How reliable are things remembered under hypnosis?
This has often arisen as both
a legal issue (as in the reliability of testimony obtained during or after
hypnotherapy) and also a social issue (regarding the use of hypnotherapy
to establish evidence of early child abuse, for example).
It is entirely true that subjects
under hypnosis frequently recall past forgotten events (or 'repressed'
memories in the jargon of psychoanalysis indicating an active role of
the individual in forgetting as a defense mechanism).
It is also true that people
under hypnosis often 'remember' things quite vividly that never actually
happened, but which have great personal significance nonetheless. Psychiatrist
William Sargent was one of the first to document the therapeutic benefit
of emotionally charged experience, or abreaction, of fantasized life events.
This is one of defining characteristics
of deep trance hypnosis in fact, the intensity of fantasies as well as
memories, and the inability to distinguish the two. This characteristic
of trance is what makes is possible to use hypnotherapy to alter personal
history in order to reduce the traumatic effects of past events on an individual's
functioning. Not simply a reliving or 'catharsis' of the trauma, but a
sometimes a lasting modification of the interpretation of the memory can
and does occur in many cases.
This apparent violability and
fallibility of human memory is frequently downplayed in discussions of
hypnotic recall because of the already difficult time that legitimate victims
of abuse have in proving what happened to them. It's not the intention
here to make life more difficult for abuse victims, only to point out that
hypnosis doesn't necessarily solve their problem of digging out facts
from old memories as neatly as we'd like it to.
The illusion of unusual veracity
of hypnotic recall appears to come from at least two main sources:
- Older models of human memory
as a simple recording and playback mechanism which preserved extreme
details of everything perceived, and which could be played back in an
enhanced way under certain conditions, like hypnosis.
- The vividness and subjective
meaningfulness often attributed to experiences under hypnosis partly
as a result of the unique characteristics of hypnotic imagery.
Recognizing the potential difficulties
arising from what some call 'false memory syndrome,' several states in
the U.S. now confine legal testimony to that obtained prior to any systematic
In 1985, a committee commissioned
by the American Medical Association cautioned against the systematic use
of hypnosis for recollection for both its unreliability (the possibility
for example of 'confabulation,' the creation of stories out of whole cloth
to help fill in missing memories) and its potential to create vivid false
memories with an artificially induced sense of certainty.
In addition to the previously
provided references for hypermnesia, here are some more specifically devoted
to the limitations of hypnotic recall:
- D. Spiegel et al, 1989,
"Hypnotic alteration of somato-sensory perception, "American Journal
- Loftus and Loftus, "On the
permanence of stored information in the human brain," American Psychologist",
35(5):409-420 (May,1980), critically evaluates the data gathered by neurologist
Wilder Penfield who had once believed he had discovered during the probing
of the brains of epileptic patients a 'sequential record of consciousness'
similar to the old tape-recorder model of human memory.
No one yet knows exactly how
human memory works in all its details, but the view of hypnotic recall
as potentially highly fallible is also supported by clinical experience
and experimental data.
Milton Erickson called the
vivid experiences under hypnosis 'vivification,' and describes how a vivified
image is experienced, regardless of whether remembered or constructed:
"... They are subjectively
experienced as external events rather than as internal processes, with
a consequent endowment of them as reality experiences."
"... They identified it with
actual past experiences and thus endowed it with a subjective validity."
"... They 'created a reality'
that permitted a responsive functioning in accord with the demands of
Are there identified physiological
correlates for such vivid recollections or re-creations of past events?
One controversial researcher, Michael Persinger, has written hundreds of
articles on the subject of neuro-physiological correlations of extraordinary
experiences of all kinds. He has reportedly reproduced something like ecstatic
mystical states with the help of electromagnetic stimulation of the cortical
temporal lobes of human subjects, and facilitated vivid imagery akin to
UFO abduction experiences. He is not alone in the observation of what is
sometimes known as 'clinical mysticism, 'which is seen in some forms of
temporal lobe epilepsy and in mechanical stimulation of areas of the temporal
lobes, but he is somewhat unique in his repeatedly published insistence
that all or virtually all unexplained phenomena and seemingly false memories
can be traced to electromagnetic effects on the brain. For an article particularly
pertinent to the issue of hypnotic recall, see:
- Persinger MA. Neuropsychological
profiles of adults who report "sudden remembering" of early childhood
memories: implications for claims of sex abuse and alien visitation/abduction
experiences. Perceptual & Motor Skills.75(1):259-66, 1992 Aug.
- "Six adults, who had recently
experienced sudden recall of preschool memories of sex abuse or alien
abduction/visitation, were given complete neuropsychological assessments.
All experiences "emerged" when hypnosis was utilized within a context
of sex abuse or New Age religion and were followed by reduction in anxiety.
As a group, these subjects displayed significant ([...] greater than 70)
elevations of childhood imaginings, complex partial epileptic-like signs,
and suggestibility. Neuropsychological data indicated right fronto-temporal
anomalies and reduced access to the right parietal lobe. MMPI profiles
were normal. The results support the hypothesis that enhanced imagery
due to temporal lobe lability within specific contexts can facilitate the
creation of memories; they are strengthened further if there is also reduction
in anxiety." (Taken from an on-line abstract).
If there is anything to this
'temporal lobe lability' hypothesis, it seems well worthwhile investigating
its relationship to hypnotic suggestibility, and the hypothetical 'Fantasy
Prone Personality' of Barber and Wilson.
As for recall under hypnosis,
the experimental observation seems to be that the subject is uniquely motivated
to remember details, but also uniquely capable of making up details and
experiencing them as if they were remembered.
In Lynn and Rhue's 1991 Theories
of Hypnosis, Robert Nadon et al. discuss a representative example of
experiments in eyewitness recall with the aid of hypnosis. Subjects were
shown a videotape of a mock armed robbery. They were then asked to recall
specific aspects 6 times:
- Twice immediately after
seeing the film.
- Twice a week after seeing
- Once during hypnosis.
- Once after hypnosis.
The result was that high hypnotizability
subjects (SHSS:C) recalled more cumulative items in hypnosis than they
did just before hypnosis. Low hypnotizability subjects did not remember
more during hypnosis. This matches our expectation of hypermnesia, that
hypnosis facilitates recall for good hypnotic subjects.
Most interestingly, both
high and low hypnotizability subjects also made more cumulative errors
during hypnosis than just before hypnosis, though the effect was stronger
with highly hypnotizable subjects.
One explanation of this kind
of result from experiments is that the hypnotic context causes subjects
to adopt a looser reporting criterion, and they are motivated to produce
more information, containing both correct and incorrect (where there is
no clear memory) details. See Klatzky and Erdely, 1985, "The response criterion
problem in tests of hypnosis and memory," International Journal of Clinical
and Experimental Hypnosis", 33, 246-257 for further discussion
of this report criterion issue.