On the development of the isolation effect in free recall: Isolation by color

Abstract

In Experiment 1, three groups of subjects (ages 8,11, and 14 years) read nine lists of nine words and immediately recalled each list. The middle item in each list was presented either in red (isolated) or in the same color as the other items (nonisolated). As age increased, the difference in recall between items isolated or nonisolated decreased, suggesting that the isolation effect and age are inversely related in free recall. Experiment 2 was conducted to determine whether this relationship was purely a function of responsiveness to the perceptual aspects of the stimuli, or was influenced also by memory capacity. Two more groups (ages 11 and 13) read lists 11 or 13 words long, respectively, with the middle item either isolated or not. The isolation effect was invariant over age. The proportion of yoked nonisolated items that were recalled varied with task difficulty, whereas the proportion of isolated items did not, thereby influencing the extent of the isolation effect. We concluded that, in this context, maturational changes in memory capacity influence the isolation effect.