, even though reinforcement rate was invariant. This increase was attributed to the progressive interference of the tandem requirement with the differential reinforcement of long interresponse times.
NOTES ON FIXED‐RATIO AND FIXED‐INTERVAL ESCAPE RESPONDING IN THE PIGEON2
Authors: Hineline Philip N. , Rachlin Howard
Published: March 2006

After learning to peck a key when each peck removed a slowly increasing series of electric shocks, pigeons were placed on fixed‐ratio and fixed‐interval escape schedules. The resulting behavior was comparable to that of other species on ratio and interval escape schedules. Thus, while the pigeon apparently requires special techniques for the initial shaping of a key‐peck response with negative reinforcement, this response, once obtained, can be subjected to intermittent schedules of negative reinforcement with no great difficulty.
FURTHER OBSERVATIONS ON OVERT “MEDIATING” BEHAVIOR AND THE DISCRIMINATION OF TIME1
Authors: Laties Victor G. , Weiss Bernard , Weiss Ann B.
Published: March 2006

When the lever‐pressing behavior of five rats was maintained by a DRL schedule (reinforcement was scheduled only when a specified waiting time between successive responses was exceeded), collateral behavior developed that apparently served a mediating function. In two cases this behavior did not arise until the experimental environment included pieces of wood that the rats started to nibble. When collateral behavior first appeared, it was always accompanied by an increase in responses spaced far enough apart to earn reinforcement. If collateral behavior was prevented, the number of reinforced responses always decreased. Extinction of lever pressing extinguished the collateral behavior. Adding a limited‐hold contingency to the schedule did not extinguish collateral behavior. It appears that the rat can better space its responses appropriately when concurrently performing some overt collateral activity. The amount of this activity apparently comes to serve as a discriminative stimulus. To assume the existence of internal events that serve as discriminative stimuli in temporal discriminations is, at least under some circumstances, unnecessary.
STIMULUS CONTROL ACQUIRED BY COMPONENTS OF TWO COLOR‐FORM COMPOUND STIMULI1
Authors: Born David G. , Peterson James L.
Published: March 2006

Four pigeons were trained to respond on one of two keys in the presence of one color‐form display, and on the other key when a second color‐form display was present. Both responses were maintained on a 2‐min variable‐internal schedule of reinforcement. Subsequently, stimulus control acquired by components of the compound stimuli was determined by brief test probes in which the colors and forms separately, and in novel combinations, appeared on the display screen. When either color component was present, both choice of response key and response rate were like responding to the training compound display containing that color. When the forms were presented separate from the colors, generally low and comparable rates of responding occurred on both keys.
SOME DETERMINANTS OF INHIBITORY STIMULUS CONTROL1
Authors: Weisman R. G.
Published: March 2006

Interspersed reinforcement and extinction during discrimination learning generate a U‐shaped gradient of inhibition about the stimulus correlated with extinction. The present work showed that extinction is not a necessary determinant of inhibitory stimulus control. In Exp. I, a reduction in the rate of reinforcement, through a shift from a multiple variable‐interval 1‐min variable‐interval 1‐min schedule to a multiple variable‐interval 1‐min variable‐interval 5‐min schedule, resulted in a post‐discrimination line orientation gradient of inhibition about the stimulus correlated with the variable‐interval 5‐min schedule. In Exp. II, the rates of reinforcement, correlated with a pair of stimuli, were held constant during a shift from a multiple variable‐interval 1‐min variable‐interval 1‐min schedule to a multiple variable‐interval 1‐min differential‐reinforcement‐of‐low‐rate schedule. Inhibitory stimulus control about the stimulus correlated with the differential reinforcement of low rate was obtained. In both experiments, a reduction in the rate of responding during one stimulus and behavioral contrast during the other stimulus preceded the observation of inhibitory stimulus control.
PROBABILITY OF REINFORCEMENT AND THE DEVELOPMENT OF STIMULUS CONTROL1
Authors: Eckerman Carol O.
Published: March 2006

Pigeons were trained with a successive discrimination procedure in which responding during the negative stimulus was never reinforced and responding during the positive stimulus was reinforced according to one of four probability values. This discrimination training followed extensive training with a single, neutral stimulus and the same temporal distribution of reinforcements. The development of stimulus control was studied by tracing the difference in rate of responding between the positive and negative stimuli over the course of discrimination training. Response rate during the positive stimulus remained constant, while that during the negative stimulus decreased to zero. The probability of reinforcement associated with the positive stimulus affected both the total number of responses emitted during the negative stimulus and the number of negative stimulus presentations during which responding occurred. However, the number of reinforcements during the positive stimulus preceding the attainment of various degrees of stimulus control was similar for all probability values.
EXTINCTION OF A DISCRIMINATIVE OPERANT FOLLOWING DISCRIMINATION LEARNING WITH AND WITHOUT ERRORS1
Authors: Terrace H. S.
Published: March 2006

