On the linearity/non-linearity of mental activity EEG for brain-computer interface design

In this study, we investigated the linearity/nonlinearity of mental activity electroencephalogram (EEG) signals for Brain-Computer Interface (BCI) designs using the recent but well established Delay Vector Variance (DVV) method. EEG data recorded from seven subjects while they were performing five different mental activities were used in the experimental study. Through the use of DVV, it was investigated whether EEG signals would become linear or nonlinear when segmented into smaller parts. Concluding, the results of the studies showed that a large percentage of the EEG signals exhibited non-linear behaviour. This is an important result as it shows that the currently used linear modelling methods are mostly unsuitable.