A method for processing EEG signals includes reading the EEG signals from two frontal electrodes of an electroencephalograph (301)； converting the EEG signals to a frequency domain (305)； determining values of a BIS/BAS response on the basis of an asymmetry between the EEG signals (208). The method includes calculating the asymmetry between the EEG signals in the frequency domain in a frequency range from 26 to 29 Hz.
