Running head: THE SIMULATION-ADAPTION THEORY OF HYPNOSIS 1 How hypnotic suggestions work – critical review of prominent theories and a novel synthesis Anoushiravan Zahedi*, Werner Sommer Humboldt Universität zu Berlin Author Note * Corresponding Author; Institut für Psychologie, Humboldt-Universität zu, Rudower Chaussee 18, 12489, Berlin, Germany. E-mail address:
[email protected] THE SIMULATION-ADAPTION THEORY OF HYPNOSIS 2 Abstract Hypnotic and posthypnotic suggestions are frequently and successfully implemented in behavioral, neurocognitive, and clinical investigations and interventions. Despite abundant reports about the effectiveness of suggestions in altering behavior, perception, cognition, and subjective sense of agency (SoA), there is no consensus about the neurocognitive mechanisms driving these changes. The present review starts with procedural descriptions of hypnosis, suggestions, and suggestibility, followed by a systematic and comparative review of prominent theories of hypnosis, highlighting their strengths and weaknesses, based on their power to explain existing observations in the domain of hypnosis. Thereafter, we propose a novel theory of hypnosis, accounting for empirical evidence and synthesizing concepts from hypnosis and neurocognitive theories. The proposed simulation- adaption theory of hypnosis (SATH) is founded on three elements: cognitive-simulation, top-down sensory-adaptation, and mental training. SATH mechanistically explains different hypnotic phenomena, such as alterations in the SoA, positive and negative hallucinations, motor suggestions, and effects of suggestions on executive functions and memory. Finally, based on SATH and its postulated neurocognitive mechanisms, a procedure-oriented definition of hypnosis is proposed. Keywords: Cognitive Control, Sense of Agency, Hypnotic Suggestions (HS), Posthypnotic Suggestions (PHS), Hypnosis, Suggestibility, Hypnotizability, Cognitive Simulation, Top-Down Sensory Adaption, Predictive Coding Model, Mental Practice, Imagination, Executive Functions.