Event Related Potential Studies of Hypnotic Suggestion (2026)
Barbara Schmidt
Institute of Psychosocial Medicine, Psychotherapy and Psychooncology, Jena University Hospital, Jena, Germany
Correspondence: barbara@barbara-schmidt.de
Keywords: Hypnosis; event related potentials; EEG; hypnotic suggestion; cognitive neuroscience
Hypnotic suggestions can profoundly alter perception and subjective experience. One of the most important tools for investigating these effects is the event-related potential (ERP), a method derived from electroencephalography (EEG) that measures rapid changes in brain activity following specific stimuli or events. ERP studies have helped clarify how hypnotic suggestions influence sensory processing, attention, conflict monitoring, and conscious awareness (Oakley & Halligan, 2009).
ERPs are especially useful in hypnosis research because they provide millisecond-level temporal resolution. This allows researchers to examine whether hypnotic suggestions alter early sensory processing, later cognitive evaluation, or both. ERP components are conventionally named according to the direction of the electrical deflection, positive (P) or negative (N), and its approximate timing after an event in milliseconds. Thus, an N100 is a negative deflection occurring at approximately 100 milliseconds, whereas a P300 is a positive deflection occurring at approximately 300 milliseconds. Components investigated in hypnosis research include the N100, P300, N400, and error-related negativity (ERN), each associated with different stages of information processing (Kallio et al., 2001; Oakley & Halligan, 2009).
One major area of ERP hypnosis research concerns suggested changes in perception. Studies of hypnotically suggested deafness or blindness have shown altered ERP responses to auditory or visual stimuli (Franz et al., 2020; Schmidt et al., 2017). In some cases, early sensory ERP components remain relatively intact, suggesting that sensory input still reaches the brain, while later components associated with conscious evaluation or attention are reduced. This pattern supports the idea that hypnotic suggestion may modify higher-order processing rather than completely blocking incoming sensory information.
A well-known example comes from suggested deafness. In the study by Franz et al. (2020), participants received suggestions that they could no longer hear tones. During the suggested deafness condition, participants reported a marked reduction in perceived loudness, while ERP recordings showed changes in later auditory processing. Importantly, the subjective experience of reduced hearing was therefore accompanied by measurable changes in cortical responses. These findings illustrate how hypnotic suggestion can alter the conscious experience of sound without simply eliminating basic auditory processing.
Similarly, ERP studies of suggested perceptual alterations have examined phenomena such as hypnotic blindness, color changes, and pain reduction (Oakley & Halligan, 2009). In hypnotic analgesia research, painful stimuli can continue to elicit early somatosensory responses, while later neural responses associated with the evaluation of pain are altered. This pattern is consistent with the subjective experience that a stimulus may still be detected while its unpleasantness or significance is reduced.
Another important line of research investigates attention and cognitive control. Hypnotic suggestions can influence conflict processing in tasks such as the Stroop paradigm. Suggestions that words are meaningless symbols, for instance, can reduce Stroop interference (Raz et al., 2006), while ERP studies indicate that hypnosis can also alter neural processes involved in conflict monitoring and cognitive control (Egner et al., 2005). Together, these findings suggest that hypnotic suggestion can modulate how competing information is monitored and controlled.
ERP studies have also contributed to debates about the mechanisms of hypnosis. Some theories propose that hypnosis reflects top-down changes in attention, expectation, and cognitive control rather than a fundamentally altered state of consciousness (Oakley & Halligan, 2009; Terhune et al., 2011). ERP findings support the view that hypnotic suggestions can influence multiple stages of information processing, although the extent and timing of these changes depend on hypnotic responsiveness, task demands, and the specific suggestion used (Kallio et al., 2001; Terhune et al., 2011).
ERP evidence also demonstrates that hypnotic experiences can be accompanied by measurable neurophysiological changes. Studies comparing hypnosis with instructed simulation have identified differences in subjective experience and cortical responses, although such differences can be subtle, and their interpretation remains debated (Franz et al., 2020). These findings are important because they allow researchers to examine how reported changes in experience relate to changes in brain processing rather than relying on subjective reports alone.
Despite important advances, ERP hypnosis research faces several challenges. As in other areas of hypnosis research, studies often include relatively small samples, particularly when highly hypnotizable participants are selected. Methodological differences can also complicate comparisons across studies. These include differences in hypnotic suggestibility scales and participant selection, as well as ERP-specific choices such as EEG preprocessing pipelines, artifact correction, component definitions, and analysis techniques. ERP measures alone also cannot fully determine whether an observed change reflects altered perception, attention, response selection, or subjective interpretation. Combining ERP methods with behavioral, phenomenological, and neuroimaging approaches may therefore provide a more comprehensive understanding of hypnotic suggestion (Oakley & Halligan, 2009).
Overall, ERP studies have significantly advanced scientific understanding of hypnosis by demonstrating that hypnotic suggestions can influence brain processes involved in perception, attention, and awareness. By linking subjective experiences to rapidly changing neural responses, ERP research provides a particularly useful window into when and how suggestion shapes conscious experience.
References
Egner, T., Jamieson, G., & Gruzelier, J. (2005). Hypnosis decouples cognitive control from conflict monitoring processes of the frontal lobe. NeuroImage, 27(4), 969–978. https://doi.org/10.1016/j.neuroimage.2005.05.002
Franz, M., Schmidt, B., Hecht, H., Naumann, E., & Miltner, W. H. R. (2020). Suggested deafness during hypnosis and simulation of hypnosis compared to a distraction and control condition: A study on subjective experience and cortical brain responses. PLOS ONE, 15(11), Article e0240832. https://doi.org/10.1371/journal.pone.0240832
Kallio, S., Revonsuo, A., Hämäläinen, H., Markela, J., & Gruzelier, J. (2001). Anterior brain functions and hypnosis: A test of the frontal hypothesis. International Journal of Clinical and Experimental Hypnosis, 49(2), 95–108. https://doi.org/10.1080/00207140108410061
Oakley, D. A., & Halligan, P. W. (2009). Hypnotic suggestion and cognitive neuroscience. Trends in Cognitive Sciences, 13(6), 264–270. https://doi.org/10.1016/j.tics.2009.03.004
Raz, A., Kirsch, I., Pollard, J., & Nitkin-Kaner, Y. (2006). Suggestion reduces the Stroop effect. Psychological Science, 17(2), 91–95. https://doi.org/10.1111/j.1467-9280.2006.01669.x
Schmidt, B., Hecht, H., Naumann, E., & Miltner, W. H. R. (2017). The power of mind: Blocking visual perception by hypnosis. Scientific Reports, 7, Article 4889. https://doi.org/10.1038/s41598-017-05195-2
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