Randich A, Haggard D
J Exp Psychol Anim Behav Process. 1983 Apr;9(2):147-59.
Three experiments demonstrated that repeated exposure to an electric-shock unconditioned stimulus (US) resulted in a decrement in retention of conditioned suppression evoked by a previously established excitatory conditioned stimulus (CS) and retarded subsequent acquisition of conditioned suppression to a novel CS paired with shock. Experiment 1 showed that 10 sessions of exposure to shock alone were required to produce a decrement in retention of conditioned suppression, whereas retardation in the acquisition of conditioned suppression was obtained following either 5 or 10 sessions of exposure to shock alone. Experiment 2 demonstrated that the magnitude of both the decrement in retention of conditioned suppression and the retardation in the acquisition of conditioned suppression produced by exposure to shock alone was directly related to the intensity of those shocks. Experiment 3 demonstrated that the decrement in retention of conditioned suppression produced by 10 sessions of exposure to shock alone was inversely related to the interval between the last exposure to shock and the test of the target CS. These findings are discussed in terms of associative and nonassociative accounts of the effects of US-alone procedures.
三项实验表明，反复暴露于电击无条件刺激（US）会导致由先前建立的兴奋性条件刺激（CS）诱发的条件性抑制的保持能力下降，并延缓随后对与电击配对的新CS的条件性抑制的习得。实验1表明，需要单独暴露于电击10次才能使条件性抑制的保持能力下降，而单独暴露于电击5次或10次后，条件性抑制的习得就会出现延缓。实验2表明，单独暴露于电击所产生的条件性抑制保持能力的下降幅度和条件性抑制习得的延缓幅度都与这些电击的强度直接相关。实验3表明，单独暴露于电击10次所产生的条件性抑制保持能力的下降与最后一次暴露于电击和目标CS测试之间的间隔呈负相关。将根据单独呈现US程序效果的联想和非联想解释来讨论这些发现。
