AI Bots Posed as Trauma Survivors on Reddit to Study Persuasion, Without Telling Anyone
What happened
A team of researchers at the University of Zurich ran an AI experiment on Reddit from November 2024 to March 2025 without telling the people it was studying. Over several months, they deployed AI-powered bots to post 1,783 comments in r/changemyview, a subreddit built around civil debate and deliberate opinion change. The bots were not labeled as bots. Moderators were not informed. The participants in the experiment were the ordinary Reddit users who responded to those comments, and none of them consented.
The bots did not post generic arguments. They were built to persuade. Before each interaction, the system scraped a target user's Reddit history and analyzed it to infer personal attributes, including political orientation, gender, age, and ethnicity, then used those inferences to tailor arguments to what the user was most likely to find convincing. Some bot personas were given sensitive identities, among them rape survivors and trauma counselors. These were not edge cases. They were deliberate choices designed to maximize credibility and persuasive impact in a forum where personal experience carries weight.
When the study came to light, it drew widespread condemnation from researchers, ethicists, and the affected community. The University of Zurich team defended the work by arguing that understanding AI's capacity to influence public opinion at scale is a legitimate research goal, one that could help identify and counter manipulation by bad actors. That framing did not hold. The university's own ethics board had not approved the specific methods used, and the conduct violated subreddit rules that explicitly prohibit undisclosed bots and AI-generated content.
The harm is not hypothetical. Users who received these targeted, fabricated arguments changed their positions in some cases without knowing they were interacting with a machine trained on their own history. Many reported feeling manipulated and violated once the study was revealed. The experiment showed that AI-driven persuasion can operate invisibly inside real human communities, indistinguishable from genuine peer conversation. That is precisely what made the researchers' justification circular: the risk they claimed to be studying was the risk they were simultaneously deploying.
The incident exposes a gap that ethics review boards are only beginning to catch up with. Academic oversight of AI-powered behavioral research has no standard requirement for a provable record of what a system did during a study, which personas were deployed, which users were targeted, and on what basis. Without that trail, an experiment can run for months, affect thousands of real people, and leave no audit path that outside reviewers can verify or challenge. That absence is the accountability failure the incident points to, not just the choices researchers made, but the missing infrastructure that would have made those choices visible before the study ended.
Reported impact
- Affected parties
- Not publicly disclosed
- Harm type
- Not publicly disclosed
- Scale
- Not publicly disclosed
- Financial impact
- Not publicly disclosed
- Regulatory action
- Not publicly disclosed
Classification
Relevant governance controls
Governance control mapping is not available for this record.
- No controls mapped
Not publicly disclosed
Control mapping is analytical. It does not state that any control would have prevented the incident.
Sources and evidence
This record was researched and written by the Index. The event is also catalogued in the following database, which is listed for cross-reference.