The Effects of Subsidiary Tasks on Memory Retrieval from Long and Short Lists
Burrows and Okada (1975) found that reaction time in an item recognition task was a monotonic but non-linear function of memory set size when set size varied from two to 20. A bilinear function with a steep slope for short lists and a shallow slope for long lists provided a good description of the data. Two experiments were conducted to determine whether the difference in slope between long and short lists arises from the extra attention devoted to, or rehearsal of, items within the span of immediate memory. Rehearsal of a prememorized list was discouraged by including a counting backwards task (Experiment I) or by presenting a second list of items that required processing (Experiment II). In neither experiment did the subsidiary task reduce the slope difference. It would appear that the slope difference is not a result of rehearsal of subspan lists.