ERPs. a, ERPs locked on stimulus offset for target (continuous lines) and nontarget (dashed lines) trials and split by drug treatment (placebo PLA: gray, methylphenidate MPH: orange, atomoxetine ATM: purple, citalopram CIT: green). ERPs are averaged across participants (PLA: N = 32; CIT: N = 31; ATM: N = 31; and MPH: N = 32). ERPs computed on two electrodes are shown: Fz (Frontal, left) and Pz (parietal, right). Colored lines show the sample average and colored areas the SEM. The yellow area ([0, 0.3] s postoffset window) shows the interval of the archetypal P3 used to compute the P3 amplitude (see Materials and Methods). b, Topographical maps of the P3 amplitude (difference of the ERP amplitude between target and nontarget trials and average on a [0, 0.3] s window) for each drug treatment. c, Topographical maps of the statistical differences in P3 amplitude between MPH and PLA (left), ATM and PLA (middle), and CIT and PLA (right). The t values obtained with paired t tests for each electrode are shown. Significant clusters of electrodes (p_cluster < 0.05) are shown with black dots (cluster-permutation approach; see Materials and Methods). A significant cluster was found only for MPH.