An error-related potential based self-correcting brain-computer interface speller

Brain-computer Interface - Electroencephalography (EEG)


Brain-computer interfaces (BCIs) provide a viable alternative means of communication for persons with severe disabilities who may not have access to functional speech or gesture. BCIs based on electroencephalography (EEG) sense the electrical activity that arises from the brain via electrodes placed on top of the head. A visual BCI speller allows people to select characters of the alphabet sequentially, simply by focusing their visual attention on the desired character amidst an array of characters that are all displayed on a computer screen and illuminated rhythmically and in random order. While visual BCI spellers show great promise for providing individuals with severe disability with access to communication, they require improved speed and accuracy to be effective. To improve the speed and accuracy, we propose to detect the error-related potential (ErrP) that is elicited in participant's EEG signal when the BCI chooses the incorrect character and use this to adapt the BCI speller. We will improve accuracy by automatically correcting the erroneously selected character when ErrPs are detected. We will improve the speed, by adjusting the number of stimulus repetitions of character illumination required to choose each letter. In effect we are using the person's recognition of a BCI error to enable it to improve its accuracy.


Tom Chau, PhD, PEng


Participate in this study

Do you want to spell on a computer using your brainwaves? Consider participating in a research study about improving a communication device so that it can automatically correct its mistakes.

Who can participate

We are looking to recruit adults with the following profile:

  • Are 18-40 years of age
  • Have no motor disorder
  • Have normal or corrected to normal vision
  • Can read and write in English
  • Have no history of seizures or epilepsy
  • Have no health issues that include:  alcoholism, psychotic depression, obsessive compulsive disorder, schizophrenia

What's Involved

We measure brain activity and use it to operate a communication device, or ‘speller’, on a computer. We hope to improve this communication method so that it can correct its mistakes and be reliably used by individuals with no other means to communicate.

  • During each session a cap will be placed on your head. Conductive gel will be used at each sensor location. The gel can be washed out of your hair afterwards.
  • You will pay attention to randomly flashing letters by mentally counting how many times they flash.
  • Each session is about 2 hours long.
  • You will attend up to 4 sessions, over 1-6 weeks.
  • All sessions will be at Holland Bloorview at convenient times for you.
  • Participants will receive a $25 gift card at each session as a small token of appreciation to thank them for their time.


Recruitment will end March 31, 2015 or when enough participants have been enrolled.

Interested in participating

If you are interested in participating in this study or have additional questions, please contact Tim Zeyl at or (416) 425-6220 ex 3270 with your interest, and they will get back to your shortly.  Contacting us does not obligate you to participate in the study.

Learn more about this study