Hypnosis is "a special psychological state with certain
physiological attributes, resembling sleep only superficially and marked
by a functioning of the individual at a level of awareness other than
the ordinary conscious state."[1]
According to "state theory", it is a
mental state, while, according to "non-state theory", it is
imaginative role-enactment.[2][3][4]
While under this state of mind, one's focus and concentration is
heightened. This individual is able to concentrate intensely on a
specific thought or memory, while blocking out all possible sources of
distraction.
[5]
Hypnosis is usually induced by a procedure known as a
hypnotic induction, which is commonly composed of a long series of
preliminary instructions and suggestions.[6]
Hypnotic suggestions may be delivered by a hypnotist in the presence of
the subject, or may be self-administered ("self-suggestion" or
"autosuggestion"). The use of hypnotism for therapeutic purposes is
referred to as "hypnotherapy",
while its use as a form of entertainment for an audience is known as "stage
hypnosis".
The term “hypnosis” comes from the Greek word hypnos which means
sleep. The words hypnosis and hypnotism both derive from
the term neuro-hypnotism (nervous sleep) coined by the Scottish
surgeon
James Braid around 1841. Braid based his practice on that developed
by
Franz Mesmer and his followers ("Mesmerism"
or "animal
magnetism"), but differed in his theory as to how the procedure
worked.
Contrary to a popular misconception—that hypnosis is a form of
unconsciousness resembling sleep—contemporary research suggests that
hypnotic subjects are fully awake and are focusing attention, with a
corresponding decrease in their peripheral awareness.[7]
Subjects also show an increased response to suggestions.[8]
In the first book on the subject, Neurypnology (1843), Braid
described "hypnotism" as a state of physical relaxation accompanied and
induced by mental concentration ("abstraction").[9]
In addition, psychiatric nurses in most medical facilities are allowed
to administer hypnosis to patients in order to relieve symptoms such as
anxiety, arousal, negative behaviors, uncontrollable behavior, and
improve self-esteem and confidence only when they have been completely
trained about their clinical side effects and while under supervision
when administering it.[10]
Characteristics
A subject under hypnosis experiences heightened suggestibility and
focus accompanied by a sense of tranquility.[11]
It could be said that hypnotic suggestion is explicitly intended to make
use of the placebo effect. For example, in 1994,
Irving Kirsch distinguished hypnosis as a "nondeceptive placebo," i.
e., a method that openly makes use of suggestion and employs methods to
amplify its effects.[12][13]
The hypnotized individual appears to heed only the communications
of the hypnotist. He seems to respond in an uncritical, automatic
fashion, ignoring all aspects of the environment other than those
pointed out to him by the hypnotist. He sees, feels, smells, and
otherwise perceives in accordance with the hypnotist's suggestions,
even though these suggestions may be in apparent contradiction to
the stimuli that impinge upon him. An example of this would be "your
eyes are slowly starting to close".
[14]
Even the subject's memory and awareness of self may be altered by
suggestion, and the effects of the suggestions may be extended
(posthypnotically) into the subject's subsequent waking activity. A
characteristic of hypnosis is that it possesses age-regression which
is it allows one to be in the conscious state of returning to a
specific age.
[15]
Definitions
The earliest definition of hypnosis was given by Braid, who coined
the term "hypnotism" as an abbreviation for "neuro-hypnotism", or
nervous sleep, which he opposed to normal sleep, and defined as:
"a peculiar condition of the nervous system, induced by a fixed and
abstracted attention of the mental and visual eye, on one object, not of
an exciting nature."[9]
Braid elaborated upon this brief definition in a later work:
[...] the real origin and essence of the hypnotic condition, is
the induction of a habit of abstraction or mental concentration,
in which, as in reverie or spontaneous abstraction, the powers
of the mind are so much engrossed with a single idea or train of
thought, as, for the nonce, to render the individual unconscious
of, or indifferently conscious to, all other ideas, impressions,
or trains of thought. The hypnotic sleep, therefore, is
the very antithesis or opposite mental and physical condition to
that which precedes and accompanies common sleep [...]
—Braid, Hypnotic Therapeutics, 1853
Therefore, Braid defined hypnotism as a state of mental concentration
that often leads to a form of progressive relaxation, termed "nervous
sleep". Later, in his The Physiology of Fascination (1855), Braid
conceded that his original terminology was misleading, and argued that
the term "hypnotism" or "nervous sleep" should be reserved for the
minority (10%) of subjects who exhibit
amnesia,
substituting the term "monoideism", meaning concentration upon a single
idea, as a description for the more alert state experienced by the
others.
A new definition of hypnosis, derived from academic psychology, was
provided in 2005, when the Society for Psychological Hypnosis, Division
30 of the
American Psychological Association (APA), published the following
formal definition:
New Definition: Hypnosis
The Division 30 Definition and Description of Hypnosis
Hypnosis typically involves an introduction to the procedure during
which the subject is told that suggestions for imaginative
experiences will be presented. The hypnotic induction is an extended
initial suggestion for using one's imagination, and may contain
further elaborations of the introduction. A hypnotic procedure is
used to encourage and evaluate responses to suggestions. When using
hypnosis, one person (the subject) is guided by another (the
hypnotist) to respond to suggestions for changes in subjective
experience, alterations in perception, sensation, emotion, thought
or behavior. Persons can also learn self-hypnosis, which is the act
of administering hypnotic procedures on one's own. If the subject
responds to hypnotic suggestions, it is generally inferred that
hypnosis has been induced. Many believe that hypnotic responses and
experiences are characteristic of a hypnotic state. While some think
that it is not necessary to use the word "hypnosis" as part of the
hypnotic induction, others view it as essential.[16]
Induction
Hypnosis is normally preceded by a "hypnotic induction" technique.
Traditionally, this was interpreted as a method of putting the subject
into a "hypnotic trance"; however, subsequent "nonstate" theorists have
viewed it differently, as a means of heightening client expectation,
defining their role, focusing attention, etc. There are an enormous
variety of different induction techniques used in hypnotism. However, by
far the most influential method was the original "eye-fixation"
technique of Braid, also known as "Braidism". Many variations of the
eye-fixation approach exist, including the induction used in the
Stanford Hypnotic Susceptibility Scale (SHSS), the most widely used
research tool in the field of hypnotism. Braid's original description of
his induction is as follows:
James Braid's Original Eye-Fixation Hypnotic Induction Method
Take any bright object (e.g. a lancet case) between the thumb and
fore and middle fingers of the left hand; hold it from about eight
to fifteen inches from the eyes, at such position above the forehead
as may be necessary to produce the greatest possible strain upon the
eyes and eyelids, and enable the patient to maintain a steady fixed
stare at the object.
