摘要:

In three experiments pigeons played (i.e., chose between two colored keys) iterated prisoner's dilemma and other 2 × 2 games (2 participants and 2 options) against response strategies programmed on a computer. Under the prisoner's dilemma pay‐off matrix, the birds generally defected (i.e., pecked the color associated with not cooperating) against both a random response (.5 probability of either alternative) and a tit‐for‐tat strategy (on trialnthe computer “chooses” the alternative that is the same as the one chosen by the subject on trialn− 1) played by the computer. They consistently defected in the tit‐for‐tat condition despite the fact that as a consequence they earned about one third of the food that they could have if they had cooperated (i.e., pecked the “cooperate” color) on all the trials. Manipulation of the values of the food pay‐offs demonstrated that the defection and consequent loss of food under the tit‐for‐tat condition were not due to a lack of sensitivity to differences in pay‐off values, nor to strict avoidance of a null pay‐off (no food on a trial), nor to insensitivity to the local (current trial) reward contingencies. Rather, the birds markedly discounted future outcomes and thus made their response choices based on immediate outcomes available on the present trial rather than on long‐term delayed outcomes over many trials. That is, the birds were impulsive, choosing smaller but more immediate rewards, and did not demonstrate self‐control. Implications for the study of cooperation and competition in both

ISSN:0022-5002    

DOI:10.1901/jeab.1995.64-1

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Six domestic hens were trained under a delayed matching‐to‐sample procedure with red and green keylights as sample and comparison stimuli and a 1.5‐s delay interval. The hens were trained to stop pecking the sample stimuli when a tone sounded. Duration of the sample stimuli (2 to 10 s) and the number of pecks required on the key on which these stimuli were presented (0 to 10) were altered across conditions. Both the response requirement on the sample key and the duration of sample presentations affected accuracy. These findings are in agreement with those of earlier studies using other species and somewhat different proce

ISSN:0022-5002    

DOI:10.1901/jeab.1995.64-19

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Experiment 1 used 6 preschool boys and Experiment 2 used 6 adult women to explore the effects of food preference on humans' choice in self‐control paradigms. The boys showed a higher proportion of responses for more delayed, larger reinforcers (a measure of self‐control) when those choices resulted in receipt of the most preferred food compared to when those choices resulted in the least preferred food. Further, the boys chose the less delayed, smaller reinforcers significantly more often when only those choices, as opposed to both choices, resulted in the most preferred food. Conversely, they chose the more delayed, larger reinforcers significantly more often when only those choices, as opposed to both choices, resulted in the most preferred food. Finally, the women demonstrated significantly less sensitivity to reinforcer amount relative to sensitivity to reinforcer delay (another measure of self‐control) when they had a higher preference for the juice received as the less delayed, smaller reinforcer than for the juice received as the more delayed, larger reinforcer. Together, the results show that subjects' food preferences can influence self‐control for food rein

ISSN:0022-5002    

DOI:10.1901/jeab.1995.64-33

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Food‐deprived rats (at 80% of their free‐feeding weights) were exposed to a fixed‐time 60‐s schedule of food‐pellet presentation and developed schedule‐induced drinking. Lick‐dependent signaled delays (10 s) to food presentation led to decreased drinking, which recovered when the signaled delays were discontinued. A major effect of this punishment contingency was to increase the proportion of interpellet intervals without any licks. The drinking of yoked control rats, which received food at the same times as those exposed to the signaled delay contingency (masters), was not consistently reduced. When food‐deprivation level was changed to 90%, all master and yoked control rats showed decreases in punished or unpunished schedule‐induced drinking. When the body weights were reduced to 70%, most master rats increased punished behavior to levels similar to those of unpunished drinking. This effect was not observed for yoked controls. Therefore, body‐weight loss increased the resistance of schedule‐induced drinking to reductions by punishment. Food‐deprivation effects on punished schedule‐induced drinking are similar to their effects on food‐maintained lever pressing. This dependency of punishment on food‐deprivation level supports the view that schedule‐induced drinking can be modified by the same variables that aff

