The Robustness of the Interleaving Benefit

Interleaving examples of to-be-learned categories, rather than blocking examples by category, can enhance learning. We examine the reliability of the interleaving effect between- (Experiments 1 and 2) and within-participants (Experiment 3). As a between-participant effect, we examined a broad spectrum of working memory by both measuring individual capacity and manipulating the task demand. Findings reveal a robust interleaving effect across the spectrum, eliminated only at the lowest and highest ends, but never reversed. In Experiment 3, we used an empirically defined source of potential heterogeneity by examining whether the size of the interleaving benefit a participant experiences on one set of stimuli predicts the size of the interleaving benefit that same participant experiences on two other sets of stimuli. It did not, with only a very small correlation between the two more similar stimuli sets. Taken together, these results add to the burgeoning literature on the robustness of the interleaving benefit.