Removing the effect of response time on brain activity reveals developmental differences in conflict processing in the posterior medial prefrontal cortex

► Fronto-parietal activity increases with RT in adults but not in children. ► Group differences in this RT-BOLD relationship may be an important confound. ► Removing the effect of RT reveals developmental differences in conflict processing. ► The RT-BOLD relationship may be a useful biomarker of brain maturity.