The American Psychological Association published a study comparing the effects of hypnosis, ordinary suggestion, and placebo in reducing pain. The study found that highly suggestible individuals experienced a greater reduction in pain from hypnosis compared with placebo, whereas less suggestible subjects experienced no pain reduction from hypnosis when compared with placebo. Ordinary non-hypnotic suggestion also caused reduction in pain compared to placebo, but was able to reduce pain in a wider range of subjects (both high and low suggestible) than hypnosis. The results showed that it is primarily the subject's responsiveness to suggestion, whether within the context of hypnosis or not, that is the main determinant of causing reduction in pain.
In a July 2001 article for Scientific American titled "The Truth and the Hype of Hypnosis", Michael Nash wrote that, "using hypnosis, scientists have temporarily created hallucinations, compulsions, certain types of memory loss, false memories, and delusions in the laboratory so that these phenomena can be studied in a controlled environment."
Not every person is hypnotizable to the same degree; some aren’t hypnotizable at all. “Hypnotizability … is modestly correlated with absorption, a personality construct reflecting a disposition to enter states of narrowed or expanded attention and a blurring of boundaries between oneself and the object of perception,” writes John F. Kihlstrom, a psychologist at the University of California, Berkeley, in a 2013 paper in Cortex. “Absorption, in turn, is related to ‘openness to experience,’ one of the ‘Big Five” dimensions of personality.”
In 10th grade my school brought a celebrity hypnotist for an event. My friend signed me up without knowing and we were called up in front of the entire school. First he has us do an experiment with our hands and how we wouldn't be able to open them - then he choose 7 people and we got to be "hypnotized" for the rest of the event (15 mins or so). I got "picked on" the most for the stuff (forgetting my name, forgetting the number 6) were the one's i did alone. Others were (playing a violin, using your shoe as a phone). I remember actively playing along in order to put on a good show - and he choose us because we were willing to play along.
Braid made a rough distinction between different stages of hypnosis, which he termed the first and second conscious stage of hypnotism; he later replaced this with a distinction between "sub-hypnotic", "full hypnotic", and "hypnotic coma" stages. Jean-Martin Charcot made a similar distinction between stages which he named somnambulism, lethargy, and catalepsy. However, Ambroise-Auguste Liébeault and Hippolyte Bernheim introduced more complex hypnotic "depth" scales based on a combination of behavioural, physiological, and subjective responses, some of which were due to direct suggestion and some of which were not. In the first few decades of the 20th century, these early clinical "depth" scales were superseded by more sophisticated "hypnotic susceptibility" scales based on experimental research. The most influential were the Davis–Husband and Friedlander–Sarbin scales developed in the 1930s. André Weitzenhoffer and Ernest R. Hilgard developed the Stanford Scale of Hypnotic Susceptibility in 1959, consisting of 12 suggestion test items following a standardised hypnotic eye-fixation induction script, and this has become one of the most widely referenced research tools in the field of hypnosis. Soon after, in 1962, Ronald Shor and Emily Carota Orne developed a similar group scale called the Harvard Group Scale of Hypnotic Susceptibility (HGSHS).