The patient must be made to understand that he is to keep the eyes
steadily fixed on the object, and the mind riveted on the idea of
that one object. It will be observed, that owing to the consensual
adjustment of the eyes, the pupils will be at first contracted: They
will shortly begin to dilate, and, after they have done so to a
considerable extent, and have assumed a wavy motion, if the fore and
middle fingers of the right hand, extended and a little separated,
are carried from the object towards the eyes, most probably the
eyelids will close involuntarily, with a vibratory motion. If this
is not the case, or the patient allows the eyeballs to move, desire
him to begin anew, giving him to understand that he is to allow the
eyelids to close when the fingers are again carried towards the
eyes, but that the eyeballs must be kept fixed, in the same
position, and the mind riveted to the one idea of the object held
above the eyes. In general, it will be found, that the eyelids close
with a vibratory motion, or become spasmodically closed.[9]
Braid himself later acknowledged that the hypnotic induction
technique was not necessary in every case and subsequent researchers
have generally found that on average it contributes less than previously
expected to the effect of hypnotic suggestions (q.v., Barber, Spanos &
Chaves, 1974). Many variations and alternatives to the original hypnotic
induction techniques were subsequently developed. However, exactly 100
years after Braid introduced the method, another expert could still
state: "It can be safely stated that nine out of ten hypnotic techniques
call for reclining posture, muscular relaxation, and optical fixation
followed by eye closure."[17]
Suggestion
When
James Braid first described hypnotism, he did not use the term
"suggestion" but referred instead to the act of focusing the conscious
mind of the subject upon a single dominant idea. Braid's main
therapeutic strategy involved stimulating or reducing physiological
functioning in different regions of the body. In his later works,
however, Braid placed increasing emphasis upon the use of a variety of
different verbal and non-verbal forms of suggestion, including the use
of "waking suggestion" and self-hypnosis. Subsequently,
Hippolyte Bernheim shifted the emphasis from the physical state of
hypnosis on to the psychological process of verbal suggestion.
I define hypnotism as the induction of a peculiar psychical
[i.e., mental] condition which increases the susceptibility to
suggestion. Often, it is true, the [hypnotic] sleep that may be
induced facilitates suggestion, but it is not the necessary
preliminary. It is suggestion that rules hypnotism. (Hypnosis &
Suggestion, 1884: 15)
Bernheim's conception of the primacy of verbal suggestion in
hypnotism dominated the subject throughout the twentieth century,
leading some authorities to declare him the father of modern hypnotism
(Weitzenhoffer, 2000).
Contemporary hypnotism makes use of a wide variety of different forms
of suggestion including: direct verbal suggestions, "indirect" verbal
suggestions such as requests or insinuations, metaphors and other
rhetorical figures of speech, and non-verbal suggestion in the form of
mental imagery, voice tonality, and physical manipulation. A distinction
is commonly made between suggestions delivered "permissively" or in a
more "authoritarian" manner. As Harvard hypnotherapist Deirdre Barrett
describes in the book “Tales from a Hypnotherapist’s Couch”, most modern
research suggestions are designed to bring about immediate responses—an
arm rises immediately, whereas hypnotheraputic suggestions are usually
post-hypnotic ones that are intended to trigger responses affecting
behavior for periods ranging from days to a lifetime in duration. The
hypnotheraputic ones are often repeated in multiple sessions before they
achieve peak effectiveness.
Consciousness vs. unconscious mind
Some hypnotists conceive of suggestions as being a form of
communication directed primarily to the subject's conscious mind,
whereas others view suggestion as a means of communicating with the "unconscious"
or "subconscious"
mind. These concepts were introduced into hypnotism at the end of 19th
century by
Sigmund Freud and
Pierre Janet. The original Victorian pioneers of hypnotism,
including Braid and Bernheim, did not employ these concepts but
considered hypnotic suggestions to be addressed to the subject's
conscious mind. Indeed, Braid actually defines hypnotism as focused
(conscious) attention upon a dominant idea (or suggestion). Different
views regarding the nature of the mind have led to different conceptions
of suggestion. Hypnotists who believed that responses are mediated
primarily by an "unconscious mind", like
Milton Erickson, made more use of indirect suggestions, such as
metaphors or stories, whose intended meaning may be concealed from the
subject's conscious mind. The concept of
subliminal suggestion also depends upon this view of the mind. By
contrast, hypnotists who believed that responses to suggestion are
primarily mediated by the conscious mind, such as
Theodore Barber and
Nicholas Spanos tended to make more use of direct verbal suggestions
and instructions.
Ideo-dynamic
reflex
The first neuropsychological theory of hypnotic suggestion was
introduced early on by James Braid who adopted his friend and colleague
William Carpenter's theory of the
ideo-motor reflex response to account for the phenomenon of
hypnotism. Carpenter had observed from close examination of everyday
experience that under certain circumstances the mere idea of a muscular
movement could be sufficient to produce a reflexive, or automatic,
contraction or movement of the muscles involved, albeit in a very small
degree. Braid extended Carpenter's theory to encompass the observation
that a wide variety of bodily responses, other than muscular movement,
can be thus affected, e.g., the idea of sucking a lemon can
automatically stimulate salivation, a secretory response. Braid,
therefore, adopted the term "ideo-dynamic", meaning "by the power of an
idea" to explain a broad range of "psycho-physiological" (mind-body)
phenomena. Braid coined the term "mono-ideodynamic" to refer to the
theory that hypnotism operates by concentrating attention on a single
idea in order to amplify the ideo-dynamic reflex response. Variations of
the basic ideo-motor or ideo-dynamic theory of suggestion have continued
to hold considerable influence over subsequent theories of hypnosis,
including those of
Clark L. Hull,
Hans Eysenck, and
Ernest Rossi. It should be noted that in Victorian psychology, the
word "idea" encompasses any mental representation, e.g., including
mental imagery, or memories, etc.
