difference. The group effect went from accounting for 6.3% to 5.3% of N2 variance when P3 amplitude was entered as a predictor. The N2 group effect was still significant (F(1, 132) = 7.42, p = 0.007), while P3 amplitude did not account for significant N2 variance (F(1, 132) = 1.84, p = 0.177). Conversely, the P3 target condition difference between groups was largely independent of N2 target condition amplitude. N2 amplitude did not account for significant P3 variance (F(1, 132) = 1.84, p = 0.177), but adding N2 as a predictor reduced the P3 effect from borderline significance to a trend (i.e., from group accounting for 2.8% to its accounting for 1.8% of P3 amplitude variance). For the latency measures, analysis of covariance showed that P3b and N2b group latency effects disappeared when P3a latency was used as a covariate, while the P3a latency effect remained (although reduced from 9.8% to about 7.5–7.9 % of variance accounted for when P3b or N2a latency was used as a covariate).
