July Research Snippet: Competing Theories of Hypnosis

The Conditioning & Inhibition Theory of Hypnosis

In previous snippets, we’ve looked at factors in the typology of suggestion, some clinical outcome studies, etc., this month I’d like to draw attention to some research attempting to support a comprehensive theory of hypnosis.  As the psychologist Kurt Lewin famously remarked: “Nothing is as practical as a good theory.”  That phrase came to mind when reading Alfred Barrios’ recent series of articles which concisely and systematically outline a relatively simple “conditioning and inhibition” theory of hypnosis (Barrios, 2001), which recently led to an exchange with Steven Jay Lynn relating to the similarities and differences between Barrios’ theory and the influential “socio-cognitive” theory of hypnosis. 

            Barrios’ theory ultimately derives, I think, from the “cortical inhibition” theory of hypnosis which crowned Pavlov’s physiological research on animals at the turn of last century – a theory further developed by Platonov and other Soviet hypnotherapists.  Anyway, Barrios does an admirable job of carefully spelling out his modern variation, with intermittent references to supporting research data.  In a nutshell, Barrios draws on a revised form of conditioning theory to describe hypnosis as a method for reinforcing the subject’s tendency to progressively fade out (“inhibit”) intrusive thoughts and sensations in a way that heightens their sensitivity to learned associations between words, such as hypnotic suggestions, and physiological responses such as emotions.  From this point of view, words, such as verbal suggestions, function as stimuli which in turn evoke “cognitive stimuli” (ideas and images) in a way that triggers hypnotic responses.  Barrios’ use of behavioural learning theory obviously has the potential to highlight certain overlaps between the theory and practice of hypnosis and behaviour therapy. 

Barrios’ theory consists of the following seven hypotheses, divided into three groups,

A. Hypnotic induction

1. “Hypnotic induction is a conditioning process.”

2. “The response conditioned during hypnotic induction is an inhibitory set, a set which tends to inhibit stimuli incompatible with the response suggested by the hypnotist.”

3. “A positive response to a suggestion will induce within the responding person a more or less generalised increase in the normally existent tendency to respond to succeeding suggestions.”

B. Explanation of hypnotic phenomena

4. “A suggestion produces the desired response by first evoking a cognitive stimulus which is associated with that process.”

5. “The inhibitory set facilitates the suggested response by inhibiting stimuli competing with the cognitive stimulus.”

C. Post-hypnotic suggestion

6. “Suggestion leads to behaviour change by a form of higher-order conditioning called C-C [cognitive-cognitive] conditioning.”

7. “Hypnosis facilitates the C-C conditioning produced by suggestion.”

Barrios published two subsequent articles, the first of which explores the relationship between his “conditioning and inhibition” theory and four other modern theories of hypnosis: sociocognitive theory (Spanos/Lynn), Neo-dissociation (Hilgard), response expectancy (Kirsch), and Milton Erickson’s approach (Barrios, 2007).  The second reviews the possible benefits and applications of the theory to understanding phenomena such as the placebo effect, improving the effectiveness of hypnotic induction, improving post-hypnotic suggestions, and the development of Barrios’ therapeutic technique called Self-Programmed Control (Barrios, 2007b).

Comparison Between Theories

In the current edition of Contemporary Hypnosis, Steven Jay Lynn and Sean O’Hagen have responded in some detail to Barrios’ comparison between the conditioning and inhibition and sociocognitive theories of hypnosis.  

Sociocognitive theories reject the traditional view that hypnotic experiences require the presence of an altered state of consciousness.  Rather, the same social and cognitive variables that determine mundane complex social behaviours are said to determine hypnotic responses and experiences. (Lynn & O’Hagan, 2009)

They praise Barrios for providing a systematic and comprehensive account of his theory and its practical implications.  Indeed, contrary to Barrios’, they conclude that his theory is itself one of several falling under the broad “sociocognitive” umbrella term.  However, while endorsing some of his points, they disagree with others, citing several research studies in support of their own position.  In particular,

