Impact of stimulus presentation speed in a visual ERP-based BCI under RSVP

Rapid serial visual presentation (RSVP) is one of the most effective gaze-independent paradigms for event-related potential (ERP)-based brain-computer interfaces (BCIs), particularly for individuals with limited muscle and eye movement control. The speed of visual stimulus presentation is a critical factor influencing system performance and warrants thorough investigation. This study evaluates the impact of different stimulus presentation speeds on the performance of an ERP-BCI used for pictogram selection under RSVP. Thirteen participants tested the ERP-BCI across three experimental conditions, each with a different stimulus onset asynchrony (SOA): 80 ms (C080), 160 ms (C160), and 320 ms (C320). In addition to performance metrics such as accuracy, information transfer rate (ITR), and pictograms per minute (PPM), a subjective evaluation of the user experience was conducted for each condition. The results indicate that C160 outperformed both C080 and C320 across all performance metrics, achieving an ITR of 26.49 bit/min (81.28% accuracy in 4.8 s). Subjective evaluations also revealed a preference for C160 and C320 over C080. Therefore, among the SOAs evaluated, 160 ms appears to be the most suitable for enhancing system usability. These findings underscore the crucial role of stimulus presentation speed in the usability of ERP-BCIs for pictogram selection under RSVP, emphasizing its importance in future gaze-independent ERP-BCI designs for communication purposes.