Poster: Characters vs. Words: Observations on Command Design for Brain-Computer Interfaces

Mohit Agarwal, Raghupathy Sivakumar

Abstract: Brain-computer interfaces (BCIs) allow users to communicate to a nearby computing device (computer, smartphone, etc.) using thoughts or other covert actions that result in a detectable change in brain-waves. Consider a BCI command to be a word consisting of a sequence of characters. Each character is a thought or action that can be reliably detected through brain waves. For this work, we specifically consider eye-blinks as the user action of interest. Eye-blinks are an interesting modality for BCI commands because of their easy detectability and naturalness (and hence covertness). It turns out that there is an interesting trade-off between the complexity of characters and the length of words. In this work, we perform a user-study to answer a simple, but important, question pertaining to eye-blinks based BCI command design: do users prefer shorter characters (and hence longer words) or shorter words (and hence longer characters) when performing commands?. We present a simple eye-blink language consisting of words and characters and use real user-experiments to study the aforementioned trade-off.