Alpha topographies were consistent across the three groups, but nonresponders showed substantially less alpha than responders and controls, particularly in the eyes-closed condition. The smaller condition-dependent alpha in nonresponders is illustrated in Figure 2A, and this group difference was supported by a significant Condition × Group interaction, F[2, 75] = 3.56, p = .033. No additional Group effects attained significance, and there were no significant Gender interactions.3 An Age (covariate) effect (F[1,75] = 12.0, p = .001; corresponding Pearson r = −.41, p < .001 for grand mean) indicating alpha decreases with age, and a Condition × Age interaction (F[1, 75] = 10.9, p = .001; corresponding Pearson r = −.38, p < .001 for mean closed-minus-open difference) were also observed, but they did not interact with Group. Aside from the defining Condition effect (F[1, 75] = 36.4, p < .001 cf. Fig. 1), there were no additional significant effects.
