Mazur J E, Vaughan W
Harvard University, Cambridge, Massachusetts 02138.
J Exp Anal Behav. 1987 Sep;48(2):251-61. doi: 10.1901/jeab.1987.48-251.
In a discrete-trials procedure, pigeons chose between a fixed-ratio 81 schedule and a progressive-ratio schedule by making a single peck at the key correlated with one or the other of these schedules. The response requirement on the progressive-ratio schedule began at 1 and increased by 10 each time the progressive-ratio schedule was chosen. Each time the fixed-ratio schedule was chosen, the requirement on the progressive-ratio schedule was reset to 1 response. In conditions where there was no intertrial interval, subjects chose the progressive-ratio schedule for an average of about five consecutive trials (during which the response requirement increased to 41), and then chose the fixed-ratio schedule. This ratio was larger than that predicted by an optimality analysis that assumes that subjects respond in a pattern that minimizes the response-reinforcer ratio or one that assumes that subjects respond in a pattern that maximizes the overall rate of reinforcement. In conditions with a 25-s or 50-s intertrial interval, subjects chose the progressive-ratio schedule for an average of about eight consecutive trials before choosing the fixed-ratio schedule. This change in performance with the addition of an intertrial interval was also not predicted by an optimality analysis. On the other hand, the results were consistent with the theory that choice is determined by the delays to the reinforcers delivered on the present trial and on subsequent trials.
在离散试验程序中，鸽子通过对与这两种程序之一相关的按键进行单次啄击，在固定比率81程序和累进比率程序之间做出选择。累进比率程序的反应要求从1开始，每次选择累进比率程序时增加10。每次选择固定比率程序时，累进比率程序的要求重置为1次反应。在没有试验间隔的情况下，受试者平均连续约五次试验选择累进比率程序（在此期间反应要求增加到41），然后选择固定比率程序。这个比率大于最优性分析预测的比率，最优性分析假设受试者以最小化反应-强化物比率的模式做出反应，或者假设受试者以最大化总体强化率的模式做出反应。在有25秒或50秒试验间隔的情况下，受试者在选择固定比率程序之前平均连续约八次试验选择累进比率程序。添加试验间隔后性能的这种变化也没有被最优性分析预测到。另一方面，结果与选择由当前试验和后续试验中给予强化物的延迟决定的理论一致。
