Correlations between within-subject variability of pain intensity reports and rubber hand illusion proprioceptive drift

Duarte Santos, Mariana Agostinho, Roi Treister, Rita Canaipa

Research output: Contribution to journalArticlepeer-review


Introduction: Consistent with the Bayesian brain hypothesis, the within-subject variability of pain intensity reports as captured with the Focused Analgesia Selection Test (FAST) might be a surrogate measure of the certainty in ascending noxious signals. The outcomes of a non-pain-related task, the rubber hand illusion, were hypothesized to reflect the same construct. This study aimed to explore whether within-subject differences in variability of pain intensity reports and the outcomes of the rubber hand illusion might be related. Methods: Nonclinical participants underwent the classic rubber hand illusion under synchronous (experimental) and asynchronous (control) conditions. Two outcomes were assessed: proprioceptive drift and feeling of ownership. Thereafter, participants underwent the FAST to assess the within-subject variability of pain reports in response to heat stimuli. Intraclass correlation (ICC) and the correlation coefficient (R2) were the main outcomes. Spearman's correlations were used to assess associations between the outcomes of the 2 tasks. Results: Thirty-six volunteers completed the study. Both FAST outcomes—ICC (Spearman's r = 0.355, p = 0.033) and R2 (Spearman's r = 0.349, p = 0.037)—were positively correlated with proprioceptive drift in the synchronous but not asynchronous conditions (p > 0.05). The subjective feeling of ownership and FAST outcomes did not correlate (p > 0.05). Conclusions: The associations between the 2 tasks’ outcomes imply that both tasks at least partly assess similar constructs. Current knowledge suggests that this construct represents the person's certainty in perceiving ascending sensory signals, or, in Bayesian terminology, the certainty of the likelihood.

Original languageEnglish
Article number137319
JournalNeuroscience Letters
StatePublished - 27 Jul 2023

Bibliographical note

Publisher Copyright:
© 2023 Elsevier B.V.


  • Bayesian brain
  • Pain assessment
  • Predictive coding
  • Rubber hand illusion
  • Within-subject variability

ASJC Scopus subject areas

  • General Neuroscience


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