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Trait responsiveness to verbal suggestions predicts placebo responses: A multi-level meta-analysis
Background: Placebo responding involves the reduction of symptoms in response to contextual features of an intervention (e.g., verbal suggestions), yet it is characterized by pronounced heterogeneity. Although verbal suggestions are widely recognised as a hallmark method for inducing placebo responses, an open question is whether variability in placebo responding can be partly attributed to individual differences in trait responsiveness to verbal suggestions (REVS). We conducted a pre-registered meta-analysis (PROSPERO registration number CRD420250654692) to quantitatively synthesize available research on the association between trait REVS and placebo responding. Methods: PsycInfo, PubMed, MEDLINE, and Embase were searched up to June 2026 for original clinical or experimental studies involving both the assessment of REVS and symptom measures (self-report, behavioural, and/or physiological) in response to an inactive intervention (placebo). Results: Of 1,512 search results, 24 articles presenting 66 correlations between REVS and placebo responding were analysed (N = 1,137). A multi-level meta-analysis revealed a significant, albeit weak, positive correlation between REVS and placebo responses, r = 0.18 [95% CI: 0.13, 0.24], such that individuals with higher REVS reported greater symptom relief in response to the placebo. Meta-regression analyses did not identify any significant moderators of the correlation between REVS and placebo responding and sensitivity analyses based on Bayesian subgroup estimates indicated that the aggregate correlation was stable across methodological quality indicators and study features. Conclusion: These findings suggest that individual differences in REVS may partly explain variability in symptom reduction in response to placebos, with implications for the sources of variance in placebo effects in experimental and applied contexts. ### Competing Interest Statement The authors have declared no competing interest. ### Clinical Protocols <https://www.crd.york.ac.uk/PROSPERO/view/CRD420250654692> ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes All data relevant to the present meta-analysis is provided in the article. Data are freely available from previous research studies.
