摘要:

Six adult male research volunteers, in two groups of 3 subjects each, lived in a residential laboratory for 15 days. All contact with the experimenters was through a networked computer system, and subjects' behavior was monitored continuously and recorded. During the first part of each day, subjects remained in private rooms doing planned work activities, and during the remainder of each day, they were allowed to socialize. Two cigarettes containing active marijuana (2.7% Δ9‐THC) or placebo were smoked during the private work period and the period of access to social activities. Three‐day contingency conditions requiring subjects to engage in a low‐probability work activity (instrumental activity) in order to earn time that could be spent engaging in a high‐probability work activity (contingent activity) were programmed during periods of placebo and active‐marijuana smoking. During placebo administration, the contingency requirement reliably increased the amount of time that subjects spent engaged in the low‐probability instrumental activity and decreased the time spent engaged in the high‐probability contingent activity. During active‐marijuana administration, however, the increases in instrumental activity were consistently larger than observed under placebo conditions. The decreases in contingent activity were similar to those seen under placebo conditions. Smoking active marijuana was thus observed to produce increments in instrumental activity under motivational conditions involving contingencies for

ISSN:0022-5002    

DOI:10.1901/jeab.1990.53-5

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Children aged 4.5, 7, or 11 years received an experimental session in which a contingency was placed on button‐press duration. Each discrete trial was followed by a brief verbal probe asking a question about the contingency requirement. Other groups of children received an identical task followed by a postexperimental interview. Level of adaptation to the duration contingency tended to increase with age in subjects receiving posttrial verbal probes, but not for those who were interviewed. Eleven‐year‐olds in the verbal probe condition showed a strong correlation between accurate temporal differentiation and number of verbalizations relating to response duration or timing. The younger subjects, with one exception, showed no association between timing‐related verbalizations (which were almost totally absent) and response duration differentiation. This developmental difference occurred even though the younger subjects verbalized after almost every trial. The results suggest that although 11‐year‐old children apparently produce rule‐governed behavior under verbal control as adults do, the behavior of younger children may be controlled directly by reinforcement contingencies even when their verbal repertoires are hig

ISSN:0022-5002    

DOI:10.1901/jeab.1990.53-21

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Two experiments examined human subjects' sensitivity to variation in reinforcer amount under different methods of reinforcer delivery. Subjects chose between schedules varying in terms of amount and/or delay of reinforcement, the reinforcer being points exchangeable for money. In Experiment 1, reinforcer amount was manipulated by varying the monetary value of the points across conditions while the number of seconds of access to a consummatory response remained constant. Choice was strongly sensitive to reinforcer amount and indicative of self‐control, as in previous experiments. In Experiment 2, reinforcer amount was manipulated by automatically delivering different numbers of points during the amount period, and the consummatory response was eliminated. Sensitivity to variation in reinforcer amount was significantly lower than in Experiment 1. Furthermore, the subjects in Experiment 2 exhibited significantly less self‐control than did the subjects in Experiment 1. Humans' sensitivity to variation in reinforcer amount appears to be affected by factors that enhance the discriminability of the consequences of respond

ISSN:0022-5002    

DOI:10.1901/jeab.1990.53-33

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

In Experiment 1, 3 adult females were taught with verbal instructions and contingencies to select, in sequence, three arbitrary visual stimuli from an array of five stimuli. After four different sequences were taught, match‐to‐sample tests assessed emergent conditional relations among all stimuli that had been selected in the same order in the sequences. Subjects' performances indicated development of four stimulus classes, three based on ordinal position and one based on nonselection. Next, match‐to‐sample training established conditional relations between each of four novel figures and one member of each of the ordinal stimulus classes. Tests confirmed that the classes were equivalence classes, each expanded by one new member. In subsequent sequence tests, the new stimuli were selected in a sequence that was consistent with ordinal class membership. Experiment 2 replicated Experiment 1 with 2 different adult females, but the verbal instructions were omitted. Results were similar to Experiment 1, except that extensive review and retesting were required before expansion of the ordinal classes with the novel figures was o

ISSN:0022-5002    

DOI:10.1901/jeab.1990.53-47

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Six experiments were used to examine the effects of explicit response, stimulus, and temporal dependencies on responding in an interfood interval. The first two experiments demonstrated that 10‐segment 60‐s interfood clocks controlled similar distributions of key pecking in pigeons regardless of whether response‐reinforcement contiguity was required, allowed, or precluded. The third and fourth experiments found that in the absence of an explicit response‐reinforcement dependency, systematic explicit stimuli in an interfood interval were sufficient to establish and maintain the characteristic distribution of key pecking and that an interval without an explicit clock failed to establish or maintain key pecking. The last two experiments demonstrated that the interfood interval need not be of fixed length, and that a simple correlation of stimuli with increments from either a minimum to a maximum imminency or probability of food presentation controlled behavior in a similar manner. Successively higher rates generally occurred to successively later stimuli in the upper half of th

