A new dual-frequency stimulation method to increase the number of visual stimuli for multi-class SSVEP-based brain–computer interface

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Paper

Link: http://nec.kumoh.ac.kr/theme/community/Journal%20paper/10.pdf
Year: 2013

Summary

• as SSVEP frequencies are generally limited by the monitor, this method allow us to increase the number of visual stimuli when necessary
• ITR 33.26 bits/min, accuracy of 87.23%

Methods

• foveal test
• 10 subjects
• black–white checkerboard pattern
• distinct SSVEP responses at different frequencies could be generated by combining four different stimulation frequencies
• These four stimuli were identical to the traditional pattern-reversal checkerboard stimuli that elicit SSVEP peaks at 6 Hz, 6.66 Hz, 7.5 Hz, and 8.57 Hz, respectively. The other six stimuli were generated by combining two different frequencies, i.e., 3–3.33 Hz, 3–3.75 Hz, 3–4.285 Hz, 3.33–3.75 Hz, 3.33–4.285 Hz, and 3.75–4.285 Hz
• chose the four frequencies (3, 3.33, 3.75, and 4.285 Hz) in order to make the resultant SSVEP peaks appear at frequencies outside alpha and beta bands.

Results

Comments