Approximate entropy analysis on the electroencephalogram signal evoked by mental tasks

Approximate entropy of the electroencephalogram (EEG) signal recorded at five different mental tasks was calculated in this paper. The results indicate that the approximate entropy of EEG signal vary greatly when different mental tasks are implemented, which implies that the approximate entropy can be employed as a feature of EEG signal to distinct different mental tasks. For different subjects, the approximate entropy still vary greatly even the EEG signal are recorded from the same electrode under the same mental task, which implies that the subjects´ individual differences should be considered fully when the approximate entropy is employed to distinct different mental tasks.