current or past psychopathology. Participants in both groups were predominantly right-handed as indicated by their Laterality Quotient (LQ) using the Edinburgh Inventory (Oldfield, 1971). Although handedness has been reported to influence the amplitude of anterior P3 (Alexander & Polich, 1995), four left-handed patients (LQ<0) were included because critical findings were preserved when these patients were excluded. Reports of nicotine use, which may affect P3 amplitude (Anokhin et al., 2000), were not solicited. Most patients met DSM-IV criteria for major depressive disorder (MDD; n = 26), dysthymia (n = 9), or both disorders (n = 11). Of the remaining 3 patients, 1 was bipolar (depressive phase) and 2 had diagnoses of depression not otherwise specified. Eight patients had a comorbid anxiety disorder. Beck Depression Inventory (Beck, Ward, Mendelson, & Erbaugh, 1961) scores of patients ranged from 13 to 41 (mean = 23.0 ± 7.2).
