EEG Patterns and Hypnotizability 

By D. Corydon Hammond, PhD, ABPH, ECNS, QEEG-D

Department of Physical Medicine and Rehabilitation, University of Utah School of Medicine, Salt Lake City, UT


After reviewing the relationship of hypnotizability and EEG activity, a discussion follows of how modifying EEG activity may increase hypnotic responsiveness. This is followed by a brief summary of the relationship of hypnotizability to clinical symptoms. Relationship of Hypnotic Responsiveness and EEG Activity. There have been many studies on the relationship of brainwave activity and hypnotic responsiveness. We certainly do not have all the answers yet, but this is a fascinating body of literature. The situation is made even more complex by the fact that the brain’s activity differs in hypnosis depending on the nature of the suggestions (e.g., for pain relief, relaxation, hallucinations, etc.).

There is considerable evidence that greater theta brainwave activity is found in high hypnotizable individuals both in and out of hypnosis. Furthermore, low and high hypnotizable persons experience an increase in theta brainwaves when going into hypnosis. Crawford (1990), for example, reported that high hypnotizable persons exhibited significantly greater power in the higher theta range (5.5–7.5 Hz) than persons low
in hypnotic responsivity.

Schacter (1977) described two types of theta brainwaves: theta associated with feelings of drowsiness, and another type of theta brainwave associated with focused attention and involved in
complex problem solving (e.g., mental arithmetic). He believed that enhanced theta activity during problem solving represented “a combination of selective, narrowly focused processing, and intensive ‘mental effort’” (p. 59). This kind of theta has been interpreted as demonstrating strongly focused attention (e.g.,
Inouye, Ishihara, & Shinosaki, 1984, 1985; Mizuki, 1987; Mizuki, Tanaka, Isozaki, & Inanaga, 1976; Mizuki, Tanaka, Isozaki, Nishijima, & Inanaga, 1980), and we commonly define hypnosis as being a state of focused attention and concentration (Hammond, 1998).

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