Williams Ben A
Department of Psychology, University of California, San Diego, La Jolla, CA 92093-0109, USA.
Anim Learn Behav. 2002 Feb;30(1):1-20. doi: 10.3758/bf03192905.
Behavioral contrast is defined as a change in response rate during a stimulus associated with a constant reinforcement schedule, in inverse relation to the rates of reinforcement in the surrounding stimulus conditions. Contrast has at least two functionally separable components: local contrast, which occurs after component transition, and molar contrast. Local contrast contributes to molar contrast under some conditions, but not generally. Molar contrast is due primarily to anticipatory contrast. However, anticipatory contrast with respect to response rate has been shown to be inversely related to stimulus preference, which challenges the widely held view that contrast effects reflect changes in stimulus value owing to the reinforcement context. More recent data demonstrate that the inverse relation between response rate and preference with respect to anticipatory contrast is due to Pavlovian contingencies embedded in anticipatory contrast procedures. When those contingencies are weakened, anticipatory contrast and stimulus preference are positively related, thus reaffirming the view that the reinforcing effectiveness of a constant schedule is inversely related to the value of the context of reinforcement in which it occurs. The underlying basis of how the context of reinforcement controls reinforcement value remains uncertain, although clear parallels exist between contrast and the effects of contingency in both Pavlovian and operant conditioning.
行为对比被定义为在与固定强化程序相关的刺激期间反应率的变化，与周围刺激条件下的强化率呈反比关系。对比至少有两个功能上可分离的成分：局部对比，发生在成分转换之后；以及整体对比。在某些条件下，局部对比会促成整体对比，但一般情况并非如此。整体对比主要归因于预期对比。然而，关于反应率的预期对比已被证明与刺激偏好呈反比关系，这对广泛持有的观点提出了挑战，即对比效应反映了由于强化背景导致的刺激价值变化。最新数据表明，关于预期对比的反应率与偏好之间的反比关系是由于预期对比程序中所包含的巴甫洛夫式偶然因素。当这些偶然因素被削弱时，预期对比与刺激偏好呈正相关，从而再次证实了这样一种观点，即固定程序的强化效果与它所处的强化背景的价值呈反比关系。尽管在巴甫洛夫式条件反射和操作性条件反射中，对比与偶然因素的影响之间存在明显的相似之处，但强化背景如何控制强化价值的潜在基础仍然不确定。
