Does phase-modulation of applied 40-Hz transcerebral magnetic fields affect subjective experiences and hypnotic induction?

Perceptual and motor skills · 2003 · Mixed · Low evidence

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MixedLow evidencePaper 3708

Study snapshot

PublicationPerceptual and motor skills · 2003

Study typerandomized_trial

Reported directionMixed

Evidence ratingLow

Abstract

12 men and 12 women were exposed to a sham-field, a 5-Hz sine-wave magnetic field, a 40-Hz sine-wave magnetic field, or the latter field-phase modulated five times per sec. (5-Hz) for 30 min. between two administrations of the Spiegel's Hypnotic Induction Profile. To replicate the geometry that has produced significant increases in these scores in previous studies, the weak (1 microT) magnetic fields were applied over the right parietotemporal region through a modified helmet. The hypothesis that the enhanced suggestibility previously observed was due to an intrinsic phase-modulation of the fields was not supported. However, the ratings of overall pleasantness of the experiences were negatively correlated (r = -.36) with global geomagnetic activity at the time of the experiment. The pleasantness was ranked significantly greater by subjects exposed to the 40-Hz field (explaining 41% of the variance) relative to subjects exposed to the 5-Hz field who also reported more visual experiences within their left peripheral visual fields. The percentages of time alpha rhythms were measured over the temporal lobes (but not frontal or occipital lobes) during the treatments were moderately and positively correlated with scores on questionnaires administered before the experiment, from which the capacity to imagine, temporal lobe signs, and religious (but not exotic) beliefs were inferred. The groups exposed to either the 5-Hz or 40-Hz/5-Hz phase-modulated field displayed greater durations of alpha rhythms over the temporal lobes than the other two groups.

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AI evidence extraction

Structured fields below were generated from the paper’s abstract and metadata to make the evidence easier to inspect. Automated extraction may be incomplete or incorrect; verify important details against the original paper.

Study typerandomized_trial

Effect directionmixed

Population12 men and 12 women

Sample size24

ExposureELF · 30 min

Evidence strengthLowConfidence: 74% · Peer reviewed: yes

Main findings

Participants were exposed to sham, 5-Hz, 40-Hz, or 40-Hz phase-modulated at 5 times/sec magnetic fields (1 microT) over the right parietotemporal region for 30 minutes between two hypnotic induction assessments. The hypothesis that enhanced suggestibility was due to intrinsic phase-modulation was not supported. Pleasantness ratings were higher in the 40-Hz group than the 5-Hz group, and pleasantness was negatively correlated with global geomagnetic activity (r = -0.36). The 5-Hz group reported more left peripheral visual experiences, and the 5-Hz and 40-Hz/5-Hz phase-modulated groups showed greater durations of temporal-lobe alpha rhythms than the other two groups.

Outcomes measured

Spiegel's Hypnotic Induction Profile (hypnotic induction/suggestibility)
Subjective experience ratings (overall pleasantness)
Visual experiences (left peripheral visual field)
EEG alpha rhythms (temporal lobes)
Correlations with geomagnetic activity
Questionnaire-derived traits (capacity to imagine, temporal lobe signs, religious beliefs)

Limitations

Randomization/blinding procedures not described in the abstract
No quantitative results reported for hypnotic induction outcomes beyond stating the hypothesis was not supported
Small sample size (n=24)
Exposure details beyond intensity (1 microT), location (right parietotemporal), and waveform conditions are not provided in the abstract

View raw extracted JSON

{
  "study_type": "randomized_trial",
  "exposure": {
    "band": "ELF",
    "source": "transcerebral magnetic field (helmet-applied)",
    "frequency_mhz": null,
    "sar_wkg": null,
    "duration": "30 min"
  },
  "population": "12 men and 12 women",
  "sample_size": 24,
  "outcomes": [
    "Spiegel's Hypnotic Induction Profile (hypnotic induction/suggestibility)",
    "Subjective experience ratings (overall pleasantness)",
    "Visual experiences (left peripheral visual field)",
    "EEG alpha rhythms (temporal lobes)",
    "Correlations with geomagnetic activity",
    "Questionnaire-derived traits (capacity to imagine, temporal lobe signs, religious beliefs)"
  ],
  "main_findings": "Participants were exposed to sham, 5-Hz, 40-Hz, or 40-Hz phase-modulated at 5 times/sec magnetic fields (1 microT) over the right parietotemporal region for 30 minutes between two hypnotic induction assessments. The hypothesis that enhanced suggestibility was due to intrinsic phase-modulation was not supported. Pleasantness ratings were higher in the 40-Hz group than the 5-Hz group, and pleasantness was negatively correlated with global geomagnetic activity (r = -0.36). The 5-Hz group reported more left peripheral visual experiences, and the 5-Hz and 40-Hz/5-Hz phase-modulated groups showed greater durations of temporal-lobe alpha rhythms than the other two groups.",
  "effect_direction": "mixed",
  "limitations": [
    "Randomization/blinding procedures not described in the abstract",
    "No quantitative results reported for hypnotic induction outcomes beyond stating the hypothesis was not supported",
    "Small sample size (n=24)",
    "Exposure details beyond intensity (1 microT), location (right parietotemporal), and waveform conditions are not provided in the abstract"
  ],
  "evidence_strength": "low",
  "confidence": 0.74,
  "peer_reviewed_likely": "yes",
  "keywords": [
    "ELF magnetic field",
    "40 Hz",
    "5 Hz",
    "phase modulation",
    "1 microT",
    "right parietotemporal",
    "helmet",
    "hypnotic induction",
    "suggestibility",
    "pleasantness",
    "visual experiences",
    "EEG alpha rhythms",
    "geomagnetic activity"
  ],
  "suggested_hubs": [
    {
      "slug": "other",
      "weight": 0.2,
      "reason": "Experimental ELF magnetic field exposure with neuropsychological/EEG outcomes; no clear match to specific RF/5G/Wi-Fi/occupational hubs."
    }
  ]
}

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AI-extracted fields are generated from the abstract and metadata and may be incomplete or incorrect. This material is for informational purposes and is not medical advice.

Identifiers and source

DOI: 10.2466/pms.2003.97.3f.1031
PubMed: 15002842

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