Fig. 8.

Spelling performance of participants T2 and T6 when using local field potential (LFP)-based FlashSpeller communication brain-computer interface (BCI). Dots on the left show participants’ spelling performance, as measured by correct characters per minute, as a function of decoder age when using same-day and historical decoders during copy-phrase blocks (yellow and blue dots, respectively) and when using historical decoder during free spelling with the word completion option (purple dots). Broken lines show the linear ordinary least squares fit over all sessions with P values for testing significant correlation between the spelling performance and the age of the historical decoder shown below the lines. Bars on the right side show the mean spelling performance over all sessions. Error bars show 95% confidence intervals. ns, Nonsignificant difference (P ≥ 0.05); *P < 0.05. CCPM, correct characters per minute.