Group-level statistics were performed using ANOVAs. Data from each subject were taken from a 100-ms, 4-Hz window surrounding the condition-averaged peak time–frequency point. This provides a compromise between a subject-specific data-driven approach (each subject retains his or her unique time–frequency maxima) while addressing the large multiple comparison problem (there are 155,520 time–frequency–space pixels that could possibly be tested). In order to facilitate visualization of spatial topographies, t-tests at each electrode were performed and electrodes with non-significant results at an uncorrected two-tailed p < 0.01 were set to zero (green color). Similarly, black contour lines on the time–frequency plots indicate continuous significance at two-tailed p < 0.01, with a minimum of 300 ms and three frequency bands.
