摘要:

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

ISSN:0022-5002    

DOI:10.1901/jeab.1980.33-3

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

In two experiments, pigeons' key pecking for food on concurrent variable‐interval schedules was punished with electric shock according to concurrent variable‐interval punishment schedules. With unequal frequencies of food but equal rates of punishment associated with the two keys and at several intensities of shock, the response and time allocation of all six pigeons overmatched the obtained relative frequency of food. The overmatching was predicted by a subtractive model of the interaction between punishment and positive reinforcement but not by two alternative models. Increases in thekandreparameters of the generalized matching law could not account for the observed shifts in prefere

ISSN:0022-5002    

DOI:10.1901/jeab.1980.33-15

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

Previous studies of choice between two delayed reinforcers have indicated that the relative immediacy of the reinforcer is a major determinant of the relative frequency of responding. Parallel studies of choice between two interresponse times have found exceptions to this generality. The present study looked at the choice by pigeons between two delays, one of which was always four times longer than the other, but whose absolute durations were varied across conditions. The results indicated that choice is not uniquely determined by the relative immediacy of reinforcement, but that absolute delays are also involved. Models for concurrent chained schedules appear to be more applicable to the present data than the matching relation; however, these too failed to predict choice for long delays.

ISSN:0022-5002    

DOI:10.1901/jeab.1980.33-27

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

Pigeons acquired a successive delayed matching‐to‐sample task at delay intervals ranging from 2.5 to 7 seconds. Test sessions were conducted during which delay‐interval illumination conditions were changed from those illumination conditions that prevailed during the baselines. Compared to baseline delayed matching performance, changing delay‐interval illumination disrupted matching. This disruption occurred whether the change in delay‐interval illumination represented an increase or a decrease, relative to the baseline, and whether there was or was not a change in illumination during the test session. It was concluded that illumination per se introduced during delay intervals of delayed matching tasks does not interfere with pigeon short‐term memory. Rather, a change in delay‐interval illumination, relative to the baseline, appears to retroactively interfere in pigeon shor

ISSN:0022-5002    

DOI:10.1901/jeab.1980.33-39

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

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

ISSN:0022-5002    

DOI:10.1901/jeab.1980.33-51

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

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

ISSN:0022-5002    

DOI:10.1901/jeab.1980.33-59

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

Eight severely retarded young men learned color and line‐tilt discriminations. After 95% accuracy was achieved for both dimensions, they were combined to form “conflict‐compound” stimuli in which prior reinforcement history was reversed for one element of the compound and unchanged for the other. When responding to the compound was 95% accurate, control exerted by each element was measured. The unchanged element consistently exercised control in agreement with the reinforcement contingencies associated with the compound, regardless of whether it was color or line orientation. The reversed element, which had a conflicting prior history or reinforcement, most often exerted control associated with original training, or no control, suggesting that it had been “ignored” during the compound. Conflict compounds produced selective attention. When elements were combined to form “compatible‐compound” stimuli, both exercised control in agreement with the compound in post‐tests. Selective attention was not produced by c

ISSN:0022-5002    

DOI:10.1901/jeab.1980.33-77

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

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 background

ISSN:0022-5002    

DOI:10.1901/jeab.1980.33-87

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

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 wasnotfound 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

ISSN:0022-5002    

DOI:10.1901/jeab.1980.33-101

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

We studied the variables controlling the temporal location of polydipsic licking. Four rats were trained on a mixed fixed‐ratio 10 (no tone) chained fixed‐ratio 10 (no tone) fixed‐ratio 90 (tone) schedule and on a multiple fixed‐ratio 10 (tone) fixed ratio 100 (no tone) schedule. On the multiple schedule, drinking followed pellets if a fixed ratio 100 was upcoming for all four subjects and for two of the subjects if a fixed ratio 10 was upcoming. On the mixed schedule, drinking preceded the fixed‐ratio 90 component of the chain. Two subjects also drank after pellet delivery on the mixed schedule before both the fixed ratio 10 and the chain components. The number of licks was greater following a pellet than following a response. In a second phase with two of these subjects, the total response requirement of the chain was held constant at 100, while the size of the two ratios that constituted the chain was varied inversely. The tone signaled onset of the second link. Drinking followed the tone when it signaled fixed‐ratio 90, 95, or 100 but not when it signaled fixed ratio 75, 80, or 85. These results show, on the one hand, that polydipsic licking is controlled by discriminative properties of the pellet rather than by its eliciting or “thirst‐producing” characteristics. On the other hand, the fact that drinks were longer following a pellet than following a response suggests a contribution of thi

ISSN:0022-5002    

DOI:10.1901/jeab.1980.33-119

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY