Multi-target SSVEP-based BCI using Multichannel SSVEP Detection

Spatial filtering method and fast Fourier transform (FFT) based spectrum estimation method are applied to reveal the presence of steady state visual evoked potential (SSVEP) in multiple-electrodes electroencephalogram (EEG) signals used in Brain-Computer Interface (BCI) system. The SSVEP responses are elicited by visual stimuli in the form of flickering light emitting diode (LED) array and computer animation on the screen monitor. The essence of this method is to extract a narrowband frequency component of SSVEP in EEG. Subjects are instructed to shift their gaze during the trial to elicit multiple components of SSVEP spectrums. This approach which is called multi-target SSVEP is proposed to extend the feasibility of a BCI system. Using four subjects with two distinct stimuli, the experiment give a result of 41.6% accuracy for detecting dualfrequency combinations.