Fluctuations in emotional valence and arousal are differentially linked to cognitive performance and subjective mental effort

Background: Emotional states vary dynamically, such that their momentary levels and variability are linked to mental health. However, it remains unclear how these dynamics relate to cognitive performance, both objectively and subjectively. We examined whether momentary levels of valence and arousal, and their temporal variability, are associated with objective working memory performance and subjective mental effort.Methods: Two studies were conducted. Experiment 1 (online cohort, n = 289) validated four state items (happiness, calmness, energy, fatigue) as markers of valence and arousal using a semantic association task and exploratory factor analysis. Experiment 2 was a five-day ecological momentary assessment study (n = 59) with three sessions per day, in which participants reported these items and completed a working memory task, followed by a subjective report of mental effort, and a control motor speed task. Linear mixed models tested associations between emotional dynamics and behavior.Results: Across both experiments, happiness and calmness loaded highly on a valence factor, whereas energy and fatigue loaded highly on an arousal factor. In Experiment 2, higher momentary arousal, but not momentary valence, was associated with lower perceived mental effort. Greater between-day variability in valence was associated with lower working memory accuracy, driven by increased intrusion errors, but with lower perceived mental effort. Conclusions: Valence and arousal dynamics are differentially associated with cognition. Daily fluctuations in valence are associated with lower working memory performance, and lower subjective mental effort, possibly reflecting reduced cognitive control. Emotional variability, particularly cross-day changes, may reflect an important target for research on motivation, depression, and self-regulation.