Discrimination of "Yes" and "No" Responses by Auditory Stimuli Multiple-choice Questions in Human EEG

Patients with severe physical disorders but who are cognitively intact find it difficult to communicate with the outside world. Researches on the brain-computer interface (BCI) are aimed to help such patients. This study analyzes the characteristics of brainwaves and classifies between "yes" and "no" responses when a subject thinks of a "yes" or "no" response to an auditory stimuli question. Experiment using auditory stimuli of the form of multiple-choice questions is performed. We discriminate between the activities of the brainwaves of the "yes" and "no" responses using the alpha power. Nineteen healthy subjects (7 females and 12 males), aged between 20 and 35 years, volunteered to participate in the experiments. In the experiment, for 17 out of 19 subjects (89.4%), the average alpha power for the "yes" response is greater than that for the "no" response. Also, Fisher\´s discriminant is performed to classify what the subject responses based on the average alpha power. 88.9% of original grouped cases (38 cases) and 83.3% of ungrouped cases (6 cases) are correctly classified.