An amplitude-modulated visual stimulation for reducing eye fatigue in SSVEP-based brain-computer interfaces.

Area of Science:

• Neuroscience
• Biomedical Engineering
• Human-Computer Interaction

Background:

• High-frequency steady-state visual evoked potential (SSVEP) has been proposed for brain-computer interfaces (BCIs) to minimize eye fatigue.
• However, high-frequency SSVEP often exhibits suboptimal performance, necessitating alternative stimuli.
• Amplitude-modulated SSVEP (AM-SSVEP) emerges as a potential solution to balance performance and user comfort.

Purpose of the Study:

• To investigate the efficacy of AM-SSVEP as a viable alternative for BCI applications.
• To evaluate the performance and user experience of AM-SSVEP compared to traditional SSVEP stimuli.

Main Methods:

• Generated AM-SSVEP stimuli by modulating a carrier frequency (fc > 40 Hz) with a modulating frequency (fm) in the alpha band (9-12 Hz).
• Conducted offline experiments with four targets using varying fm and fc, and online experiments with two additional targets.
• Analyzed harmonic components in the AM-SSVEP spectra and assessed accuracy and user-reported eye fatigue.

Main Results:

• Identified seven harmonic components in AM-SSVEP spectra, including 2fc, 2fm, fc±fm, fc±3fm, and 2fc-4fm.
• Online experiments demonstrated AM-SSVEP accuracy comparable to low-frequency SSVEP.
• Subjective evaluations revealed that AM-SSVEP stimuli induced significantly less eye fatigue and flicker sensation than low-frequency stimuli.

Conclusions:

• AM-SSVEP leverages high-frequency carrier waves for reduced eye fatigue while utilizing fundamental and harmonic frequencies for robust SSVEP recognition.
• This approach combines the high power of low-frequency SSVEPs with the low eye fatigue of high-frequency SSVEPs.
• AM-SSVEP is confirmed as a feasible and promising technology for practical BCI systems demanding both high performance and user comfort.