Susceptibility
Braid made a rough distinction between different stages of hypnosis,
which he termed the first and second conscious stage of hypnotism;[citation
needed] he later replaced this with a distinction
between "sub-hypnotic", "full hypnotic", and "hypnotic coma" stages.[citation
needed]
Jean-Martin Charcot made a similar distinction between stages named
somnambulism, lethargy, and catalepsy. However,
Ambroise-Auguste Liébeault and Bernheim introduced more complex
hypnotic "depth" scales, based on a combination of behavioural,
physiological and subjective responses, some of which were due to direct
suggestion and some of which were not. In the first few decades of the
20th century, these early clinical "depth" scales were superseded by
more sophisticated "hypnotic susceptibility" scales based on
experimental research. The most influential were the Davis-Husband and
Friedlander-Sarbin scales developed in the 1930s.
Andre Weitzenhoffer and
Ernest R. Hilgard developed the Stanford Scale of Hypnotic
Susceptibility in 1959, consisting of 12 suggestion test items following
a standardised hypnotic eye-fixation induction script, and this has
become one of the most widely referenced research tools in the field of
hypnosis. Soon after, in 1962,
Ronald Shor and
Emily Carota Orne developed a similar group scale called the Harvard
Group Scale of Hypnotic Susceptibility (HGSHS).
Whereas the older "depth scales" tried to infer the level of
"hypnotic trance" based upon supposed observable signs, such as
spontaneous amnesia, most subsequent scales measure the degree of
observed or self-evaluated responsiveness to specific suggestion
tests, such as direct suggestions of arm rigidity (catalepsy). The
Stanford, Harvard, HIP, and most other susceptibility scales convert
numbers into an assessment of a person's susceptibility as 'high',
'medium', or 'low'. Approximately 80% of the population are medium, 10%
are high and 10% are low. There is some controversy as to whether this
is distributed on a “normal” bell-shaped curve or whether it is bi-modal
with a small “blip” of people at the high end.[18]
Hypnotizability Scores are highly stable over a person’s lifetime.
Research by
Deirdre Barrett has found that there are two distinct types of
highly susceptible subjects, which she terms fantasizers and
dissociaters. Fantasizers score high on absorption scales, find it easy
to block out real-world stimuli without hypnosis, spend much time
daydreaming, report imaginary companions as a child and grew up with
parents who encouraged imaginary play. Dissociaters often have a history
of childhood abuse or other trauma, learned to escape into numbness, and
to forget unpleasant events. Their association to “daydreaming” was
often going blank rather than vividly recalled fantasies. Both score
equally high on formal scales of hypnotic susceptibility.[19][20][21]
Individuals with
dissociative identity disorder have the highest hypnotizability of
any
clinical group, followed by those with
posttraumatic stress disorder.[22]
History
Precursors
According to his writings, Braid began to hear reports concerning
various Oriental
meditative practices soon after the release of his first publication
on hypnotism, Neurypnology (1843). He first discussed some of
these oriental practices in a series of articles entitled Magic,
Mesmerism, Hypnotism, etc., Historically & Physiologically Considered.
He drew analogies between his own practice of hypnotism and various
forms of Hindu yoga meditation and other ancient spiritual practices,
especially those involving
voluntary burial and apparent
human hibernation. Braid’s interest in these practices stems from
his studies of the
Dabistān-i Mazāhib, the “School of Religions”, an ancient
Persian text describing a wide variety of Oriental religious rituals,
beliefs, and practices.
Last May [1843], a gentleman residing in Edinburgh, personally
unknown to me, who had long resided in India, favored me with a
letter expressing his approbation of the views which I had published
on the nature and causes of hypnotic and mesmeric phenomena. In
corroboration of my views, he referred to what he had previously
witnessed in oriental regions, and recommended me to look into the
“Dabistan,” a book lately published, for additional proof to the
same effect. On much recommendation I immediately sent for a copy of
the “Dabistan”, in which I found many statements corroborative of
the fact, that the eastern saints are all self-hypnotisers, adopting
means essentially the same as those which I had recommended for
similar purposes.[23]
Although he rejected the transcendental/metaphysical interpretation
given to these phenomena outright, Braid accepted that these accounts of
Oriental practices supported his view that the effects of hypnotism
could be produced in solitude, without the presence of any other person
(as he had already proved to his own satisfaction with the experiments
he had conducted in November 1841); and he saw correlations between many
of the "metaphysical" Oriental practices and his own "rational"
neuro-hypnotism, and totally rejected all of the fluid theories and
magnetic practices of the mesmerists. As he later wrote:
In as much as patients can throw themselves into the nervous
sleep, and manifest all the usual phenomena of Mesmerism, through
their own unaided efforts, as I have so repeatedly proved by causing
them to maintain a steady fixed gaze at any point, concentrating
their whole mental energies on the idea of the object looked at; or
that the same may arise by the patient looking at the point of his
own finger, or as the Magi of Persia and Yogi of India have
practised for the last 2,400 years, for religious purposes, throwing
themselves into their ecstatic trances by each maintaining a steady
fixed gaze at the tip of his own nose; it is obvious that there is
no need for an exoteric influence to produce the phenomena of
Mesmerism. […] The great object in all these processes is to induce
a habit of abstraction or concentration of attention, in which the
subject is entirely absorbed with one idea, or train of ideas,
whilst he is unconscious of, or indifferently conscious to, every
other object, purpose, or action.[24]
Franz Mesmer
Franz Mesmer (1734–1815) believed that there is a magnetic force or
"fluid" within the universe that influences the health of the human
body. He experimented with magnets to influence this field and, so,
cause healing. By around 1774, he had concluded that the same effects
could be created by passing the hands, at a distance, in front of the
subject's body, referred to as making "Mesmeric passes." The word
mesmerize originates from the name of Franz Mesmer, and was
intentionally used to separate its users from the various "fluid" and
"magnetic" theories embedded within the label "magnetism".
In 1784, at the request of
King Louis XVI, a Board of Inquiry started to investigate whether
Animal Magnetism existed. Three of the board members include a
founding father of modern chemistry
Antoine Lavoisier,
Benjamin Franklin and an expert in pain control
Joseph-Ignace Guillotin. They investigated the practices of a
disaffected student of Mesmer, one Charles d'Eslon (1750–1786), and
despite the fact that they accepted that Mesmer's results were valid,
their
placebo-controlled experiments following d'Eslon's practices
convinced them that mesmerism was most likely due to belief and
imagination rather than to any sort of invisible energy ("animal
magnetism") transmitted from the body of the mesmerist.
In writing the majority opinion, Franklin said, "This fellow Mesmer
is not flowing anything from his hands that I can see. Therefore, this
mesmerism must be a fraud." Mesmer left Paris and went back to Vienna to
practise mesmerism.
