A stochastic control approach to optimally designing hierarchical flash sets in P300 communication prostheses.
The P300-based speller is a well-established brain-computer interface for communication. It displays a matrix of objects on the computer screen, flashes each object in sequence, and looks for a P300 response induced by flashing the desired object. Most existing P300 spellers uses a fixed set of flash objects. We demonstrate that performance can be significantly improved by sequential selections from a hierarchy of flash sets containing variable number of objects. Theoretically, the optimal hierarchy of flash sets--with respect to a given statistical language model--can be found by solving a stochastic control problem of low computational complexity. Experimentally, statistical analysis demonstrates that the average time per output character at 85% accuracy is reduced by over 50% using our variable-flash-set approach as compared to traditional fixed-flash-set spellers.
Department of Bioengineering, University of California-San Diego, La Jolla, CA 92093, USA. r5ma@ucsd.edu
Rui
R
Ma
Navid
N
Aghasadeghi
Julian
J
Jarzebowski
Timothy
T
Bretl
Todd P
TP
Coleman
D000293:Adolescent; D000328:Adult; D000465:Algorithms; D001921:Brain / Q000502:physiology*; D003627:Data Interpretation, Statistical; D018913:Event-Related Potentials, P300 / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D015233:Models, Statistical; D010775:Photic Stimulation; D015203:Reproducibility of Results; D012984:Software; D013269:Stochastic Processes; D014584:User-Computer Interface; D055815:Young Adult