Working Paper Article Version 1 This version is not peer-reviewed

Simultaneous Decoding of Eccentricity and Direction Information for a Single-Flicker SSVEP BCI

Version 1 : Received: 14 October 2019 / Approved: 15 October 2019 / Online: 15 October 2019 (12:21:12 CEST)

How to cite: Chen, J.; Maye, A.; Engel, A.K.; Wang, Y.; Gao, X.; Zhang, D. Simultaneous Decoding of Eccentricity and Direction Information for a Single-Flicker SSVEP BCI. Preprints 2019, 2019100169 Chen, J.; Maye, A.; Engel, A.K.; Wang, Y.; Gao, X.; Zhang, D. Simultaneous Decoding of Eccentricity and Direction Information for a Single-Flicker SSVEP BCI. Preprints 2019, 2019100169

Abstract

The feasibility of a steady-state visual evoked potential (SSVEP) brain-computer interface (BCI) with a single flicker stimulus for multiple-target decoding has been demonstrated in a number of recent studies. The single-flicker BCIs have mainly employed the direction information for encoding the targets, i.e. different targets are placed at different spatial directions relative to the flicker stimulus. The present study explored whether visual eccentricity information can also be used to encode target for the purpose of increasing the number of targets in the single-flicker BCIs. A total number of 16 targets were encoded, placed at eight spatial directions, and two eccentricities (2.5° and 5°) relative to a 12 Hz flicker stimulus. Whereas distinct SSVEP topographies were elicited when participants gazed at targets of different directions, targets of different eccentricities were mainly represented by different signal-to-noise ratios (SNRs). Using a canonical correlation analysis-based classification algorithm, simultaneous decoding of both direction and eccentricity information was achieved, with an average offline 16-class accuracy of 66.8±16.4% averaged over 12 participants and a best individual accuracy of 90.0%. Our results demonstrate a single-flicker BCI with a substantially increased target number towards practical applications.

Subject Areas

steady-state visual evoked potential; brain-computer interface; direction; eccentricity; canonical correlation analysis

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