The four-month experiment involved semi-automated AI accounts posting 1,783 comments across r/changemyview threads, with researchers creating fictional personas including sensitive identities such as sexual assault victims, trauma counselors, and individuals with specific political views.12 These AI-generated comments were crafted in two distinct styles: generic responses addressing general opinions, and personalized comments tailored to users' inferred attributes (age, gender, ethnicity, location, political orientation) which were extracted from their public Reddit history using a separate AI model.34

All AI-generated content underwent manual review by the research team before posting "to ensure no harmful or inappropriate content" was shared, though this did not prevent the ethical issues that later emerged.5 The effectiveness of the AI's persuasive abilities was measured using "Deltas" (∆), awards given by CMV users to comments that successfully changed their views, with the experiment ultimately collecting 137 Deltas across the AI-generated comments.46

The AI-powered accounts demonstrated remarkable persuasion capabilities, achieving success rates three to six times higher than average human users on the subreddit.12 Particularly effective were the personalized AI comments, which reached the 99th percentile of human performance for collecting Deltas, with an overall persuasion rate of up to 18% compared to the typical human baseline of approximately 3%.31

Perhaps most concerning was that throughout the entire experiment, not a single Reddit user detected that they were interacting with AI-generated content rather than genuine human participants.4 This inability to distinguish between human and AI-generated arguments highlights the sophisticated nature of modern language models and raises significant questions about the future of online discourse and the potential for undetected AI manipulation in public forums.24

The experiment violated multiple ethical standards and platform rules, including Reddit's user agreement and the subreddit's explicit ban on undisclosed AI and bots.12 CMV moderators characterized the research as "psychological manipulation" and emphasized that the creation of sensitive personas-such as sexual assault survivors and domestic violence victims-put vulnerable users at risk of emotional harm.34 Particularly troubling was that the University of Zurich's ethics board had initially approved a more limited study, but researchers expanded its scope without seeking additional review.5

Despite researchers' claims that their work was necessary to understand AI's real-world persuasive capabilities before malicious actors could exploit them, critics pointed out that conducting experiments without informed consent fundamentally undermines research ethics.67 The controversy highlights growing tensions between academic research goals and digital ethics, especially as AI becomes increasingly indistinguishable from human communication in online spaces.89

In response to the controversy, Reddit announced it was issuing "formal legal demands" against the researchers for violating the platform's terms of service.1 The company's chief legal officer confirmed that the experiment violated site rules, while CMV moderators banned all accounts associated with the research and requested that the university block publication of the findings.21

The University of Zurich issued a formal warning to the lead investigator and committed to improving coordination with research subjects in future studies.2 This incident follows a similar controversy where OpenAI previously used content from r/ChangeMyView to test its AI models' persuasiveness, suggesting a troubling pattern of researchers viewing Reddit communities as experimental laboratories without proper consent protocols.3