ISSN:0022-5002    

DOI:10.1901/jeab.1990.53-65

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

ISSN:0022-5002    

DOI:10.1901/jeab.1990.53-86

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Pigeons were trained on a variant of the autoshaping procedure devised by Matthews and Lerer (1987) in which a keylight stimulus ramp of increasing brightness signaled the passing of a 30‐s interfood interval. This procedure generates two distinct behavioral components: key pecking and locomotor activity. The effects of three psychoactive drugs on these behavior classes were measured.d‐Amphetamine had negligible effects on both types of behavior, whereas diazepam and pentobarbital increased key pecking and decreased activity in a dose‐dependent fashion. In Experiment 2, the possibility that drug effects were suppressed by excessively strong stimulus control exerted in Experiment 1 was tested by decreasing the discriminability of the stimulus ramp. The direction of the effects of diazepam and pentobarbital was the same as in Experiment 1 but the magnitude of the effects tended to be larger. The effects ofd‐amphetamine, however, remained quite small, suggesting that, under these conditions, locomotor activity and key pecking are less sensitive tod‐amphetamine. In Experiments 3 and 4, key pecking was eliminated by removing the keylight. Reinforcers were presented at fixed intervals in Experiment 3 and at variable intervals in Experiment 4. The drug effects on activity observed in Experiments 1 and 2 disappeared in both Experiments 3 and 4. The results suggest that diazepam and pentobarbital affect activity indirectly by increasing key‐pecking behavior, which, in turn, competitively decreas

ISSN:0022-5002    

DOI:10.1901/jeab.1990.53-87

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Two experiments with pigeons examined the relation of the duration of a signal for delay (“delay signal”) to rates of key pecking. The first employed a multiple schedule comprised of two components with equal variable‐interval 60‐s schedules of 27‐s delayed food reinforcement. In one component, a short (0.5‐s) delay signal, presented immediately following the key peck that began the delay, was increased in duration across phases; in the second component the delay signal initially was equal to the length of the programmed delay (27 s) and was decreased across phases. Response rates prior to delays were an increasing function of delay‐signal duration. As the delay signal was decreased in duration, response rates were generally higher than those obtained under identical delay‐signal durations as the signal was increased in duration. In Experiment 2 a single variable‐interval 60‐s schedule of 27‐s delayed reinforcement was used. Delay‐signal durations were again increased gradually across phases. As in Experiment 1, response rates increased as the delay‐signal duration was increased. Following the phase during which the signal lasted the entire delay, shorter delay‐signal‐duration conditions were introduced abruptly, rather than gradually as in Experiment 1, to determine whether the gradual shortening of the delay signal accounted for the differences observed in response rates under identical delay‐signal conditions in Experiment 1. Response rates obtained during the second exposures to the conditions with shorter signals were higher than those observed under identical conditions as the signal duration was increased, as in Experiment 1. In both experiments, rates and patterns of responding during delays varied greatly across subjects and were not systematically related to delay‐signal durations. The effects of the delay signal may be related to the signal's role as a discriminative stimulus for adventitiously reinforced intradelay behavior, or the delay signal may have served as a conditioned reinforcer by virtue of the temporal relation be

ISSN:0022-5002    

DOI:10.1901/jeab.1990.53-103

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Four pigeons performed on three types of schedules at short (i.e., 10, 30, or 60 s) interreinforcement intervals: (a) a delay‐dependent schedule where interreinforcement interval was held constant (i.e., increases in waiting time decreased food delay), (b) an interreinforcement‐interval‐dependent schedule where food delay was held constant (i.e., increases in waiting time increased interreinforcement interval), and (c) a both‐dependent schedule where increases in waiting time produced increases in interreinforcement interval but decreases in food delay. Waiting times were typically longer under the delay‐dependent schedules than under the interreinforcement‐interval‐dependent schedules. Those under both‐dependent schedules for 1 subject were intermediate between those under the other two schedule types, whereas for the other subjects waiting times under the both‐dependent procedure were similar either to those under the delay‐dependent schedule or to those under the interreinforcement‐interval‐dependent schedule, depending both on the subject and the interreinforcement interval. These results indicate that neither the interreinforcement interval nor food delay is the primary variable controlling waiting time, but rather that the two interact in a complex manner to

ISSN:0022-5002    

DOI:10.1901/jeab.1990.53-123

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Pigeons pecked a key under two‐component multiple variable‐ratio schedules that offered 8‐s or 2‐s access to grain. Postreinforcement pausing and the rates of responding following the pause (run rates) in each component were measured as a function of variable‐ratio size and the size of the lowest ratio in the configuration of ratios comprising each schedule. In one group of subjects, variable‐ratio size was varied while the size of the lowest ratio was held constant. In a second group, the size of the lowest ratio was varied while variable‐ratio size was held constant. For all subjects, the mean duration of postreinforcement pausing increased in the 2‐s component but not in the 8‐s component. Postreinforcement pauses increased with increases in variable‐ratio size (Group 1) and with increases in the lowest ratio (Group 2). In both groups, run rates were slightly higher in the 8‐s component than in the 2‐s component. Run rates decreased slightly as variable‐ratio size increased, but were unaffected by increases in the size of the lowest ratio. These results suggest that variable‐ratio size, the size of the lowest ratio, and reinforcer magnitude interact to determine the duration

ISSN:0022-5002    

DOI:10.1901/jeab.1990.53-133

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY