A multimenu system based on the P300 component as a time saving procedure for communication with a brain-computer interface

ThepresentstudyinvestigatesaBrain-ComputerInterface(BCI)spellingprocedurebasedontheP300evokedpotential.Itusesasmallmatrixofwordsarrangedinatree-shapedorganization(“multimenu”),andallowstheusertobuildphrasesonewordatatime,insteadofletterbyletter.Experimentswereperformedintwosessionsonagroupofsevenhealthyvolunteers.Intheformer,the“multimenu”wastestedwithatotalof60choices:30“externally-imposed”selectionsand30“free-choice”selections.Inthelatter,3×3matriceswerecomparedwith6×6matrices.Eachmatrixwascomposedoflettersorwords,foratotaloffourmatrices.Differencesinclassifieraccuracy,bitrateandamplitudeoftheevokedP300wereevaluated.Averageaccuracyinallsubjectswas87%withnodifferencesbetweentheselectionmethods.The3×3“multimenu”obtainedthesamelevelofclassifieraccuracyasthe6×6matrices,evenwithasignificantlyloweramplitudeoftheP300.Bitratewasincreasedwhenusingthe3×3matricescomparedtothe6×6ones.The“multimenu”systemwasequallyeffective,butfasterthanconventional,letter-basedmatrices.Byimprovingthespeedofcommunication,thismethodcanbeofhelptopatientswithseveredifficultiesincommunication.