A: That's a difficult question to answer quickly and precisely. Some people think that it is an 'altered state of consciousness', but since there is currently no agreed definition of consciousness this argument can go around in circles. When we talk about hypnosis we often tend to be either talking about the relaxed, focussed, absorbed feelings associated with a 'trance state' (although some people don't like the term trance), or we tend to be talking about the interesting things people can do when hypnotised - these are the products of 'suggestion'. For more detail a good place to start reading is the definitions page, otherwise follow the links on the left for more information about the research in hypnosis and its uses.
A: Short answer: yes! Hypnotic suggestions can alter people's sensations and perceptions. For example, hypnotic suggestion can be used to generate vivid hallucinations, or alter your perception of pain. Studies which measure brain activity have shown that hypnosis and hypnotic suggestions alter the way that the brain processes information. Randomised controlled clinical trials have shown that hypnosis can be an effective treatment for pain, and an effective part of treatments for other conditions. People often doubt whether hypnosis is real because it would be very easy to 'fake' a hypnotic response, and while this is true, there are also real measurable effects.
A: Yes, everybody is hypnotizable to some extent - some more than others. Susceptibility to hypnosis can be measured with a hypnotic susceptibility scale (see 'measurement of hypnosis'. Researchers tend to classify people as 'highs', 'mediums', or 'lows'. About 80% of people are in the 'medium' band - meaning that they can experience many of the effects of hypnotic suggestion, and are likely to benefit from its clinical use if necessary. Approximately 10% of the population are considered highly hypnotizable - meaning that they can readily experience quite dramatic changes in sensation and perception with hypnosis. Roughly 10% are classified as 'low' - meaning that they have not responded strongly to hypnosis (although there are some skills programmes which aim to increase susceptibility to hypnosis).
Some clinicians, notably Milton Erickson, have felt that everybody can be hypnotised but that the hypnotist must modify the style or content of what they do. However, since the only way we have of measuring suggestibility is to look at how people respond to suggestions, and since suggestibility is not often measured in clinical settings, it is difficult to bring any evidence to bear upon this argument.
A: Training programmes have been devised which aim to increase how well participants respond on tests of suggestibility. Some researchers have argued that increases brought about through this method are not genuine and are simply the result of participants being encouraged to respond without necessary experiencing their response as involuntary (a criteria Weitzenhoffer set as a 'true' response to suggestion). However, other researchers have argued that the subjective responses of such 'trained high suggestible' participants are indistinguishable from participants who were 'naturally high suggestible' without training. Some drugs have also been found to be effective in increasing suggestibility. See modifying suggestibility for more detailed information.
A: Hypnosis is not in itself a dangerous procedure, but there are concerns that if it is not used properly then it could lead to negative reactions. The risks associated with hypnosis (for example, participants very occasionally experience a mild headache) have been shown not to differ from those associated with attending a university lecture (Lynn, 2000).
Complications may occur due to faulty technique on the part of the hypnotist or because of misconceptions on the part of the subject regarding hypnosis. For a fuller discussion on the potential dangers of hypnosis read this section of Campbell Perry's discussion of hypnosis on the False Memory Syndrome's website.
A: The simple answer is no, you can't be made to do anything you don't want to do in hypnosis. In hypnosis you retain power over your ability to act upon suggestions, although if you do allow yourself to act upon a suggestion you may feel as though the effects are happening by themselves.
Orne & Evans conducted a study to find out if they could make hypnotised subjects perform antisocial acts, such as throwing a jar of acid in the face of a research assistant (for safety the jar didn't actuallly contain acid, but the subjects in the experiment didn't know this). They found that 5 out of 6 high hypnotizable participants did throw the 'acid', but that 6 out of 6 low hypnotizable participants who were asked to simulate being in hypnosis threw the 'acid' too. This experiment shows that it's not something special about being in hypnosis which could make people perform antisocial acts, but rather something about the social situation the experiment was conducted in. The logic of the experiment is that if you can get people to commit antisocial acts without hypnosis (the low hypnotizables who were being asked to pretend) then there is no need to use hypnosis to explain what people are doing (for more information on experiments involving authority read about Stanley Milgram's famous experiment here).
A: The short answer is no. Although the word hypnosis is derived from the Greek god of sleep, Hypnos, studies have shown that hypnosis and sleep differ. Studies of brain activity have shown that although there are characteristic patterns of brain activity associated with sleep the same has not been demonstrated of hypnosis. To observers hypnosis might appear to be like sleep because suggestions of relaxation are commonly given as part of a hypnotic routine, but hypnotised people are in a state more similar to wakefulness (and hypnosis has even been induced in people riding exercise bicycles - so called 'active alert' hypnosis).
