Summary

Suggestion Effects

Madeline Stein, 1. 4. 2025

At the research meeting with Madeline Stein, a PhD student from King's College London, we explored a wide range of areas where the influence of suggestion plays a key role in shaping human experience and behavior. Our discussion covered the following topics:

Hypnosis, where suggestion is used to support therapeutic goals;
Placebo and nocebo effects, with meta-analytic evidence showing that higher suggestibility predicts stronger nocebo responses;
Advertising and fake news, where individuals differ in their responsiveness due to varying levels of suggestibility;
Psychopathology, especially in dissociative disorders, where suggestibility, trauma, and dissociation are deeply interconnected;
Forensics, particularly in the context of interrogative suggestibility;
Implicit suggestions, such as subtle cues that influence perception, as seen in the case of phantom limb experiences potentially shaped by suggestion.

Suggestibility is a relatively stable trait that develops through childhood, peaks in adolescence, and remains largely consistent in adulthood. It is normally distributed in the general population and shows high variability among highly suggestible individuals. A hallmark of classic suggestion effects is the feeling of involuntariness—the sense that the response is not consciously controlled.

We distinguish between direct (hypnotic and non-hypnotic) and indirect (e.g., sensory or interrogative) suggestibility. Direct suggestibility is typically measured using behavioral scales that assess the degree of response to progressively more complex suggestions. One such measure is the Phenomenological Control Scale, which captures non-hypnotic verbal suggestibility.

Related concepts discussed include:

Compliance – the conscious decision to follow instructions without an actual shift in experience;
Expectations, which can influence both perception and behavior, and are often difficult to separate from suggestibility in experimental settings;
Context, which often acts as a moderating variable but can also have a direct effect. For example, a study by Olson et al. (2020) found that participants reported psychedelic experiences without receiving any actual substances—highlighting the powerful role of contextual cues.

The meeting raised important questions about how both explicit and implicit suggestions shape experience and how such effects can be rigorously studied in complex settings.