Evaluation of the Bremen SSVEP based BCI in real world conditions

Abstract

A brain-computer interface (BCI) provides the possibility to translate brain neural activity patterns into control commands without user's movement. The brain activity is most commonly measured non-invasively via standard electroencephalography (EEG), i.e., with electrodes placed on the surface of the scalp. In this article, we evaluate a BCI system based on steady-state visual evoked potentials (SSVEPs) in real world conditions. Although the performance of this type of BCI has already been proved by several research groups with healthy users in laboratory settings assisted by scientific researchers, there are still many difficulties in changing from demonstration systems to practical BCIs. The Bremen-BCI was evaluated in this case study with 37 naive subjects (without any SSVEP-BCI experience), including 8 handicapped users, at the international rehabilitation fair RehaCare2008. In spite of unsuitable environment conditions on the fair, the spelling tasks were successfully completed by 32 participants with a mean accuracy of over 92% and an average information transfer rate (ITR) of 22.6[bits/min]. No significant dependency of the physical disability of participants on the ITR could be observed.