Retraining of extinguished Pavlovian stimuli.

Five Pavlovian magazine approach experiments with rat subjects examined the mechanisms by which reconditioning restores extinguished responding. Experiments 1, 2, and 3 found that retraining did not destroy the spontaneous recovery with the passage of time that is characteristic of extinguished stimuli. Experiments 4 and 5 found evidence that retaining after extinction enhanced the strength of the originally trained associations. Together these results suggest that, just as extinction does not destroy original acquisition but superimposes some decremental process, so retraining does not destroy that decremental process but instead superimposes further associative learning.