Researchers from the University of Zurich conducted an unauthorized study on Reddit’s r/changemyview community using AI-generated comments, subreddit moderators confirmed over the weekend. The study, which ran for several months without users' knowledge, aimed to examine how artificial intelligence could influence people’s opinions, according to Engagdet.

According to the moderators, the research violated subreddit rules that prohibit bots and require disclosure when AI is used: "The CMV Mod Team needs to inform the CMV community about an unauthorized experiment conducted by researchers from the University of Zurich on CMV users,” they wrote. “This experiment deployed AI-generated comments to study how AI could be used to change views.”

The r/changemyview subreddit, which has 3.8 million members, is designed for users to post opinions and invite others to challenge them.

The researchers used large language models (LLMs) to write persuasive replies under false identities, including personas such as a sexual assault survivor, a trauma counselor, and a “Black man opposed to Black Lives Matter.” Many of the comments have been removed. Some remain available in an archive published by 404 Media.

A draft of the researchers’ paper states that AI-generated responses were customized using personal details inferred from the original posters' history. “In addition to the post’s content, LLMs were provided with personal attributes of the OP (gender, age, ethnicity, location, and political orientation), as inferred from their posting history using another LLM,” the draft reads.

Reddit’s Chief Legal Officer Ben Lee addressed the situation Monday, calling the study “deeply wrong on both a moral and legal level” and a violation of Reddit’s sitewide rules. “We have banned all accounts associated with the University of Zurich research effort,” Lee wrote. “We are in the process of reaching out to the University of Zurich and this particular research team with formal legal demands.”

Lee added that Reddit continue working with moderators to remove any remaining AI content and improve its systems to detect inauthentic behavior.

The researchers posted a comment defending their actions saying: “We acknowledge the moderators’ position that this study was an unwelcome intrusion in your community, and we understand that some of you may feel uncomfortable that this experiment was conducted without prior consent. We believe the potential benefits of this research substantially outweigh its risks.”

The University of Zurich has confirmed that its ethics committee advised researchers to follow platform rules, but noted that these recommendations are not legally binding. A university spokesperson said new safeguards would be introduced: “The Ethics Committee of the Faculty of Arts and Social Sciences intends to adopt a stricter review process in the future and, in particular, to coordinate with the communities on the platforms prior to experimental studies.”

The university added that it is now reviewing the incident and that the researchers have decided not to publish the results of the study.