Figure 3.

Left: Grand average of feedback performance within each run (horizontal bars and dots for each group of 20 trials) for subjects of Cat. I (N = 6), Cat. II (N = 2) and Cat. III (N = 3). An accuracy of 70% is assumed to be a threshold required for BCI applications. Note that all runs of one subject have been recorded within one session. Right: For one subject of Cat. III, spectra in channel CP3 and scalp topographies of band-power differences (signed r²-values) between the motor imagery conditions are compared between the beginning (runs 1 + 2) and the end (runs 7 + 8) of the experiment.