Kendall S B
Psychology Dept., University of Western Ontario, London, Ontario Canada, N6A 5C2.
Behav Processes. 1987 Jun;14(3):247-66. doi: 10.1016/0376-6357(87)90072-6.
Two experiments were conducted in which pigeons were trained to perform a complex operant consisting of a peck to one key followed by a peck to another key. In the first experment this performance was reinforced on a variable-interval schedule and the birds were then subjected to a multiple schedule in which the variable-interval was alternated with extinction. The first two pigeons trained showed some deterioration of the cohesiveness of the response sequence. After measures were taken to correct this the pigeon gave evidence of behavioral contrast in a condition where sessions with discrimination were alternated rapidly with sessions with no discrimination (variable-interval only). Another two birds were trained on variable-interval followed by discrimination. One of these birds showed evidence of contrast but the results of the other were not clear. Experiment II was a three phase experiment in which animals were first trained to make the complex response. In the second phase they were extinguished by providing noncontingent reinforcement in each of two components. In the third phase reinforcement was removed from one component, providing for a stimulus-reinforcer contingency. In the third phase the complex response reappeared temporarily. The results of these two studies indicate that a complex response may show behavioral contrast and that it may be enhanced by stimulus-reinforcer contingencies if it has already been trained.
进行了两项实验，其中训练鸽子执行一种复杂的操作性行为，即先啄一个按键，然后再啄另一个按键。在第一个实验中，这种行为按照可变间隔时间表得到强化，然后让这些鸟接受一种多重时间表，其中可变间隔与消退交替进行。最初训练的两只鸽子表现出反应序列的连贯性有所下降。在采取措施纠正这一情况后，这些鸽子在一种条件下表现出行为对比，即有辨别力的实验环节与无辨别力的实验环节（仅可变间隔）快速交替。另外两只鸟先按照可变间隔进行训练，然后进行辨别训练。其中一只鸟表现出对比的迹象，但另一只鸟的结果不明确。实验二是一个三阶段实验，在这个实验中，动物首先被训练做出复杂反应。在第二阶段，通过在两个组成部分中的每一个都提供非偶然性强化来使其消退。在第三阶段，从一个组成部分中撤去强化，形成刺激 - 强化物的偶然性。在第三阶段，复杂反应暂时重新出现。这两项研究的结果表明，一种复杂反应可能表现出行为对比，并且如果它已经经过训练，那么刺激 - 强化物的偶然性可能会增强这种对比。
