Balancing stability and flexibility in cognitive control and learning: the effects of arousal

The stability-flexibility balance is crucial for effective cognitive control and learning. Stability, achieved by strengthening relevant processes, supports goal-directed behavior, while flexibility enables adaptation to changing demands. However, these two mechanisms can be in opposition: promoting stability may hinder flexibility, and vice-versa. This thesis uses behavioral and computational analyses to investigate how varying levels of arousal impact this balance across a range of cognitive tasks. Three distinct studies were designed to explore this complex relationship, each focusing on a different aspect of arousal and its effects on cognitive performance. The first study investigated the impact of a combined cognitive and social-evaluative stressor, representing a state of supra-optimal arousal, on working memory and its gating mechanisms, which are considered fundamental to broader cognitive control processes. Using the reference-back paradigm, this study revealed that acute stress selectively impaired working memory stability without significantly affecting flexibility. The second study explored how reward incentives, representing a state of optimal arousal, and switch-frequency expectations modulated performance on a task-switching paradigm. The results indicated that rewards optimized performance by increasing processing speed and enhancing stability, particularly in contexts characterized by low switch frequency. Finally, the third study investigated the impact of sleep restriction, representing a state of suboptimal arousal, on learning and inhibitory control, recognizing the increasingly evident link between learning and control processes. This study demonstrated that sleep restriction impaired learning and adaptation to shifting probabilities, specifically by reducing volatility estimation, while leaving inhibitory control processes largely unaffected. Overall, the findings from these three studies reveal a complex and nuanced relationship between arousal and the stability-flexibility. While acute stress appears to impair stability, rewards enhance it, and sleep restriction primarily affects flexibility. These insights contribute to our understanding of how arousal modulates cognitive control and learning processes.