ISSN:0022-5002    

DOI:10.1901/jeab.1995.64-47

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Four pigeons deprived to 80% of their laboratory free‐feeding weights pecked keys under a multiple fixed‐ratio 30 fixed‐interval 5‐min schedule of food presentation. Components alternated strictly with 15‐s timeouts separating them; each was presented six times. When rates of pecking were stable, 2 pigeons' weights were reduced to 70%, and the other 2 pigeons' weights were increased to 82.5% to 85% of free‐feeding levels. Cocaine (1.0, 3.0, 5.6, and 10.0 mg/kg and saline) was administered 5 min prior to sessions. When each dose had been tested twice, pigeons' weights were adjusted to the level that they had not yet experienced, and cocaine was tested again. Cocaine reduced response rates in a dose‐dependent manner under the fixed‐ratio schedule and under the fixed‐interval schedule at high doses, and increased rates under the fixed‐interval schedule at low doses. Reductions in pecking rates occurred at lower doses under both schedules in 3 of 4 pigeons when they were less food deprived compared to when they were more food deprived. Low doses of cocaine increased low baseline rates of pecking in the initial portions of the fixed‐interval schedules by a greater magnitude when pigeons were more food deprived. Thus, food‐deprivation levels altered both the rate‐decreasing and rate‐increasing effects of cocaine. The implications of these results for the mechanisms by which food deprivation increases cocaine self‐administration and for the dependence of cocaine's effects on the baseline strength of o

ISSN:0022-5002    

DOI:10.1901/jeab.1995.64-61

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

ISSN:0022-5002    

DOI:10.1901/jeab.1995.64-74

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Rats pressed keys or levers for water reinforcers delivered by several multiple variable‐interval schedules. The programmed rate of reinforcement varied from 15 to 240 reinforcers per hour in different conditions. Responding usually increased and then decreased within experimental sessions. As for food reinforcers, the within‐session changes in both lever and key pressing were smaller, peaked later, and were more symmetrical around the middle of the session for lower than for higher rates of reinforcement. When schedules provided high rates of reinforcement, some quantitative differences appeared in the within‐session changes for lever and key pressing and for food and water. These results imply that basically similar factors produce within‐session changes in responding for lever and key pressing and for food and water. The nature of the reinforcer and the choice of response can also influence the quantitative properties of within‐session changes at high rates of reinforcement. Finally, the results show that the application of Herrnstein's (1970) equation to rates of responding averaged over the session requires careful cons

ISSN:0022-5002    

DOI:10.1901/jeab.1995.64-75

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Previous studies examining the relationship between response rate and reinforcement rate on variable‐interval schedules (the variable‐interval response function) have confounded elapsed session time with within‐session changes in food density. The present experiments attempted to manipulate these factors independently and thus isolate their effects on responding. In Experiment 1, 7 rats pressed a bar for food on a series of four variable‐interval schedules (7.5 s, 15 s, 30 s, and 480 s). Elapsed session time was held constant while food density was manipulated via a presession feeding. Changes in food density altered the form of the variable‐interval response function, independently of elapsed session time. In Experiment 2, 8 rats responded on the same series of variable‐interval schedules as in Experiment 1, but food density was held constant and elapsed session time was manipulated via the use of timeout periods. The results revealed no evidence for an effect of elapsed session time independent of food density. The present results extend a recent analysis of the variable‐interval response function by Dougan, Kuh, and Vink (1993) by identifying food density as an important factor determining the form of the function. The present results also help clarify the controversy over the correct empirical form of the variable‐interval response function by further defining the variables responsible for differences in the form o

ISSN:0022-5002    

DOI:10.1901/jeab.1995.64-95

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

ISSN:0022-5002    

DOI:10.1901/jeab.1995.64-111

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY