Chaotic features analysis of EEG signals during hallucination tasks of waterloo-stanford standard

Abstract

The present study looks carefully at EEG (Electroen-cephalograph) signals of people after the hypnosis inductions. Subjects were in three different categories of hypnotizability based on Waterloo-Stanford crite-ria; low, medium and high. Signals recorded during hallucination tasks of Waterloo-Stanford standard were applied to study the underlying dynamics of tasks and investigate the influence of hypnosis depth and concentration on recorded signals. To fulfill this objective, chaotic methods were employed; Higuchi dimension and correlation dimension. The results of the study indicate channels whose chaotic features are significantly different among people with various levels of hypnotizability. Moreover, a great consis-tency exists among channels involved in each task with brain's dominant hemisphere and brain lobes' functions. Another considerable result of the study was that the medium hypnotizable subjects were mostly affected by inductions and instructions of the hypnotizer (more than low or high hypnotizable sub-jects). The present study demonstrates a remarkable innovation in the analysis of hypnotic EEG; investi-gating the EEG signals of the hypnotized as doing hallucination tasks of Waterloo-Stanford standard orders.