INTRODUCTION
For more than two centuries, the modality known today as hypnosis has been applied effectively to the treatment of a wide array of psychological and med-ical conditions that are described in other sections of this book and elsewhere (Rhue, Lynn, & Kirsch, 1993). These clinical uses are based on the many phenomena of hypnosis, especially hypermnesia, which refers to the increase in memory that can be elicited through hypnosis. It is this aspect of the modality that has been particularly helpful—and controversial—in the legal field, as well as in psychotherapy, where retrieval of repressed memories is an important treatment technique.
The term generally given to such application is forensic hypnosis, although investigative hypnosis has sometimes been used (Reiser, 1980).
Both descriptors refer to essentially the same process.
For more than a century, scientific investigators and clinicians have noted the potential for memory distortions associated with hypnosis. Moll, a noted nineteenth-century authority, commented that “Retroactive hallucinations are of great importance in law. They can be used to falsify testimony. People can be made to believe that they have witnessed certain scenes, or even crimes” (Moll 1889/1958, pp. 345–346). The pioneer hypnosis practitioner, Bernheim, observed, “I have shown how a false memory can cause false testi-mony given in good faith, and how examining magistrates can unwittingly cause false testimony by suggestion” (Bernheim, 1891/1980, p. 92). Similar findings have been observed by later legal commentators, as will be noted the following discussion.
The first documented application of hypnosis in the investigation of a crime in the United States was reported in 1945 when it was used to obtain information from a witness concerning a theft (Gravitz, 1983). Another
case was published in 1848 and involved an interview with a witness in a murder trial; the hypnotically obtained testimony was admitted by the court without any issue (Anonymous, 1948). But it was not until July 25, 1976, that a sensational case in California made headlines throughout the country and lent to forensic hypnosis a resurgence that has continued.
A busload of 26 school children and their adult driver was abducted off a country road by three masked men near the farming community of Chowchilla. The victims were then taken in several vans to a repositioned enclosure that had been partially buried in a quarry. The driver and two of the older boys eventually succeeded in digging their way out, and they made their way to the nearby highway where they contacted the author-ities. During the investigation that followed, the driver was hypnotized, as a result of which he was able to identify a license plate on one of the vans.
With the exception of one transposed digit, this number was matched to the vehicle of a man who, together with two accomplices, was subsequently convicted and sentenced to life imprisonment (Kroger & Douce, 1979). In my own experience, the correct retrieval of a license tag number is difficult to obtain, probably because such a combination of letters and numbers is usually non-meaningful information for all practical purposes; scientific research has amply demonstrated that meaningful stimuli are learned faster, retained better, and remembered in greater detail than that which is non-meaningful (Council of Scientific Affairs, 1985).
VARIETIES OF FORENSIC HYPNOSIS
There are a number of modern uses of hypnosis in the legal arena (Gravitz, 1980). Foremost of these is that it can be a helpful method to develop leads in police investigations by interviewing witnesses and victims of crime (Johnson, 1981; Shaw, 1991). The modality has also been employed in the enhance-ment of the memory of parties in civil actions (Hughes, 1991). While such use does not assume the truth, the whole truth, and nothing but the truth, important details about a case frequently can be recalled. Hypnosis is not a
“lie detector,” and in fact it is possible for a subject to dissemble. Another application is to lift the veil of amnesia and thereby to aid in the preparation of the defense of an accused whose recollections may be faulty, perhaps because of the repressive impact of trauma. Hypnosis can also be utilized as an aid in the evaluation of a person’s state of mind, specific intent, or mental condition (mens rea, in the legal sense), as for example, in the differentiation between malingering and the claim of multiple personality disorder. In every application, it should just be recognized that hypnosis is not necessarily com-plete or infallible, but then no psychological method is.
The forensic hypnotist may be called upon to perform other services.
As an expert in the field, he or she may be asked to comment on or testify about hypnosis interviews conducted by someone else. In this instance, a Hypnosis and Hypnotherapy 54
recording or typescript would be reviewed, or the expert could listen to testimony in court and then be examined on that.
