Single-Exposure Messages for Child Sexual Abuse Prevention: A Randomized Controlled Online Trial Testing Educational and Humanizing Approaches

Background Child sexual abuse and exploitation, including online material depicting such acts, constitute a major public health concern. Effective prevention requires public understanding and destigmatization, yet communication strategies on this topic face persistent misconceptions and strong emotional reactions. This randomized controlled online study examined whether brief educational and humanizing communication interventions could improve knowledge, attitudes, and behavioral intentions related to prevention, while avoiding adverse emotional or ethical effects. Methods A total of 2,019 adults from Spain and Portugal were recruited via an online panel and randomly assigned to one of four conditions: an educational message, a humanizing message with empathy focus, a humanizing message with prevention focus, or a neutral control message. Each intervention consisted of a short video and accompanying text presented as part of a health information campaign. Measures included affective state, stigma-related attitudes, literacy about therapeutic options, openness toward the topic, and behavioral intention to seek information. Linear mixed-effects, nonparametric longitudinal, and ordinal mixed-effects models were used to assess intervention effects over time. Moderation analyses examined demographic influences, and chi-square tests assessed differences in dropout rates. Results Exposure to any intervention message led to significant short-term changes in affective responses, with lower positive valence and slightly higher arousal compared to the control group (medium effect for valence, small for arousal). No significant differences emerged for stigma dimensions, knowledge, openness, or behavioral intentions. All three intervention formats performed similarly. No evidence of adverse or rebound effects on stigma or help-seeking beliefs was observed. Moderation analyses revealed that gender, education, parental status, language background, and adverse childhood experiences influenced affective or attitudinal responses, whereas age did not. Dropout rates did not differ across conditions, indicating no differential attrition. Conclusions Brief, ethically sound communication interventions can evoke emotional engagement without increasing stigma or avoidance. While single exposures appear insufficient to change attitudes or behavior, such formats may serve as a foundation for repeated, multi-channel prevention messaging integrated into broader educational efforts. Trial registration German Clinical Trials Register (DRKS), DRKS00038927, retrospectively registered on 09/01/2026.