Experimental andTheoretical Studies on the Expectancy and Aftereffect of Aversive Stimuli of Different Durations

本研究的目的是研究在大鼠舔食条件性抑制的情况下，增加电击强度是否也会通过增加电击持续时间来获得效果。在实验一中，五种不同持续时间的无信号格子袜子的厌恶性是从总体舔抑制的角度来测量的。在实验2中，这些持续时间为5次的电击被用作条件刺激，但持续时间对条件反射没有影响。在实验3中，0.7秒和4.9秒的电击被用作USS，这两种电击在实验1中的厌恶程度有显著差异，它们的影响采用了受试者之间和受试者内的设计。与实验2的结果一致，电击持续时间对受试者间设计的条件反射没有影响。但是，在受试者内部的设计中，与TJE 4.9秒电击配对的CS的条件性抑制被证明明显大于配对0.7秒电击的CS。这种效果归因于这样一个事实，即在后一种设计中，大鼠有机会“比较”两种不同持续时间的电击。在实验4中，通过改变从0.7秒电击到4.9秒电击或从4.9秒电击到0.7秒电击的转换次数，系统地操纵了大鼠必须比较电击持续时间的机会。结果表明，较多的相变次数有利于激波-持续时间的辨别。在最后一个实验中，研究了9个不同持续时间的地震的后遗症，从它们对紧接着条件抑制的抑制效应方面进行了研究。在条件性抑制之后，较长的电击比较短的电击具有更大的去抑制效应。作为一个整体，我们参考了当代经典条件反射理论以及对立-过程理论对结果进行了讨论。

The purpose of the present research was to investigate whether or not effects obtained by increasing the intensity of an electric shock would also be obtained by increasing its duration, in a licking conditioned suppression situation with rats. In Experiment 1, the aversiveness of unsignaled grid-socks of five different durations was measured in terms of overall lick suppression. These shocks of five durations were used as USs in Experiment 2, but the US-duration had no effect upon conditioning. In Experiment 3, 0.7-sec and 4.9-sec shocks, which were shown to be significantly different in aversiveness in Experiment 1, were used as USs, and their effects were assessed using both beteen- and within-subjects designs. In agreement with results of Experment 2, shock duration had no effect upon conditioning with the between-subjects design. But conditioned suppression to the CS paired with tje 4.9-sec shock proved to be significantly greater than that to the CS paired with the 0.7-sec shock, with the within-subjects design. This effect was attributed to the fact that, with the latter design, rats had chances to "compare" shocks of two different durations. In Experiment 4, chances rats had to compare shock durations were systematically manipulated by varying the number of within-session transitions from the 0.7-sec shock to the 4.9-sec shock, or vice versa. The results showed that the shock-duration discrimination was facilitated under the condition of greater number of transitions. In the last experiment, the aftereffects of shocks of nine different durations were investigated in terms of their dissuppressing effects upon immediately following conditioned suppression. Longer shocks proved to have greater dissuppressing effect upon following conditioned suppression than shorter shocks. The results as a whole were discussed with reference to contemporary theories of classical conditioning, as well as to the opponent-process theory.