Components of Hypnosis

Response set theory (1997) builds on response expectancy theory to add automaticity by talking about behavior in terms of automatic sets of responses that we only think we have control over. The very short version is that conscious thought is the very last step in the chain of processing; by the time we decide to do things, the brain has already decided to do it for us. A follow up paper, The Response Set Theory of Hypnosis (2000), cleared up some misconceptions on the earlier paper, but still held that actions are fully automatic.

Integrative response set theory (2022) steps back from fully automatic actions, instead saying that varying degress of automaticity precede actions, and uses a "weak" model of response expectancy that reflects more recent studies. The integrative theory provides a practical mechanism for response expectancies by integrating the model with the hierarchical predictive processing model in cognitive neuroscience, stating "an expectancy is by definition a prediction."

Response sets are vital in everyday habits and in complex decision-making like driving, sports, or computer games, where there simply isn’t time to make a conscious decision. Response sets themselves have been in use for a while; Erickson in particular was fond of yes sets for cuing behavior and implicit knowledge and deautomatizing maladaptive response sets.

Importantly, response sets can be either be conscious intentions or unconscious expectancy. The conscious attribution of agency differs, but the underlying automaticity is the same.

Here’s a great talk going into the details of response set theory starting at 41:26 (it is in French, so you will want to turn on auto-translate).

How can you have a response set in response to a suggestion that has never been given before? This is explained through the idea of a response set consisting of a generalized response expectancy or implementation intention: a motivated commitment to respond. At a high level, the hypnotee decides that they will follow suggestions, and committing to that intention creates a prediction about future actions. Once an intention is activated, it alters perception to put the steps to complete the intention at the front of the brain while sidelining irrelevant information.

You don’t need conscious awareness of the instruction or the cue. As long as there’s clear instruction and no further decision making is required, then complex goals-directed actions can be triggered directly by situational cues. If following instructions is the goal, then following instructions feels automatic.

Automaticity is subtle because the degree of automaticity only becomes apparent during response inhibition, leading people to believe that they are following the suggestion "of their own free will" until they try resisting suggestions. This behavior can be seen in a game of Simon Says, where the response set to immediately respond to the leader giving the instruction is given repeatedly. At some point, the leader gives an instruction without saying "Simon Says" and everyone has to inhibit their response to following the instruction. In just a few minutes, following the response set feels completely natural, and inhibiting that response is jarring.

This means that there are at least three different processes at work for the hypnotee:

Richard Feynman has an anecdote showing how response sets can feel intentional while following a suggestion.

This example also suggests how involuntariness arises, in that either the suggestion is resisted or the suggestion itself places agency outside of self by suggesting that something is happening to the hypnotee.

At this point, the big question is how response set theory matches to how the brain works, and why this is a better model than the "hidden observer" theories popular in hypnosis books from the 1970s. The answer is that there is no subconscious mind, only unconscious processing.

The question is how that processing turns thought into action. Predictive processing theory (2020) provides an idea of how expectancies and higher level response sets turn into low level actions and nonvolitional responses. It describes cognitive processes as a set of internal models that are continually tested and updated by underlying models, eventually taking input from sensory channels. If a model conflicts with the underlying input, it’s described as a "prediction error" and sent upstream until the error is corrected.

This youtube video gives a good overview predictive brain theory:

From The Interoceptive Mind From Homeostasis to Awareness there is this diagram showing how the core models integrate information that has already been filtered and processed through many layers of predictive processing:

The core models do not ever interact with raw data, but only deal with lower level models which propagate their errors upstream.

This provides a neat explanation of how hypnosis can change perception, because all perception is built by comparing sensory input against an predicted internal model and noting prediction errors.

Predictive processing is also an explanation of agency and decision making, because beliefs and desires are essentially free-standing predictions.

Predictive processing can provide the neural correlates for response expectancy, but it does not provide a model of how the brain can cause nonvolitional changes in the body and account for the "mind/body identity assumption" in response expectancy theory.

Similar to the way that the brain perceives its environment, the brain also senses its own internal state through interoception and maintains an internal model of the body. The interoception and imagination loop in hypnotic phenomena (2019) provides a starting point for viewing hypnotic phenomena through interoception.

