Fig 6. Predicted individual preferred tACS phases in the pretarget tACS condition from EEG data measured in the entrained time window at sensor F3.

(A) Step 1: For each participant i, data from all remaining participants were used to estimate the average difference between φ_tACS and φ_EEGvsSound. (B) Step 2: φ_EEGvsSound was determined for participant i. (C) Step 3: This φ_EEGvsSound was shifted by the phase difference obtained in step 1, yielding the predicted φ_tACS for participant i. (D) Step 4: The predicted φ_tACS was used to estimate the tACS phase lag with highest perceptual accuracy for participant i, and the corresponding behavioural data were shifted so that highest accuracy was located at a centre phase bin. Prior to this step, the behavioural data measured at the 6 different phase lags were interpolated to enable realignment with higher precision. (E) Step 5: This procedure was repeated for all participants. (F) Step 6: The realigned data were averaged across participants (blue). For comparison, the procedure was repeated for the ongoing tACS condition (using EEG data from the same sensor; brown). The shaded areas show SEM, corrected for within-subject comparison. (G). Same as in (F), but aligned at the predicted worst phase for word report accuracy. Please refer to S1 Data for the numerical values underlying panels F and G. EEG, electroencephalography; SEM, standard error of mean; tACS, transcranial alternating current stimulation.