Contribution of left and right hemispheres to classification success. (a) Point-biserial correlation coefficient contrasting spectral power for shifts to right versus left directions. The sgn r2 is peaking over the left hemisphere only. No differential effect is observed over the right hemisphere. (b) Peak classification accuracy when only left hemisphere electrodes, only right hemisphere electrodes, or both sets are used for classification. For illustrative purposes, data points belonging to the same electrode montage have been connected by lines. The graph suggests that left hemisphere electrodes yield a higher performance than right hemisphere electrodes.