Domjan M, Best M R
J Exp Psychol Anim Behav Process. 1977 Oct;3(4):310-21. doi: 10.1037//0097-7403.3.4.310.
Taste aversions were conditioned in rats by giving the subjects an injection of lithium following exposure to saccharin. Treatment with lithium shortly (30 to 60 min.) before such a conditioning trial disrupted the taste-aversion learning produced by the postsaccharin drug injection. In Experiment 1, this interference effect was found to be a monotonically decreasing function of the preexposure-to-conditioning interval. The greatest disruption of conditioning was observed with a 30-min. preexposure-to-conditioning interval, and no interference occurred if the preexposure was administered 1 or 2 days before conditioning. These results suggest that in addition to the more durable effects of unconditioned stimulus (US) preexposure emphasized by previous investigators, US preexposure also activates temporary mechanisms that likewise attenuate subsequent conditioning. Experiment 2 demonstrated that lithium given before saccharin exposure disrupts the conditioning produced by a postsaccharin drug injection even if the presaccharin injection would itself otherwise be effective in producing a "backward" conditioned saccharin aversion. This outcome indicates that proximal US preexposure can have two opposite and paradoxical effects: It can interfere with as well as condition a taste aversion.
通过在大鼠接触糖精后给它们注射锂来建立味觉厌恶条件反射。在这种条件反射试验前不久（30至60分钟）用锂进行处理，会干扰糖精注射后药物注射所产生的味觉厌恶学习。在实验1中，发现这种干扰效应是预暴露至条件反射间隔时间的单调递减函数。在预暴露至条件反射间隔时间为30分钟时，观察到对条件反射的最大干扰，而如果在条件反射前1天或2天进行预暴露，则不会产生干扰。这些结果表明，除了先前研究者所强调的非条件刺激（US）预暴露的更持久效应外，US预暴露还激活了同样会减弱后续条件反射的临时机制。实验2表明，即使糖精注射前的注射本身在其他情况下能有效产生“逆向”条件性糖精厌恶，在接触糖精前给予锂也会干扰糖精注射后药物注射所产生的条件反射。这一结果表明，近端US预暴露可以产生两种相反且矛盾的效应：它既可以干扰味觉厌恶，也可以建立味觉厌恶。
