title: Visual stimuli for the P300 brain-computer interface: a comparison of white/gray and green/blue flicker matrices.
abstract: OBJECTIVE
  The white/gray flicker matrix has been used as a visual stimulus for the so-called P300 brain-computer interface (BCI), but the white/gray flash stimuli might induce discomfort. In this study, we investigated the effectiveness of green/blue flicker matrices as visual stimuli.
  
  
  METHODS
  Ten able-bodied, non-trained subjects performed Alphabet Spelling (Japanese Alphabet: Hiragana) using an 8 x 10 matrix with three types of intensification/rest flicker combinations (L, luminance; C, chromatic; LC, luminance and chromatic); both online and offline performances were evaluated.
  
  
  RESULTS
  The accuracy rate under the online LC condition was 80.6%. Offline analysis showed that the LC condition was associated with significantly higher accuracy than was the L or C condition (Tukey-Kramer, p < 0.05). No significant difference was observed between L and C conditions.
  
  
  CONCLUSIONS
  The LC condition, which used the green/blue flicker matrix was associated with better performances in the P300 BCI.
  
  
  CONCLUSIONS
  The green/blue chromatic flicker matrix can be an efficient tool for practical BCI application.
authors: Cognitive Functions Section, DRSF, Research Institute of National Rehabilitation Center for Persons with Disabilities, Tokorozawa, Saitama, Japan.
authors: Kouji
authors: K
authors: Takano
authors: Tomoaki
authors: T
authors: Komatsu
authors: Naoki
authors: N
authors: Hata
authors: Yasoichi
authors: Y
authors: Nakajima
authors: Kenji
authors: K
authors: Kansaku
mesh_terms: D000328:Adult; D001931:Brain Mapping; D003118:Color Perception / Q000502:physiology*; D015350:Contrast Sensitivity / Q000502:physiology*; D004569:Electroencephalography; D018913:Event-Related Potentials, P300 / Q000502:physiology*; D005260:Female; D007839:Functional Laterality; D006801:Humans; D008297:Male; D008875:Middle Aged; D009862:Online Systems; D010775:Photic Stimulation / Q000379:methods*; D011930:Reaction Time / Q000502:physiology; D014584:User-Computer Interface; D014793:Visual Cortex / Q000502:physiology*