Learning pain from others: a systematic review and meta-analysis of studies on placebo hypoalgesia and nocebo hyperalgesia induced by observational learning.

"raw data used for the analyses is available in supplementary table s5"

"Sponsorships or competing interests that may be relevant to content are disclosed at the end of this article."

"The work was funded by a grant awarded by the National Science Centre in Poland (grant no. 2019/35/B/HS6/04320). Neither the study nor the open access license of the publication was funded by the Strategic Programme Excellence Initiative at the Jagiellonian University, Kraków, Poland."

"The review protocol was designed according to the Preferred Reporting Items for Systematic Review and Meta-Analyses Protocols (PRISMA-P checklist form) guidelines. It follows the recommendations for data searching and data processing described in the Cochrane Handbook for Systematic Reviews and was preregistered in the PROSPERO database (ID: CRD42021241091). All reviewers were trained in the screening and extraction procedures before conducting these stages. The review procedures were piloted to ensure the validity and consistency of the assessment strategies. The search and assessment criteria were discussed and standardized a priori."