Qualified forensic hypnotists may be asked to train law enforcement officers and other professionals in the criminal justice system in the proper utilization of the method. The training would not instruct in how to do hypnosis, since that would be inappropriate, but rather how to work effec-tively with the psychologist who performs the actual interview.
Another area of function is to advise others about the effects and the implications of hypnosis. As an example, a psychologist was asked by an attorney for an expert opinion on the possibility of harm being done to someone listening to a television advertisement by a political candidate who sought, as a public service, to hypnotize the audience to vote. The psychologist reviewed the relevant scientific findings that addressed the question and prepared a written statement, which the law firm then incor-porated in its defense of a television station that had been sued for declin-ing to sell air time for such purposes. The spurned candidate had accused the station of infringing on his right to speak on his own behalf, and the defendant’s defense was based on the possibility that a listener could expe-rience an undue or even harmful reaction for which the station could then be held liable. The responsible federal government regulatory agency upheld the defendant’s position. The candidate lost the election.
MEMORY AND HYPNOSIS
At this point, it will be useful to consider the mechanisms of memory and how hypnosis impacts them. While our modern understanding of these mechanisms is incomplete and not fully understood, there is a theoretical paradigm that provides a working frame of reference. This model assumes that an individual acquires and processes incoming information from vari-ous conscivari-ous and unconscivari-ous sensory sources, as well as certain prior experiences that have been stored in a bioelectrical memory bank. Based on the needs of the individual, there is then a rapid preliminary sorting of this information that results in short-term memory (STM). Some of these STMs are personally meaningful and are therefore retained (“coded”) in the form of a memory trace in long-term memory (LTM). But some of the incoming information is not coded as personally significant and is there-fore not retained—it is permanently forgotten and cannot ever be retrieved, either by hypnosis or other means. These experiences that are stored in LTM, however, may be retrieved by a variety of means including hypnosis, provided there has been no organic deterioration. Thus, memory is an active process of acquisition, retention, and retrieval. It is also a func-tion of the needs and condifunc-tion of the person at the time the original event occurred—this memory is state dependent. The latter may include mood, affect, stress, and biochemical factors, such as drugs and alcohol.
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In the process of recollection, there is a restructuring of the memory traces for LTM; therefore, memory is more or less naturally imperfect, and perfect reproduction cannot be assured. There may also be gaps in mem-ory, and these are subject to confabulation, which refers to the process whereby one fills in the gaps based on one’s needs and past experience.
Memory is not a photograph-like or film/tape recorder-like exactness, even though some who use hypnosis may erroneously claim that is so.
The enhancement of memory by hypnosis, then, may produce a melange of fact and fancy in proportions that cannot be determined or separated either by the subject or an observer. These recollections may have the force of truth for the subject, as well. Accordingly, hypnotically facilitated memories should be corroborated so independent verification may be obtained. While many police officers have been impressed by hyp-nosis because they have observed firsthand how useful it can be in certain cases, jurors tend to be skeptical (Greene, Wilson, & Loftus, 1989; Labelle, Lamarche, & Laurence, 1990).
Certain inaccuracies of memory that may occur in whole or in part, includ-ing non-hypnotic recollections that are found to be invalid, however, may lead in turn to the uncovering of new and valid information and evidence.
Since it has been observed that individuals are capable of simulating or faking hypnosis and of making willful false statements while hypnotized, care must be exercised in attesting that a subject is “in” hypnosis or not.
While some in the field question the very existence of hypnosis as an altered state, others seem to consider virtually any human behavior as evi-dence of the condition (Lynn & Rhue, 1991). A more reasoned approach was offered by a study panel convened by the American Medical Associa-tion (Council for Scientific Affairs, 1985), which concluded that hypnosis
“can be recognized by administering a series of different test suggestions of varying degrees of known difficulty, typically involving alterations of per-ception, motor control, or memory. The degree to which these suggestions were followed and experienced as real and involuntary indicates the extent to which hypnosis has taken place” (p. 1919). Accordingly, in forensic cases it is important to consider any information that may be developed as a lead, which must then be subject to further investigation. In this regard, the forensic hypnotist is not an appropriate investigative officer.
