Cultic Studies Journal, Vol. 13, No. 1, 1996, page 33
temporarily reinstituted during hypnotic age regression illustrates the convincing nature of
memories recounted during hypnosis.
During the past 15 years, considerable research has been done on the effects of hypnosis
on memory. A number of such studies appeared in the 1980s and 1990s (e.g., Dywan &
Bowers, 1983 Spanos, Quigley, Gwynn, Glatt, &Perlini, 1991). Books, chapters, and review
articles appeared subsequently (e.g., Laurence &Perry, 1988 McConkey &Sheehan, 1995
Orne, Whitehouse, Dinges, &Carota Orne, 1988 Scheflin &Shapiro, 1989). This research
found that hypnosis causes heightened production of information. Much of the new material
gained in hypnosis, however, is incorrect. Hypnosis also produces an overall increase in
confidence about both correct and incorrect memories (cf. Sheehan, 1988). Subjects are
ordinarily more confident about their memory for correct rather than incorrect information
(for a recent review, see Sporer, Penrod, Read, &Cutler, 1995).
Because the hypnotic subject experiences increased confidence in both accurate and
inaccurate memories, the usual correlation between certainty and accuracy is abrogated,
making cross-examination more difficult (Sheehan, 1988). Further, the frequent inclusion of
confabulated, vivid detail in the new material makes hypnotically influenced memories more
credible (Dywan, 1995). Fantasies entirely unrelated to historical events may also be
suggested during hypnosis and remembered as veridical (Laurence, Nadon, Nogrady, &
Perry, 1986 Laurence &Perry, 1983). Finally, subjects are often unable to discriminate
accurately what they remembered of the original events before hypnosis, what material
they learned subsequently from other sources, and what additional material they
remembered during hypnosis (Orne, Whitehouse, Carota Orne, &Dinges, 1996).4
To some degree, these effects are independent of individual differences in response to
hypnosis. Hypnotizability, as measured by response to standardized inductions and
suggestions, is a stable personality trait. The test-retest reliability of the Stanford Scale of
Hypnotic Susceptibility, Form A, is approximately .70 when individuals, originally measured
when undergraduates at Stanford University, were measured again between 10 and 25
years later (Morgan, Johnson, &Hilgard, 1974 Piccione, Hilgard, &Zimbardo, 1989). These
results compare favorably with the test-retest reliability of other personality dimensions,
and are exceeded only by the full-scale stability of multitask measures of intelligence.
However, even those relatively insusceptible to hypnosis show increased productivity, error,
and confidence when hypnosis is used to influence memory (Carota Orne, Whitehouse,
Dinges, &Orne, 1996). The amount of change, however, is usually somewhat greater for
highly hypnotizable subjects than less hypnotizable subjects.
Examples of Modern Forensic Cases Leading to the Per Se Exclusion of
Hypnotically Influenced Testimony
The problems related to hypnosis are not limited to the laboratory. In numerous modern
cases, the problems attendant to hypnotically influenced recall have endangered the cause
of justice in both the criminal and civil arenas. As a result, many state courts have excluded
such testimony on a per se basis, either in its entirety or with specific exceptions. The
following brief review of three early cases may illustrate the reasons underlying the per se
exclusion rule.
People v. Kempinski (1980). An eyewitness identification of Michael Kempinski was made
by a man present at a stabbing death. Prior to hypnosis, the witness was unable to identify
either of the two assailants because he was sitting in a truck approximately 250 feet away,
it was night, and the lighting was poor. During hypnosis, the hypnotist told the witness he
could remember what he saw as if he were watching a videotape of the event on a mental
screen. He could increase or decrease its speed, reverse, stop, or zoom in on any part of his
videotape. After hypnosis, the witness indicated he recognized the assailant as a person he
knew, and identified Michael Kempinski from a photograph in a book of mug shots.
temporarily reinstituted during hypnotic age regression illustrates the convincing nature of
memories recounted during hypnosis.
During the past 15 years, considerable research has been done on the effects of hypnosis
on memory. A number of such studies appeared in the 1980s and 1990s (e.g., Dywan &
Bowers, 1983 Spanos, Quigley, Gwynn, Glatt, &Perlini, 1991). Books, chapters, and review
articles appeared subsequently (e.g., Laurence &Perry, 1988 McConkey &Sheehan, 1995
Orne, Whitehouse, Dinges, &Carota Orne, 1988 Scheflin &Shapiro, 1989). This research
found that hypnosis causes heightened production of information. Much of the new material
gained in hypnosis, however, is incorrect. Hypnosis also produces an overall increase in
confidence about both correct and incorrect memories (cf. Sheehan, 1988). Subjects are
ordinarily more confident about their memory for correct rather than incorrect information
(for a recent review, see Sporer, Penrod, Read, &Cutler, 1995).
Because the hypnotic subject experiences increased confidence in both accurate and
inaccurate memories, the usual correlation between certainty and accuracy is abrogated,
making cross-examination more difficult (Sheehan, 1988). Further, the frequent inclusion of
confabulated, vivid detail in the new material makes hypnotically influenced memories more
credible (Dywan, 1995). Fantasies entirely unrelated to historical events may also be
suggested during hypnosis and remembered as veridical (Laurence, Nadon, Nogrady, &
Perry, 1986 Laurence &Perry, 1983). Finally, subjects are often unable to discriminate
accurately what they remembered of the original events before hypnosis, what material
they learned subsequently from other sources, and what additional material they
remembered during hypnosis (Orne, Whitehouse, Carota Orne, &Dinges, 1996).4
To some degree, these effects are independent of individual differences in response to
hypnosis. Hypnotizability, as measured by response to standardized inductions and
suggestions, is a stable personality trait. The test-retest reliability of the Stanford Scale of
Hypnotic Susceptibility, Form A, is approximately .70 when individuals, originally measured
when undergraduates at Stanford University, were measured again between 10 and 25
years later (Morgan, Johnson, &Hilgard, 1974 Piccione, Hilgard, &Zimbardo, 1989). These
results compare favorably with the test-retest reliability of other personality dimensions,
and are exceeded only by the full-scale stability of multitask measures of intelligence.
However, even those relatively insusceptible to hypnosis show increased productivity, error,
and confidence when hypnosis is used to influence memory (Carota Orne, Whitehouse,
Dinges, &Orne, 1996). The amount of change, however, is usually somewhat greater for
highly hypnotizable subjects than less hypnotizable subjects.
Examples of Modern Forensic Cases Leading to the Per Se Exclusion of
Hypnotically Influenced Testimony
The problems related to hypnosis are not limited to the laboratory. In numerous modern
cases, the problems attendant to hypnotically influenced recall have endangered the cause
of justice in both the criminal and civil arenas. As a result, many state courts have excluded
such testimony on a per se basis, either in its entirety or with specific exceptions. The
following brief review of three early cases may illustrate the reasons underlying the per se
exclusion rule.
People v. Kempinski (1980). An eyewitness identification of Michael Kempinski was made
by a man present at a stabbing death. Prior to hypnosis, the witness was unable to identify
either of the two assailants because he was sitting in a truck approximately 250 feet away,
it was night, and the lighting was poor. During hypnosis, the hypnotist told the witness he
could remember what he saw as if he were watching a videotape of the event on a mental
screen. He could increase or decrease its speed, reverse, stop, or zoom in on any part of his
videotape. After hypnosis, the witness indicated he recognized the assailant as a person he
knew, and identified Michael Kempinski from a photograph in a book of mug shots.
