Day-to-day fluctuations in cognitive precision predict the domain-general intention-behavior gap

The idea that better cognitive functioning helps to close the gap between goals and behavior seems self-evident, yet empirical work has found unusually weak interindividual associations between cognitive task performance and real-world, goal-relevant outcomes. Here, we resolve this paradox by shifting from trait-level to state-level analysis. Leveraging a microtask design to measure daily fluctuations in cognitive function, goal setting and goal progress, mood, sleep, and motivation over a 12-week intensive longitudinal study of university students (<i>N</i> = 184, time points = 9248), we show that within-person upswings in domain-general cognitive processing precision precede and predict same-day self-reported goal setting and achievement across both academic and nonacademic domains, even controlling for other factors. A one-standard-deviation change in cognitive precision had an effect statistically equivalent to ~40 min of work, with similar or larger predictive effects compared to fluctuations in mood/motivation and no moderation by trait-level self-control or conscientiousness. Our work addresses long-standing controversies and highlights the power of intraindividual analysis to reveal relationships missed by cross-sectional approaches.