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Somatosensory illusions elicited by sham electromagnetic field exposure: Experimental evidence for a predictive processing account of somatic symptom perception

Psychosomatic medicine · 2020 · Mixed · Moderate evidence

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MixedModerate evidencePaper 1772

In a randomized on/off sham Wi-Fi condition after viewing a film promoting adverse EMF health effects, participants expecting a Wi-Fi signal showed a significantly more liberal response bias (c) for tactile stimuli (p = .010, ηp = .08), consistent with increa…

Study snapshot

PublicationPsychosomatic medicine · 2020
Study typerandomized_trial
Reported directionMixed
Evidence ratingModerate

Abstract

Somatosensory illusions elicited by sham electromagnetic field exposure: Experimental evidence for a predictive processing account of somatic symptom perception Carolin Wolters, Jana Harzem, Michael Witthöft, Alexander L Gerlach, Anna Pohl. Somatosensory illusions elicited by sham electromagnetic field exposure: experimental evidence for a predictive processing account of somatic symptom perception. Psychosom Med. 2020 Nov 2. doi: 10.1097/PSY.0000000000000884. Abstract Objective: According to the predictive processing theory of somatic symptom generation, body sensations are determined by somatosensory input and central nervous predictions about this input. We examined how expectations shape predictions and consequently bodily perceptions in a task eliciting illusory sensations as laboratory analogue of medically unexplained symptoms. Methods: Using the framework of signal detection theory, the influence of sham Wi-Fi on (i) response bias (c) and (ii) somatosensory sensitivity (d') for tactile stimuli was examined using the somatic signal detection task (SSDT). A healthy student sample (n = 83) completed the SSDT twice (sham Wi-Fi on/off) in a randomized order after watching a film that promoted adverse health effects of electromagnetic fields (EMF). Results: When expecting a Wi-Fi signal to be present, participants showed a significantly more liberal response bias c (p = .010, ηp = .08) for tactile stimuli in the SSDT as evidence of a higher propensity to experience somatosensory illusions. No significant alteration of somatosensory sensitivity d' (p = .76, ηp < .002) was observed. Conclusions: Negative expectations about the harmfulness of EMF may foster the occurrence of illusory symptom perceptions via alterations in the somatosensory decision criterion. The findings are in line with central tenets of the predictive processing account of somatic symptom generation. This account proposes a decoupling of percept and somatosensory input so that perception becomes increasingly dependent on predictions. This biased perception is regarded as a risk factor for somatic symptom disorders. pubmed.ncbi.nlm.nih.gov

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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
PopulationHealthy student sample
Sample size83
ExposureNot supplied
Evidence strengthModerateConfidence: 74% · Peer reviewed: yes

Main findings

In a randomized on/off sham Wi-Fi condition after viewing a film promoting adverse EMF health effects, participants expecting a Wi-Fi signal showed a significantly more liberal response bias (c) for tactile stimuli (p = .010, ηp = .08), consistent with increased somatosensory illusions. Somatosensory sensitivity (d') was not significantly altered (p = .76, ηp < .002).

Outcomes measured

  • Response bias (c) in somatic signal detection task (SSDT)
  • Somatosensory sensitivity (d') for tactile stimuli in SSDT
  • Propensity to experience somatosensory illusions under sham Wi-Fi expectation

Limitations

  • Exposure was sham Wi-Fi (expectation/nocebo context rather than actual EMF exposure)
  • Sample consisted of healthy students, which may limit generalizability
View raw extracted JSON
{
  "study_type": "randomized_trial",
  "exposure": {
    "band": null,
    "source": "Wi-Fi (sham)",
    "frequency_mhz": null,
    "sar_wkg": null,
    "duration": null
  },
  "population": "Healthy student sample",
  "sample_size": 83,
  "outcomes": [
    "Response bias (c) in somatic signal detection task (SSDT)",
    "Somatosensory sensitivity (d') for tactile stimuli in SSDT",
    "Propensity to experience somatosensory illusions under sham Wi-Fi expectation"
  ],
  "main_findings": "In a randomized on/off sham Wi-Fi condition after viewing a film promoting adverse EMF health effects, participants expecting a Wi-Fi signal showed a significantly more liberal response bias (c) for tactile stimuli (p = .010, ηp = .08), consistent with increased somatosensory illusions. Somatosensory sensitivity (d') was not significantly altered (p = .76, ηp < .002).",
  "effect_direction": "mixed",
  "limitations": [
    "Exposure was sham Wi-Fi (expectation/nocebo context rather than actual EMF exposure)",
    "Sample consisted of healthy students, which may limit generalizability"
  ],
  "evidence_strength": "moderate",
  "confidence": 0.74,
  "peer_reviewed_likely": "yes",
  "keywords": [
    "sham EMF exposure",
    "Wi-Fi",
    "expectations",
    "nocebo",
    "predictive processing",
    "somatic symptom perception",
    "somatosensory illusions",
    "signal detection theory",
    "SSDT"
  ],
  "suggested_hubs": [
    {
      "slug": "school-wi-fi",
      "weight": 0.55,
      "reason": "Study uses sham Wi-Fi exposure as the experimental context for symptom perception."
    }
  ]
}
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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: 10.1097/psy.0000000000000884
PubMed: 33141791

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