James Braid
Following the French committee's findings, in his Elements of the
Philosophy of the Human Mind (1818),[25]
Dugald Stewart, an influential academic philosopher of the "Scottish
School of Common Sense", encouraged physicians to salvage elements
of Mesmerism by replacing the supernatural theory of "animal magnetism"
with a new interpretation based upon "common sense" laws of
physiology and
psychology. Braid quotes the following passage from Stewart:[26]
It appears to me, that the general conclusions established by
Mesmer’s practice, with respect to the physical effects of the
principle of imagination [...] are incomparably more curious than if
he had actually demonstrated the existence of his boasted science
[of "animal magnetism"]: nor can I see any good reason why a
physician, who admits the efficacy of the moral [i.e.,
psychological] agents employed by Mesmer, should, in the exercise of
his profession, scruple to copy whatever processes are necessary for
subjecting them to his command, any more than that he should
hesitate about employing a new physical agent, such as electricity
or galvanism.[25]
In Braid's day, the
Scottish School of Common Sense provided the dominant theories of
academic psychology and Braid refers to other philosophers within this
tradition throughout his writings. Braid therefore revised the theory
and practice of Mesmerism and developed his own method of "hypnotism" as
a more rational and "common sense" alternative.
It may here be requisite for me to explain, that by the term
Hypnotism, or Nervous Sleep, which frequently occurs in the
following pages, I mean a peculiar condition of the nervous system,
into which it may be thrown by artificial contrivance, and which
differs, in several respects, from common sleep or the waking
condition. I do not allege that this condition is induced through
the transmission of a magnetic or occult influence from my body into
that of my patients; nor do I profess, by my processes, to produce
the higher [i.e., supernatural] phenomena of the Mesmerists. My
pretensions are of a much more humble character, and are all
consistent with generally admitted principles in physiological and
psychological science. Hypnotism might therefore not inaptly be
designated, Rational Mesmerism, in contra-distinction to the
Transcendental Mesmerism of the Mesmerists.[27]
Despite briefly toying with the name "rational Mesmerism", Braid
ultimately emphasised his approach's uniqueness, carrying out informal
experiments throughout his career to refute the arguments invoking
supernatural practices, and demonstrate instead the role of ordinary
physiological and psychological processes such as suggestion and focused
attention in producing the observed effects.
Braid worked very closely with his friend and ally the eminent
physiologist Professor
William Benjamin Carpenter, an early neuro-psychologist, who
introduced the "ideo-motor reflex" theory of suggestion. Carpenter had
observed examples of expectation and imagination apparently influencing
involuntarily muscle movement. A classic example of the ideo-motor
principle in action is the so-called "Chevreul
pendulum" (named after
Michel Eugène Chevreul). Chevreul claimed that divinatory pendulae
were made to swing by unconscious muscle movements, brought about by
appropriate concentration alone.
Braid soon assimilated Carpenter's observations into his own theory,
realising that the effect of focusing attention was to enhance the
ideo-motor reflex response. Braid extended Carpenter's theory to
encompass the influence of the mind upon the body more generally, beyond
the muscular system, and therefore referred to the "ideo-dynamic"
response and coined the term "psycho-physiology" to refer to the study
of general mind/body interaction.
In his later works, Braid reserved the term "hypnotism" for cases in
which subjects entered a state of amnesia resembling sleep. For the
rest, he spoke of a "mono-ideodynamic" principle to emphasise that the
eye-fixation induction technique worked by narrowing the subject's
attention to a single idea or train of thought ("monoideism"), which
amplified the effect of the consequent "dominant idea" upon the
subject's body by means of the ideo-dynamic principle.
Hysteria vs.
suggestion
For several decades, Braid's work became more influential abroad than
in his own country, except for a handful of followers, most notably Dr.
John Milne Bramwell. The eminent neurologist Dr.
George Miller Beard took Braid's theories to America. Meanwhile his
works were translated into German by
Wilhelm T. Preyer, Professor of Physiology at
Jena University. The psychiatrist
Albert Moll subsequently continued German research, publishing
Hypnotism in 1889. France became the focal point for the study after
the eminent neurologist Dr.
Étienne Eugène Azam presented Braid's research to the French
Academy of Sciences. Azam also translated Braid's last manuscript (On
Hypnotism, 1860) into French. At the request of Azam,
Paul Broca, and others, the
French Academy of Science, who had examined Mesmerism in 1784,
examined Braid's writings shortly after his demise.
Azam's enthusiasm for hypnotism influenced
Ambroise-Auguste Liébeault, a country doctor.
Hippolyte Bernheim discovered Liébeault's enormously popular group
hypnotherapy clinic and subsequently became an influential hypnotist.
The study of hypnotism subsequently revolved around the fierce debate
between
Jean-Martin Charcot and
Hippolyte Bernheim, the two most influential figures in late
19th-century hypnotism.
Charcot operated a clinic at the
Pitié-Salpêtrière Hospital (thus, also known as the "Paris School"
or the "Salpêtrière School"), while Bernheim had a clinic in
Nancy (also known as the "Nancy
School"). Charcot, influenced more by the Mesmerists, argued that
hypnotism is an abnormal state of nervous functioning found only in
certain hysterical women. He claimed that it manifests in a series of
physical reactions that could be divided into distinct stages. Bernheim
argued that anyone could be hypnotised, that it is an extension of
normal psychological functioning, and that its effects are due to
suggestion. After decades of debate, Bernheim's view dominated.
Charcot's theory is now just a historical curiosity.
Pierre Janet
Pierre Janet (1859–1947) reported studies on a hypnotic subject in
1882. Charcot subsequently appointed him director of the psychological
laboratory at the
Salpêtrière in 1889, after Janet completed his doctorate in
philosophy, which dealt with psychological
automatism. In 1898, Janet was appointed psychology lecturer at the
Sorbonne, and in 1902 became chair of experimental and comparative
psychology at the
Collège de France. Janet reconciled elements of his views with those
of Bernheim and his followers, developing his own sophisticated hypnotic
psychotherapy based upon the concept of psychological
dissociation, which, at the turn of the century, rivaled Freud's
attempt to provide a more comprehensive theory of psychotherapy.
Sigmund Freud
Sigmund Freud, the founder of
psychoanalysis, studied hypnotism at Paris school and briefly
visited the Nancy school.
