Interference in short-term memory from vocalization: aural versus visual modality differences.

The Peterson and Peterson short-term memory paradigm involves an interpolated task with several potential dimensions from which interference may orginate: Similarity of items and vocalization. Here we assess the relative interference potency of each on material presented either aurally or visually. Interpolated activity consisting of numbers or words was performed either vocally or silently after either aural or visual presentation of nouns, for which recall was tested after 0, 10, and 30 sec. The magnitude of the vocalization interference effect accounted for 59% and 53% of the total variance at 30 and 10 sec, respectively, whereas the variance associated with similarity was negligible. The effect of similarity emerged dramatically only in the visual presentation condition wherein the silent word task created greater interference than the silent number task. Vocal and silent activity produced differential interference, in partial accord with the dual memory hypothesis.