After training on a vertical-horizontal visual discrimination problem, groups of male albino rats were given ECS at 10 sec., 2 min., 1 hr., or 4 hr. after reaching learning criterion. After a two-day interval all groups relearned the discrimination. Results indicated significant memory deficit in all groups but the 4-hr.; the latter did not differ from normal controls. Implications for physiological basis of memory are discussed. (PsycINFO Database Record (c) 2006 APA, all rights reserved)