Conducted 3 experiments with male albino rats (N = 42) in which delayed alternation was used to study the effects of amount of repetition and degree of temporal spacing of repetitions on short-term retention. It was found in Exp I and II that spaced repetition of an event slowed the rate at which the event was forgotten relative to massed repetition. In addition, it was revealed that repetition alone may increase performance on retention tests by establishing an initially stronger memory of the event to be remembered. Exp III showed that increases in the spacing interval were accompanied by increases in retention only within a band of spacing intervals lying between 20 and 60 sec. (PsycINFO Database Record (c) 2006 APA, all rights reserved)