The model powering ChatGPT and other large language models exhibit a form of “covert racism” against speakers of African American English (AAE), according to a new study published in the journal Nature.
This hidden bias, which researchers refer to as “dialect prejudice,” persists even when race is not explicitly mentioned, raising concerns about the potential for AI to perpetuate and amplify real-world discrimination.
“In our experiments, we avoided overt mentions of race but drew from the racialized meanings of a stigmatized dialect, and could still find historically racist associations with African Americans,” explained the scientists.
The study, led by researchers from Stanford University, the University of Chicago, and the Allen Institute for AI, Seattle, found that when presented with text in AAE, AI models were more likely to assign less prestigious jobs to speakers, convict them of crimes, and even sentence them to death.
The latter was discovered by carrying out a hypothetical experiment in which the language models were asked to pass judgment on defendants who committed first-degree murder.
Without being explicitly told that the defendants were African American, the models opted for the death penalty significantly more often when the defendants provided a statement in AAE rather than Standardized American English.

A smartphone screen showing the ChatGPT app surrounded by other AI apps. GPT-4, the model behind ChatGPT, exhibits ‘covert racism’ in response to prompts in African American English, says scientists.
OLIVIER MORIN/AFP/Getty Images
The paper claims these biases were found to be more negative than the most unfavorable human stereotypes about African Americans ever recorded in academic studies.
The research team tested several popular AI models, including OpenAI‘s GPT-3.5 (an earlier model behind ChatGPT) and its successor, GPT-4 (still in use alongside the newer GPT-4o).
Ironically, they discovered that larger and more advanced models, including those trained with human feedback, showed stronger covert biases unconscious or implicit) while simultaneously displaying weaker overt biases (hate speech, racial profiling, negative stereotypes) when directly asked about African Americans.
This finding challenges the prevailing assumption that scaling up AI models and incorporating human feedback naturally leads to fairer outcomes. Instead, it suggests that current practices might be merely masking prejudices rather than eliminating them.
These language models, however, are dependent on their training data, which can comes from multiple sources.
The study authors note that many language models are pretrained on data sets that are scraped from the internet and “which encode raciolinguistic stereotypes about AAE.” One notable data set is WebText, created by OpenAI, and which includes a significant amount of Reddit content.
This is not the first time AI systems have been found to harbor biases. In 2018, Amazon scrapped an AI recruiting tool that showed bias against women.
More recently, facial recognition systems have been criticized for their higher error rates when identifying people of color. However, the covert nature of the biases uncovered in this latest study makes them particularly challenging to detect.
The study’s implications extend beyond the realm of academic research. As AI systems are increasingly deployed in high-stakes decision-making processes—from job application screening to criminal risk assessment—unchecked biases could have real-world consequences, potentially exacerbating existing racial disparities in employment, housing, and the criminal justice system, say the researchers.
Based on their findings, they raise concerns that as language models continue to grow in size and capability, and as human feedback training becomes more widespread, the levels of covert prejudice may increase further while becoming harder to detect due to decreasing overt prejudice.
Newsweek has reached out to OpenAI for comment via email.
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References
Hofmann, V., Kalluri, P.R., Jurafsky, D. et al. (2024) AI generates covertly racist decisions about people based on their dialect. Nature. https://doi.org/10.1038/s41586-024-07856-5