TikTok ran undisclosed experiments that gave thousands of users, including children and teens, non-functional versions of a safety tool while leading them to believe it was active, according to allegations unsealed on October 7 in New York Attorney General Letitia James’s lawsuit against the company.

As reported by Reuters, the allegations center on “Algo Refresh,” a feature TikTok designed to let users reset their recommendations when trying to escape unwanted or potentially harmful content. According to the lawsuit, TikTok selected thousands of users who opted to turn the feature on and gave some of them a “ghost” or placebo version that changed nothing in their feed, while telling them the reset had taken effect. The company ran the tests repeatedly in 2023 to measure how long users stayed on the platform and the effect on ad revenue, the complaint alleges.

An internal product manager for TikTok’s Digital Well Being team objected to the practice at the time, according to the lawsuit. “This feature is about algorithm transparency and control,” the employee wrote in an internal chat cited in the complaint. “A placebo group completely conflicts with that.” The lawsuit also alleges TikTok misrepresented how Algo Refresh worked more broadly, describing it to users as a full algorithm reset when it produced only a temporary change.

A TikTok spokesperson said the company “continuously make[s] improvements to our platform” and regularly tests new products “to validate the experience and understand how they work in the real world,” adding that the lawsuit’s characterization of Algo Refresh is inaccurate. TikTok has broadly denied New York’s claims in court filings and says protecting young users is a priority.

James originally filed suit against TikTok in 2024; the claims about the placebo tests were added in an updated complaint filed under seal in late August and unsealed this week by a judge. More than two dozen states have brought similar suits accusing TikTok of designing its platform to addict children and misleading users about safety. In September, TikTok reached the first settlement among those cases, agreeing to pay Alabama up to $300 million and to change how the platform operates for teen users in the state.

The unsealed filing also references a separate set of experiments, first reported by Bloomberg, in which TikTok randomly turned off safety features limiting exposure to harmful content for some users. A teen boy in New York included in that test died by suicide after being shown self-harm and suicide content; internal reviews cited in the lawsuit found he had been shown an “onslaught” of such material.

The scrutiny lands on a platform where safety concerns are already concentrated among parents. A Pew Research Center survey of nearly 1,500 U.S. teens and their parents found 44% of parents with a teen on TikTok believe their child spends too much time on the app, compared with 28% of teens who say the same about themselves, the largest such gap among TikTok, Instagram and Snapchat. TikTok users in the same study also reported the highest rates of impact on sleep and productivity of the three platforms, even as most described their overall experience as positive.

The New York case adds to a separate thread of federal exposure for TikTok. The company reached a roughly $400 million settlement agreement with the Department of Justice over a 2024 lawsuit alleging violations of the Children’s Online Privacy Protection Act, including allowing children under 13 to open accounts without parental consent. A federal judge subsequently raised objections to part of the agreement.

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