Refer, Infer, or Abstain: Investigating Latent Skill Selection of Large Language Models under Contextual Question Answering Uncertainty

Emil Kalbaliyev, Kairit Sirts


Abstract
Contextual question answering (CQA) involves uncertainty regarding the use of available knowledge in forming an answer. In CQA, large language models (LLMs) should decide whether to Refer to explicitly stated information, Infer from contextual evidence using commonsense knowledge, or Abstain when an answer cannot be supported. We investigate whether LLMs implicitly select among these skills under CQA uncertainty. Combining prompting analysis with layer-wise probing, we examine latent skill selection across instruction-tuned LLMs. We find that the models distinguish Refer from Infer more easily than Infer from Abstain. In particular, erroneous abstentions disproportionately occur on inference-based questions, and the Infer–Abstain distinction is the least separable in model representations. We further find that models represent contextual knowledge gaps more strongly than contextual knowledge sufficiency. These results characterize the emergence and limitations of latent skill selection in LLMs under CQA uncertainty.
Anthology ID:
2026.uncertainlp-main.39
Volume:
The Proceedings of the Third Workshop on Uncertainty-Aware NLP
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Wilker Aziz, Jonathan Berant, Bryan Eikema, Evgenia Ilia, Marie-Catherine de Marneffe, Barbara Plank, Artem Shelmanov, Swabha Swayamdipta, Jörg Tiedemann, Artem Vazhentsev, Raúl Vázquez, Chrysoula Zerva
Venues:
UncertaiNLP | WS
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
657–671
Language:
URL:
https://aclanthology.org/2026.uncertainlp-main.39/
DOI:
Bibkey:
Cite (ACL):
Emil Kalbaliyev and Kairit Sirts. 2026. Refer, Infer, or Abstain: Investigating Latent Skill Selection of Large Language Models under Contextual Question Answering Uncertainty. In The Proceedings of the Third Workshop on Uncertainty-Aware NLP, pages 657–671, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Refer, Infer, or Abstain: Investigating Latent Skill Selection of Large Language Models under Contextual Question Answering Uncertainty (Kalbaliyev & Sirts, UncertaiNLP 2026)
Copy Citation:
PDF:
https://aclanthology.org/2026.uncertainlp-main.39.pdf