At first, Freud was an enthusiastic proponent of hypnotherapy, and
soon began to emphasise hypnotic regression and ab reaction (catharsis)
as therapeutic methods. He wrote a favorable encyclopedia article on
hypnotism, translated one of Bernheim's works into German, and published
an influential series of case studies with his colleague Joseph Breuer
entitled
Studies on Hysteria (1895). This became the founding text of the
subsequent tradition known as "hypno-analysis" or "regression
hypnotherapy."
However, Freud gradually abandoned hypnotism in favour of
psychoanalysis, emphasizing free association and interpretation of the
unconscious. Struggling with the great expense of time that
psychoanalysis required, Freud later suggested that it might be combined
with hypnotic suggestion to hasten the outcome of treatment,
It is very probable, too, that the application of our therapy to
numbers will compel us to alloy the pure gold of analysis
plentifully with the copper of direct [hypnotic] suggestion.[28]
However only a handful of Freud's followers were sufficiently
qualified in hypnosis to attempt the synthesis. Their work had a limited
influence on the hypno-therapeutic approaches now known variously as
"hypnotic regression", "hypnotic progression", and "hypnoanalysis".
Émile Coué
Émile Coué (1857–1926) assisted
Ambroise-Auguste Liébeault for around two years at Nancy. After
practicing for several years as a hypnotherapist employing the methods
of Liébeault and Bernheim's Nancy School, Coué developed a new
orientation called "conscious
autosuggestion." Several years after Liébeault's death in 1904, Coué
founded what became known as the New Nancy School, a loose collaboration
of practitioners who taught and promoted his views. Coué's method did
not emphasise "sleep" or deep relaxation and instead focused upon
autosuggestion involving a specific series of suggestion tests. Although
Coué argued that he was no longer using hypnosis, followers such as
Charles Baudouin viewed his approach as a form of light
self-hypnosis. Coué's method became a renowned
self-help and
psychotherapy technique, which contrasted with
psychoanalysis and prefigured self-hypnosis and
cognitive therapy.
Clark L. Hull
The next major development came from
behavioral psychology in American university research.
Clark L. Hull, an eminent American psychologist, published the first
major compilation of laboratory studies on hypnosis, Hypnosis &
Suggestibility (1933), in which he proved that hypnosis and sleep
had nothing in common. Hull published many quantitative findings from
hypnosis and suggestion experiments and encouraged research by
mainstream psychologists. Hull's behavioural psychology interpretation
of hypnosis, emphasizing conditioned reflexes, rivaled the Freudian
psycho dynamic interpretation emphasizing unconscious transference.
Dave Elman
Although
Dave Elman was a noted radio host, comedian and (song)writer, he
also made a name as a hypnotist. He led many courses for physicians and
wrote in 1964 the classic book: 'Findings in Hypnosis', later to be
re-titled 'Hypnotherapy' (published by Westwood Publishing). Perhaps the
most well known aspect of Elman's legacy is his method of induction,
which was originally fashioned for speed work and later adapted for the
use of medical professionals; his students routinely obtained states of
hypnosis adequate for medical and surgical procedures in under three
minutes. His book and recordings provide much more than just his rapid
induction techniques, however. The first heart operation using hypnosis
rather than normal anesthesia (because of severe problems with the
patient) was performed by his students with Dave Elman in the operating
room as "coach".
Milton Erickson
Milton H. Erickson, M.D. was one of the most influential post-war
hypnotherapists. He wrote several books and journal articles on the
subject. During the 1960s, Erickson popularized a new branch of
hypnotherapy, known as
Ericksonian hypnotherapy, characterised primarily by indirect
suggestion, "metaphor" (actually analogies), confusion techniques, and
double binds in place of formal hypnotic inductions. However, the
difference between Erickson's methods and traditional hypnotism led
contemporaries such as
André Weitzenhoffer, to question whether he was practicing
"hypnosis" at all, and his approach remains in question.
Erickson had no hesitation in presenting any suggested effect as
being "hypnosis", whether or not the subject was in a hypnotic
state. In fact, he was not hesitant in passing off behaviour that
was dubiously hypnotic as being hypnotic.[29]
Cognitive-behavioural
In the latter half of the twentieth century, two factors contributed
to the development of the cognitive-behavioural approach to
hypnosis. 1 Cognitive and behavioural theories of the nature of hypnosis
(influenced by the theories of Sarbin[30]
and Barber[31]
became increasingly influential. 2 The therapeutic practices of
hypnotherapy and various forms of
cognitive-behavioural therapy overlapped and influenced each other.[32]
Although cognitive-behavioural theories of hypnosis must be
distinguished from cognitive-behavioural approaches to hypnotherapy,
they share similar concepts, terminology, and assumptions and have been
integrated by influential researchers and clinicians such as
Irving Kirsch,
Steven Jay Lynn, and others.[33]
At the outset of
cognitive-behavioural therapy during the 1950s, hypnosis was used by
early behaviour therapists such as
Joseph Wolpe[34]
and also by early cognitive therapists such as
Albert Ellis.[35]
Barber, Spanos & Chaves introduced the term "cognitive-behavioural" to
describe their "nonstate" theory of hypnosis in Hypnotism:
Imagination & Human Potentialities (1974).[31]
However,
Clark L. Hull had introduced a behavioural psychology as far back as
1933, which in turn was preceded by
Ivan Pavlov.[36]
Indeed, the earliest theories and practices of hypnotism, even those of
Braid, resemble the cognitive-behavioural orientation in some respects.[9]
Applications
There are numerous applications for hypnosis across multiple fields
of interest including medical/psychotherapeutic uses, military uses,
self-improvement, and entertainment.
Hypnotism has also been used in
forensics,
sports,
education,
physical therapy and
rehabilitation.[37]
Hypnotism has also been employed by artists for creative purposes most
notably the surrealist circle of
André Breton who employed hypnosis,
automatic writing and sketches for creative purposes. Hypnotic
methods have been used to re-experience drug states,[38]
and mystical experiences.[39][40]
Self-hypnosis is popularly used to quit smoking and reduce stress, while
stage hypnosis can persuade people to perform unusual public feats.[41]
Some people have drawn analogies between certain aspects of hypnotism
and areas such as crowd psychology, religious hysteria, and ritual
trances in preliterate tribal cultures.[42][page needed]
Hypnotherapy
Main article:
Hypnotherapy
Hypnotherapy is the use of hypnosis in psychotherapy.[43]
It is used by licensed physicians, psychologists, and others. Physicians
and psychiatrists may use hypnosis to treat depression, anxiety, eating
disorders, sleep disorders, compulsive gaming, and posttraumatic stress,[44][45][46]
while certified hypnotherapists who are not physicians or psychologists
often treat smoking and weight management.