  1. Barrios emphasises the power of hypnotist prestige but sociocognitive researchers have generally found the qualities of the hypnotist to be of less importance than the qualities of the subject, e.g., their level of motivation, expectations, and imaginative capacity.
  2. Following Spanos, Barrios emphasises the power of “goal directed fantasies”, or mental imagery, in evoking hypnotic responses but, according to Lynn, research has failed to show that imagery alone can account for hypnotic responses without the aid of factors such as motivation and expectation.
  3. Barrios, like many hypnotherapists, naturally assumes that hypnotic suggestions are more effective when presented in order of difficulty, giving the subject an increasing confidence in their ability to respond. However, Lynn cites evidence from experimental studies showing that this is not the case and subjects respond just as well when suggestions are given in descending order of difficulty.
  4. They do, however, find support for Barrios’ contention that subjects increase in responsiveness to genuine suggestion tests after first being duped into believing they are hypnotised, e.g., by surreptitiously playing quiet music in the background while suggesting that they will hallucinate the sound of music, etc.
  5. They raise doubts over Barrios’ claim that some induction techniques induce hypnosis more “deeply” than others. Research has consistently failed to demonstrate much difference between different induction techniques.
  6. Moreover, the increase in suggestibility following hypnotic induction techniques is around 20% on average, which seems to show that the presence of a hypnotic state (“trance”), even if such a thing did exist, would be far less important to hypnotism than other factors such as the personality of the subject, their attitudes, and the type of suggestions given.

It’s truly fascinating to observe these debates between researchers from different theoretical traditions because they highlight the pros and cons of their respective points of view.  This is research in action; the competition between contrasting hypotheses, appealing to their respective supporting evidence.  It’s through this kind of dialogue that genuine progress is achieved in hypnotic research and we work our way gradually closer to an accurate and comprehensive theory of hypnosis and hypnotherapy. 


Barrios, A. A. (2001). A Theory of Hypnosis based on Principles of Conditioning & Inhibition. Contemporary Hypnosis , 18 (4), 163-203.

Barrios, A. A. (2007). Commentary on a Theory of Hypnosis based on Principles of Conditioning & Inhibition, Part I: Contrasts with Other Perspectives & Supporting Evidence. Contemporary Hypnosis , 24 (3), 109-122.

Barrios, A. A. (2007b). Commentary on a Theory of Hypnosis based on Principles of Conditioning & Inhibition, Part II: Benefits of the Theory. Contemporary Hypnosis , 24 (3), 123-138.

Lynn, S. J., & O’Hagan, S. (2009). The Sociocognitive and Conditioning and Inhibition Theories of Hypnosis. Contemporary Hypnosis , 26 (2), 121-125.

June Research Snippet: Eysenck’s Typology of Hypnotic Suggestion

Okay, research snippet time and it’s back into the past again for a look at an important historical piece of research. Many of you will be familiar with the name of Hans Eysenck (1916-1997). He was allegedly the most widely-referenced psychologist in scientific literature at one point during his lifetime and a pioneer of behaviour therapy. Well, hypnotherapists may not know that Eysenck also carried out some seminal research on the different factors in suggestion and the relationship between hypnosis and personality traits. His original research on hypnosis was published in a well-known journal article and reviewed in his book Dimensions of Personality (1947) which contains a whole chapter on hypnosis and suggestion.

Basically, Eysenck’s research is important for two reasons,

1. He provided data which contradicted the traditional assumption that “hysterical” patients were particularly hyper-suggestibile, i.e., that hypnosis itself is a form of “artificial hysteria.”
2. He was one of the first people to provide evidence which suggested a distinction between different species of suggestion and suggestibility.

Eysenck carried out a series of studies, and reviewed other research. He collated data from over a thousand military personnel and psychiatric patients. Essentially, he found that so-called “hysterics” were no more hypnotisable than other emotionally disturbed patients. However, he did find data pointing to a link between trait neuroticism and hypnotic suggestibility. In the preface to the 1998 edition of the book, presumably written just before his death, he neatly sums up his findings on suggestion,

I was trying to extend my experimental approach to psychiatric concepts, and chose certain specific statements from psychiatric textbooks for testing. It had been almost universally claimed that hysterics are suggestible, but there was no experimental evidence. I applied a number of standard tests of suggestibility to groups of hysteria and anxiety states, as well as non-neurotic controls, and found that there were at least two kinds of suggestibility which I called “primary” and “secondary”. Hysterics did not differ from anxiety states, but neurotics as a group differed profoundly from normals, being much more suggestible. When I showed the results to Sir Aubrey Lewis, my boss, he immediately summoned all the patients I had tested to make sure the hysteria had been correctly diagnosed – he agreed that they had.