The brain takes note of differences between its internal state and its anticipated internal state, and resolves the difference through allostasis as a control feedback loop. Crucially, allostasis is a predictive homeostasis — it allows the body to proactively prepare for events before they happen and react accordingly.

This potentially closes the loop on how the brain affects the body through hypnosis. Allostasis as control mechanism very neatly explains hypnotic phenomena that don’t fit into environment-based nonvolitional responses, like wart removal. (I am extrapolating here. As far as I know, there are no papers directly linking hypnotic phenomena with allostasis.)

Dr Lisa Feldman Barrett discusses Allostasis and Interoception in Brain Function in this youtube video:

Because internal responses in the body can be ambiguous and interpreted in many different ways, expectancies about responses are self-confirming: we may feel the way we anticipate feeling, including how we feel emotions and motivation, and our perception of self. Emotions in particular are described as cognitively created conscious experiences, with arousal and interoception as non-emotional ingredients. This is an area of active research, and some papers are downright fascinating, for example describing fatigue and depression as a self-belief (read: response expectancy) in the body’s inability to self-regulate effectively.

This also provides some hints into how strong beliefs about hypnosis efficiency can cause more effective outcomes; a response expectancy that hypnosis can cause allostatic hypercompetance could be self-fulfilling. Likewise, a sense of involuntary action could be described as interoceptive prediction error, where the sense of self does not account for hypnotic suggestion.

Hypnosis, Suggestion, and Suggestibility: An Integrative Model (2015) walks through the steps in a hypnosis session and describes various contributing factors (much like this page does) that go into it, including a description of response sets. In particular, the paper points out that the best results are achived with those "motivated by curiosity, the wish to achieve an altered state of consciousness, and succeed at the task at hand."

In recreational hypnosis, motivation is something that improves naturally with every positive session. It’s common for people who are lukewarm or even slightly negative on hypnosis to become highly motivated as they find what works for them and what they really enjoy in the experience.

An educational training procedure called the Carleton Skill Training Program (CSTP) was developed to model effective hypnotic behavior and has shown good results. The original CSTP is over an hour long, but a four minute version is just as effective, and is reproduced here.

The CSTP does a good job of describing imagination, but the language is a bit stiff. Another way of phrasing the same idea is the automatic imagination model, which asks the hypnotee to follow the suggestion intentionally, then imagine that the suggestion is automatic.

Here’s a Youtube video showing a demonstration of the automatic imagination model:

One of the concepts that both the CSTP and the automatic imagination model recommend is to evoke the feeling of automaticity and involuntariness while making the responses, and then internalize that feeling.

This goes beyond response expectancy and ties into a theory of hypnosis as self deception, where deliberately role-playing and thinking of a response as involuntary can make subsequent responses feel more involuntary. This is a fascinating paper that has elements of suspension of disbelief, followed by resolution of cognitive dissonance that crosses over into self-gaslighting.

Along the same lines, adding implementation instructions of the form "I will suppress any thoughts about my intended behavior while performing the tasks!" and then adding the if-then plan "And if I receive a new task, then I will tell myself: Suppress now any thoughts about my intended behavior!" also provides an increase in hypnotic responsiveness.

As implied by the CSTP and the automatic imagination model, hypnosis is not a stable trait; in other words, hypnosis is a skill that can be improved with practice.

Academic papers tend to focus on many participants rather than building the skills of a few. Likewise, hypnosis is typically treated in books as an introduction for hypnotees, and does not focus on skill-building. The exception is Mind Games, which consists of hypnosis exercises broken up into four sections of increasing difficulty.

Recreational hypnosis has several instances of people who have improved their ability over the years through consistent practice and feedback. In particular, sleepingirl has written extensively on becoming a skilled subject along with specific exercises for exploring spontaneity, getting comfortable with thoughts, and understanding process.

Hypnosis, Hypnotic Phenomena, and Hypnotic Responsiveness: Clinical and Research Foundations — A 40-Year Perspective (2019) describes a "readiness to respond" ability factor which seems to characterize some common behaviors in highly hypnotizable individuals. Integrative response set theory (2022) discusses the readiness response set in more detail — An Empirically-Informed Integrative Theory of Hypnosis (2024) also digs even deeper into this but is not covered here.

