Hypnosis and evidence: help or hindrance?

Clarifying misconceptions about hypnosis can reduce confusion about the place of hypnosis in forensic medicine. Hypnosis identifies a person's capacity for attentive, receptive concentration with parallel awareness. While in trance concentration, memory recall under interrogation should not only be subject to all the usual investigative safeguards with checks and balances, but even more so because the leverage effect of hypnotically enhanced memory is achieved at the risk of contamination by external and/or internal cues. This Janus-like feature enables incredibly accurate revivification and recall of perceived events but can also evoke false memories, false confessions, and the "honest liar syndrome." The internal and external factors that account for these contradictory possibilities--and the appropriate safeguards--are considered with case illustrations. In addition, a new use of trance capacity assessment contributes to clarifying diagnosis and the mental defect/disease issue. Knowledge of the uses and limits of hypnosis by the interrogating professionals enhance the judicious process of eliciting information and evidence.