That’s the finding of a new experiment out of Munich-based global economic research network CESifo, which tracked more than 12,000 French adults over the course of four weeks, and found having conversations with sometimes sycophantic AI chatbots left people thinking the conversation went better than it would have otherwise gone with a human.

For 28 days, half of the 12,365 people in the study were tasked with holding personal conversations with AI chatbots, while the rest went about their normal days. At the end of the month, the three researchers found the group that was typing their personal narratives with chatbots rated the “conversations” as enjoyable and even more pleasant, on average, than the control group.

However, the same group also self-reported their loneliness rose, just as their life satisfaction fell, and depressive affect ticked up, in comparison to the control group. They also had more meals alone and spent less time in-person with friends and family per week. 

“I would imagine that in some cases an AI conversation may reinforce grievances or prolong rumination, leaving someone slightly less inclined to go out, call somebody, or have dinner with another person,” Louis Fréget, one of the three researchers behind the experiment, told Fortune.

The working paper is one of the largest causal tests yet of a proposal  tech leaders have been making—that AI chatbots can help with the loneliness epidemic. Meta’s CEO Mark Zuckerberg has argued that most people want more social connection and that chatbots could help, and a KPMG survey found that 99% of professionals surveyed were interested in  a chatbot that could become a close friend at work. 

Technology takes on the loneliness epidemic

The format of the interaction also matters, since interacting with an AI interface doesn’t feel as fulfilling because it doesn’t know the person the way another human would, according to Nicholas Epley, a University of Chicago behavioral scientist who studies social connection.

“The data here suggests that having a conversation with a chatbot doesn’t get that sense of being known by another person like you get in a conversation, and therefore also doesn’t create any meaningful sense of connection because, in the end, there’s nothing there,” Epley said

This is an ongoing debate, with researchers, workers, and users landing in very different places. One loneliness researcher warned that AI is about to make the epidemic worse, pointing to a study where first-year college students who texted daily with a chatbot built to act like an “ideal friend” showed no drop in loneliness — while those paired with a random human peer did. With more than a billion people worldwide reporting loneliness, according to Gallup, and former Surgeon General Vivek Murthy calling it an epidemic, AI chatbots have moved into that gap. Some users have taken that further still, forming romantic attachments to chatbots — a pattern psychotherapists worry could deepen isolation rather than ease it.

Accordingly, people can feel the difference between talking to a chatbot and another person, even if the conversations are pleasant with the former. 

“When you form social connections using typed language, so like text messages or chatting or email, those social connections don’t evoke as many positive emotions, and they’re also not as strong as those that we develop face to face,” Valeria Pfeifer, an Assistant Professor of Psychology and Counseling the University of Missouri–Kansas City, told Fortune recently. She’s the author of a recent study that found we’re saying 30% fewer words than we did two decades ago, and technology is one of the major reasons why.  

“Even if they’re similar in their depth or intensity, they don’t tend to have the same kind of psychological implications,” Pfeiffer said of texts or written communications. 

Still, the study joins a small but growing body of research on AI and loneliness, and it’s leading to real-world results. One pilot program in New York had nearly 1,000 older adults interact with an AI chatbot and reported a decline in loneliness. But Nancy Berlinger, a bioethicist at the Hastings Center for Bioethics, previously told Fortune that talking to a chatbot can’t replace in-person connection even if there is temporary relief.

“It’s not going to replace all of that richness of relationships, but it’s not nothing,” Berlinger said.