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

Extra free time improves working memory (WM) performance. This free-time benefit becomes larger across successive serial positions, a phenomenon recently labeled the "fanning-out effect". Different mechanisms can account for this phenomenon. In this study, we implemented these mechanisms computationally and tested them experimentally. We ran three experiments that varied the time people were allowed to encode items, as well as the order in which they recalled them. Experiment 1 manipulated the free-time benefit in a paradigm in which people recalled items either in forward or backward order. Experiment 2 used the same forward-backward recall paradigm coupled with a distractor task at the end of encoding. Experiment 3 used a cued recall paradigm in which items were tested in random order. In all three experiments, the best-fitting model of the free-time benefit included (1) a consolidation mechanism whereby a just-encoded item continues to be re-encoded as a function of the total free-time available and (2) a stabilization mechanism whereby items become more resistant to output interference with extra free time. Mechanisms such as decay and refreshing, as well as models based on the replenishment of encoding-resources, were not supported by our data.