How many people can use a BCI system?

Abstract

Most brain–computer interface (BCI) systems utilize one of three approaches: sensorimotor rhythms (SMRs), P300s, or steady-state visually evoked potentials (SSVEPs). Numerous groups have reported that these approaches do not provide effective communication for a small percentage of users. This phenomenon has been called BCI illiteracy, inefficiency, or other terms. This chapter reviews this challenge across the three major BCI approaches. We review studies with a large number of users to assess how many people can use each type of BCI and discuss new efforts that could bring BCIs to broader user groups. Improved signal processing and feedback could benefit SMR BCI users, the face-speller may help P300 BCI users, and limited training could help SSVEP BCI users. Nonvisual BCIs could also enable people who are minimally conscious to answer “yes” or “no” questions. While there remain some people who cannot use a BCI, progress is being made to extend BCI technology to broader groups.