Psychological Inoculation for Credibility Assessment, Sharing Intention, and Discernment of Misinformation: Systematic Review and Meta-Analysis

Background The prevalence of misinformation poses a substantial threat to individuals’ daily lives, necessitating the deployment of effective remedial approaches. One promising strategy is psychological inoculation, which pre-emptively immunizes individuals against misinformation attacks. However, uncertainties remain regarding the extent to which psychological inoculation effectively enhances the capacity to differentiate between misinformation and real information. Objective To reduce the potential risk of misinformation about digital health, this study aims to examine the effectiveness of psychological inoculation in countering misinformation with a focus on several factors, including misinformation credibility assessment, real information credibility assessment, credibility discernment, misinformation sharing intention, real information sharing intention, and sharing discernment. Methods Following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines, we conducted a meta-analysis by searching 4 databases (Web of Science, APA PsycINFO, Proquest, and PubMed) for empirical studies based on inoculation theory and outcome measure–related misinformation published in the English language. Moderator analyses were used to examine the differences in intervention strategy, intervention type, theme, measurement time, team, and intervention design. Results Based on 42 independent studies with 42,530 subjects, we found that psychological inoculation effectively reduces misinformation credibility assessment (d=–0.36, 95% CI –0.50 to –0.23; P<.001) and improves real information credibility assessment (d=0.20, 95% CI 0.06-0.33; P=.005) and real information sharing intention (d=0.09, 95% CI 0.03-0.16; P=.003). However, psychological inoculation does not significantly influence misinformation sharing intention (d=–0.35, 95% CI –0.79 to 0.09; P=.12). Additionally, we find that psychological inoculation effectively enhances credibility discernment (d=0.20, 95% CI 0.13-0.28; P<.001) and sharing discernment (d=0.18, 95% CI 0.12-0.24; P<.001). Regarding health misinformation, psychological inoculation effectively decreases misinformation credibility assessment and misinformation sharing intention. The results of the moderator analyses showed that content-based, passive inoculation was more effective in increasing credibility and sharing intention. The theme of climate change demonstrates a stronger effect on real information credibility. Comparing intervention types showed that pre-post interventions are more effective for misinformation credibility assessment, while post-only interventions are better for credibility discernment. Conclusions This study indicated that psychological inoculation enhanced individuals’ ability to discern real information from misinformation and share real information. Incorporating psychological inoculation to cultivate an informed public is crucial for societal resilience against misinformation threats in an age of information proliferation. As a scalable and cost-effective intervention strategy, institutions can apply psychological inoculation to mitigate potential misinformation crises.


Information sources
6 Specify all databases, registers, websites, organisations, reference lists and other sources searched or consulted to identify studies.Specify the date when each source was last searched or consulted.

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Search strategy 7 Present the full search strategies for all databases, registers and websites, including any filters and limits used.Appendix 1 Selection process 8 Specify the methods used to decide whether a study met the inclusion criteria of the review, including how many reviewers screened each record and each report retrieved, whether they worked independently, and if applicable, details of automation tools used in the process.

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Data collection process 9 Specify the methods used to collect data from reports, including how many reviewers collected data from each report, whether they worked independently, any processes for obtaining or confirming data from study investigators, and if applicable, details of automation tools used in the process.

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where item is reported Data items 10a List and define all outcomes for which data were sought.Specify whether all results that were compatible with each outcome domain in each study were sought (e.g. for all measures, time points, analyses), and if not, the methods used to decide which results to collect.
Appendix 3 10b List and define all other variables for which data were sought (e.g.participant and intervention characteristics, funding sources).Describe any assumptions made about any missing or unclear information. 7 Study risk of bias assessment 11 Specify the methods used to assess risk of bias in the included studies, including details of the tool(s) used, how many reviewers assessed each study and whether they worked independently, and if applicable, details of automation tools used in the process.

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Effect measures 12 Specify for each outcome the effect measure(s) (e.g.risk ratio, mean difference) used in the synthesis or presentation of results.7 Synthesis methods 13a Describe the processes used to decide which studies were eligible for each synthesis (e.g.tabulating the study intervention characteristics and comparing against the planned groups for each synthesis (item #5)).

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13b Describe any methods required to prepare the data for presentation or synthesis, such as handling of missing summary statistics, or data conversions.

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13c Describe any methods used to tabulate or visually display results of individual studies and syntheses.6-7 13d Describe any methods used to synthesize results and provide a rationale for the choice(s).If meta-analysis was performed, describe the model(s), method(s) to identify the presence and extent of statistical heterogeneity, and software package(s) used.

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13e Describe any methods used to explore possible causes of heterogeneity among study results (e.g.subgroup analysis, meta-regression).6-7 13f Describe any sensitivity analyses conducted to assess robustness of the synthesized results.

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Reporting bias assessment 14 Describe any methods used to assess risk of bias due to missing results in a synthesis (arising from reporting biases).19 For all outcomes, present, for each study: (a) summary statistics for each group (where appropriate) and (b) an effect estimate and its precision (e.g.confidence/credible interval), ideally using structured tables or plots.

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Results of syntheses 20a For each synthesis, briefly summarise the characteristics and risk of bias among contributing studies.

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20b Present results of all statistical syntheses conducted.If meta-analysis was done, present for each the summary estimate and its precision (e.g.confidence/credible interval) and measures of statistical heterogeneity.If comparing groups, describe the direction of the effect.

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20c Present results of all investigations of possible causes of heterogeneity among study results.7-13 20d Present results of all sensitivity analyses conducted to assess the robustness of the synthesized results.

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Reporting biases 21 Present assessments of risk of bias due to missing results (arising from reporting biases) for each synthesis assessed.
methods used to assess certainty (or confidence) in the body of evidence for an outcome.7RESULTSStudy selection16a Describe the results of the search and selection process, from the number of records identified in the search to the number of studies included in the review, using a flow diagram.516bCite studies that might appear to meet the inclusion criteria, but which were excluded, and explain why they were excluded.