Brain-computer interface controlled gaming: evaluation of usability by severely motor restricted end-users.
OBJECTIVE
Connect-Four, a new sensorimotor rhythm (SMR) based brain-computer interface (BCI) gaming application, was evaluated by four severely motor restricted end-users; two were in the locked-in state and had unreliable eye-movement.


METHODS
Following the user-centred approach, usability of the BCI prototype was evaluated in terms of effectiveness (accuracy), efficiency (information transfer rate (ITR) and subjective workload) and users' satisfaction.


RESULTS
Online performance varied strongly across users and sessions (median accuracy (%) of end-users: A=.65; B=.60; C=.47; D=.77). Our results thus yielded low to medium effectiveness in three end-users and high effectiveness in one end-user. Consequently, ITR was low (0.05-1.44bits/min). Only two end-users were able to play the game in free-mode. Total workload was moderate but varied strongly across sessions. Main sources of workload were mental and temporal demand. Furthermore, frustration contributed to the subjective workload of two end-users. Nevertheless, most end-users accepted the BCI application well and rated satisfaction medium to high. Sources for dissatisfaction were (1) electrode gel and cap, (2) low effectiveness, (3) time-consuming adjustment and (4) not easy-to-use BCI equipment. All four end-users indicated ease of use as being one of the most important aspect of BCI.


CONCLUSIONS
Effectiveness and efficiency are lower as compared to applications using the event-related potential as input channel. Nevertheless, the SMR-BCI application was satisfactorily accepted by the end-users and two of four could imagine using the BCI application in their daily life. Thus, despite moderate effectiveness and efficiency BCIs might be an option when controlling an application for entertainment.
Institute of Psychology, University of Würzburg, Marcusstr. 9-11, 97070 Würzburg, Germany. Electronic address: elisa.holz@uni-wuerzburg.de.
Elisa Mira
EM
Holz
Johannes
J
Höhne
Pit
P
Staiger-Sälzer
Michael
M
Tangermann
Andrea
A
Kübler
D062207:Brain-Computer Interfaces; D006801:Humans; D008875:Middle Aged; D010243:Paralysis / Q000503:physiopathology*; D017060:Patient Satisfaction; D012720:Severity of Illness Index
Assistive technology; Brain–computer interface; Evaluation; Sensorimotor rhythm; Usability; User-centred design