Figure 4. Main results.

A-C. Average word report accuracy (as Log Odd’s Ratio, LOR) as a function of the phase relation between tACS and speech rhythm. As required by the two applied statistical analyses (see Section Data Analyses and Fig. 3), individual data was aligned in different ways before being averaged across participants, shown in rows A-C. Bins used for alignment, by definition maximal or minimal, are shown as open circles. Shaded areas show standard error of mean (SEM) after between-participant variation has been removed as appropriate for repeated-measures comparisons of different phase bins (Cousineau, 2005). The pi/-pi bin is plotted twice for visualization purposes. D-I. Distribution of values (relevant phase bins are color-coded in A-C) which are compared to 0 to test for a phasic modulation (D,E), enhancement (F,G), or disruption (H,I) of speech perception, respectively. Dots show data from single participants, mean and confidence interval (1.96*SEM) are shown by red lines and red-colored areas, respectively. In all panels, right y-axes show LOR converted into changes in word report accuracy, given, on average, 50% correctly identified target words. Note that these changes are expressed relative to the Sham condition (A-C, F-I) or relate two phase bins in the Stim condition (D,E). In panel E, LOR difference values (d1-d2) and corresponding changes in accuracy were divided by two, to take into account the fact that this difference involves two comparisons of phase bins (d1, cf. panel B, and d2, cf. panel C). This was not necessary for the corresponding statistical test (see Section Data Analyses) which is unaffected by such scaling factors. Figure panels shaded grey correspond to those relevant for the pre-registered analysis.