**3. Results**

#### *3.1. Behavioral Data in Patients with ADHD and Healthy Controls*

Participants' reaction times and accuracy data are presented in Table 1. Participants with ADHD responded more slowly (*p* < 0.01) but as accurately (*p* = 0.77) as HC. Two (congruency: congruen<sup>t</sup> vs. incongruent) by two (group: ADHD vs. HC) repeated-measures ANOVA on correct RT and accuracy revealed main e ffects of congruency (RT: F (1,152) = 352.4, *p* < 0.001; accuracy: F (1,152) = 470.4, *p* < 0.001) and a trend-level significance of interaction between congruency and group for reaction times (F (1,152) = 3.22, *p* = 0.08), but no such interaction in accuracy (F (1,152) = 0.88, *p* = 0.35). Incongruent trials were completed more slowly and less accurately than congruen<sup>t</sup> trials in both groups. Participants with ADHD tended to have a larger RT congruency e ffect (86.3 msec vs. 69.5 msec, *p* = 0.08). Moreover, participants with ADHD exhibited smaller post-error slowing (*p* = 0.006) and larger RTV (*p* = 0.005) than HC (Table 1).


incongruent accuracy; ERN, error-related negativity; CRN, correct-related negativity; dERN, ERN minus CRN; con, congruent; inc, incongruent; dN2, incongruent N2 minus congruent

N2; dP3, incongruent P3 minus congruent P3. \*\* *p* < 0.01, \* *p* < 0.05, @ *p* < 0.10.


Age in all subjects was negatively associated with overall RT (r = −0.647, *p* < 0.001), RTV (r = −0.620, *p* < 0.001) and RT congruency e ffect (incongruent minus congruen<sup>t</sup> RT, r = −0.215, *p* = 0.007), and was positively correlated with post-error slowing (*r* = 0.220, *p* = 0.006) and overall accuracy (*r* = 0.264, *p* = 0.001). With age increasing, participants responded faster and more accurately, and showed smaller RT congruency e ffects and RTV. A correlation of age with post-error slowing was evident in ADHD but not in HC (ADHD: *r* = 0.339, *p* = 0.003; HC: *r* = 0.034, *p* = 0.767; ADHD vs. HC, *p* = 0.012). There was no correlation of age with the accuracy congruency e ffect. Correlation of age with behavioral measures in individual groups is presented in Table 1.

#### *3.2. ERP Data in Patients with ADHD and Healthy Controls*
