Stimulus selection influences prediction of individual phenotypes in naturalistic conditions

Understanding individual differences and brain-behaviour relationships is an essential goal of human neuroscience. Recent studies have shown the great potential of naturalistic stimuli, e.g., movie clips, in advancing this pursuit. While the use of naturalistic stimuli attracts increasing interest, the influence of stimulus selection remains largely unclear. In this study, we show that brain activity is generally sensitive to the choice of movie stimuli at both group and individual subject levels. Using sex classification as an example, we demonstrate that brain activity elicited by different stimuli can lead to distinct prediction performance and unique predictive features. The stimuli that yield better classification performance often elicit stronger synchrony of brain activity across all subjects and are mostly derived from Hollywood films with rich social content and cohesive narratives. Our results highlight the importance of stimulus selection and provide practical guidance for choosing appropriate stimuli, opening up new avenues for future studies on individual differences and brain-behaviour relationships.