Broad brain networks support curiosity-motivated incidental learning of naturalistic dynamic stimuli with and without monetary incentives

Curiosity—the intrinsic desire to know—is central to the human mind and knowledge acquisition. Experimental studies have shown that curiosity facilitates memory encoding and exhibits reward-like properties similar to extrinsic incentives by eliciting dopaminergic responses in the reward network. It remains unclear whether these findings generalize to naturalistic dynamic stimuli and how curiosity and extrinsic incentives jointly affect learning and neural activation. Across two behavioral studies (N₁ = 77, N₂ = 78) and one fMRI study (N = 50), participants viewed videos of magic tricks, rated their curiosity, and performed a judgment task incentivized for half the sample. Incidental memory for the tricks was assessed a week later. Integrated results showed that both curiosity and the availability of extrinsic incentives enhanced encoding without interacting. Curiosity influenced only high-confidence recognition memory, whereas incentives affected memory regardless of confidence, suggesting distinct encoding mechanisms. fMRI analyses using intersubject synchronization revealed that curiosity-related memory effects localized to the hippocampus and dopaminergic areas, yet neither curiosity nor incentive effects themselves were found in the canonical reward network; instead, effects were associated with cortical areas involved in uncertainty processing and attention. These findings challenge a traditional reward-network focus on curiosity and highlight broader brain network involvement.