3.2.1. Response-Locked ERN

The two (response type: error vs. correct) by two (group: ADHD vs. HC) repeated-measures ANOVA revealed a main e ffect of response type (F (1,149) = 118.46, *p* < 0.001) and an interaction between response type and group (F (1,149) = 4.72, *p* = 0.031). Error trials elicited a larger ERN (more negative) than correct trials; the ERN e ffect (i.e., dERN) was smaller in participants with ADHD than in HC (Table 1; Figure 1). There was no main e ffect of group (F < 1, *p* = 0.449).

**Figure 1.** ERN and Pe waveforms for participants with ADHD and HC, and topography for error response (ERN: 0–80 ms; Pe: 200–400 ms; Baseline: −200–−50 ms) in all participants. Responses occurred at 0 msec. ADHD, attention deficits/hyperactive disorder; HC, healthy controls; ERN, error-related negativity; Pe, error positivity.

Age was negatively correlated with ERN amplitude (*r* = −0.286, *p* < 0.001) and dERN (*r* = −0.364, *p* < 0.001), and positively correlated with CRN (*r* = 0.167 *p* = 0.040) across all subjects. There was no significant group di fference in correlations with age. With age increasing, participants showed a larger ERN, smaller CRN, and larger ERN e ffect. When covarying age, CRN was negatively correlated with overall RT (*r* = −0.318, *p* < 0.001), RTV (*r* = −0.263, *p* = 0.001), accuracy (*r* = −0.162, *p* = 0.047), and positively correlated with post-error slowing (*r* = −0.204, *p* = 0.012); the ERN e ffect was positively correlated with overall RT (*r* = 0.311, *p* < 0.001) and RTV (*r* = 0.212, *p* = 0.009) and negatively correlated with post-error slowing (*r* = −0.276, *p* = 0.001). There was no ERN correlation with behavioral performance and no group di fference in the correlation between ERN/CRN/dERN and behavioral performance.
