Fig. 1.

Overview of the child-adapted AX-CPT and children's behavioral performance. (A) In the AX-CPT, 4 stimuli are presented sequentially; AX trials occur with 70% frequency, and other trials with 10% probability each. Stimuli were replaced with cartoon characters; an adaptive allowable response time was set per subject. (B) Only 8-year-olds (white bars) show the significantly exaggerated reaction times on AY trials expected of proactive control. (C) Simple accuracy measures do not significantly distinguish reactive vs. proactive control, but only 8-year-olds show numerically fewer BX than AY errors, as expected of proactive control. Conditionalized accuracy measures reveal distinct reactive and proactive profiles (see SI Text).