Ayahuasca-inspired DMT/harmine formulation alters creative thinking dynamics during artistic creation

Background: While psychedelics are often claimed to enhance creativity, their precise effects on distinct stages of creative cognition remain poorly understood. This study investigated the acute effects of an ayahuasca-inspired formulation combining N,N-dimethyltryptamine (DMT) and harmine (DMT/HAR), as well as harmine alone (HAR), on micro-level (divergent/convergent thinking) and macro-level (creative process dynamics) creativity. Methods: In a double-blind, placebo-controlled, within-subject design, 30 healthy male participants completed three sessions (DMT/HAR, HAR, placebo). Micro-level creativity was assessed using the picture concept task (convergent thinking) and alternative uses task (divergent thinking). Macro-level dynamics were examined through a real-world painting task using the creative process report diary, which captured dynamic stage transitions. Subjective experiences were also recorded to explore their predictive value for creativity. Results: DMT/HAR significantly impaired convergent thinking, particularly in individuals with higher baseline reasoning. Divergent thinking showed no overall effect but revealed trend-level reductions in fluency and elaboration under DMT/HAR. At the macro-level, both DMT/HAR and HAR reduced incubation-related transitions, while DMT/HAR uniquely decreased transitions from incubation to illumination, suggesting altered pathways to insight. Subjective experiences such as altered meaning perception and increased insightfulness selectively predicted divergent, but not convergent, thinking outcomes. Conclusions: This study demonstrates that the effects of DMT/HAR on creativity are not uniform. By capturing real-world creative behavior through an ecologically valid painting task, this study offers the first evidence that psychedelics influence not only creative cognition but also the dynamic processes that give rise to it. These findings highlight the importance of integrating cognitive, phenomenological and process-level perspectives to better understand creative thinking under altered states. Future research should further investigate how individual differences in subjective experience and cognitive style modulate the unfolding of creative processes under psychedelics.