Andrew Benjamin J, Harris Justin A
School of Psychology, University of Sydney, New South Wales, Australia.
J Exp Psychol Anim Behav Process. 2011 Oct;37(4):385-93. doi: 10.1037/a0024553.
Three experiments used delay conditioning of magazine approach in rats to examine the summation of responding when two conditioned stimuli (CSs) are presented together as a compound. The duration of each CS varied randomly from trial-to-trial around a mean that differed between the CSs. This meant that the rats' response rate to each CS was systematically related to the reinforcement rate of that CS, but remained steady as time elapsed during the CS (Harris & Carpenter, 2011; Harris, Gharaei, & Pincham, 2011). When the rats were presented with a compound of two CSs that had been conditioned separately, they responded more during the compound than during either of the CSs individually. More significantly, however, in all three experiments, the rats responded to the compound at the same rate as they responded to a third CS that had been reinforced at a rate equal to the sum of the reinforcement rates of the two CSs in compound. We discuss the implications of this finding for associative models (e.g., Rescorla & Wagner, 1972) and rate-based models (Gallistel & Gibbon, 2000) of conditioning.
三项实验运用大鼠食物趋近延迟条件反射，来检验当两个条件刺激（CS）作为一个复合刺激同时呈现时反应的总和。每次CS的时长在每次试验中围绕一个均值随机变化，该均值在不同CS之间存在差异。这意味着大鼠对每个CS的反应速率与该CS的强化速率存在系统关联，但在CS持续期间随着时间推移保持稳定（哈里斯和卡彭特，2011；哈里斯、加拉伊和平查姆，2011）。当给大鼠呈现两个分别进行过条件反射的CS组成的复合刺激时，它们在复合刺激呈现期间的反应比单独呈现任何一个CS时都更多。然而，更显著的是，在所有三项实验中，大鼠对复合刺激的反应速率与它们对第三个CS的反应速率相同，第三个CS的强化速率等于复合刺激中两个CS强化速率之和。我们讨论了这一发现对条件反射的联想模型（如雷斯克拉和瓦格纳，1972）以及基于速率的模型（加利斯泰尔和吉本，2000）的意义。
