Free time, sharper mind: A computational dive into working memory improvement

Extra free time improves working memory (WM) performance. One aspect of this improvement is that it becomes larger across successive serial positions, a phenomenon recently labelled the "fanning-out" effect. Oberauer (2022) tested different models to account for this phenomenon and found that an encoding-resource mechanism perfectly aligned with it. However, we argue that the fanning-out effect might also result from output-related processes. We tested this hypothesis via behavioral experiments and modeling. Participants memorized lists of six items presented at varying speeds. They recalled items in either forward or backward order, with recall conditions being post-cued. We observed that the fanning-out effect occurred as a function of output position. That is, a greater benefit from extra free-time across serial positions depended on the direction in which items were retrieved, not the way they were encoded. Using a comprehensive set of simulations, we show that our empirical data are best explained via (1) a consolidation mechanism and (2) a stabilization mechanism whereby items become more resistant to output interference with extra free time.