Modern hypnotherapy has been used in a variety of forms with varying
success, such as:
In a January 2001 article in Psychology Today[56]
Harvard psychologist
Deirdre Barrett wrote:
A hypnotic trance is not therapeutic in and of itself, but
specific suggestions and images fed to clients in a trance can
profoundly alter their behavior. As they rehearse the new ways they
want to think and feel, they lay the groundwork for changes in their
future actions...
and she described specific ways this is operationalized for habit
change and amelioration of phobias. In her 1998 book of hypnotherapy
case studies,[45]
she reviews the clinical research on hypnosis with dissociative
disorders,
smoking cessation, and insomnia and describes successful treatments
of these complaints.
In a July 2001 article for
Scientific American titled "The Truth and the Hype of Hypnosis",
Michael Nash wrote:
...using hypnosis, scientists have temporarily created
hallucinations, compulsions, certain types of memory loss,
false memories, and delusions in the laboratory so that these
phenomena can be studied in a controlled environment.[57]
Irritable
bowel syndrome
Hypnotherapy has been studied for the treatment of
irritable bowel syndrome.[58]
Hypnosis for IBS has received moderate support in the
National Institute for Health and Clinical Excellence guidance
published for UK health services.[59]
It has been used as an aid or alternative to chemical
anesthesia,[60][61][62]
and it has been studied as a way to soothe skin ailments.[63]
Pain management
Relaxation techniques and suggestion have been used to
reduce pain in childbirth (sometimes called '
hypnobirthing')
[64]
A number of studies show that hypnosis can reduce the pain
experienced during burn-wound debridement, bone marrow aspirations, and
childbirth. The International Journal of Clinical and Experimental
Hypnosis found that hypnosis relieved the pain of 75% of 933
subjects participating in 27 different experiments.[57]
In 1996, the
National Institutes of Health declared hypnosis effective in
reducing pain from cancer and other chronic conditions.[57]
Nausea and other symptoms related to incurable diseases may also be
managed with hypnosis.[65][66][67][68]
For example, research done at the
Mount Sinai School of Medicine studied two patient groups facing
breast cancer surgery. The group that received hypnosis reported less
pain, nausea, and anxiety post-surgery. The average hypnosis patient
reduced treatment costs by an average $772.00.[69][70]
The American Psychological Association published a study
comparing the effects of hypnosis, ordinary suggestion and placebo in
reducing pain. The study found that highly suggestible individuals
experienced a greater reduction in pain from hypnosis compared with
placebo, whereas less suggestible subjects experienced no pain reduction
from hypnosis when compared with placebo. Ordinary non-hypnotic
suggestion also caused reduction in pain compared to placebo, but was
able to reduce pain in a wider range of subjects (both high and low
suggestible) than hypnosis. The results showed that it is primarily the
subject's responsiveness to suggestion, whether within the context of
hypnosis or not, that is the main determinant of causing reduction in
pain.[71]
Other medical and psychotherapeutic uses
Treating skin diseases with hypnosis (hypnodermatology)
has performed well in treating warts,
psoriasis, and atopic dermatitis.[72]
The success rate for habit control is varied. A meta-study
researching hypnosis as a quit-smoking tool found it had a 20 to 30
percent success rate, similar to other quit-smoking methods,[73]
while a 2007 study of patients hospitalised for cardiac and pulmonary
ailments found that smokers who used hypnosis to quit smoking doubled
their chances of success.[74]
Hypnosis may be useful as an adjunct therapy for
weight loss. A 1996 meta-analysis studying hypnosis combined with
cognitive-behavioural therapy found that people using both
treatments lost more weight than people using CBT alone.[75]
The
virtual gastric band procedure mixes hypnosis with
hypnopedia. The hypnosis instructs the stomach it is smaller than it
really is and hypnopedia reinforces alimentary habits.
Controversy surrounds the use of hypnotherapy to retrieve memories,
especially those from early childhood or (alleged) past-lives. The
American Medical Association and the
American Psychological Association caution against
repressed memory therapy in cases of alleged childhood trauma,
stating that "it is impossible, without corroborative evidence, to
distinguish a true memory from a false one."[76]
Past life regression, meanwhile, is often viewed with skepticism.[77]
Military
applications
A recently declassified document obtained by the
Freedom of Information Act archive shows that hypnosis was
investigated for military applications.[78]
However, the overall conclusion of the study was that there was no
evidence that hypnosis could be used for military applications, and also
that there was no clear evidence for whether 'hypnosis' actually exists
as a definable phenomenon outside of ordinary suggestion, high
motivation and subject expectancy. According to the document,
The use of hypnosis in intelligence would present certain
technical problems not encountered in the clinic or laboratory. To
obtain compliance from a resistant source, for example, it would be
necessary to hypnotise the source under essentially hostile
circumstances. There is no good evidence, clinical or experimental,
that this can be done.
Furthermore, the document states that:
It would be difficult to find an area of scientific interest more
beset by divided professional opinion and contradictory experimental
evidence…No one can say whether hypnosis is a qualitatively unique
state with some physiological and conditioned response components or
only a form of suggestion induced by high motivation and a positive
relationship between hypnotist and subject…T.X. Barber has produced
“hypnotic deafness” and “hypnotic blindness”, analgesia and other
responses seen in hypnosis—all without hypnotizing anyone…Orne has
shown that unhypnotized persons can be motivated to equal and
surpass the supposed superhuman physical feats seen in hypnosis.
The study concludes:
It is probably significant that in the long history of hypnosis,
where the potential application to intelligence has always been
known, there are no reliable accounts of its effective use by an
intelligence service.
Research into hypnosis in military applications is further verified
by the
MKULTRA experiments, also conducted by the
CIA.[79]
According to Congressional testimony,[80]
the CIA experimented with utilizing
LSD and hypnosis for mind control. Many of these programs were done
domestically and on participants who were not informed of the study's
purposes or that they would be given drugs.[80]
The full paper explores the potentials of operational uses.[81]
Self-hypnosis
Main article:
Self-hypnosis
Self-hypnosis happens when a person hypnotises oneself, commonly
involving the use of autosuggestion. The technique is often used to
increase motivation for a
diet,
quit
smoking, or reduce stress. People who practice self-hypnosis
sometimes require assistance; some people use devices known as
mind machines to assist in the process, whereas others use hypnotic
recordings.
