Reduction of ontogenetic retention decrements in rats by pretraining stressful experiences.

Pretraining stressful experiences, either similar to or qualitatively different from the conditioning unconditioned stimulus, reduced ontogenetic retention decrements without directly influencing response acquisition. Rats that received pretreatment with footshock, hypthermia, or restraint on Days 16, 17, and 18 of age showed substantially improved long-term retention of conditioned fear learned at 20 days of age. It was also found that preshock enhanced retention of both an appetitive approach response and punishment of the approach response. Several experiments involving extinction and undertraining manipulations indicated that the facilitation of retention was not directly attributable to acquisition strength.