In the mid-1950s, hypnosis was not a respectable subject for a psychologist. It belonged to stage performers and a few clinicians. Research on it was patchy, and nobody could agree on how to tell whether a person was hypnotized, let alone how much.
One of the most eminent psychologists in America decided to change that. He had nothing to prove and a reputation to lose.
An unlikely champion
Ernest Ropiequet Hilgard, known as Jack, was born in Illinois in 1904. He first trained as a chemical engineer, considered the ministry, and then turned to psychology, taking his doctorate at Yale. He joined Stanford University in 1933 and stayed for the rest of his career.
By the 1950s he was at the top of his field: an authority on learning, a former president of the American Psychological Association, and author of an introductory textbook used by generations of students.
In 1957, with André Weitzenhoffer, he founded the Laboratory of Hypnosis Research at Stanford. That a scientist of his standing would take hypnosis seriously made others willing to.
His wife, Josephine Hilgard, a psychiatrist, was a close collaborator and an important researcher in her own right.
Measuring it
Hilgard’s first insight was that a science needs measurement.
With Weitzenhoffer he developed the Stanford Hypnotic Susceptibility Scales: Forms A and B in 1959, and Form C in 1962. Each consists of a standard induction followed by twelve suggestions of increasing difficulty, each scored pass or fail.
The scales made several things possible.
- Comparing results between laboratories
- Selecting high and low responders for experiments
- Showing that responsiveness varies widely and follows a roughly bell-shaped curve
- Tracking the same people over time
Form C is still treated as a gold standard.
A stable trait
Using the scales, Hilgard’s group showed that hypnotizability is a stable characteristic of a person. In a famous follow-up, people first tested as students were tested again 25 years later. Their scores had barely changed.
The lab also found that hypnotizability peaks in late childhood, and that it has little to do with the personality traits people had assumed, such as gullibility or submissiveness.
Pain
Hilgard made pain a central subject. Using ice water and tourniquets to produce safe laboratory pain, his group showed that:
- Hypnotic suggestion reduced pain substantially
- The reduction was greatest in the most hypnotizable people
- It was more than could be explained by relaxation or reduced anxiety
- It differed from placebo in highly hypnotizable subjects
This work laid the foundation for the clinical use of hypnosis in pain. His book with Josephine Hilgard, Hypnosis in the Relief of Pain, became a standard text. She also studied hypnosis for children with cancer.
The hidden observer
In the 1970s came his most famous and most disputed finding. A hypnotized person with a hand in ice water, given suggestions of no pain, would report feeling little. But if told that a “hidden part” could report what was really happening, by pressing a key or writing, that part reported much more pain.
Hilgard called it the hidden observer, a metaphor for a part of the mind that registers what is kept from awareness.
Neodissociation theory
From this he built a general theory. The mind, he proposed, contains multiple systems of control, normally coordinated by a central executive. In hypnosis these become partly separated. A suggestion may be carried out by one system while the executive is unaware of having initiated it, which is why hypnotic responses feel involuntary.
He set this out in his 1977 book Divided Consciousness.
The critics
Hilgard’s theory was strongly challenged. The psychologist Nicholas Spanos showed that hidden observer reports changed according to what subjects were told to expect: tell them the hidden part felt more pain and it did, tell them it felt less and it did. On that view, the hidden observer was produced by the instructions.
The argument between Hilgard’s “state” view and the “sociocognitive” view became the central debate in the field. It has never been fully settled, though most researchers now accept elements of both.
Hilgard took criticism seriously and engaged with it carefully, which was characteristic.
Josephine Hilgard
Her contributions deserve separate mention. Through long interviews with students, she found that hypnotizable people tended to have a history of deep imaginative involvement: in reading, drama, music, religion or nature. Her work was a forerunner of later research on absorption.
Legacy
Hilgard retired formally in the late 1960s but carried on working for decades. He died in 2001, aged 97.
What he left:
- Measurement, without which there is no science
- Respectability for a neglected subject
- A body of findings on pain, individual differences and stability
- A generation of researchers trained at Stanford
- A theoretical framework that still shapes the debate
What it means for you
- When you read that 10 to 15 per cent of people are highly hypnotizable, that comes from scales he built.
- When hypnosis is offered for pain, it rests on work he began.
- When someone says hypnosis feels involuntary, he gave the most influential account of why.
The bottom line
Hilgard did not discover hypnosis. He made it possible to study it properly. By building reliable measures and running careful experiments, an eminent scientist turned a fringe topic into a field, and gave later researchers something solid to argue about.
Next in the series: Hypnosis vs Sleep: Why They Are Not the Same Thing
This article is for general information and is not medical advice.