The University of British Columbia

Unlike synchronous brain computer interfaces (BCI), self-paced (asynchronous) ones have the advantage of being operational at all times and not only at specific system-defined periods. A 3-state self-paced BCI is capable of detecting two different brain states (e.g. two movements) from the ongoing EEG. However, a 2-state one can only detect one brain state from the ongoing EEG. This study evaluates the performance of a 3-state self-paced BCI in detecting right and left hand movements. At first, we compare the performance of the system in differentiating between right and left hand movements using two different inputs: (1) mono-polar, and (2) bipolar electrode setting. Using bipolar electrode setting which yielded better performance than a mono-polar one, we evaluate the overall performance of the 3-state BCI system in a self-paced testing paradigm. Using data collected from two able-bodied individuals, it is shown that the average performance (true positive rate) of the system in detecting the presence of movements is 54.7% at a fixed false positive rate of 1%, and the average performance of the system in differentiating between right and left hand movements is 70.25%.