Abstract
Current brain-computer interface (BCIs) software is often tailored to the needs of scientists and technicians and therefore complex to allow for versatile use. To facilitate home use of BCIs a multifunctional P300 BCI with a graphical user interface intended for non-expert set-up and control was designed and implemented. The system includes applications for spelling, web access, entertainment, artistic expression and environmental control. In addition to new software, it also includes new hardware for the recording of electroencephalogram (EEG) signals. The EEG system consists of a small and wireless amplifier attached to a cap that can be equipped with gel-based or dry contact electrodes. The system was systematically evaluated with a healthy sample, and targeted end users of BCI technology, i.e., people with a varying degree of motor impairment tested the BCI in a series of individual case studies. Usability was assessed in terms of effectiveness, efficiency and satisfaction. Feedback of users was gathered with structured questionnaires. Two groups of healthy participants completed an experimental protocol with the gel-based and the dry contact electrodes (N = 10 each). The results demonstrated that all healthy participants gained control over the system and achieved satisfactory to high accuracies with both gel-based and dry electrodes (average error rates of 6 and 13%). Average satisfaction ratings were high, but certain aspects of the system such as the wearing comfort of the dry electrodes and design of the cap, and speed (in both groups) were criticized by some participants. Six potential end users tested the system during supervised sessions. The achieved accuracies varied greatly from no control to high control with accuracies comparable to that of healthy volunteers. Satisfaction ratings of the two end-users that gained control of the system were lower as compared to healthy participants. The advantages and disadvantages of the BCI and its applications are discussed and suggestions are presented for improvements to pave the way for user friendly BCIs intended to be used as assistive technology by persons with severe paralysis.
Highlights
Brain-computer interfaces (BCIs) based on event-related potentials (ERPs) are widely used in research settings (Kleih et al, 2011; Mak et al, 2011)
For the first time, we investigated whether the final BCI prototype can be operated with satisfactory and similar accuracies with both the gel-based and dry electrodes by healthy participants
We evaluated the final BCI prototype implemented within the project Backhome
Summary
Brain-computer interfaces (BCIs) based on event-related potentials (ERPs) are widely used in research settings (Kleih et al, 2011; Mak et al, 2011). Research confirms that the majority of healthy study participants were able to gain control over an ERP-BCI within the first session (Guger et al, 2009). The participants are asked to focus on the symbol that they wish to select and to silently count, whenever it is highlighted. This paradigm is a variant of the oddball paradigm in which the attended rare target stimulus elicits specific ERPs of which the P3 and the N2 are the most prominent in an ERP-BCI (Kaufmann et al, 2011a). Due to the differences in the elicited ERP waveforms for the attended compared to the unattended stimuli, the target symbol can be identified at the intersection of the row and column that contain the target symbol
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