Who Do Language Models Think Is Competent? A Mechanistic Analysis of Occupational Bias

Keren Fuentes, Aaron Mueller


Abstract
Language models (LMs) often pass behavioral bias evaluations, but it remains unclear whether they no longer represent the underlying associations that give rise to biases, or have merely learned not to express them. In this study, we show that representational biases are often detectable, even when behavioral biases are not visible. We introduce a causal framework that decomposes occupational bias into two measurement points: a model’s internal representation of a user’s competence, and its observable outputs. We derive steering vectors for representations of user expertise, and verify that they causally mediate model behavior in both a question-answering task and a hiring task. Applying this framework to several open-weight models, we find that demographic attributes, such as gender, race, and socioeconomic status, influence a model’s representation of user expertise, even in cases where behavioral metrics detect no disparity between demographics. We show that these model representations can influence downstream behavior under intervention, suggesting failure modes that behavioral metrics alone may not detect.
Anthology ID:
2026.findings-emnlp.2279
Volume:
Findings of the Association for Computational Linguistics: EMNLP 2026
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
Findings
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
48778–48807
Language:
URL:
https://aclanthology.org/2026.findings-emnlp.2279/
DOI:
Bibkey:
Cite (ACL):
Keren Fuentes and Aaron Mueller. 2026. Who Do Language Models Think Is Competent? A Mechanistic Analysis of Occupational Bias. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 48778–48807, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Who Do Language Models Think Is Competent? A Mechanistic Analysis of Occupational Bias (Fuentes & Mueller, Findings 2026)
Copy Citation:
PDF:
https://aclanthology.org/2026.findings-emnlp.2279.pdf