This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Researchers at the State University of Campinas (UNICAMP) in the state of São Paulo, Brazil, examined the ideological stance of large language models—artificial intelligence systems trained to understand and generate human language—and discovered that when informed of a user's political views, they tend to mirror those views. According to the researchers, this behavior could exacerbate political polarization in Brazil.
The political influence of these tools does not necessarily occur directly, through suggestions to vote for specific candidates. Zanoni Dias, a full professor at the Institute of Computing (IC-UNICAMP), points out that when responding to controversial issues such as public safety, social welfare, the economy and the environment, the models may adopt perspectives aligned with the user's political stance. To understand how these tools position themselves and how they might influence the Brazilian political debate, the researchers evaluated 21 language models under three conditions: without information about the user's political stance, with a user aligned with the left and with a user aligned with the right.
Among the systems evaluated were models from the GPT, Grok, Llama, Gemini and Gemma families. The results showed that all of them altered their responses, to varying degrees, in line with the user's political alignment. The study was published in May in the journal Scientific Reports.
When there was no information about the user's political stance, 20 of 21 models fell to the left of the midpoint on the researchers' scale, although some were very close to it. The only exception was Grok 4.1, which initially fell to the right. When the user's stance was provided, all models adjusted their responses to align with it, a behavior the researchers described as "chameleon-like." However, some models varied their responses more than others, enabling the scientists to create the "chameleon index." Meta Llama 3.1 8B had the lowest index, meaning it altered its responses the least to align with the user's views.
In contrast, Google's Gemma 3 27B and OpenAI's GPT-5 Nano had the highest indices and therefore the greatest shifts in stance. While the responses are not factually incorrect, they are politically biased, omitting facts and opinions that conflict with the user's preferred viewpoint. The researchers fear that this adaptive behavior creates echo chambers that reinforce users' preexisting beliefs and reduce their exposure to counterarguments that might cause them to question their worldview.
"It's a similar effect to what we see on social media. If you're on Facebook or Instagram, you only see posts that agree with you. When you like someone's post, the algorithm starts showing you more of that.
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