"The data of a previously reported study [20: 3493] in learning and retention are reanalyzed here to show the importance for reminiscence of parameters which had not been treated by earlier investigators in this field . . … The major findings pertinent to reminiscence are: 1. Reminiscence after a 'rest' interval as long as 24 hours occurs under conditions of ego-orientation, not task orientation. 2. Activity is a less important parameter for reminiscence than ego-orientation. Activity aids reminiscence only if the S is ego-oriented. 3. Differences in mental set may be experimentally induced or self-induced. The failure to control such differences in previous studies in this field could account for what Buxton [17: 2632] has termed 'the-now-you-see-it-now-you-don't character of reminiscence research.' 4. The conditions associated with rehearsal are also associated with reminiscence. Active Ss, and especially ego-oriented Ss, report rehearsal during the 'rest' interval. The mere tendency to rehearse, however, is not a sufficient condition to assure reminiscence. 5. Reminiscence data can be conceptualized within the frame work of studies in the field of completed and incompleted tasks . . …" 6. The theory thus developed "is consistent with, and supplemental to, the widely accepted theory of differential forgetting." 23 references. (PsycINFO Database Record (c) 2006 APA, all rights reserved)