title: A novel hybrid BCI speller based on the incorporation of SSVEP into the P300 paradigm.
abstract: OBJECTIVE
  Although extensive studies have shown improvement in spelling accuracy, the conventional P300 speller often exhibits errors, which occur in almost the same row or column relative to the target. To address this issue, we propose a novel hybrid brain-computer interface (BCI) approach by incorporating the steady-state visual evoked potential (SSVEP) into the conventional P300 paradigm.
  
  
  METHODS
  We designed a periodic stimuli mechanism and superimposed it onto the P300 stimuli to increase the difference between the symbols in the same row or column. Furthermore, we integrated the random flashings and periodic flickers to simultaneously evoke the P300 and SSVEP, respectively. Finally, we developed a hybrid detection mechanism based on the P300 and SSVEP in which the target symbols are detected by the fusion of three-dimensional, time-frequency features.
  
  
  RESULTS
  The results obtained from 12 healthy subjects show that an online classification accuracy of 93.85% and information transfer rate of 56.44 bit/min were achieved using the proposed BCI speller in only a single trial. Specifically, 5 of the 12 subjects exhibited an information transfer rate of 63.56 bit/min with an accuracy of 100%.
  
  
  CONCLUSIONS
  The pilot studies suggested that the proposed BCI speller could achieve a better and more stable system performance compared with the conventional P300 speller, and it is promising for achieving quick spelling in stimulus-driven BCI applications.
authors: Department of Automatic Control, College of Mechatronics and Automation, National University of Defense Technology, 410073, Changsha, Hunan, People's Republic of China.
authors: Erwei
authors: E
authors: Yin
authors: Zongtan
authors: Z
authors: Zhou
authors: Jun
authors: J
authors: Jiang
authors: Fanglin
authors: F
authors: Chen
authors: Yadong
authors: Y
authors: Liu
authors: Dewen
authors: D
authors: Hu
mesh_terms: D000328:Adult; D000465:Algorithms; D062207:Brain-Computer Interfaces; D003143:Communication Devices for People with Disabilities; D003625:Data Collection; D004569:Electroencephalography; D004594:Electrophysiology; D018913:Event-Related Potentials, P300 / Q000502:physiology*; D005073:Evoked Potentials, Somatosensory / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D009862:Online Systems; D010775:Photic Stimulation; D011474:Prosthesis Design; D012815:Signal Processing, Computer-Assisted; D055815:Young Adult