Background stimuli as a reminder after spontaneous forgetting: Role of duration of cuing and cuing-test interval

With a relatively complex maze, reliable forgetting is seen clearly when the training-to-test interval is 25 days. This forgetting is demonstrated by longer time to run the maze and by an increase in the number of errors and retracings from the last training trials to the first test trial. In this case, forgetting is a lapse, not a loss, since performance attains the last training trial level at a subsequent test. Furthermore, a reminder—a 90-sec exposure to background stimuli in the experimental room just prior to the test trial—that does not in itself contain sufficient information to facilitate performance in naive animals, significantly improves maze performance in rats that have “forgotten,” even on the first test trial. Two additional experiments were aimed at assessing the role of time and duration of pretest cuing. In the first experiment, the animals were presented the reminder (90 sec in duration) at different times before the test trial. The results show that this reminder significantly alleviates forgetting only when presented just prior to the test, and is less effective when given 1 or 24 h before the test. In the second experiment, contextual cues, which were presented just prior to testing in all experimental groups, varied in duration. The results showed that (1) animals given the reminder treatment for only 10 sec perform at the same level as controls; (2) cuing for 30 sec and especially for 90 sec alleviates forgetting; and (3) a longer exposure to background stimuli (300 sec) leads to intermediate levels of performance, probably due to a partial extinction of the cue value of these stimuli.