Ganzfeld-induced hallucinatory experience, its phenomenology and cerebral electrophysiology.
Jirí Wackermann, Peter Pütz, Carsten Allefeld
Cortex 2008 DOI: 10.1016/j.cortex.2007.05.003 (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Review Peer reviewed |
|---|---|
| Topics | Philosophy of mind |
| Key findings | Argues that ganzfeld-induced percepts are not hypnagogic in origin; the steady-state is an activated state, and alpha EEG dynamics reveal attention shifts and percept formation. Contends that 'ganzfeld telepathy' research depends on unsupported hypotheses and weak conceptual grounding, with belief systems playing a role. |
Abstract
Ganzfeld, i.e., exposure to an unstructured, uniform stimulation field, elicits in most observers pseudo-hallucinatory percepts, and may even induce global functional state changes ('altered states of consciousness'). The present paper gives a comprehensive overview of the phenomenology of subjective experience in the ganzfeld and its electrophysiological correlates. Laboratory techniques for visual or multi-modal ganzfeld induction are explained. The spectrum of ganzfeld-induced phenomena, ranging from elementary percepts to complex, vivid, dream-like imagery is described, and the latter illustrated by transcripts of subjects' reports. Similarities and differences to related sensory/perceptual phenomena are also discussed. Earlier findings on electrophysiological correlates of the ganzfeld are reviewed. Our own studies of electroencephalographic (EEG) activity in the ganzfeld are presented in some detail, and a re-analysis of data on EEG correlates of hallucinatory percepts in statu nascendi is reported. The results do not support the hypothesis of the hypnagogic origin of the percepts; the ganzfeld-induced steady-state is an activated state, and the spectral EEG dynamics in the alpha frequency range reveals processes of attention shifts and percept formation. The final section is devoted to the controversial topic of allegedly anomalous communication between human subjects ('ganzfeld telepathy'). It is shown that the use of ganzfeld in this research field relies partly on unsupported hypotheses concerning ganzfeld-induced states, partly on a weak conceptual background of the experimental procedure. The rôle of a particular belief system shared by the participants and experimenters is critically discussed.
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Citations in the library
Cited by 34
- A phenomenology of meditation-induced light experiences: traditional buddhist and neurobiological perspectives Frontiers in Psychology 2014
- The incidence and determinants of visual phenomenology during out-of-body experiences Cortex June 6, 2008
- Altered states phenomena induced by visual flicker light stimulation PLoS One July 1, 2021
- Time Perception and the Experience of Time When Immersed in an Altered Sensory Environment Frontiers in Human Neuroscience October 6, 2017
- The Phenomenology of “Pure” Consciousness as Reported by an Experienced Meditator of the Tibetan Buddhist Karma Kagyu Tradition. Analysis of Interview Content Concerning Different Meditative States Philosophies June 17, 2021
and 29 more in the library
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