For TMT-A the overall model accounted for 38% of the variance (adjusted R2; F(3,49) = 11.73, p < .001). There was a significant interaction between Age × Power (Age × Power: β = −0.09, SE = 0.02, t = −3.27, p = .002; age: β = 0.31, SE = 0.09, t = 3.11, p = .003; power: β = −1.44, SE = 0.65, t = −2.22, p = .03). Figure 3b reveals a different pattern for different age groups: For older, but not younger participants, more power was associated with less completion time. For TMT-B, there was a significant interaction between delta power in central areas and age (adjusted R2 = .40, F(3,49) = 12.54, p < .001; interaction: β = −1.73, SE = 0.51, t = −3.38, p = .001; age: β = 1.18, SE = 0.33, t = 3.63, p < .001; power: β = −15.07, SE = 10.31, t = −1.46, p = .15). Figure 3c shows a negative association between power and completion time for older participants.
