3. Could Anyone Use a BCI?

Brain-computer interface (BCI) systems can provide communication and control for many users, but not all users. This problem exists across different BCI approaches; a “universal” BCI that works for everyone has never been developed. Instead, about 20% of subjects are not proficient with a typical BCI system. Some groups have called this phenomenon “BCI illiteracy”. Some possible solutions have been explored, such as improved signal processing, training, and new tasks or instructions. These approaches have not resulted in a BCI that works for all users, probably because a small minority of users cannot produce detectable patterns of brain activity necessary to a particular BCI approach. We also discuss an underappreciated solution: switching to a different BCI approach. While the term “BCI illiteracy” elicits interesting comparisons between BCIs and natural languages, many issues are unclear. For example, comparisons across different studies have been problematic since different groups use different performance thresholds, and do not account for key factors such as the number of trials or size of the BCI’s alphabet. We also discuss challenges inherent in establishing widely used terms, definitions, and measurement approaches to facilitate discussions and comparisons among different groups.