Optimizing spatial properties of a new checkerboard-like visual stimulus for user-friendly SSVEP-based BCIs

Area of Science:

• Neuroscience
• Biomedical Engineering
• Human-Computer Interaction

Background:

• Low-frequency steady-state visual evoked potential (SSVEP) brain-computer interface (BCI) systems offer high performance but cause visual discomfort.
• High-frequency SSVEP-BCI systems reduce discomfort but typically exhibit lower performance.
• Optimizing visual stimuli is crucial for balancing BCI performance and user experience.

Purpose of the Study:

• To optimize spatial properties of checkerboard-like visual stimuli for high-performance and user-friendly SSVEP-BCI systems.
• To compare novel checkerboard-like stimuli with traditional flickering stimuli regarding BCI performance and user comfort.
• To investigate the impact of spatial frequency on flicker perception and SSVEP intensity for the new stimuli.

Main Methods:

• Designed two checkerboard-like stimuli with different spatial contrasts (black- and white-background).
• Compared these stimuli with traditional flickering stimuli in SSVEP-BCI systems.
• Evaluated user experience using subjective questionnaires and measured BCI performance metrics.

Main Results:

• The black-background checkerboard-like stimulus with optimized spatial frequency achieved performance comparable to flickering stimuli but with enhanced visual comfort.
• An online nine-target BCI system using these stimuli achieved high average information transfer rates (124.0 ± 2.3 bits/min at low frequency, 109.0 ± 20.4 bits/min at high frequency).

Conclusions:

• Optimized checkerboard-like visual stimuli offer superior system performance and user experience for SSVEP-BCI.
• These stimuli have the potential to significantly advance the practical applications of BCIs in communication and control.