A Systematic Review and Meta-Analysis of Implicit Stigma Toward People with Mental Illness Among Different Groups: Measurement, Extent, and Correlates.

Introduction: Implicit association tests have been extensively applied to reveal socially unacceptable and concealed stigma. Studies have explored the implicit stigma toward mental illness in specific groups, with limited comparisons across different groups. To investigate the implicit stigma toward mental illness among different groups, along with the interaction between implicit and explicit measurements. Methods: Based on PRISMA guidelines, Web of Science, Embase, PubMed/MEDLINE, Cochrane Library, and PsycINFO were searched from 1998 to April 18, 2024. Searches were updated through February 12, 2025. The Medical Education Research Quality Instrument (MERSQI) served as the quality evaluation framework, and Stata 12.0 facilitated the conduct of a meta-analysis. Results: The analysis included fifty studies in the systematic review and thirty in the meta-analysis. Most studies used "mental illness" or related physical illness terms as concept words, paired with emotionally contrasting attribute words. Twenty-eight studies calculated the implicit effect using an improved algorithm, while thirty-eight examined the correlations between implicit and explicit measures. The pooled standardized mean differences (SMDs) revealed that the lowest Conclusion: The findings indicated that the selection of concept and attribute words, as well as the processing of data measuring implicit stigma, was not standardized. No reliable correlation was found between implicit and explicit measures. Despite the heterogeneity of included studies, the general public demonstrated the most positive attitudes, while individuals with mental illness exhibited negative attitudes. Further research is required to develop personalized anti-stigma interventions for different groups and regions based on these results, particularly from the perspective of implicit stigma.