What conditions are necessary and sufficient to produce the behaviors which have been historically associated with the term "hypnosis"? I have approached this problem in recent reviews4-10 which focused on such "hypnotic phenomena" as "age-regression," "analgesia," "dreaming," "deafness," and "color-blindness." The present paper is concerned with an additional class of performances which can be elicited by suggestions given under hypnosis, namely, "posthypnotic amnesia" and "posthypnotic behavior." The discussion focuses on 2 questions:
1. Are suggestions given under "hypnosis" or "trance" more effective than suggestions given under nontrance conditions in produc ing amnesia for experimental events and in controlling "posthypnotic" or "postexperimental" behavior?
2. If such suggestions are more effective with "hypnotized" subjects, is this effect due to the presence of "the hypnotic trance" or is it produced by other factors in the experimental situation?
The Effectiveness of Posthypnotic Suggestions