Phonemic Coding and Rehearsal in Short-Term Memory for Letter Strings.

Several new procedures were used to control vocalization during display of letter strings and rehearsal during retention intervals. Clear evidence of phonemic encoding of visually presented letters was obtained when vocalization was permitted at input but was absent when vocalization was suppressed by a categorizing task or by reduced exposure durations. However, under the latter condition, phonemic encoding occurred if rehearsal was permitted immediately following input, indicating that representations of letters can be maintained in a nonauditory form in memory for at least 1 sec following a visual display in spite of the overwriting of successive characters in the same location. Both vocalization during input and minimal rehearsal during retention intervals exerted effects on item availability and memory for order beyond those interpretable in terms of phonemic encoding.