Orne, M.T., & Dinges, D.F. Hypnosis, Forensic use of. In G. Adleman (Ed.), Encyclopedia of neuroscience, Vol. I . (2 vols.) Cambridge, MA: Birkhauser Boston, 1987. Pp. 510-511.

Hypnosis, Forensic Use of

Martin T. Orne and David F. Dinges

There is a widely held, erroneous belief that hypnosis will enhance the accuracy of memory, which is at the core of the forensic application of this technique. To appreciate how this view became widespread, it is useful to review the history of hypnosis to facilitate memory.

Before the turn of the century Sigmund Freud and Josef Breuer, working with hypnotized patients suffering from hysteria, encouraged them to remember the events surrounding the beginning of their symptoms. What they observed was that hypnotized patients would often experience intense emotions as they relived the psychic trauma. These experiences were typically accompanied by hypnotic memory reports that contained myriad details, such as facial expressions, a stain on a table, a tear in a tapestry, and so on. The intensity of affect and the detail in hypnotic memory reports were, and often still are, taken as evidence that the memory is veridical because only someone who was actually there could have manifested such intense feelings and been privy to the kind and number of details being reported. Further, Freud and Breuer observed that upon awakening from hypnosis those symptoms to which the memories were related subsided, and assumed that the clinical improvement provided support for the veridicality of the traumatic events remembered in hypnosis.

These observations led Freud to conclude that the etiology of hysteria involved the seduction of the female child by a male adult, usually the father. Shortly after enunciating this theory, however, Freud recognized that these compelling, hypnotically produced, apparent memories were, for the most part, of events that did not actually occur. Instead, the hypnotic memories were largely confabulation: representing fantasies, fears, hopes, and dreams, as well as some memories. Many of the memories, moreover, were condensed from different episodes that had occurred at very different times in childhood. From a clinical perspective, however, the "memories" were emotionally valid, despite the lack of historical accuracy, and reliving these "memories" led to symptomatic improvement. What is important psychotherapeutically is that the patient work through and deal with those emotionally-charged "memories" that he or she comes to feel have occurred, regardless of what had actually happened in the past.

The fantasy aspects of memory in hypnotic age regression are illustrated by the fact that most highly responsive subjects can be instructed to "regress" beyond birth to past lives. When this is done subjects will typically "relive" the life of someone in the 18th or 17th century, although they may choose even much earlier epochs. Similarly, it is possible to suggest that the subject is now in a future century. Under these circumstances hypnotic age progression can produce remarkably compelling fantasies about the world of the future, depending, of course, upon the subject's scientific sophistication and imagination.

Although Freud recognized the lack of historical accuracy of memories brought forth in hypnosis, this fact was not considered clinically important because of the therapeutic utility of working through the emotional content of the “memories.” Nonetheless, the phenomena of hypnotic age regression are compelling to the present-day observer for the same reasons that they originally convinced Freud at the turn of the century. It is not surprising, therefore, that despite extensive scientific data to the contrary some practitioners erroneously continue to accept the subject's intense emotions, apparent total recall, and clinical improvement as evidence for the accuracy of hypnotic recollections.

Since the mid-1950s, as hypnosis increasingly became accepted as a therapeutic modality for many medical and psychiatric conditions, there have been efforts to use it in law enforcement as a means of helping witnesses and victims recall what occurred. It is estimated that since 1970 well over 5,000 law



511 Hypnosis, Forensic Use of

enforcement officials have been trained in the induction of hypnosis in three- and four-day seminars. It would appear that hypnosis is being used with victims and witnesses to induce recall far more frequently than is generally recognized.

