RankSteer: Can Pointwise LLM Rankers Be Calibrated at the Representation Level?

Yumeng Wang, Catherine Chen, Suzan Verberne


Abstract
Large language models (LLMs) are strong zero-shot pointwise rankers, but lag behind pairwise and listwise methods. Beyond missing comparative signals, we identify a calibration gap: ranking-relevant information encoded in hidden states is not fully captured by the scalar output head. We propose RankSteer, a post-hoc activation-steering framework that calibrates ranking via projection-based interventions along multiple directions at inference time: decision, evidence, and, optionally, role. This is achieved without updating model weights or introducing cross-document comparisons. We instantiate RankSteer on two structurally distinct pointwise variants and observe improvements over their respective baselines on most TREC DL and BEIR datasets across three backbones. This suggests that the calibration gap is a general property of pointwise rankers. Our additional geometric analysis shows that steering improves ranking by concentrating each query’s document representations along an existing ranking geometry, offering new insight into how LLMs internally represent and calibrate relevance judgments.
Anthology ID:
2026.findings-emnlp.1189
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:
25111–25127
Language:
URL:
https://aclanthology.org/2026.findings-emnlp.1189/
DOI:
10.18653/2026.findings-emnlp.1189
Bibkey:
Cite (ACL):
Yumeng Wang, Catherine Chen, and Suzan Verberne. 2026. RankSteer: Can Pointwise LLM Rankers Be Calibrated at the Representation Level?. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 25111–25127, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
RankSteer: Can Pointwise LLM Rankers Be Calibrated at the Representation Level? (Wang et al., Findings 2026)
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PDF:
https://aclanthology.org/2026.findings-emnlp.1189.pdf