A: The answer is that hypnosis probably feels different for everybody. Many hypnotists (researchers & clinicians) use elements of relaxation procedures, so people commonly associate a feeling of relaxation with hypnosis. Different people have all sorts of bodily responses to relaxation instructions - some feel as though their body is very heavy, whereas some can feel very light, almost as if they were floating. Mentally, again people have all sorts of responses. People typically report feeling very focussed or absorbed, often effortlessly so. Since instructions for imagery are often used people can have very vivid imaginative experiences - many report feeling 'as if they were there'. Erika Fromm wrote a great book on self-hypnosis, based up the results of extensive research, which contains a lot of interesting descriptions from participants in her studies.
A: There is no evidence that anybody can become stuck in hypnosis. The worst that might happen could be that you fall asleep - and wake up unhypnotised! Orne & Evans conducted a famous study where participants were hypnotised, and the experimenter leaves the room under the pretense that there is a problem he has to attend to, the participant is then observed (without his knowledge) to see what happens. The result was that participants spontaneously woke up, the high hypnotisables taking slightly longer to do so.
A: Hypnosis isn't a treatment in its own right, but when used by a qualified doctor, dentist, or psychologist hypnosis can be helpful in treating: pain, anxiety conditions (including phobia, panic, PTSD), depression, irritable bowel syndrome, and many more. See the hypnotherapy section for more information.
A: Different countries regulate hypnosis and psychotherapy in varied ways and in many countires no specialist training is required in order to call oneself a 'hypnotherapist'. The International Society of Hypnosis recommends that the only therapists using hypnosis should be those who are already qualified in a professional discipline (such as medicine, dentistry, psychology or psychotherapy). To quote Martin Orne: "If a person is not professionally qualified to treat something without hypnosis, then they’re not qualified to treat something with hypnosis, either. First you look for that professional certificate on the wall -- physician, dentist, clinical psychologist, or whatever. Then you look for the certificate of hypnosis."
A: NLP, or Neuro-linguistic programming, is a set of techniques that are intended to promote personal development. Some of these techniques were developed from the work of successful hypnotherapists, notably Milton Erickson. NLP remains scientifically unvalidated and is not a part of mainstream academic psychology. There is a great account of NLP on Skepdic, the skeptic's dictionary. More skeptical accounts of NLP are available at Michael Heap's website and on wikipedia.
A: Careful use of language is certainly important when using hypnosis, but it's hard to say whether a particular word is more suggestive than another. It is now generally accepted that how well a person responds to suggestion is more to do with their individual characteristics (suggestibility, willingness, absorption) than to do with the power or authority of the hypnotist (e.g. 3). A clinician's style of hypnosis can vary from authoritarian/direct ("when I click my fingers you will feel ... ") to permissive/indirect ("as I continue to talk you might start to notice that the feeling becomes ..."), and indirect suggestion has been popularised by followers of Milton Erickson. Experiments have been carried out to compare the effects of these types of suggestion but results do not allow us to conclude that one is more effective than the other (4). (Question submitted by an anonymous user)
A: There's really not much evidence that hypnosis is an effective treatment for alcoholism. In a review Nash & Benham say that drug and alcohol addiction don't respond well to hypnosis, and two studies that I can find which compare hypnosis (or self-hypnosis) treatment to other forms of therapy such as psychotherapy or stress-management don't show any convincing benefit for using hypnosis (Jacobson, 1973; Pekala, 2004). (Question submitted by an anonymous user)
A: There are no recorded cases of hypnosis causing or playing a role in the creation of a sleep disorder. In fact, there is much evidence that hypnosis can actually play a useful role in treating sleep disorders such as insomnia (Borkovec, 1973), sleep-terror and sleepwalking (Hurwitz, 1991). (Question submitted by an anonymous user).
A: Science is a method of discovering knowledge: it's really a process of subjecting your ideas to an empirical test to see whether they are supported by evidence (see the Wikipedia entry for a much more detailed description). Many researchers take a scientific approach to studying hypnosis: they generate research questions (hypotheses), then they systematically test them to see whether they are supported. Our knowledge of hypnosis advances because of this: people used to believe that the effects of hypnosis were due to a mysterious magnetic fluid; we now believe that the effects are the result of a communication between hypnotist and subject which can affect the way the brain processes information. Research psychologists are interested in what hypnosis is, and doctors and clinical psychologists are interested in what effects hypnosis can have upon medical and psychological conditions. Their research is published in journals, and you can search the knowledge base using online tools like PubMed or Google Scholar. So there are certainly scientists interested in hypnosis, and you could say that there is a science of hypnosis.
