Research Article
The Existence of a Hypnotic State Revealed by Eye Movements
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1 School of Humanities and Informatics, University of Skövde, Skövde, Sweden, 2 Centre for Cognitive Neuroscience, University of Turku, Turku, Finland, 3 Department of Psychology, University of Turku, Turku, Finland, 4 Brain Research Unit, Low Temperature Laboratory, Aalto University School of Science, Espoo, Finland, 5 Department of Biomedical Engineering and Computational Science, Aalto University School of Science, Espoo, Finland, 6 Turku PET Centre, University of Turku, Turku, Finland
Abstract Top
Hypnosis has had a long and controversial history in psychology, psychiatry and neurology, but the basic nature of hypnotic phenomena still remains unclear. Different theoretical approaches disagree as to whether or not hypnosis may involve an altered mental state. So far, a hypnotic state has never been convincingly demonstrated, if the criteria for the state are that it involves some objectively measurable and replicable behavioural or physiological phenomena that cannot be faked or simulated by non-hypnotized control subjects. We present a detailed case study of a highly hypnotizable subject who reliably shows a range of changes in both automatic and volitional eye movements when given a hypnotic induction. These changes correspond well with the phenomenon referred to as the “trance stare” in the hypnosis literature. Our results show that this ‘trance stare’ is associated with large and objective changes in the optokinetic reflex, the pupillary reflex and programming a saccade to a single target. Control subjects could not imitate these changes voluntarily. For the majority of people, hypnotic induction brings about states resembling normal focused attention or mental imagery. Our data nevertheless highlight that in some cases hypnosis may involve a special state, which qualitatively differs from the normal state of consciousness.
Citation: Kallio S, Hyönä J, Revonsuo A, Sikka P, Nummenmaa L (2011) The Existence of a Hypnotic State Revealed by Eye Movements. PLoS ONE 6(10): e26374. doi:10.1371/journal.pone.0026374
Editor: Jan Lauwereyns, Kyushu University, Japan
Received: May 26, 2011; Accepted: September 26, 2011; Published: October 24, 2011
Copyright: © 2011 Kallio et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Funding: This study was supported by the Signe and Ane Gyllenberg Foundation (http://www.gyllenberg-foundation.fi/en/foundation/) (S.K. and P.S.), the Academy of Finland and by the aivoAALTO Grant (121031) from Aalto University (L.N.). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Competing interests: The authors have declared that no competing interests exist.
* E-mail: sakari.kallio@his.se
Editor: Jan Lauwereyns, Kyushu University, Japan
Received: May 26, 2011; Accepted: September 26, 2011; Published: October 24, 2011
Copyright: © 2011 Kallio et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Funding: This study was supported by the Signe and Ane Gyllenberg Foundation (http://www.gyllenberg-foundation.fi/en/foundation/) (S.K. and P.S.), the Academy of Finland and by the aivoAALTO Grant (121031) from Aalto University (L.N.). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Competing interests: The authors have declared that no competing interests exist.
* E-mail: sakari.kallio@his.se
