When Targeted Grounded Gains Hide Complementary Abstraction Regression: DION-Bench and a Conjunctive Evaluation Protocol

Zida Yang, Guquan You, Jiexin Zheng, Yijie Peng


Abstract
Post-training with internal feedback can improve a targeted knowledge-grounded behavior while silently degrading complementary abstraction and logical-consistency capabilities. We propose a conjunctive evaluation protocol that accepts a method only when a designated target improves and complementary probes remain non-inferior (with a stricter secondary criterion requiring complementary equivalence), while also reporting retention and predictive drift. We instantiate the protocol in DION-Bench, combining two lexical/ontological probes (same-category exceptions; abstraction recovery) with a synthetic SAT-checked logical-consistency probe. On Qwen3-8B-Base, a task-specific self-judged DPO adaptation improves OntoNeg-WN by 5.27 percentage points but reduces ConceptShift by 37.50 points—despite humans reaching 82.7% and frontier LLMs 44–73% on OntoNeg—whereas mean change across five external accuracy suites is only −1.70 points. A development-tuned decoding rule partially mitigates ConceptShift regression to 12.93/14.60 points on the original/holdout splits while retaining most of the target gain. These results show that faithful post-training claims require joint reporting of gain, complementary abstraction regression, retention, drift, and equivalence—not proof that a single shared knowledge item degraded.
Anthology ID:
2026.groundlm-1.77
Volume:
Proceedings of the 1st Workshop on Grounding Language Models: Learning Faithfully and Efficiently (GroundLM 2026)
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Yimu Wang, Yee Man Choi, Di Wu, Siqi Ouyang, Mozhgan Nasr Azadani, Yi R. (May) Fung
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GroundLM | WS
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Publisher:
Association for Computational Linguistics
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Pages:
1091–1115
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URL:
https://aclanthology.org/2026.groundlm-1.77/
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Cite (ACL):
Zida Yang, Guquan You, Jiexin Zheng, and Yijie Peng. 2026. When Targeted Grounded Gains Hide Complementary Abstraction Regression: DION-Bench and a Conjunctive Evaluation Protocol. In Proceedings of the 1st Workshop on Grounding Language Models: Learning Faithfully and Efficiently (GroundLM 2026), pages 1091–1115, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
When Targeted Grounded Gains Hide Complementary Abstraction Regression: DION-Bench and a Conjunctive Evaluation Protocol (Yang et al., GroundLM 2026)
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https://aclanthology.org/2026.groundlm-1.77.pdf
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