Hypnotherapy is the name we give to using hypnosis to treat psychological and medical conditions, and there is relevant research about using hypnosis to treat illness. However, 'hypnotherapy' is a controversial term. Professional organisations such as the ISH, ASCH, and ESH believe that only suitably qualified professionals (such as doctors, dentists, psychologists) should use hypnosis, and that they should use it as a tool alongside their other professional skills. In their view hypnosis isn't a treatment in its own right, so a clinician would say "I'm a psychologist/doctor/dentist who uses hypnosis" rather than"I'm a hypnotherapist". People who call themselves 'hypnotherapists' don't (in general) tend to have any healthcare qualifications other than hypnotherapy training, and they don't tend to publish much research. Given that, it might be fair to say that there is a science of hypnotherapy, but that 'hypnotherapists' don't contribute much to it. (Question submitted by an anonymous user).
A: The idea that we can learn while we are asleep, so called 'hypnopaedia', was popular during the 1950's. That is also the time when most of the research was done. Results don't seem to be very promising though: one study by Emmons & Simon) found that participants who had been played recordings while asleep did not better than control participants at identifying words from a list. Not much research has been done since which indicates that this is probably not a fruitful topic of research. More contemporary research has examined whether it is possible for people undergoing general anaesthesia to learn. In these experiments very simple 'learning' is tested: much simpler than the kinds of deep level learning that you might want from a hypnosis CD. The indications are that it might be possible for very simple associations to be formed, but that the complex meanings of events are not truly learned (Deeprose, 2006). In summary, the evidence so far seems to point towards hypnosis requiring the participant to be awake. (Question submitted by a reader).
A: No more or less than they do when they are not under hypnosis. Hypnosis cannot compel people to do things they don't want to do, and it can't force them to be truthful either. Suggestions given during hypnosis can deliberately or inadvertently affect memories, and for this reason hypnotically-assisted memory recall is not admissable in court in most countries. (Question submitted by an anonymous reader).
A: See the answer above about whether hypnosis can make people do things they don't want to do. The short answer is no: hypnotised participants generally have the ability to refuse a suggestion. (Question submitted by an anonymous user).
A: I don't know what context you're working in, but unless you're properly qualified I would think it best not to ask questions about childhood memories or past lives while clients are hypnotised. Although hypnosis is often used to re-visit events from an individual's past, there is no evidence that hypnosis can help people to recall memories from childhood with any special accuracy. When not done properly you run the risk of creating false memories, which can be especially unhelpful in patients with histories of trauma. There is no scientific evidence supporting the existence of past lives, and no evidence that it is helpful to introduce the concept in therapy. The only time I ever give suggestions for past lives is as a teaching demonstration, to show how creative people's imaginations are.
If clients/volunteers are abruptly awakening or falling asleep, and don't do so for other parts of a hypnosis session, it would indicate to me that they are not comfortable with what is happening and have not agreed to the process. Unless you really know what you are doing I would urge you not to use regression techniques. (Question submitted by a reader)
A: The snappy answer is "people who don't want to be hypnotised", but it's worth clearing up a few misconceptions. Scientists measure hypnotisability on a continuum - it's not that someone can or can't be hypnotised. A better question is "how hypnotisable is this person?". Hypnotisablity follows a normal distribution, so a small proportion of people are 'highs', a small proportion are 'lows', and the majority can experience some effects of suggestion in hypnosis. It's easy to be 'un-hypnotisable', just don't allow yourself to be hypnotised - nobody can be hypnotised against their will. Interestingly some drugs such as nitrous oxide (laughing gas) and alcohol seem to increase hypnotisability. It depends on the drug though, others such as diazepam don't seem to have any effect. See the page on modifying hypnotisability for more information. (Question submitted by a reader)
A: No more than it invalidates the concept of a 'broken leg' if someone pretends to be injured. The fact that it is possible to pretend to be hypnotised makes it a really interesting phenomenon. Stage hypnotists don't really care very much whether their participants are faking or not, as long as the audience are laughing. Researchers have a harder time sorting out the real responses from the pretenders, but they have developed some interesting tools. One technique is to use the real/simulator design. In this design you deliver the same suggestions to people high and low in hypnotisability, with the lows told to act 'as if' they were hypnotised. If the two groups perform the same then your result is probably not due to hypnosis, but if the highs perform differently then it is assumed that some of the suggested effect was genuine. More recently, brain imaging techniques have been used to test the 'genuineness' of hypnotic effects. (Question submitted by a reader)
A: The answer to this will depend a lot on what 'the problem' is. It is easy to imagine that someone is more likely to, say, give up smoking after a single session than they are to recover from a more serious mental health problem such as chronic depression or post-traumatic stress disorder (PTSD).
