A meta-analysis of 54 cases testing the effectiveness of inoculation theory at conferring resistance and examining the mechanisms of the theory was conducted. The analyses revealed inoculation messages to be superior to both supportive messages and notreatment controls at conferring resistance. Additionally, the results revealed refutational same and refutational different preemptions to be equally effective at reducing attitude change. However, the data were not consistent with some predictions made in narrative reviews of inoculation. No significant increase in resistance as a function of threat or involvement was found. Further, instead of a curvilinear effect for delay on resistance, the point estimates from our meta-analysis revealed equivalent resistance between immediate and moderate delays between inoculation and attack, with a decay in resistance after two weeks.

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This investigation examined the boundaries of inoculation theory by examining how inoculation can be applied to conspiracy theory propaganda as well as inoculation itself (called metainoculation). A 3‐phase experiment with 312 participants compared 3 main groups: no‐treatment control, inoculation, and metainoculation. Research questions explored how inoculation and metainoculation effects differ based on the argument structure of inoculation messages (fact‐ vs. logic‐based). The attack message was a 40‐minute chapter from the 9/11 Truth conspiracy theory film, Loose Change: Final Cut. The results indicated that both the inoculation treatments induced more resistance than the control message, with the fact‐based treatment being the most effective. The results also revealed that metainoculation treatments reduced the efficacy of the inoculation treatments.

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This paper presents a meta-analysis of 79 cases (N = 21,857) testing the effectiveness of mediated intergroup contact on prejudice. Positive mediated contact decreased (r = −.23; 95% CI, −.29 to −.17), whereas negative mediated contact increased prejudicial attitudes (r = .31; 95% CI, .24 to .38) and intergroup anxiety and empathy were both significant mediators of these relationships. Furthermore, the data revealed no significant differences between parasocial and vicarious effects, positive and negative mediated-contact effects, or the effects of the duration of mediated-contact stimulus exposure on prejudice. However, the data did reveal experiments to have stronger effects than survey research. These and other results are discussed along with implications, limitations, and future research directions.