Optimizing the proportion of stimulation area in a grid stimulus for user-friendly SSVEP-based BCIs

Area of Science:

• Neuroscience
• Biomedical Engineering
• Human-Computer Interaction

Background:

• Steady-state visual evoked potentials (SSVEPs) are vital for brain-computer interfaces (BCIs) but traditional high-contrast flicker stimulation can be uncomfortable.
• Improving user experience in SSVEP-based BCIs is essential for wider adoption and practical application.

Purpose of the Study:

• To develop and evaluate a novel grid stimulation paradigm for SSVEPs with reduced flicker perception.
• To identify optimal stimulation proportions and frequencies that balance BCI performance and user comfort.

Main Methods:

• Investigated SSVEPs evoked by grid stimuli with varying low stimulation proportions in offline experiments.
• Analyzed simulation performance in a four-class BCI task and collected user experience data.
• Selected optimal paradigms for implementation in online four-target BCI systems.

Main Results:

• Ultra-low stimulation proportions (e.g., 0.94%, 2.10%) effectively evoked strong SSVEP responses, particularly in the 3-5 Hz range.
• Optimal balance between performance and user experience was achieved with 0.94% and 2.10% proportions for 3-5 Hz stimuli.
• For higher frequencies up to 20 Hz, proportions of 2.10%, 3.75%, and 8.43% maintained benefits.

Conclusions:

• Novel grid stimulation paradigms with minimal stimulation area can significantly improve user experience in SSVEP-based BCIs.
• These findings pave the way for more comfortable and efficient BCI systems utilizing SSVEPs.
• The study provides specific, evidence-based recommendations for stimulation parameters in future BCI designs.