Research on the Effect of Stimulus Areas on Steady-State Visual Evoked Potential

‍ ‍Brain-computer interface （BCI） systems based on steady-state visual evoked potential （SSVEP） preferred to use large-size stimuli to induce stronger electroencephalography（EEG） features， but the utilization of this kind of stimuli was likely to cause users unpreferred symptoms like fatigue， tension， or headache. These side effects limited the practical application of SSVEP-BCI. To solve this problem， the present study aimed at the influence of different stimulus areas（measured by angle sizes， ranging from 0.1° to 13°） on the SSVEPs with amplitude， signal-to-noise ratio， canonical correlation coefficient， and task-related coefficient as indicators. The results demonstrated that the SSVEPs initially enlarged as the angle sizes increase before reaching 3° and kept flat after that. It is concluded that the SSVEP-BCI can achieve the best performance when the angle sizes of stimuli are about 3°， considering system comfort and signal strength. This study provides a promising approach for optimizing the angle sizes of stimuli for SSVEP-BCI， which is significant in BCI development.