Time-dependent fluctuations of retention performance in an aversively motivated task

The main aim of this series of experiments was to clearly establish the spontaneous development of retention performance following partial aversively motivated training. Experiment 1 indicated that following 15 training trials of a brightness discrimination in a Y-maze, performance spontaneously and transitorily deteriorated 1 h following inital training (Kamin effect) before it improved 8 to 14 days following training (long-term spontaneous improvement). Both of these fluctuations preceded the more durable deterioration that corresponds to long-term forgetting. Experiment 2 replicated the basic findings of the first experiment, always with a brightness discrimination, but using an avoidance paradigm. These results demonstrated the multiphasic nature of the retention curve and emphasized the reliability of retention performance fluctuations.