In the delta frequency, significant interactions were observed for both TMT-A (right temporal region) and TMT-B (central region). Entering IAF as a covariate did not improve model fit. Specifically, for TMT-A in the right temporal region, AIC was 422.71 for the regression model including IAF and 422.71 for the reduced model (AIC difference < .01). For TMT-B in the central region, AIC was 547.47 for the full and 545.52 for the reduced model (AIC difference = 1.95). F-tests showed no significant contribution of IAF (TMT-A: F(1,48) = 1.84, p = .18; TMT-B: F(1,48) = 0.04, p = .84), therefore the simpler models were retained.
