McLean Anthony P, Grace Randolph C, Pitts Raymond C, Hughes Christine E
University of Canterbury, New Zealand.
J Exp Anal Behav. 2014 May;101(3):317-36. doi: 10.1002/jeab.84. Epub 2014 Mar 27.
Preference pulses are thought to represent strong, short-term effects of reinforcers on preference in concurrent schedules. However, the general shape of preference pulses is substantially determined by the distributions of responses-per-visit (visit lengths) for the two choice alternatives. In several series of simulations, we varied the means and standard deviations of distributions describing visits to two concurrently available response alternatives, arranged "reinforcers" according to concurrent variable-interval schedules, and found a range of different preference pulses. Because characteristics of these distributions describe global aspects of behavior, and the simulations assumed no local effects of reinforcement, these preference pulses derive from the visit structure alone. This strongly questions whether preference pulses should continue to be interpreted as representing local effects of reinforcement. We suggest an alternative approach whereby local effects are assessed by subtracting the artifactual part, which derives from visit structure, from the observed preference pulses. This yields "residual" preference pulses. We illustrate this method in application to published data from mixed dependent concurrent schedules, revealing evidence that the delivery of reinforcers had modest lengthening effects on the duration of the current visit, a conclusion that is quantitatively consistent with early research on short-term effects of reinforcement.
偏好脉冲被认为代表了强化物在并发程序中对偏好的强烈短期影响。然而，偏好脉冲的总体形状在很大程度上取决于两种选择方案的每次访问反应分布（访问时长）。在一系列模拟中，我们改变了描述对两个同时可用反应方案访问的分布的均值和标准差，根据并发可变间隔程序安排“强化物”，并发现了一系列不同的偏好脉冲。由于这些分布的特征描述了行为的全局方面，且模拟假设强化没有局部影响，这些偏好脉冲仅源于访问结构。这强烈质疑了偏好脉冲是否应继续被解释为代表强化的局部影响。我们提出了一种替代方法，即通过从观察到的偏好脉冲中减去源于访问结构的人为部分来评估局部影响。这产生了“剩余”偏好脉冲。我们将此方法应用于混合依赖并发程序的已发表数据进行说明，揭示了强化物的交付对当前访问时长有适度延长作用的证据，这一结论在数量上与早期关于强化短期影响的研究一致。
