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Mobile instant messaging services (MIMS) such as WhatsApp and Telegram are used to spread misinformation, yet evidence on effective countermeasures within these spaces is limited. Guided by inoculation theory, we conducted an online experiment ( N = 154) to examine the extent to which refutational-same (argument-matched) inoculation or cross-protection (cross-topic) conditions influence the credibility and sharing of false and true information within MIMS. We analyzed whether critical thinking abilities, information literacy, and messenger use moderate the effectiveness of these measures. Results show that refutational-same inoculation only reduced the perceived credibility of misinformation but did not lower sharing intentions, whereas no cross-protection effects were observed. Overall, inoculation had no effect on credibility or sharing of true information. No moderators were detected across critical thinking measures, information literacy, or messenger use, although political orientation consistently predicted perceived credibility and sharing intentions of misinformation. These results suggest that inoculation messages within MIMS might be more effective when they are content-specific.
Ancina et al. (2026) studied this question.