Analysis of evoked EEG patterns from controlled cognitive states

This study was undertaken to establish relationships between the electroencephalogram (EEG) and cognitive states evoked by visual stimuli. Stimulus effects were depicted by spectral power differences, on a relative and absolute basis, for five EEG frequency bands using FFT-based analysis. In order to extract information hidden in the EEG data, power difference results were summarized and classified according to data processing technique, electrode site, subject, stimulus, data window, and frequency band. Results demonstrated that each subject displayed reproducible EEG signatures for some stimuli, despite the fact that subjects were not allowed to practice and were not given any feedback on the kinds of signatures their brains were generating.<>