Preston R A, Fantino E
University of California-San Diego, Department of Psychology, La Jolla 92093-0109.
J Exp Anal Behav. 1991 Mar;55(2):155-75. doi: 10.1901/jeab.1991.55-155.
The delay-reduction hypothesis of conditioned reinforcement states that the reinforcing value of a food-associated stimulus is determined by the delay to primary reinforcement signaled by the onset of the stimulus relative to the average delay to primary reinforcement in the conditioning situation. In contrast, most contemporary models of conditioned reinforcement strength posit that the reinforcing strength of a stimulus is some simple function only of the delay to primary reinforcement in the presence of stimulus. The delay-reduction hypothesis diverges from other conditioned reinforcement models in that it predicts that a fixed-duration food-paired stimulus will have different reinforcing values depending on the frequency of its presentation. In Experiment 1, pigeons' key pecks were reinforced according to concurrent-chains schedules with variable-interval 10-second and variable-interval 20-second terminal-link schedules. The initial-link schedule preceding the shorter terminal link was always variable-interval 60 seconds, and the initial-link schedule requirement preceding the longer terminal link was varied between 1 second and 60 seconds across conditions. In Experiment 2, the initial-link schedule preceding the longer of two terminal links was varied for each of three groups of pigeons. The terminal links of the concurrent chains for the three groups were variable-interval 10 seconds and 20 seconds, variable-interval 10 seconds and 30 seconds, and variable-interval 30 seconds and 50 seconds. In both experiments, preference for the shorter terminal link was either a bitonic function or an inverse function of the initial-link schedule preceding the longer terminal-link schedule. Consistent with the predictions of the delay-reduction hypothesis, the relative values of the terminal-link stimuli changed as a function of the overall frequency of primary reinforcement. Vaughan's (1985) melioration model, which was shown to be formally similar to Squires and Fantino's (1971) delay-reduction model, can be modified so as to predict these results without changing its underlying assumptions.
条件性强化的延迟减少假说指出，与食物相关的刺激的强化值取决于该刺激开始时所预示的初级强化延迟与条件作用情境中初级强化的平均延迟的对比。相比之下，当代大多数条件性强化强度模型假定，刺激的强化强度仅是刺激出现时初级强化延迟的某种简单函数。延迟减少假说与其他条件性强化模型的不同之处在于，它预测固定时长的与食物配对的刺激会因其呈现频率而具有不同的强化值。在实验1中，鸽子的按键行为依据并发链程序进行强化，终端链程序为可变间隔10秒和可变间隔20秒。较短终端链之前的初始链程序始终是可变间隔60秒，较长终端链之前的初始链程序要求在不同条件下在1秒至60秒之间变化。在实验2中，对三组鸽子中的每一组，改变两个终端链中较长终端链之前的初始链程序。三组并发链的终端链分别为可变间隔10秒和20秒、可变间隔10秒和30秒、可变间隔30秒和50秒。在两个实验中，对较短终端链的偏好要么是双调函数，要么是较长终端链程序之前初始链程序的反函数。与延迟减少假说的预测一致，终端链刺激的相对值随初级强化的总体频率而变化。沃恩（1985年）的改善模型，已证明在形式上与斯奎尔斯和范蒂诺（1971年）的延迟减少模型相似，可以进行修改以预测这些结果，而无需改变其基本假设。
