Hypnosis is a social interaction in which one person suggests to another that certain perceptions, feelings, thoughts, or behaviors will spontaneously occur. The participant often experiences a narrowed focus of attention and an increased willingness to accept suggestions.

Susceptibility varies widely. Some people respond dramatically; others show little effect. Standardized scales measure the degree of responsiveness. Hypnosis can reduce pain, aid in the retrieval of memories (with the risk of confabulation), and help modify habits such as smoking. Brain-imaging studies show changes in activity consistent with the suggested experiences, yet the underlying mechanism remains debated. Dissociation theories propose a split in consciousness; social-cognitive theories emphasize role-playing and expectation.

Hypnosis is not a reliable method for recovering accurate lost memories, nor does it grant special powers. It is a collaborative process that depends on the participant’s imaginative involvement and trust in the situation. Used responsibly, it can be a useful clinical tool; used carelessly, it can create false beliefs.

Hypnosis alters the usual relationship between suggestion and experience. The extent of that alteration differs from person to person.