Behind the scenes in one of Reddit’s largest communities, something creepy has been brewing. For four months, AI-powered bots masqueraded as humans, swaying opinions and earning thousands of upvotes.
The experiment appeared to be working—until everyone found out.
Reddit announced plans earlier this week to tighten user verification after learning that researchers from the University of Zurich conducted an unauthorized experiment on the r/changemyview subreddit, using AI bots to manipulate users without their knowledge or consent.
The researchers had deployed the bots, which used sensitive personas—including trauma counselors, sexual assault survivors, and controversial political identities—from late 2024 to early 2025, and posted over 1,700 comments. The AI entities also analyzed users’ posting histories to craft persuasive, personalized responses—all without disclosing that they were AI agents.
In a post to the community, Reddit’s Chief Legal Officer Ben Lee condemned the experiment as “deeply wrong on both a moral and legal level,” citing violations of the platform’s user agreement and research ethics. The company has banned all accounts linked to the research and filed formal complaints with the University of Zurich.
Keeping Reddit human means sharing more info
“Reddit works because it’s human,” CEO Steve Huffman wrote in a recent platform update. “It’s one of the few places online where real people share real opinions… If we lose trust in that, we lose what makes Reddit… Reddit.”
The experiment hit at the heart of what makes online communities function: trust. Moderators described it as “psychological manipulation,” noting that users join the subreddit expecting genuine human interactions, not to be unwitting test subjects.
That said, the AI bots were remarkably effective, collecting over 20,000 upvotes and 137 “deltas”—awards given when someone successfully changes another user’s view. However, the experiment only gained steam after the researchers revealed their work. To prevent another incident—even a secret one—Reddit is now fast-tracking measures to verify that users are human without compromising privacy.
“To keep Reddit human and to meet evolving regulatory requirements, we are going to need a little more information,” Huffman explained. “Specifically, we will need to know whether you are a human, and in some locations, if you are an adult. But we never want to know your name or who you are.”
The company plans to partner with third-party verification services to conduct such checks.
Huffman emphasized that maintaining anonymity remains a cornerstone of the platform: “Anonymity is essential to Reddit. We have been—and will continue to be—extremely protective of your personal information.”
While Reddit already uses AI tools for tasks like content moderation and spam filtering, the company has set a limit when it comes to bots impersonating users. “Our focus is, and always will be, on keeping Reddit a trusted place for human conversation,” Huffman affirmed.
The platform currently bans “bad” bots, but the incident highlighted critical vulnerabilities in the current system. As AI becomes increasingly sophisticated, distinguishing between human and machine-generated content presents mounting challenges for online communities.
Reddit didn’t reply to a request for comment, but Reddit user Apprehensive_Song490, who serves as a moderator at r/changemyview, told Decrypt that interactions with AI for research purposes would be carefully examined by the moderators. “My general impression is that the team is always receptive to researchers and that we would consider requests on a case-by-case basis,” he said.
As Reddit approaches its 20th anniversary, the incident underscores a pivotal moment for the platform and similar online communities. The challenge ahead lies in harnessing AI’s benefits while preserving the human connection that makes these spaces valuable in the first place.
“The internet is changing rapidly, and human perspectives have never been more important,” Huffman noted. “No solution is perfect—including the status quo—but we will do our best to preserve both the humanness and anonymity of Reddit.”
Edited by James Rubin
