Hypnotic depth scales:
how deep is deep enough?

The Stanford Hypnotic Susceptibility Scale — Form C

The Stanford Hypnotic Susceptibility Scale, Form C (SHSS:C) was developed by André Weitzenhoffer and Ernest Hilgard and published in 1962. It remains one of the better-known standardised research instruments. A trained assessor presents a sequence of suggestions and scores the person's responses using defined criteria. The 12 scored items yield a total between 0 and 12. [1, 2]

The original presentation also includes an initial eye-closure procedure, often called item 0, but this is not included in the 12-point score. The list below preserves the subject matter of the original blog while making the scoring distinction clearer.

These are descriptive item names, not the full copyrighted test instructions or clinical assessment criteria. Administration and interpretation require appropriate training. Items involving odours, hallucinations or regression should not be improvised with clients.

How is it scored?

Each item is scored against an established criterion. The total represents the number of items passed (0–12), not how far a person travelled along a staircase of progressively deeper hypnotic states. It is possible to respond to a later item without responding to an earlier one. A higher total generally indicates greater responsiveness on that test; it does not mean a person has reached a medically defined depth of trance.

Modern reviews also point out limitations of binary pass/fail scoring, one-off assessments and the fact that different suggestions tap different experiences. These limitations matter when we try to draw conclusions about an individual. [1, 10]

The Friedlander–Sarbin scale

Joseph Friedlander and Theodore Sarbin developed an influential early measure of response to hypnotic suggestions in 1938. Their work helped shape later systematic approaches, including the Stanford scales. Rather than simply asking whether a subject felt hypnotised, the assessor looked for responses to a range of specified tasks. [3]

Descriptions of the historical twelve-item scale commonly include postural sway, hand movements, catalepsy, verbal inhibition and amnesia. The original article listed the following sequence, which I have preserved here as a historical teaching overview:

This is a historical summary rather than a reproduced, validated scoring manual. Exact wording and procedure should be checked against the original instrument before any formal research use.

This scale is worth understanding because it helps explain why much early hypnosis research concentrated on observable phenomena. It also reminds us that modern measurement developed gradually: later scales attempted to make assessment more standardised and comparable between participants and studies.

Harry Arons and the traditional six stages

Many hypnosis practitioners will have come across Harry Arons' six-stage depth model. Unlike the Stanford Form C test, this is best understood as a traditional descriptive framework used in hypnosis teaching, not a modern, validated six-step measurement that every person must progress through.

It gives us useful historical vocabulary, but it should not be mistaken for six clinically proven levels of brain function.

Two words are sometimes linked with the lighter end of this discussion. Hypnagogic refers to experiences around falling asleep, while hypnopompic refers to the transition out of sleep. They can be useful comparisons, but hypnosis is not simply the same as sleep, and these terms should not be treated as diagnostic stages of hypnosis.

As a teaching tool, the Arons model offers a way to talk about phenomena historically associated with different levels of responsiveness. As a scientific measurement, however, I would place greater weight on well-researched instruments and on the person's actual experience rather than on trying to assign them a stage number.

Do we always need a hypnotic induction?

This is where the discussion becomes particularly interesting. Research has demonstrated that people can respond to imaginative suggestions without a formal hypnotic induction. One study found that imaginative suggestibility and response expectations predicted responses in hypnotic and non-hypnotic conditions, while its induction manipulation did not show an additional effect in that experiment. [5]

It would be a mistake, though, to turn this into a universal claim that inductions do nothing. Different studies use different methods, suggestions and populations. Inductions may influence the experience of absorption, expectations or responses in some circumstances. Research continues to examine when these factors matter.

In Solution Focused Hypnotherapy, I use guided relaxation and carefully considered suggestions as part of a collaborative process when suitable. For most clients, I am not trying to manufacture impressive phenomena. I'm interested in creating a comfortable, respectful opportunity to pause, focus and explore helpful possibilities alongside the therapeutic conversation.

If you are interested in the practical distinction, my related article on suggestibility tests in hypnosis looks at why they are used, including in training and demonstration settings.

Does a higher score mean better therapy results?

Not necessarily. There is evidence that higher hypnotisability is associated with greater benefit from some hypnosis interventions, but the relationship is variable and not strong enough to make an individual promise. A meta-analysis involving 10 clinical studies reported a small overall association between hypnotic suggestibility and treatment outcomes. [7]

A later clinical discussion also highlights the limited number of studies that directly examine this question and the importance of considering treatment type and context. [6]

And what about expectations?

Expectations can influence how we engage with suggestions and how we interpret an unfamiliar experience. But I would avoid telling a client that the mind “cannot tell the difference between what is real and imagined”. That phrase is too broad to be scientifically accurate.

Instead, I prefer to be straightforward: a low test score does not mean somebody has failed, lacks imagination or can never benefit from an appropriate intervention. Nor does a high score guarantee improvement. We should discuss individual needs, the evidence and alternatives, and review what is actually changing.

What matters in a Solution Focused Hypnotherapy session?

When somebody comes to see me, I don't start by asking how dramatic a hypnotic experience I can produce. I want to understand what has brought them to therapy, what they would like to be different and how we can approach those goals safely and realistically.

That means paying attention to the things which matter outside the therapy room: confidence, coping, sleep, decisions, day-to-day behaviour and how the person themselves describes progress. Hypnosis or guided relaxation may be part of that work when appropriate; it is not an obligation or a substitute for an assessment of the underlying concern.

1. Begin with the person, not a score. Listen, clarify their aims and explore the most suitable options.
2. Explain hypnosis accurately. People usually retain awareness and choice, and responses vary.
3. Choose techniques for a reason. A relaxation exercise or suggestion should support an agreed purpose, rather than demonstrate hypnotic prowess.
4. Check suitability and consent. Consider mental and physical health, medication, safeguarding and referral where appropriate.
5. Review meaningful outcomes. Ask what is changing in the person's life, not simply whether they felt “deep”.

This perspective is also central to my work as a lecturer. Learning the history of hypnosis is worthwhile, but professional practice depends on knowing the difference between an interesting demonstration and a safe, evidence-informed therapeutic decision.

For a broader introduction to how I work, see About Gary Smith. If you're exploring professional training, visit the Hypnotherapy in Practice Diploma information.

What about hypnosis during surgery?

My original article mentioned work at the University of Liège in Belgium. This is a useful example, but it is important to describe it correctly. A published clinical report from the Liège team described more than 1,400 surgical patients since 1992 who received hypnosis alongside local anaesthesia and conscious sedation. The authors reported associations with patient comfort, anxiety, medication requirements and recovery in their clinical experience. [8]

That is very different from claiming that people routinely undergo surgery under hypnosis alone, that a certain score is required, or that everybody recovers faster. The earlier figure of 12,000 cases was not sufficiently established in the source I could verify, so I have not repeated it as a fact.

Research and sources

This article distinguishes historical practice models from findings based on standardised research. The references below are included for readers and students who would like to explore the evidence more closely.

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