Stable tendencies in spontaneous working memory usage during flexible behaviour.

Unlike standard working memory (WM) tasks, real-world settings allow individuals to spontaneously adapt how much information to use from WM before resampling the environment. Here, we considered whether individuals exhibit distinct, trait-like tendencies in their spontaneous use of WM. Across three studies (N = 220) using an Object Copying Task, we show that some participants consistently exhibited greater WM usage than others. These tendencies were reliable, stable across time, and predicted individuals' task efficiency and responses to changing task demands. Finally, spontaneous WM usage could only partially be explained by established measures of WM capacity and attentional control - two plausible predictors of natural WM usage. In summary, we find stable tendencies in individuals' spontaneous WM usage, despite the variable nature of self-structured natural behaviour. Our results position inter-individual variability as an important dimension in understanding natural, memory-guided behaviour, highlighting the need to investigate its broader determinants and behavioural consequences.