Numerical estimation of the state of mind

The EEG is rich with information on electric brain activity but only a small part of it has been understood. The state of mind is manifested in spatial-temporal behavior of EEGs. The set of cross-correlation coefficients of EEGs collected with scalp electrodes forms a state vector. The emotional state under interest occupies its small subspace which is spanned by the four orthogonal elementary states referring to anger, sadness, joy, and relaxation. This method is called ESAM. This system is currently used for analyzing emotional responses to TV commercials, acoustic noise of automobiles, comfortableness of furniture, etc.