This book provides a wide range of data about dissociated states such as fugue, multiple personality, amnesia, dreaming, hallucination, automatic writing and age regression. Hilgard examines these states as they present themselves in everyday life and as produced in the laboratory with the aid of hypnotic procedures. Based on his laboratory findings he proposes a reexamination of the classical theory of dissociation.

In experiments using hypnosis for pain reduction, Hilgard shows that two channels of information can be processed parallelly. The hypnotized person may feel no pain, but a concealed part of him registers and stores information about it which is then revealed by special techniques like automatic writing and automatic talking. Hilgard produces evidence to support his premise that this “hidden observer” represents a form of consciousness quite different from the conscious-unconscious model presented by Freud and Jung.