Labelle, Lamarche, and Laurence (1990) and others have found that hypnotized witnesses display greater confidence in the validity of their rec-ollections than do control subjects, regardless of accuracy; and the effect of confidence is greater in highly hypnotizable persons. Since not all research has disclosed a difference between normal and hypnotized subjects in their level of confidence, it appears that this effect is a potential and into a per se accompaniment of hypnosis.
Complicating the acceptance of hypnotically obtained reports as valid is the fact that confabulation appears to be a normal component of human Hypnosis and Hypnotherapy 56
memory. The hypnotized subject may incorporate these confabulated recollections as part of his or her memory and then tend to accept such recollections with confidence and as the truth. Even when such memories are in fact false, hypnosis may produce a greater degree of confidence or belief that they are real (Dywan & Bowers, 1983).
LABORATORY EXPERIMENTS
There are a number of laboratory investigations that have been designed to study the nature and effectiveness of hypnotically influenced memory. These have been reviewed by Pettinati (1988) and Smith (1983).
In general, these research studies have been based on contrived, analogue methodologies using uninvolved laboratory volunteer subjects and not real-life events and people who were personally involved, as in a crime.
The laboratory experiments have tended to show limited and even nega-tive results from the use of hypnosis.
REAL-LIFE STUDIES
There is a relative paucity of published reports of hypnotic efficacy based on real-life cases, which may be explained in part by the fact that practi-tioners as a group do not publish their clinical findings as frequently as do their academic colleagues. Even so, a number of such reports are available.
In a review of experiences in the Los Angeles Police Department, Reiser (1980) reported more than 90 percent verification of the additional infor-mation obtained by hypnosis. In one sample of 67 interviews, new investi-gative leads were obtained in 78 percent of these cases, and the solutions of 16 percent of these cases were directly attributable to the hypnosis. In another series of 348 cases, 79 percent yielded additional information not previously known.
In further comment on the hypnosis program in the Los Angeles Police Department, Reiser and Nielson (1980) revealed that in some 374 interviews, 92 percent of subjects reached a light to deep hypnotic depth; 85 percent improved recollections from a slight to significant degree; and 80 percent produced additional information with hypnosis, two-thirds of which was con-sidered important to the case. Where corroboration was possible, 91 percent was found to be accurate and seven percent was determined to be inaccurate.
Hypnosis was considered a significant factor in the resolution of 65 percent of these cases. Another finding was that no subject experienced ill effects from the interview, while 40 percent felt emotional relief or benefit. Similar psychological benefit is frequently reported by others.
Yuille and Kim (1987) reported results of a Canadian study of 41 cases.
Hypnotic interviews nearly tripled the amount of total information obtained, and every subject displayed an increase. Accuracy was found in
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82 percent of the recollections. They also noted that 80 percent “Of the information provided in the initial (i.e., nonhypnotic) interviews was repeated in the hypnotic interviews. This repeated information constituted only 32.1 percent of the facts recalled under hypnosis, which means that 67.9 percent of the facts from the hypnosis interview were new. Of the in-formation that was comparable between the two interviews, 94.1 percent was consistent” (p. 424).
Kleinhauz, Horowitz, and Tobin (1977) described a series of Israeli police cases in which hypnosis was instrumental in increasing recollections in 24 of 40 instances. Sixteen of these 24 cases were further studied to ascertain the accuracy of the memories, and of these, 14 showed a signifi-cant increase.
In a symposium presentation at the 1992 annual meeting of the Society for Clinical and Experimental Hypnosis, Gravitz, Ault, Gelles, and Hibler (1992) reported on efficacy outcomes in investigative hypnosis interviews conducted by several law enforcement agencies. Successful results were found in 10–75 percent of the cases.
It is evident that hypnotic interviews in real-life cases can be a useful technique in assisting the resolution of police cases that, typically, were at a dead end in their investigation.