Eysenck’s factor analysis of the data from hypnotic suggestion tests seemed to show that indirect (“secondary”) suggestion functioned by means of a fundamentally different mechanism from direct (“primary”) suggestion. Indeed, Eysenck concluded that indirect suggestibility was probably not a single trait and probably not directly related to hypnotism as traditionally understood. He was not alone in this conclusion as earlier researchers such as Binet and Hull had produced similar findings.

In two factorial studies of altogether 16 different tests of suggestibility, it was shown that these tests define two entirely different and separate types of suggestibility: (1) Primary suggestibility, characterised by dependence on ideo-motor action, and (2) Secondary suggestibility, characterised by dependence on indirection. Primary suggestibility was shown to be closely related to hypnosis; secondary suggestibility showed no such relation. (Eysenck, 1947: 201)

If Eysenck’s interpretation of the data is correct then, to put it in plain English, the concept of “indirect hypnosis” becomes a bit of a problem because what we know about traditional hypnotism probably can’t be applied to the use of indirect suggestion. For instance, there’s good evidence that direct (“primary”) suggestibility tends to increase (albeit by a modest amount on average) following a standard hypnotic eye-fixation induction. It wouldn’t follow from this, though, that indirect suggestions would become stronger following the same induction. Moreover, Hull and others had found evidence that direct (primary) suggestion responses tend to increase with practice whereas responses to indirect (secondary) suggestion do not seem to do so, and may even weaken with repetition.

Of course, questions have been raised in the past over the relatioship between Milton Erickson’s indirect approach and traditional hypnotherapy. Eysenck’s analysis is part of the backdrop to that riddle and his intelligent discussion of the research evidence provides some interesting facts and figures to chew over.

You can read a more detailed discussion of this research on my blog article below,


May Research Snippet: Multiple Sclerosis

Apologies for the delay, but here we are again… Research snippets… but first some news…

Stephanie Kirke’s research on hypnotic pain management, sponsored by NCH, is nearing publication and that will probably be summarised in the NCH Journal.

Incidentally, the NCH page on Facebook now has over 300 members and we’re posting research snippets there on a regular basis. There are now ways to subscribe to various RSS news feeds online whereby you can receive updates on research news and journal articles as they’re published, updated in real time. Scientific American even have a news feed that links to 60 second audio podcasts summarising news snippets about psychology, much of which would be of interest to hypnotherapists. You can beam psychology factoids directly into your brain via your ipod while you’re playing sardines on the underground. Technology races ahead of us!

I should also give a plug for my own research into cognitive-behavioural hypnotherapy for noise-related stress, and my historical article in this month’s IJCEH, which presents a backward translated version of James Braid’s last article On Hypnotism (1860), also published in the new NCH book The Discovery of Hypnosis: The Complete Writings of James Braid, the Father of Hypnotherapy. You can now order the book online at Amazon UK. In the same edition of IJCEH as Braid’s “lost manuscript” we find an intersting outcome study by a team of ten (!) researchers, let’s call them Jensen, Barber, Romano, et al., entitled ‘A comparison of self-hypnosis versus progressive muscle relaxation in patients with multiple sclerosis and chronic pain’ (IJCEH, 57(2): 198-221).

Twenty-two participants were recruited for this study (which is just short of the 25 required for an empirically-supported treatment). Self-hypnosis was compared head-to-head against progressive muscle relaxation (PMR) for its ability to help management of pain in multiple sclerosis and, basically, those receiving self-hypnosis reported significantly greater pain reduction during sessions, and following treatment, than those using PMR., this was maintained at 3-month follow-up. (The use of an established relaxation technique as an active treatment control group serves here as a valid alternative to a placebo control group.)

Two predictor variables were measured: hypnotic susceptibility and the Treatment Expectancy Scale (TES). The TES is a common measure of expectancy which I think might have some useful applications in clinical practice. It basically asks the client to rate their response to four questions (0-10),

1. How logical does this type of treatment seem to you?
2. How confident are you that this treatment will be succesful in eliminating your symptoms?
3. How succesful do you feel that this treatment will be in reducing your symptoms?
4. How confident would you be in recommending this treatment to a friend who is suffering badly from the same symptoms?

Despite having similar outcome expectations, however, in both relaxation and self-hypnosis groups, the hypnotic subjects experienced more improvement. In other words, their improvement probably exceeded the effect of expectation alone. However, overall there was a moderate correlation between expectation and outcome across both groups (r=.40). In other words, expectation probably contributed substantially but does not account for all of the effects of self-hypnosis. Hypnotic susceptibility, by contrast, was not found to correlate with outcome. (Both findings which have been reported in other studies.)