Different groups of pigeons were trained to respond to red and not to green with and without errors (responses to green) under a free operant procedure, in which responding to red was intermittently reinforced, and under a trial procedure in which all responses to red were reinforced. The response to red was then extinguished under a procedure in which the discriminative stimuli were successively alternated as during discrimination training. The performances of those birds that learned the discrimination without errors under the trial procedure were seriously disrupted during extinction; the birds persistently responded to green for the first time. The performances of those subjects that learned the discrimination without errors under the free operant procedure were not disrupted during extinction. In a second experiment, the same discrimination was trained without errors under a trial procedure in which the response to red was intermittently reinforced. Extinction did not disrupt discrimination performance. Thus, errorless discrimination performance was shown to remain intact during extinction so long as the response to red was intermittently reinforced during discrimination training.
MULTIPLE FIXED‐INTERVAL SCHEDULES: TRANSIENT CONTRAST AND TEMPORAL INHIBITION1
Authors: Staddon J. E. R.
Published: March 2006

Pigeons were exposed to four cycles per session of a multiple schedule in which each cycle involved twelve 60‐sec fixed intervals followed by four 180‐sec intervals [(12 FI 60‐sec)(4 FI 180‐sec) schedule]. Post‐reinforcement pauses were shorter during the first few short intervals of each cycle than during later short intervals, and increased over the four long intervals of each cycle (positive and negative transient contrast). A (12 FI 15‐sec)(4 FI 45‐sec) schedule showed similar results. These two schedules differed in some other respects indicating effects of absolute FI duration on stimulus control. Differences in contrast properties between both these procedures and multiple variable‐interval schedules were related to the pause‐producing property of reinforcement on FI (temporal inhibition). Behavior under two other multiple fixed‐interval schedules—(2 FI 360‐sec)(1 FI 720‐sec) and (3 FI 360‐sec)(1 FI 720‐sec)—differed in certain respects from both the (12 FI x‐sec)(4 FI 3x‐sec) schedules. These differences may be related to differences in the number of successive fixed intervals within a component (run length).
THE EFFECT OF REINFORCEMENT MAGNITUDE UPON RESPONDING UNDER FIXED‐RATIO SCHEDULES1
Authors: Powell Robert W.
Published: March 2006

Responding under fixed‐ratio schedules was studied as a function of two durations of food presentation. Latency of the first response after food presentation (post‐reinforcement pause) was consistently shorter when food was presented for the longer duration. Only one of the four pigeons studied showed a consistently higher response rate, exclusive of post‐reinforcement pause, as a function of the longer access to food. When ratio size was reduced, pause durations decreased, and the differences related to the two durations of food presentations became progressively smaller.
TWO TEMPORAL PARAMETERS OF FREE OPERANT DISCRIMINATED AVOIDANCE IN THE RHESUS MONKEY1
Authors: Hyman Arnold
Published: March 2006

Four monkeys were exposed to free operant discriminated avoidance (discriminated Sidman avoidance) in a parametric study of safe stimulus and warning stimulus duration. The safe stimulus was assigned values of 2, 5, 10, 20, and 40 sec, the warning stimulus values of 2, 5, and 20 sec. Rate of responding was a decreasing negatively accelerated function of safe stimulus duration, with a small effect attributable to warning stimulus duration. Control of response rate by safe stimulus duration was due to the predominance of responding in the presence of the warning stimulus. Responding during the safe stimulus was independent of the temporal parameters except at schedules combining short safe and short warning stimulus durations. Latencies of responses in the warning stimulus were analyzed, and mean latency was found to be a direct function of warning stimulus duration, with only one exception, resulting from the order in which the warning stimulus values were presented. Shock rate was not systematically related to either of the manipulated parameters.
SHAPING AVOIDANCE BEHAVIOR IN RESTRAINED MONKEYS1
Authors: Lockard Joan S.
Published: March 2006

Lever‐pulling avoidance behavior of 24 monkeys was actively shaped with a manual shock control box and a closed‐circuit TV system. A negative reinforcement procedure was used wherein a periodically occurring body shock was postponed each time the subject moved toward the lever. All subjects were trainable with this method, two‐thirds of them in fewer than five, 1‐ to 2‐hr sessions. Negative reinforcement was more effective than a punishment procedure.
A TWO‐STATE ANALYSIS OF FIXED‐INTERVAL RESPONDING IN THE PIGEON1
Authors: Schneider Bruce A.
Published: March 2006

