Mind-wandering facilitates creative performance in a musical improvisation task

• Novel experience sampling approach linked mental states to ongoing creative performance. • Fine-grained mental state classification revealed distinct functional outcomes within on-task and off-task states. • Mind-wandering associated with increased musical creativity, compared to task-focused attention. • Task-related interference associated with decreased creativity; mind-blanking was neutral. • Expertise moderated mind-wandering effects: benefits strongest for novices. Mind-wandering is widely assumed to impair ongoing task performance, yet findings from creative cognition research suggest that it can be beneficial under some conditions — an inconsistency rooted in coarse mental state classifications and low-ecological-validity tasks. We tested whether mind-wandering during active creative production facilitates or impairs real-time creative output in the ecologically valid setting of live jazz improvisation. 52 musicians performed a musical improvisation task while random thought-probes sampled ongoing mental states: focused attention, mind-wandering, mind-blanking, and task-related interference. Expert judges rated each performance for creativity and overall improvisational quality. Mental states were phenomenologically distinct across dimensions of intentionality and meta-awareness, and critically, this phenomenological heterogeneity translated into functional heterogeneity in their associations with creative output. Mind-wandering predicted higher creativity than focused attention, task-related interference suppressed creativity, and mind-blanking was neutral to modestly positive. Overall quality was mainly driven by expertise. State × expertise interactions revealed that the creative benefits of mind-wandering were strongest for less- and mid-experienced improvisers. These findings show that during improvisatory creative action, mind-wandering need not derail performance. Instead, it may mark adaptive loosening of cognitive control that supports generative spontaneity and flexibility crucial to creative expression.