Regarding smoking, there is some evidence that a proportion of people will become abstinent after one session of hypnosis. In one study 23% were abstinent two years after a single session of hypnosis. However, the evidence also seems to indicate that hypnosis is not any more effective than other smoking cessation treatments - so it is likely that roughly this proportion of people would be helped to quit smoking after a single session of any type of therapy, which makes hypnosis appear rather less special.
Regarding single-session treatments for other psychological problems, there does not appear to be much strong evidence for the efficacy of such interventions. There is a 'brief therapy' movement (often called 'solution focused brief therapy') for which there is some evidence of effectiveness for certain conditions. Within the brief therapy movement are some therapists who are interested in 'single-session psychotherapy', but there is very little controlled evidence to suggest that it is effective.
In contrast to single-session treatments there are hundreds of randomised controlled trials for the use of cognitive-behavioural therapy (CBT) for the treatment of psychological problems. These controlled studies typically indicate that at least 6-20 sessions of psychotherapy are necessary for treatment of mild to moderate difficulties. Thinking more broadly about the context in which much therapy is delivered, CBT is widely used in many financially-constrained medical services around the world. The fact that CBT is recommended indicates that it is probably one of the most efficient treatments around: this judgement is also supported by treatment review bodies such as the National Institute for Health and Clinical Excellence. If brief therapy or single session therapy is really effective then the onus is on the practitioners to demonstrate it via controlled studies, this remains to be demonstrated. (Question submitted by a reader)
A: Dissociation theories of hypnosis (e.g. Hilgard's neodissociation theory, Woody & Bower's dissociated control theory) propose that hypnosis produces 'splits' or dissociations in systems of cognitive control. Consistent with this there is evidence that hypnotisability is higher in patients with 'dissociative' disorders such as post-traumatic stress disorder. However, dissociation theories also predict that healthy people who dissociate more in day-to-day life should also be more hypnotisable. This doesn't seem to be the case: studies correlating hypnotic suggestibility with scores on the dissociative experience scale (DES) aren’t significant. (e.g. Dienes et al, 2009). Given this, it doesn’t seem as though dissociation is terribly valuable when trying to explain responsiveness to hypnotic suggestions.
On the other hand, scores of imaginative suggestibility (non-hypnotic suggestibility) tend to correlate very highly with hypnotic suggestibility (Kirsch & Braffman, 2001). This indicates that the two are related, but there are two issues remaining:
(1) some people argue that 'hypnosis' encompasses a wide domain of suggestion, and that hypnotic and non-hypnotic suggestion are essentially the same thing
(2) ok, you might have explained variance in responsiveness to hypnotic suggestion, but you haven’t explained the mechanism by which people respond to non-hypnotic suggestion.
What seems to be needed is a theory to explain how people respond to non-hypnotic suggestions. Kirsch & Braffman (2001) argue that these factors include: response expectancy, attitudes towards hypnosis, fantasy proneness, absorption, and go/no-go reaction time. However, they caution that these variables do not account for all of the variability in non-hypnotic suggestibility. It is possible that there is an underlying ability, perhaps with a genetic contribution to suggestibility (Raz, 2008), or associations between suggestibility and the size of certain brain regions (Horton et al, 2004). (Question submitted by a reader).
A: Does the fact that a motivated person can fake a broken leg invalidate the notion of broken legs? Or does the fact that someone can fake depression invalidate the concept of depression? Just because something can be faked doesn't make it any less real.
I think the bit I'd take issue with is the "unique state of consciousness". Scientifically it's very hard to differentiate between different 'states of consciousness'. We're pretty good at measuring whether people are 1) awake, 2) asleep, or 3) in a coma, but the science isn't very good at differentiating between more subtle states of consciousness.
Rather than general 'states of consciousness', it is possible to think about more specific brain activity associated with hypnosis and hypnotic effects. There is lots of neuroimaging evidence to suggest that there is something special about the effects of suggestion given in hypnosis, and that it produces genuine effects. For instance, a hypnotised person given suggestions for pain relief can feel less pain, and this is associated with reduced activity in the network of brain regions involved in pain.