Although there are dramatic anecdotes about how hypnosis has helped solve cases, these are not matched by the results of careful research. Numerous scientific studies on the effect hypnosis has on memory have shown that there is no increased recall for meaningless material, such as numbers or nonsense syllables, to which individuals have been exposed prior to hypnosis. Nevertheless, anecdotal evidence for the efficacy of hypnosis to aid recall comes from reports that license plate numbers have been obtained using hypnosis. The most widely cited is a celebrated case of mass kidnapping, in which a license plate number was apparently remembered during hypnosis. In that case, however, the person claims to have recalled four of the license plate numbers prior to hypnosis, and two inure numbers during hypnosis, one of which was correct and the other incorrect.

Scientific studies of recognition memory--where an individual is asked to respond either yes or no to an item, or where the person is asked to choose one of several items, as in a police line-up--have not yielded evidence of an increase in accuracy by hypnosis. In fact, two major investigations have shown that line-up identification is either unimproved or under some circumstances severely denigrated by hypnosis.

Finally, experiments on the effects of hypnosis on free recall, where an individual tells in his or her own words what happened, have shown that hypnosis causes an increase in the amount of material reported by the person. but not an increase in the accuracy of that information. Rather, with hypnosis individuals recall some additional correct items, and many Inure incorrect items.

The effects of hypnosis on recollections do not just involve an increase in the amount of information reported. Hypnosis has also been found in memory studies to produce a decrease in accuracy without a decrease in confidence that the person places in the memories, or even more troublesome, an increase in the confidence without a concomitant increase in the accuracy of those memories.

Because the scientific data have consistently failed to demonstrate hypnotic enhancement of memory, the relevant scientific community has not endorsed the use of hypnosis for memory enhancement. Consequently, an increasing number of state supreme courts have ruled that memory "enhanced" or created during hypnosis should not be permitted to form the basis of testimony in court regardless of whether it is "independently" verified or not. For example, this view represents the official position of the American Medical Association. The only use of hypnosis that is endorsed by the American Medical Association for forensic application is during the investigative phase of a forensic case, when it may not matter whether an individual who comes up with a dozen new details in hypnosis is wrong on ten of them because the two he or she is correct about may help solve the case. Since the police often need to use leads provided by unreliable witnesses, there is little problem, as long as the law enforcement agencies clearly understand that hypnotic statements are less reliable than normal memory, and as long as the witness who has been hypnotized does not testify in court.

The use of hypnosis to help exonerate defendants is also fraught with difficulties. People can lie during hypnosis, and even untrained individuals are capable of feigning hypnosis successfully. Feigned hypnosis is extremely difficult to detect even for highly experienced hypnotists. Nonetheless, the risks here are not quite as great since judge or jury are likely to take the defendant's hypnotic statements with some reservation, recognizing that they may well be self-serving. It is helpful if, as the American Medical Association's policy requires, the hypnotist makes explicit that hypnosis does not make statements more reliable or trustworthy, and no expert on hypnosis is capable of determining the differences between correct statements and incorrect statements.

Hypnosis has many fascinating and useful applications, but extensive research indicates that reliable enhancement of accurate memory is not among them.

See also Hypnosis: Memory Consolidation

Further reading

American Medical Association (1985): Policy statement on hypnotically enhanced memory. JAMA 253:1918-1923

Udolf R (1983): Forensic Hypnosis: Psychological and Legal Aspects. Lexington. Mass: Lexington Books

Orne MT, Soskis DA, Dinges DF, Ome EC (1984): Hypnotically induced testimony. In: Eyewitness Testimony: Psychological Perspectives. Wells GL, Loftus EF, eds. New York: Cambridge University Press

Sanders GS, Simmons WL (1983): Use of hypnosis to enhance eyewitness accuracy: Does it work? J Appl Psychol 68:70-77

The preceding paper is a reproduction of the following entry (Orne, M. T., & Dinges, D. F. Hypnosis, Forensic use of. In G. Adelman (Ed.), Encyclopedia of neurosciene, Vol. I. (2 vols.) Cambridge, MA: Birkhauser Boston, 1987. Pp. 510-511.). Now an imprint of Springer-Verlag, it is reproduced here with the kind permission of Springer-Verlag.