LEGAL ISSUES
There are several principal areas of legal concern that pertain to the admissibility of hypnotically based testimony in a court of law (Worthington, 1979). These include the general acceptance by the scientific community involved that such evidence is reliable (the Frye Rule), the allegation that the use of hypnosis denies an accused the constitutional right of confronta-tion and cross-examinaconfronta-tion, the possible denial of due process since the hyp-notized subject is said to be vulnerable to suggestion, and the legal theory that material evidence in the form of a memory “trace” may be either negli-gently or deliberately damaged or destroyed. While the first of these concerns is the one that is most often raised, the others could be introduced, and the expert witness must be prepared to confront them.
A number of landmark legal decisions have shaped developments in the field (Worthington, 1979). If a court rules that the testimony of a witness who has been hypnotized was not admissible, then judicial and law enforcement authorities understandably would be averse to utilizing the method, as that could then prevent victims and witnesses from testifying and could thereby negatively impact their case. While various courts over the past hundred years have ruled for and against hypnosis, there has been a mitigating trend especially over the past quarter century toward greater acceptance, since the California Supreme Court in People v. Ebanks (1897) ruled that all testimony by a hypnotist was excludable because “the law of Hypnosis and Hypnotherapy 58
the United States does not recognize hypnotism” (p. 1053) in the matter of a defendant who, while hypnotized, had denied his guilt. Following that early decision, there have been a series of cases that either supported or were critical of the use of hypnosis in assisting recollection. In Leyra v.
Denno (1954), confessions obtained by hypnosis were rejected on the grounds that such statements were per se involuntarily given, a belief con-sistent with the contemporary understanding of hypnosis. Likewise, the claim that hypnosis renders all statements true has also been consistently rejected (People vs. Blair, 1979). In People v. Quaglino (1977), a California trial court permitted and the Court of Appeals upheld a conviction for murder, in part because the defense had failed to object to the use of hyp-nosis. In State v. McQueen (1978), a North Carolina court held hypnotic testimony to be admissible and left it to the jury to determine the weight to be assigned to the evidence. In that decision, the court ruled that hyp-notically refreshed memory did not render the witness incompetent to testify regarding present recollections. Hypnotic regression as an uncover-ing technique was upheld in the civil case of Wyler v. Fairchild Hiller Corp.
(1974), although here too the court held that it was up to the jury to determine the credibility and reliability of the testimony.
In the Maryland case of Harding v. State (1968), the court permitted the testimony of a rape victim who had remembered important details fol-lowing hypnosis. The appeals court ruled that the admissibility of expert testimony is basically a matter for the hearing judge to determine, and it emphasized the importance of the professional credentials and expertise of the psychologist who had administered the hypnosis.
In State v. Jorgenson (1971), an Oregon court held that hypnosis of a prosecution witness was admissible provided that an adequate cross exami-nation was possible by the defense. In the civil suit of Kline v. Ford Motor Company (1975), an accident victim who had sustained head trauma and amnesia recalled in full the events leading up to the injury. Although the trial court excluded this testimony on the grounds that hypnosis per se made the subject incompetent to testify to the facts recalled after hypnosis, the appellate court found this ruling to be erroneous.
In Cornell v. Superior Court (1959), the court upheld the position that an accused’s rights to counsel included the right to be hypnotized in order to aid in the preparation of his defense, and the sheriff was ordered to provide appropriate facilities for the interview.
In a highly unusual case (State v. Nebb, 1962), a defendant testified while in hypnosis in the courtroom. As a result of the disclosures made in that testimony, the prosecution reduced the charges against him. In this instance, the court ruled that hypnotically obtained evidence would be excludable if it incriminated the witness.
In the landmark case of State v. Hurd (1981), the New Jersey Supreme Court recognized the risks of confabulation and suggestibility, but it sought
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to minimize or negate these problems by requiring procedural guidelines.
The facts in this important case were that the sole prosecution witness, who had been the victim of a knife attack during the night in her home, was “unable or unwilling” to identify her assailant. At the initiative of the
The facts in this important case were that the sole prosecution witness, who had been the victim of a knife attack during the night in her home, was “unable or unwilling” to identify her assailant. At the initiative of the