72 undergraduates paced themselves through either auditory or visual presentation of 15-item lists. Ss were instructed to either (a) rehearse cumulatively, (b) actively rehearse primacy items while passively attending to recency items (active-passive), or (c) rehearse by choosing their own strategy (free). Study times showed that when no restraints were placed on rehearsal, Ss receiving auditory presentation required longer processing time than did Ss receiving visual presentation. Modality had no effect on correct responding but did influence the order of recall in the free and active-passive conditions. Results are discussed in terms of a proposed hypothesis concerning interference arising from the similarity between acoustic trace information and the articulatory-acoustic mode for subvocal rehearsal. (18 ref) (PsycINFO Database Record (c) 2006 APA, all rights reserved). © 1974 American Psychological Association.