The behavior of pigeons on six geometrically spaced fixed‐interval schedules ranging from 16 to 512 sec is described as a two‐state process. In the first state, which begins immediately after reinforcement, response rate is low and constant. At some variable time after reinforcement there is an abrupt transition to a high and approximately constant rate. The point of rapid transition occurs, on the average, at about two‐thirds of the way through the interval. Response rate in the second state is an increasing, negatively accelerated function of rate of reinforcement in the second state.
RELATIONS BETWEEN PATTERNS OF RESPONDING AND THE PRESENTATION OF STIMULI UNDER SECOND‐ORDER SCHEDULES1
Authors: Byrd Larry D. , Marr M. Jackson
Published: March 2006

Key‐pecking behavior in the pigeon was maintained under second‐order schedules in which food was presented after a variable number of 2‐min fixed‐interval components were completed. When either the same stimulus (Exp. I) or different stimuli (Exp. II) appeared on the key during consecutive components, and a stimulus that was occasionally paired with food was presented briefly at completion of each component, (1) patterns of positively accelerated responding were maintained during the components, and, (2) mean response rates were generally as high during the initial components of a sequence as during the later components. In both experiments, when the food‐paired stimulus was omitted and either no stimulus or a stimulus never paired with food was presented at completion of each component, mean rates of responding increased, but patterns of positively accelerated responding were not maintained during individual components. When a food‐paired stimulus was not presented at completion of the components, mean response rates in Exp. I were low during the initial components of a sequence and gradually increased during subsequent components; in Exp. II mean response rates were variable, and pauses and abrupt changes in response rates were typical.
CONCURRENT PERFORMANCES: INHIBITION OF ONE RESPONSE BY REINFORCEMENT OF ANOTHER1
Authors: Catania A. Charles
Published: March 2006

In an analysis of interactions between concurrent performances, variable‐interval reinforcement was scheduled, in various sequences, for both keys, for only one key, or for neither key of a two‐key pigeon chamber. With changeover delays of 0.5 or 1.0 sec, and with each key's reinforcements discriminated on the basis of key‐correlated feeder stimuli, reinforcement of pecks on one key reduced the pecking maintained by reinforcement on the other key. The decrease in pecking early after reinforcement was discontinued on one key was not substantially affected by whether pecks on the other key were reinforced, but after reinforcement was discontinued on both keys, reinstatement of reinforcement for one key sometimes produced transient increases in pecking on the other key. Correlating the availability of right‐key reinforcements with a stimulus, which maintained right‐key reinforcement while reducing right‐key pecking to negligible levels, demonstrated that these interactions depended on concurrent reinforcement, not concurrent responding. Thus, reinforcement of a response, but not necessarily the occurrence of the response, inhibits other reinforced responses. Compared with accounts in terms of excitatory effects of extinction, often invoked in treatments of behavioral contrast, this inhibitory account has the advantage of dealing only with observed dimensions of behavior.
GENERALIZATION GRADIENTS AND STIMULUS CONTROL IN DELAYED MATCHING‐TO‐SAMPLE1
Authors: Sidman Murray
Published: March 2006

Neurological patients were subjects in delayed visual matching‐to‐sample. The sample and choice stimuli were ellipses of varying size. By measuring the difference in size between the sample on a given trial and the ellipse the subject chose on that trial, gradients of differences between samples and choice stimuli could be plotted. These difference gradients broadened with increasing delays. Sharp gradients were controlled by the samples. Flat gradients were controlled by features of the choice display, independently of the samples. Intermediate gradients reflected combined control by the samples and by the choice displays.
RUNNING‐WHEEL ACTIVITY AND AVOIDANCE IN THE MONGOLIAN GERBIL1
Authors: Powell Robert W. , Peck Stephen
Published: March 2006

