A former radio DJ is on trial for allegedly killing his girlfriend, and his psychologist says that his version of the story is probably true it was tested under hypnosis.
The case is taking place in South Africa, but it may surprise many people to know that the admissibility of testimony retrieved under hypnosis has been ruled on by the United States Supreme Court in the case of Rock vs. Arkansas (107 S.Ct. 2704).
Rock, who was charged with shooting her husband, sought to introduce testimony recalled in hypnosis. The trial court ruled, and the Arkansas Supreme Court affirmed, that the testimony was inadmissible because it was unreliable. The U.S. Supreme Court overturned the ruling, basically because a person has a right to testify on their own behalf, including testimony that is refreshed by hypnosis.
The opinion of the U.S. Supreme Court was that “Hypnosis by trained physicians or psychologists has been recognized as a valid therapeutic technique since 1958…” and “the procedure has been credited as instrumental in obtaining particular types of information.” However, the Court also recognized that “Hypnosis does not guarantee the accuracy of recall.” A person can lie or confabulate (i.e. fabricate false memory without being aware of it and without an intent to deceive) under hypnosis. Therefore, testimony retrieved in hypnosis is not “immune to the traditional means of evaluating credibility.” It is treated as any other testimony, “subject to verification by corroborating evidence and other traditional means of assessing accuracy.”
Forensic hypnosis can be valuable for victims and witnesses of crimes, and for the wrongly accused who may remember some detail that will help their case. However, I would be surprised to see a case where a criminal defendant incriminates himself or herself under hypnosis. A hypnotized person knows what they are saying while they speak, just as in non-hypnotic states, and the psychological principle of self-preservation is not eliminated for a person in hypnosis. Hypnosis can not make someone speak while in an unconscious state and with no control over what they say.