A high-speed brain speller using steady-state visual evoked potentials

Masaki Nakanishi, Yijun Wang, Yu Te Wang, Yasue Mitsukura, Tzyy Ping Jung

Research output: Contribution to journalArticle

135 Citations (Scopus)

Abstract

Implementing a complex spelling program using a steady-state visual evoked potential (SSVEP)-based brain-computer interface (BCI) remains a challenge due to difficulties in stimulus presentation and target identification. This study aims to explore the feasibility of mixed frequency and phase coding in building a high-speed SSVEP speller with a computer monitor. A frequency and phase approximation approach was developed to eliminate the limitation of the number of targets caused by the monitor refresh rate, resulting in a speller comprising 32 flickers specified by eight frequencies (8-15 Hz with a 1 Hz interval) and four phases (0°, 90°, 180°, and 270°). A multi-channel approach incorporating Canonical Correlation Analysis (CCA) and SSVEP training data was proposed for target identification. In a simulated online experiment, at a spelling rate of 40 characters per minute, the system obtained an averaged information transfer rate (ITR) of 166.91 bits/min across 13 subjects with a maximum individual ITR of 192.26 bits/min, the highest ITR ever reported in electroencephalogram (EEG)-based BCIs. The results of this study demonstrate great potential of a high-speed SSVEP-based BCI in real-life applications.

Original languageEnglish
Article number1450019
JournalInternational journal of neural systems
Volume24
Issue number6
DOIs
Publication statusPublished - 2014 Sep

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Keywords

  • Steady-state visual evoked potential
  • brain-computer interface
  • mixed frequency and phase coding
  • speller

ASJC Scopus subject areas

  • Computer Networks and Communications

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