Cognitive control—the ability to regulate one’s behavior in accordance with internal goals—is fundamental to adaptive behavior. Despite substantial progress in our understanding of different cognitive control functions supporting goal-directed behavior, most studies rely on externally instructed tasks, whereas in real-world contexts, people often have the autonomy to choose which task to perform. Although research suggests that having the opportunity to choose can enhance a variety of psychological processes (e.g., motivation or learning), it remains unclear whether and how cognitive control differs

between instructed and voluntarily chosen tasks. The present study addresses this question using a novel paradigm to investigate how one core function of cognitive control—the flexibility to switch between tasks—differs between self-determined (free-choice) and externally determined (forced-choice) tasks. We reasoned that self-determined task choice may enable individuals to optimize control more effectively (e.g., by switching when control demands are relatively low) and/or may motivate individuals to invest more effort in flexibility-related control processes. Consistent with performance optimization and

motivational accounts, switch costs in task performance (in particular, reaction times [RTs]) were reduced under free-choice compared to forced-choice tasks across multiple experiments. This reduction was driven specifically by shorter RTs on switch trials in free-choice tasks, suggesting that voluntary task choice takes advantage of control processes that promote cognitive flexibility, such as disengaging from a previous task or reconfiguring a new one. Overall, the present study provides new evidence linking self-determined task choice to improvements in higher-order cognitive control functions—specifically, cognitive flexibility.