Self-hypnosis is claimed to help with stage fright, relaxation, and
physical well-being.[82]
Stage hypnosis
Main article:
Stage hypnosis
Stage hypnosis is a form of entertainment, traditionally employed in
a club or theatre before an audience. Due to stage hypnotists'
showmanship, many people believe that hypnosis is a form of mind
control. Stage hypnotists typically attempt to hypnotise the entire
audience and then select individuals who are "under" to come up on stage
and perform embarrassing acts, while the audience watches. However, the
effects of stage hypnosis are probably due to a combination of
psychological factors, participant selection, suggestibility, physical
manipulation, stagecraft, and trickery.[83]
The desire to be the centre of attention, having an excuse to violate
their own fear suppressors and the pressure to please are thought to
convince subjects to 'play along'.[84][page needed]
Books by stage hypnotists sometimes explicitly describe the use of
deception in their acts, for example,
Ormond McGill's New Encyclopedia of Stage Hypnosis describes
an entire "fake hypnosis" act that depends upon the use of private
whispers throughout.
The
state versus non-state debate
The central theoretical disagreement is known as the "state versus
nonstate" debate. When Braid introduced the concept of hypnotism, he
equivocated over the nature of the "state", sometimes describing it as a
specific sleep-like neurological state comparable to animal hibernation
or yogic meditation, while at other times he emphasised that hypnotism
encompasses a number of different stages or states that are an extension
of ordinary psychological and physiological processes. Overall, Braid
appears to have moved from a more "special state" understanding of
hypnotism toward a more complex "nonstate" orientation.
State theorists interpret the effects of hypnotism as due primarily
to a specific, abnormal, and uniform psychological or physiological
state of some description, often referred to as "hypnotic trance" or an
"altered state of consciousness." Nonstate theorists rejected the idea
of hypnotic trance and interpret the effects of hypnotism as due to a
combination of multiple task-specific factors derived from normal
cognitive, behavioural, and social psychology, such as social
role-perception and favorable motivation (Sarbin),
active imagination and positive cognitive set (Barber), response
expectancy (Kirsch), and the active use of task-specific subjective
strategies (Spanos).
The personality psychologist Robert White is often cited as providing
one of the first nonstate definitions of hypnosis in a 1941 article:
Hypnotic behaviour is meaningful, goal-directed striving, its
most general goal being to behave like a hypnotised person as this
is continuously defined by the operator and understood by the
client.[85]
Put simply, it is often claimed that whereas the older "special
state" interpretation emphasises the difference between hypnosis and
ordinary psychological processes, the "nonstate" interpretation
emphasises their similarity.
Comparisons between hypnotised and non-hypnotised subjects suggest
that if a "hypnotic trance" does exist it only accounts for a small
proportion of the effects attributed to hypnotic suggestion, most of
which can be replicated without hypnotic induction.[citation
needed]
Hyper-suggestibility
Braid can be taken to imply, in later writings, that hypnosis is
largely a state of heightened suggestibility induced by expectation and
focused attention. In particular,
Hippolyte Bernheim became known as the leading proponent of the
"suggestion theory" of hypnosis, at one point going so far as to declare
that there is no hypnotic state, only heightened suggestibility. There
is a general consensus that heightened suggestibility is an essential
characteristic of hypnosis.
If a subject after submitting to the hypnotic procedure shows no
genuine increase in susceptibility to any suggestions whatever,
there seems no point in calling him hypnotised, regardless of how
fully and readily he may respond to suggestions of lid-closure and
other superficial sleeping behaviour.[86]
Conditioned
inhibition
Ivan Pavlov stated that hypnotic suggestion provided the best
example of a conditioned reflex response in human beings, i.e., that
responses to suggestions were learned associations triggered by the
words used. Pavlov himself wrote:
Speech, on account of the whole preceding life of the adult, is
connected up with all the internal and external stimuli which can
reach the cortex, signaling all of them and replacing all of them,
and therefore it can call forth all those reactions of the organism
which are normally determined by the actual stimuli themselves. We
can, therefore, regard ‘suggestion’ as the most simple form of a
typical reflex in man.[87]
He also believed that hypnosis was a "partial sleep" meaning that a
generalised inhibition of cortical functioning could be encouraged to
spread throughout regions of the brain. He observed that the various
degrees of hypnosis did not significantly differ physiologically from
the waking state and hypnosis depended on insignificant changes of
environmental stimuli. Pavlov also suggested that lower-brain-stem
mechanisms were involved in hypnotic conditioning.[88][page needed][89]
Pavlov's ideas combined with those of his rival Bekhterev and became
the basis of hypnotic psychotherapy in the Soviet Union, as documented
in the writings of his follower K.I. Platonov. Soviet theories of
hypnotism subsequently influenced the writings of Western
behaviourally-oriented hypnotherapists such as
Andrew Salter.
Neuropsychology
Neurological imaging techniques provide no evidence of a neurological
pattern that can be equated with a "hypnotic trance". Changes in brain
activity have been found in some studies of highly responsive hypnotic
subjects. These changes vary depending upon the type of suggestions
being given.[90][91]
However, what these results indicate is unclear. They may indicate that
suggestions genuinely produce changes in perception or experience that
are not simply a result of imagination. However, in normal circumstances
without hypnosis, the brain regions associated with motion detection are
activated both when motion is seen and when motion is imagined, without
any changes in the subjects' perception or experience.[92]
This may therefore indicate that highly suggestible hypnotic subjects
are simply activating to a greater extent the areas of the brain used in
imagination, without real perceptual changes. It is, however, premature
to claim that hypnosis and meditation are mediated by
similar brain systems and neural mechanisms.
Another study has demonstrated that a color hallucination suggestion
given to subjects in hypnosis activated color-processing regions of the
occipital cortex.[93]
A 2004 review of research examining the EEG laboratory work in this area
concludes:
Hypnosis is not a unitary state and therefore should show
different patterns of EEG activity depending upon the task being
experienced. In our evaluation of the literature, enhanced theta
is observed during hypnosis when there is task performance or
concentrative hypnosis, but not when the highly hypnotizable
individuals are passively relaxed, somewhat sleepy and/or more
diffuse in their attention.
