title: A multimenu system based on the P300 component as a time saving procedure for communication with a brain-computer interface.
abstract: The present study investigates a Brain-Computer Interface (BCI) spelling procedure based on the P300 evoked potential. It uses a small matrix of words arranged in a tree-shaped organization ("multimenu"), and allows the user to build phrases one word at a time, instead of letter by letter. Experiments were performed in two sessions on a group of seven healthy volunteers. In the former, the "multimenu" was tested with a total of 60 choices: 30 "externally-imposed" selections and 30 "free-choice" selections. In the latter, 3 × 3 matrices were compared with 6 × 6 matrices. Each matrix was composed of letters or words, for a total of four matrices. Differences in classifier accuracy, bit rate and amplitude of the evoked P300 were evaluated. Average accuracy in all subjects was 87% with no differences between the selection methods. The 3 × 3 "multimenu" obtained the same level of classifier accuracy as the 6 × 6 matrices, even with a significantly lower amplitude of the P300. Bit rate was increased when using the 3 × 3 matrices compared to the 6 × 6 ones. The "multimenu" system was equally effective, but faster than conventional, letter-based matrices. By improving the speed of communication, this method can be of help to patients with severe difficulties in communication.
authors.affiliation: Department of Life Sciences, B.R.A.I.N. Center for Neuroscience, University of Trieste Trieste, Italy.
authors.forename: Joanna
authors.initials: J
authors.lastname: Jarmolowska
authors.forename: Marcello M
authors.initials: MM
authors.lastname: Turconi
authors.forename: Pierpaolo
authors.initials: P
authors.lastname: Busan
authors.forename: Jie
authors.initials: J
authors.lastname: Mei
authors.forename: Piero P
authors.initials: PP
authors.lastname: Battaglini
keywords: P300; brain-computer interface; electroencephalography; semantic organization; spelling