We calculated mean and standard deviations of accuracy and RTs for each memory and control block, and each subject and stimulation condition from data recorded before, during, and after the administration of HD-tACS, depending on the experiment. RTs deviating 2.5 standard deviations from the mean of each subject were defined as outliers and discarded. RT and accuracy results from the non-memory control block did not significantly differ from those of the memory block for either age group or stimulation condition (Experiment 1, RT ts41 < 0.683, ps > 0.498; accuracy, ts41 < 0.626, ps > 0.535; Experiment 2, RT ts27 < 0.321, ps > 0.750; accuracy ts27 < 0.641, ps > 0.527; Experiment 3, RT ts17 < 0.604, ps > 0.554; accuracy, ts17 < 1.141, ps > 0.270; Experiment 4, RT ts13 < 0.857, ps > 0.407; accuracy, ts13 < 1.392, ps > 0.187), confirming the success of the trial-by-trial dynamic adjustment procedure we used for matching difficulty level across blocks.