[94]
The induction phase of hypnosis may also affect the activity in brain
regions that control
intention and process
conflict. Anna Gosline claims:
"Gruzelier and his colleagues studied brain activity using an
fMRI while subjects completed a standard cognitive exercise,
called the
Stroop task. The team screened subjects before the study and
chose 12 that were highly susceptible to hypnosis and 12 with
low susceptibility. They all completed the task in the fMRI
under normal conditions and then again under hypnosis.
Throughout the study, both groups were consistent in their task
results, achieving similar scores regardless of their mental
state. During their first task session, before hypnosis, there
were no significant differences in brain activity between the
groups. But under hypnosis, Gruzelier found that the highly
susceptible subjects showed significantly more brain activity in
the
anterior cingulate gyrus than the weakly susceptible
subjects. This area of the brain has been shown to respond to
errors and evaluate emotional outcomes. The highly susceptible
group also showed much greater brain activity on the left side
of the
prefrontal cortex than the weakly susceptible group. This is
an area involved with higher level cognitive processing and
behaviour."
[95][96]
Dissociation
Pierre Janet originally developed the idea of
dissociation of consciousness from his work with hysterical
patients. He believed that hypnosis was an example of dissociation,
whereby areas of an individual's behavioural control separate from
ordinary awareness. Hypnosis would remove some control from the
conscious mind, and the individual would respond with autonomic,
reflexive behaviour. Weitzenhoffer describes hypnosis via this theory as
"dissociation of awareness from the majority of sensory and even
strictly neural events taking place."[97][page needed]
Neodissociation
Ernest Hilgard, who developed the "neodissociation" theory of
hypnotism, hypothesised that hypnosis causes the subjects to divide
their consciousness voluntarily. One part responds to the hypnotist
while the other retains awareness of reality. Hilgard made subjects take
an ice water bath. They said nothing about the water being cold or
feeling pain. Hilgard then asked the subjects to lift their index finger
if they felt pain and 70% of the subjects lifted their index finger.
This showed that even though the subjects were listening to the
suggestive hypnotist they still sensed the water's temperature.[98]
Mind-dissociation
|
This
section's factual accuracy is
disputed. (June 2011) |
This theory was proposed by Y.D. Tsai in 1995[99]
as part of his psychosomatic theory of
dreams.
Inside each brain, there is a program "I" (the conscious self), which is
distributed over the conscious brain and coordinates mental functions
(cortices), such as thinking, imagining, sensing, moving and reasoning.
"I" also supervises memory storage. Many bizarre states of consciousness
are actually the results of dissociation of certain mental functions
from "I".
There are several possible types of dissociation that may occur:
- the subject's imagination is dissociated and sends the imagined
content back to the sensory cortex resulting in dreams or
hallucinations
- some senses are dissociated, resulting in hypnotic anesthesia
- motor function is dissociated, resulting in immobility
- reason is dissociated and he/she obeys the hypnotist's orders
- thought is dissociated and not controlled by reason, hence, for
example striving to straighten the body between two chairs.
A hypnotist's suggestion can also influence the subject long after
the hypnosis session, as follows. In a normal state of mind, the subject
will do or believe as his reason dictates. However, when hypnotized,
reason is replaced by the hypnotist's suggestions to make up decisions
or beliefs, and the subject will be very uneasy in later days if he/she
does not do things as decided or his/her belief is contradicted.
Hypnotherapy is also based on this principle.
Social
role-taking theory
The main theorist who pioneered the influential role-taking theory of
hypnotism was
Theodore Sarbin. Sarbin argued that hypnotic responses were
motivated attempts to fulfill the socially constructed roles of hypnotic
subjects. This has led to the misconception that hypnotic subjects are
simply "faking". However, Sarbin emphasised the difference between
faking, in which there is little subjective identification with the role
in question, and role-taking, in which the subject not only acts
externally in accord with the role but also subjectively identifies with
it to some degree, acting, thinking, and feeling "as if" they are
hypnotised. Sarbin drew analogies between role-taking in hypnosis and
role-taking in other areas such as method acting, mental illness, and
shamanic possession, etc. This interpretation of hypnosis is
particularly relevant to understanding stage hypnosis in which there is
clearly strong peer pressure to comply with a socially constructed role
by performing accordingly on a theatrical stage.
Hence, the social constructionism and role-taking theory of
hypnosis suggests that individuals are enacting (as opposed to merely
playing) a role and that really there is no such thing as a hypnotic
trance. A socially constructed relationship is built depending on how
much
rapport has been established between the "hypnotist" and the subject
(see
Hawthorne effect,
Pygmalion effect, and
placebo effect).
Psychologists such as
Robert Baker and Graham Wagstaff claim that what we call hypnosis is
actually a form of learned social behaviour, a complex hybrid of social
compliance, relaxation, and suggestibility that can account for many
esoteric behavioural manifestations.[100][page needed]
Cognitive-behavioural theory
Barber, Spanos, & Chaves (1974) proposed a nonstate
"cognitive-behavioural" theory of hypnosis, similar in some respects to
Sarbin's social role-taking theory and building upon the earlier
research of Barber. On this model, hypnosis is explained as an extension
of ordinary psychological processes like imagination, relaxation,
expectation, social compliance, etc. In particular, Barber argued that
responses to hypnotic suggestions were mediated by a "positive cognitive
set" consisting of positive expectations, attitudes, and motivation.
Daniel Araoz subsequently coined the acronym "TEAM" to symbolise the
subject's orientation to hypnosis in terms of "trust", "expectation",
"attitude", and "motivation".
Barber et al., noted that similar factors appeared to mediate the
response both to hypnotism and to cognitive-behavioural therapy (CBT),
in particular systematic desensitization. Hence, research and clinical
practice inspired by their interpretation has led to growing interest in
the relationship between hypnotherapy and CBT.
Information theory
An approach loosely based on
Information theory uses a brain-as-computer
model. In adaptive systems,
feedback increases the
signal-to-noise ratio, which may converge towards a steady state.
Increasing the signal-to-noise ratio enables messages to be more clearly
received. The hypnotist's object is to use techniques to reduce
interference and increase the receptability of specific messages
(suggestions).[101]
Systems theory
Systems theory, in this context, may be regarded as an extension of
Braid's original conceptualization of hypnosis[9][page needed]
as involving a process of enhancing or depressing nervous system
activity. Systems theory considers the
nervous system's organization into interacting
subsystems. Hypnotic phenomena thus involve not only increased or
decreased activity of particular subsystems, but also their interaction.
A central phenomenon in this regard is that of
feedback loops, which suggest a mechanism for creating hypnotic
phenomena.[102][103]