The retention interval between a study event of a given item and its subsequent test event consists of two components : an intercycle rest or Type I interval, and the work or Type II interval filled with study and test events of other items within the list. To investigate effects of the Type I interval on relative performance differences between anticipation and study-test methods, the two methods were compared in paired-associate experiments 6 times utilizing spaced practice, i.e., long Type I intervals with 140 college students. Quite contrary to Battig's view (1973), nonsignificant results between the two methods were observed : Under the most favorable spaced practice conditions, i.e., using 30 second Type I intervals, 3 comparisons out of ,5 were nonsignificant. In contrast, the existence of both significant and nonsignificant superiority of the study-test method over the anticipation method, with spaced practice, supported the retention interval hypothesis (Izawa, 1972), intimating thereby that it may be a core concept for the development of more comprehensive theoretical constructs than are now available.