Warning messages have been used to disrupt individuals seeking online child sexual abuse material (CSAM) and promote engagement with support services, yet large-scale field evidence on message content remains limited, particularly in high anonymity environments. This study reports a field experiment on Ahmia.fi, a Tor search engine, examining how warning message content influences behavior. Across a 140-day period, almost 20 million searches were observed, with over 3 million searches containing known CSAM-related terms that triggered a warning linking to an anonymous self-help program. Users were exposed to warning messages varying in thematic content and framing, or a neutral message. Across a randomized comparison, a campaign-wide analysis, and interrupted time series models, message content consistently influenced engagement with help resources. All active messages increased click-through rates to help resources relative to the neutral condition, with a harm-focused message producing the strongest effects. At the platform level, click-through rates increased from 8.73% before the intervention to 15.67% during the campaign. These findings highlight the importance of message content in shaping responses to warning interventions, supporting an approach in which messaging is refined and adapted to increase engagement with support resources.

翻译：警告信息已被用于阻断个体搜索儿童性虐待材料（CSAM）并促进其参与支持服务，但关于信息内容的大规模实地证据仍然有限，尤其是在高匿名性环境中。本研究在Tor搜索引擎Ahmia.fi上进行了一项实地实验，考察警告信息内容如何影响行为。在140天的观察期内，共记录了近2000万次搜索，其中超过300万次搜索包含已知的CSAM相关术语，这些搜索触发了指向匿名自助程序的警告信息。用户被暴露于主题内容和框架各异的警告信息，或中性信息。通过随机对比、全活动分析以及中断时间序列模型，信息内容始终影响用户对帮助资源的参与度。所有积极信息相较于中性条件均提高了帮助资源的点击率，其中以危害为主题的信息效果最为显著。在平台层面，点击率从干预前的8.73%上升至活动期间的15.67%。这些发现凸显了信息内容在塑造对警告干预反应中的重要性，支持通过优化和调整信息内容以增加用户对支持资源参与度的策略。