RBCorr: Response Bias Correction in Language Models

Om Bhatt, Anna A Ivanova


Abstract
Language models (LMs) are known to be prone to response biases, which present as option preference biases in fixed-response questions. It is therefore imperative to develop low-cost and effective response bias correction methods to improve LM performance and enable more accurate evaluations of model abilities. Here, we propose a simple response bias correction strategy, RBCorr, and test it on 12 open-weight language models using yes-no, entailment, and multiple choice questions. We show that response bias is prevalent in LMs pre-correction and that RBCorr effectively eliminates bias and boosts model performance. We also explore the generalizability of bias behavior across models, datasets, and prompt formats, showing that LogProbs-based correction is highly dependent on all three of these aspects. Overall, RBCorr is an easy-to-use method that can boost the performance of smaller LMs and ensure that LM performance on closed-response benchmarks aligns more closely with their true capabilities.
Anthology ID:
2026.gem-main.51
Volume:
Proceedings of the Fifth Workshop on Generation, Evaluation and Metrics (GEM)
Month:
July
Year:
2026
Address:
San Diego, California, USA
Editors:
Simon Mille, Sebastian Gehrmann, Patrícia Schmidtová, Ondřej Dušek, Marzieh Fadaee, Kyle Lo, Enrico Santus, Gabriel Stanovsky
Venues:
GEM | WS
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
540–553
Language:
URL:
https://preview.aclanthology.org/ingest-acl-workshops/2026.gem-main.51/
DOI:
Bibkey:
Cite (ACL):
Om Bhatt and Anna A Ivanova. 2026. RBCorr: Response Bias Correction in Language Models. In Proceedings of the Fifth Workshop on Generation, Evaluation and Metrics (GEM), pages 540–553, San Diego, California, USA. Association for Computational Linguistics.
Cite (Informal):
RBCorr: Response Bias Correction in Language Models (Bhatt & Ivanova, GEM 2026)
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PDF:
https://preview.aclanthology.org/ingest-acl-workshops/2026.gem-main.51.pdf