In the first of two experiments, running‐wheel activity and unsignaled (Sidman) avoidance were studied in gerbils and albino rats. All gerbils ran at higher rates than any of the four rats studied. Under the avoidance procedure, four rats developed effective responding; the other two performed much less successfully. While avoidance developed more slowly in the gerbils, all showed asymptotic performance as effective as the four superior rats. The rats showed a consistent warm‐up effect, receiving 60% to 80% of the total shocks in the initial third of the session. The gerbils displayed no warm‐up, with shocks being evenly distributed over the session. Warm‐up in the rats was not related to either response rate or to how effectively the animal was avoiding. When shock was removed, extinction occurred more rapidly in the rats than the gerbils. In the second experiment, which involved two‐way shuttle avoidance, gerbils and albino mice quickly acquired the response. All animals met a criterion of 90% avoidance over 80 trials.
ENHANCEMENT OF OFF‐KEY PECKING BY ON‐KEY PUNISHMENT1
Authors: Dunham Philip J. , Mariner Anne , Adams Harry
Published: March 2006

Under a variable‐interval food reinforcement schedule, some of a pigeon's pecking responses land on the wall area adjacent to the response key. These off‐key pecks increase in frequency when key responses produce shocks and decrease when shock is removed.
FREQUENCY OF ATTACK IN SHOCK‐ELICITED AGGRESSION AS A FUNCTION OF THE PERFORMANCE OF INDIVIDUAL RATS1
Authors: Powell D. A. , Francis J. , Braman M. J. , Schneiderman N.
Published: March 2006

Fighting rates between paired rats were investigated as a function of the probability of attack by a single animal. Animals from stable high‐fighting and low‐fighting frequency pairs were intermatched to detect individual high‐fighting and low‐fighting rats. Pairs of high‐fighting animals then received saline or different chlorpromazine dosages during successive sessions. Finally, single high‐fighting members of each pair also received the different drug dosages. The chief findings were that: (a) rats showing high fighting rates when matched against each other revealed low fighting rates when matched against one, but not the other member of a low‐fighting pair; and (b) high‐fighting rats decreased their fighting rates as their own or their opponent's chlorpromazine dosage increased. These results indicated that a low rate of fighting on the part of one rat results in a low fighting rate on the part of its opponent.
CHOICE AS TIME ALLOCATION1
Authors: Baum William M. , Rachlin Howard C.
Published: March 2006

When pigeons' standing on one or the other side of a chamber was reinforced on two concurrent variable‐interval schedules, the ratio of time spent on the left to time spent on the right was directly proportional to the ratio of reinforcements produced by standing on the left to reinforcements produced by standing on the right. The constant of proportionality was less than unity for all pigeons, indicating a bias toward the right side of the chamber. The biased matching relation obtained here is comparable to the matching relation obtained with concurrent reinforcement of key pecks. The present results, together with related research, suggest that the ratio of time spent in two activities equals the ratio of the “values” of the activities. The value of an activity is the product of several parameters, such as rate and amount of reinforcement, contingent on that activity.
BEHAVIORAL CONTRAST IN CHAINED SCHEDULES1
Authors: Wilton R. N. , Gay Robert A.
Published: March 2006

In each of two experiments, the rate of key pecking maintained by a variable‐interval food reinforcement schedule was measured, first when that schedule was studied in isolation, and then when it was correlated with the second component of a two‐component chained schedule. In the first experiment, the first component of the chained schedule was correlated with a fixed‐interval schedule; in the second experiment it was correlated with a variable‐interval schedule. In both experiments, behavioral contrast was demonstrated in the second component of the chained schedule. Compared to the rate of responding on the food‐reinforcement schedule when it had operated in isolation, the rate of responding on the food‐reinforcement schedule when it was correlated with the second component was higher, while the rate on the schedule of the first component was lower. The results are discussed with reference to the determinants of contrast.
THE CASE AGAINST ALLEN'S GENERALIZATION OF THE MATCHING LAW
Authors: Houston Alasdair I.
Published: March 2006

Allen (1981) claims to have established the formal validity of a power‐function generalization of the matching law. This paper argues that Allen's proof is not correct when schedules are presented in pairs and that his initial assumptions are too restrictive when all schedules are simultaneously available.
CHOICE AND SEGMENTED INTERREINFORCEMENT INTERVALS
Authors: Moore Jay
Published: March 2006

Pigeons were trained on a two‐key concurrent schedule, where food reinforcers on one key were arranged by a simple variable‐interval schedule and on the other key by a chain variable‐interval variable‐interval schedule. When the initial link of the chain was in effect, the pigeons tended to respond more on the simple variable‐interval schedule, and hence less on the chain, than would be expected from a comparison of both the local and overall rates of reinforcement of the two schedules. When the terminal link of the chain was in effect, the pigeons responded more on the chain than would be expected from a comparison of the rates of reinforcement of the schedules then in effect. Overall responding on the chain was not proportional to overall reinforcement on the chain but rather was a by‐product of responding during initial‐ and terminal‐link phases.
INSTRUCTED VERSUS SHAPED HUMAN VERBAL BEHAVIOR: INTERACTIONS WITH NONVERBAL RESPONDING
Authors: Catania A. Charles , Matthews Byron A. , Shimoff Eliot
Published: March 2006

