Progressive-ratio schedules: effects of later schedule requirements on earlier performances.
Four rats were studied with variants of a progressive-ratio schedule with a step size of 6 in which different terminal components followed completion of the 20th ratio: (a) a reversal of the progression, (b) a fixed-ratio 6 schedule, or (c) extinction. Responding in the progressive-ratio components of these schedules was compared to performances under conventional progressive-ratio baselines. Under baseline conditions, postreinforcement pauses increased exponentially as a function of increasing ratio size, whereas running rates showed modest declines. The procedure of linking the progressive-ratio schedule to the reversed progression or to the fixed-ratio component resulted in decreased pausing. Linking the progressive-ratio schedule to the extinction component had the opposite effect, that of producing weakened progressive-ratio performances as evidenced by increased pausing. Subjects whose responses were reinforced on half of the ratios also showed exponential increases; however, pauses were substantially shorter following ratios on which the reinforcer was omitted. The results suggested that progressive-ratio pausing reflects the influence of remote as well as local contingencies.
Baron
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Department of Psychology, University of Wisconsin-Milwaukee, 53201, USA. ab@uwm.edu
Derenne
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D000818:Animals; D001245:Association Learning; D003216:Conditioning, Operant; D005108:Extinction, Psychological; D008297:Male; D011939:Mental Recall; D009042:Motivation; D051381:Rats; D017207:Rats, Sprague-Dawley; D012055:Reinforcement Schedule