Analysis of the levels of clinically significant reduction in pain showed that at 3-month follow-up, 47% of self-hypnosis subjects reported clinically meaningful pain reduction compared to only 29% of the relaxation group. (Although below 50%, this is a reasonably good outcome for a clinical trial of this kind.)

This study provides some support for the view that relatively simple self-hypnosis techniques can be effective in managing pain associated with multiple sclerosis, and is substantially superior to relaxation training, and probably therefore superior to placebo. It adds further to the body of evidence showing that treatment outcome expectations are an important factor in determining the outcome of therapy, but far from being the only factor. And it also adds to those studies which question the value of hypnotic susceptibility scales in predicting treatment outcome. Either these scales are flawed, perhaps because they measure the wrong type of responses, or being highly hypnotisable isn’t more helpful than being moderately hypnotisable when it comes to the kind of suggestions used in therapy.

How to find research on hypnotherapy

“Where do I find research on hypnosis and xyz?”, is the most common question I get asked as NCH research director, and in my job as a trainer. See my news item in the current NCH journal for more information on searching for studies online, and also the table of Empirically-Validated Treatments in hypnotherapy for additional references to well-designed research studies.

There are several research journals in the field of hypnosis. The most important is the International Journal for Clinical & Experimental Hypnosis (IJCEH). The good news is that the publishers of IJCEH provide a superb “advanced” search facility, free of charge, on their website. It contains the abstracts from every single article published since the launch of the journal in 1953. Full copies of the articles can also be purchased online (this is not cheap). The abstracts will usually contain a brief report of the results of the study, though. See the link below. If you’re looking for research on hypnosis and diabetes just type “diabetes” in the search box under the picture of the journal cover (4 hits),
Continue reading

Become a “fan” of NCH on Facebook

NCH have a new Facebook page which has been up and running for several weeks. We already have nearly 200 “fans” on Facebook and more people are joining every day. If you don’t have a Facebook account, it’s easy to set one up; just visit the link below and you’ll soon figure out how to sign up for Facebook so you can add your own personal page. It’s a good way to network with other hypnotherapists and promote your services.

The NCH Facebook page is hooked up to publish news snippets, etc., from the NCH website and has been stuffed full of links to articles and other goodies. You can join in discussion with other hypnotherapists there about how to get more clients, etc. Be there or be square!

The National Council for Hypnotherapy (NCH) Facebook Page

Research Snippet – March 2009


Donald Robertson

Donald Robertson

Apologies for the delay while I settled into the research director role. We’re up and running now and I thought I’d begin with a different type of research snippet. We’ll look at some recent studies shortly – and NCH members can also read my article in this month’s Hypnotherapy Journal. However, first of all, let’s go back to the beginning. The beginning of modern psychotherapy outcome research can arguably be dated to the following widely-referenced study, whose authors introduced the statistical technique of meta-analysis.


In their seminal The Benefits of Psychotherapy (1980), Mary Lee Smith and her team of colleagues used the new technique of “meta-analysis” to process data from large numbers of controlled research studies on different modes of psychotherapy. Advanced statistical methods were used to derive an overall “effect size” for different forms of psychotherapy based on a review of all available research on psychotherapy prior to 1980. Their review identified 475 waiting list or placebo group controlled studies of adequate quality for inclusion in the meta-analysis. Continue reading

New NCH Book: The Complete Writings of James Braid

The Discovery of Hypnosis

The Discovery of Hypnosis

The Discovery of Hypnosis: The Complete Writings of James Braid, the Father of Hypnotherapy.
Donald Robertson (editor)


This book has been published,

• To help inform and educate hypnotherapists about the origins of their field.

• To provide a resource to raise the credibility of modern hypnotherapy by drawing attention to its empirical roots.

Visit the link below to purchase a copy or review the book at Amazon. We hope to shortly make available a browsable online PDF version through Amazon and Google books.

The Discovery of Hypnosis: The Complete Writings of James Braid the Father of Hypnotherapy

Several excerpts from this book have been published in the Hypnotherapy Journal of NCH, and a recent article has been published in the International Journal of Clinical & Experimental Hypnosis (IJCEH). Click the link below to view the IJCEH abstract, or order a PDF of the article online.

Braid’s Lost Manuscript, “On Hypnotism” (1860)