PSYC 444 - Topic 5: Experimental Hypnosis & Measuring Hypnotizability

Development of Scales:
- Stanford and Harvard scales are two primary methods for measuring hypnotizability.
- Incorporates historical insights from 19th-century French literature and earlier experiments regarding hypnosis depth.
- Incorporates previous attempts that looked at the depth of state hypnosis
Transition in Scale Design:
- Shifted from assessing depth of state to evaluating performance based on response diversity and difficulty.
Significance:
- Created standardized processes for scientific experimentation.
- Established scale norms that are recognized in over 20 countries.

Harvard Scale Items:
- Head falling
- Eye closure
- Hand lowering (left)
- Arm immobilization (right)
- Finger lock
- Arm rigidity (left)
- Hands moving together
- Communication inhibition
- Fly hallucination
- Eye catalepsy
- Posthypnotic suggestion
- Posthypnotic amnesia
Stanford Scale Items:
- Hand lowering (right)
- Moving hands apart
- Mosquito hallucination
- Taste hallucination
- Arm rigidity (right)
- Dream induction
- Age regression
- Arm immobilization (left)
- Anosmia to ammonia
- Hallucinated voice
- Negative visual hallucination
- Posthypnotic amnesia

Stanford Hypnotic Susceptibility Scale: Form C Test Items:
1. Hand lowering (right): Subject imagines a weight pulling down the hand.
2. Moving hands apart: Suggestion of a force pushing hands apart leads to motion.
3. Mosquito hallucination: Responses to hallucinated presence of a mosquito.
4. Taste hallucination: Sensation of sweet or sour taste upon suggestion.
5. Arm rigidity: Inability to bend the arm when suggested it is stiff.
6. Dream: Report of dreaming about hypnosis upon suggestion.
7. Age regression: Subject behaves and writes as younger self during suggestion.
8. Arm immobilization: Suggestion makes subject feel unable to lift the arm.
9. Anosmia: Inability to smell ammonia during suggestion.
10. Hallucinated voice: Responding to imagined questions via intercom suggestion.
11. Negative visual hallucination: Reporting seeing fewer objects than present.
12. Posthypnotic amnesia: Inability to recall experiences during hypnosis.
Harvard Group Hypnotic Susceptibility Scale: Form A Items:
- Similar list with specific descriptions for each test item aligned with the Harvard scale.

Types of Suggestions:
- Ideomotor Items:
  - Thinking of a movement elicits a corresponding motor response (Direct-ideomotor)
  - Examples: arm lowering, head falling.
- Challenge Items:
  - Combines ideomotor item followed by a counter-suggeestion (Challenge-ideomotor)
  - Examples: arm rigidity, finger clasp.
- Cognitive Items:
  - Based on imaginative or cognitvely-based suggestions (Perceptual/Cognitive).
  - Examples: hallucinations, regression, amnesias, dream states, amnesia.

Three Factor Structures Model:
- F1: Ideomotor responses
- F2: Challenge responses
- F3: Cognitive responses
Reference to structural equation modeling and the study by Zahedi and Sommer (2021).

Overview of suggestion categories:
- Direct Ideomotor: (e.g., head falling, eye closure)
- Challenge Ideomotor: (e.g., arm rigidity, communication inhibition)
- Cognitive-Perceptual: (e.g., hallucinations, posthypnotic suggestions).
G-Factor:
- If we throw 12 items in, do we have a good factor, no. not all factors are not hanging in there or related enough with other items to fit.
Three-Factor Model
- Ideomotor, challenge, and cognitive item are separated

Cognitive-Simulation Suggestions:
- Process enhances predictions based on sensory inputs.
- The suggestion fits what you would normally do in that situation (eventually). You’re ready to do it, it makes sense to you cognitively, so you do it.
Simulation-Adaptation Suggestions:
- Involves adaptation following simulation experiences.
- There is a sensory adaptation, as there’s a challenge item here (response to challenge item, e.g., “you’ll have trouble undoing your hands”). Your brain makes a sensory adaptation in order to not feel like you can do something that you normally can do.
Problem-Solving Suggestions:
- Relates to executive functions utilizing mental practices (e.g., cognitive-perceptual).
- Brain has a novel strategy in order to allow you to hear something that doesn’t exist (for the hearing a fly example).
Takeaway:
- Each different category of suggestions is associated with different brain gymnastics, so-to-speak
It may also be easier for some people to do motor stuff but not experience cognitive stuff (related to hypnotizability).

Item Difficulty Index (DI):
- Scales ranked by proportion of subjects passing each item.
- High DI indicates easier items.
- Items generally ranked from ideomotor to cognitive concerning difficulty.
- Comparison of suggestibility types and responses.

Average percentage data across various samples indicating item difficulty over the years, highlighting stability across trials.

Graph illustrating mean depth of hypnosis responses across HGSHS:A items, showcasing distributions in subject experiences based on their responses.
Depth of experience of hypnotization related to hypnotizability

Subjective reports on awareness during hypnosis with data on feelings of compulsion, changes in perception, and experiences related to different susceptibility levels.
Diverse responses across high, medium, low, and non-susceptible classifications.

Comparative analysis of classification between HGSHS:A and SHSS:C scales to evaluate correlations among hypnotizability determined by different methods.

Statistical correlations assessed between several hypnotic susceptibility scales, indicating similarity in measuring hypnotizability.
This highlights the convergence of different measurement tools used in research.

Test-retest reliability highlights that hypnotizability is stable across lifespan with peak measurements noted before teenage years.
Basically, your hypnotizability level cements at ages 12-13, and this remains for the remainder of the lifespan. It is a reliable measure: test-retest reliability is over .70 (more stable than IQ)

Allows for standardized measurement of hypnotizability or non-hypnotic suggestibility
Makes it easier to compare results from different experiments
If not measured, difficult to differentiate context effects from hypnotizability effects
Hypnotizability can be looked at as a stable individual difference across the lifespan
A major factor in both intrinsic and instrumental research on hypnosis