Undergraduate students' presses on left and right buttons occasionally made available points exchangeable for money. Blue lights over the buttons were correlated with multiple random‐ratio random‐interval components; usually, the random‐ratio schedule was assigned to the left button and the random‐interval to the right. During interruptions on the multiple schedule, students filled out sentence‐completion guess sheets (e.g., The way to earn points with the left button is to …). For different groups, guesses were shaped with differential points also worth money (e.g., successive approximations to “press fast” for the left button), or were instructed (e.g., Write “press slowly” for the left button), or were simply collected. Control of rate of pressing by guesses was examined in individual cases by reversing shaped or instructed guesses, by instructing pressing rates, and/or by reversing multiple‐schedule contingencies. Shaped guesses produced guess‐consistent pressing even when guessed rates opposed those characteristic of the contingencies (e.g., slow random‐ratio and fast random‐interval rates), whereas guesses and rates of pressing rarely corresponded after unsuccessful shaping of guesses or when guessing had no differential consequences. Instructed guesses and pressing were inconsistently related. In other words, when verbal responses were shaped (contingency‐governed), they controlled nonverbal responding. When they were instructed (rule‐governed), their control of nonverbal responding was inconsistent: the verbal behavior sometimes controlled, sometimes was controlled by, and sometimes was independent of the nonverbal behavior.
TOPOGRAPHY OF SIGNAL‐CENTERED BEHAVIOR IN THE RAT: EFFECTS OF DEPRIVATION STATE AND REINFORCER TYPE
Authors: Davey Graham C. L. , Cleland Gary G.
Published: March 2006

In a series of three experiments, groups of food‐deprived and water‐deprived rats were given pairings of a retractable lever (CS+) with response‐independent deliveries of either solid or liquid reinforcers. In Experiment 1 food‐deprived rats given a solid‐pellet reinforcer differentially tended to sniff, paw, mouth, and bite the CS+ lever more often than a lever that was not paired with food (CS−), whereas food‐deprived rats given a liquid reinforcer tended to differentially sniff, paw, and lick the CS+ lever. 23½‐hour water‐deprived rats given liquid reinforcers showed very little CS+ contact. In Experiment 2 increasing the severity of water deprivation from 23½ to 47½ hours significantly increased CS+ contact. In Experiment 3, subjects that were simultaneously food and water deprived and given a water reinforcer failed to exhibit differential CS+ contact, but subjects that were simultaneously food and water deprived and given a food reinforcer did acquire differential CS+‐contact behavior. These results suggest that (a) even under a single motivational state the nature of signal‐centered behavior can be determined by type of reinforcer, (b) although water reinforcement produces less signal contact than food reinforcement, this can be facilitated with more severe water‐deprivation levels, and (c) high CS‐contact rates using food reinforcement are not simply a product of reductions in body weight with food deprivation.
DELAYED STIMULUS CONTROL: RECALL FOR SINGLE AND RELATIONAL STIMULI
Authors: White K. Geoffrey , McKenzie Julie
Published: March 2006

In a discrete‐trial symbolic matching‐to‐sample procedure, pigeons' left‐key responses were reinforced following presentation of one center‐key sample, and right‐key responses were reinforced following presentation of another. Recallability was measured by the difference between log ratios of left to right responses following each sample. In Experiment 1, samples were successively presented same or different wavelengths in the relational discrimination, or individual wavelengths in the single discrimination. The rate at which recallability decreased with increasing delay since sample presentation was the same for single and relational discriminations, but the initial level of performance differed, indicating that the relational discrimination was more difficult. In Experiment 2, recall functions for easy and difficult discriminations between individual wavelengths also differed in levels of initial performance but not in rate of decrement of recallability over time. Recall for stimuli differing in complexity may therefore reflect differences in discrimination difficulty.
CHOICE AND THE RELATIVE IMMEDIACY OF REINFORCEMENT
Authors: Dunn Roger , Fantino Edmund
Published: March 2006

The relative immediacy of reinforcement in concurrent‐chain schedules was varied while the relative reduction in the overall average time to reinforcement associated with terminal‐link entry was held constant. For each of four pigeons, choice did not vary with relative immediacy of reinforcement. Subsequently, choice by the same subjects was shown to be sensitive to relative reduction in average time to reinforcement.