Stimulator Selection in SSVEP-Based Spatial Selective Attention Study

Figure 2

Dual visual field stimulus paradigm by LED (Miaoqi Electronic, BQ-3401UGC, 505 nm~530 nm; 6000–8000 mcd). The four bars on each side showed the four possible color configurations for each bar. A red circle represented a red LED while the green one represented a green LED. Cue and fixation “+” were displayed by monitor. The distance between the monitor and subjects was 60 cm while the view angle was 5 degrees. Frequency and pattern of LED flicker were controlled by FPGA (CYCLONE IV E, EP4CE15F17C8N) and GRRRG pattern (R means red, G means green) was regarded as the target and subjects were required to push a button once it appears, in order to enhance their focus.