Impact of mental focus on steady-state visually evoked potential under eyes closed condition for binary brain computer interface.

The steady-state visually evoked potential (SSVEP), is found to be affected by mental focusing on the stimuli under eyes closed condition. The amplitude d change of the SSVEP in concentrating on flicker stimuli was investigated for a novel brain computer interface (BCI) based on the SSVEP with eyes closed for severely disabilities who were not able to control their eye movement to use conventional SSVEP-based BCIs. The amplitude of the SSVEP in the posterior region was found to be reduced by more than 20 % in 10 out of 11 healthy adults when the subjects concentrated on the flicker stimuli under the conditions of flicker frequency of 10 Hz and stimulus intensity of 5 lx. Such an effect was observed in the occipital region under the condition of 14Hz and 5 lx. These results suggest the possibility of SSVEP-based binary BCI with eyes closed in terms of the mental focus.