Overview of power spectra.

<p>The three panels show power spectra for the three participants for whom the BCI system worked most effectively. For participant P01 and P03, the system selected the <i>β</i>-feature and for participant P02 the <i>α</i>-feature. Here, all three users control the system by causing oscillatory power of the sensorimotor rhythms to decrease (event-related desynchronization, c.f. <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0101168#pone.0101168-Pfurtscheller1" target="_blank">[2]</a>).