Multiple color stimulus induced steady state visual evoked potentials

Steady state visual evoked potentials (SSVEP) are of the characteristics of high SNR and effectiveness in short-term identification of evoked responses. In most of the SSVEP experiments, single high frequency stimuli are used. To characterize the complex rhythms in SSVEP, a new multiple color stimulus pattern is proposed in this paper. FFT and bispectrum analysis methods are used to detect the phase coupling of the two stimulation frequencies in the recorded SSVEP. The results show that the rhythms at the duplation, sum or difference of the two-stimulation frequencies can be evoked by multiple color stimulus.