The paper breaks down into three main areas: singlemindedness, cognitive flexibilty, and a focus on attainable goals. Some of this may be strategy based, and some may be hard-wired abilities. Some combination of neurological differences may have an impact on readiness, as brain correlates have been found in highly hypnotizable individuals, such as differences in central executive network (CEN) and default network (DN) processing.

Singlemindedness

The paper lists four factors that together can be classified as "singlemindedness of thought."

Cognitive Flexibility

In addition, somehow these individuals are very good at translating imaginings into "felt sensations."

Attainable Goals

Finally, highly hypnotizable individuals tend to set attainable goals to meet the suggestion using whatever skills and creativity they have.

Some of the techniques can be seen in this case comparison that gives helpful examples of intentional belief, saying "in order to block out the third box, you just tell yourself that you don’t see it."

Unfortunately, asking this question is tantamount to asking what hypnosis really is, with the same problems. Wikipedia has a subsection saying "Hypnotic suggestibility is a trait-like, individual difference variable reflecting the general tendency to respond to hypnosis and hypnotic suggestions." Specifically, suggestibility is an indication on an experimental scale of how many suggestions the hypnotee can follow, ranging from lifting an arm to amnesia and hallucination.

There’s been criticism about the methodology of suggestibility scales, and more recent studies prefer component models of suggestibility showing differences in responsiveness to suggestion or even discount the concept of suggestibility altogether.

Is there anything more we can pull from the academic literature that has been proven to increase suggestibility?

Unfortunately, it’s far easier to show what has been proven to not increase suggestibility. This blog post on myths and misconceptions provide the most accurate overview.

Looking at all the recent papers, there are ways to improve general suggestibility beyond what has already been mentioned. We can look at specific techniques of the people who are the best at hypnosis, and we can practice exercises that are hypnosis-adjacent to encourage different patterns of thought.

Neurofeedback appears to be a way to increase suggestibility, although I suspect that any focused interoception would produce the same results.

It’s possible to manipulate the environment such that people think a hypnotic suggestion is working. you can take a lightbulb and change the color very slightly and convince people that their perception is changing in response to hypnotic suggestion. This will cause them to be more responsive to other suggestions in general, even after telling them how it worked. This approach appears to work well even without a hypnotic context and can be attributed to pavlovian conditioning.

Another possible technique is to let the hypnotee provide their own suggestions. One paper (I cannot find it right now) related the story of a woman, given the suggestion that she could not speak because words wouldn’t come out, instead gave herself the suggestion that a man was choking her. Giving the hypnotee a suggestion to provide the most effective suggestion does seem like cheating, but it importantly gives the hypnotee some creative freedom and agency in suggestions.

Most people fail "Simon Says" because it requires response inhibition against expectancy. A good suggestibility maximizer would be one that adds ambiguity, lowers inhibition, and increases impulsivity: in short, alcohol. The study involved around 5 glasses of wine over 30 minutes for a 70kg (154lb) person, which frankly sounds like overkill if all you want to do is fuzz perception a bit. For recreational purposes, I’d say one glass of wine during the pre-talk is fine.

A recent study found that people with lower responsiveness may benefit from tDCS, but it was ineffective on medium-high responsiveness and this is not a DIY activity.

Another study looked at increasing responsiveness with TMS but this got heavily dinged on review.

Oxytocin was found to increase the level of hypnotic responding in low hypnotizable people, probably due to increase in rapport.

I have not seen research into how exercises like wake-initiated lucid dreaming or imagination based activities like improv classes could alter baseline suggestibility, but I suspect any activity that encourages flexible perception and exercising belief would help.

More directly, this paper looked the research on the effectiveness on hypnotic inductions. One of the recommendations was the finding that increase absorption and reduce critical thinking, with endearingly clunky suggestions like "Allow yourself to let go completely …​ don’t question what you’re being asked to do and experience …​ just go with the flow" and "Allow yourself to feel completely focused …​ let your attention narrow down …​ focus only on the things I say …​ and the things I ask you to experience and do."