@inproceedings{bakos-etal-2026-pre,
title = "A Pre-Generation Epistemic Routing Axis in Language Models",
author = "Bakos, Steve and
Davoudi, Heidar and
An, Aijun",
editor = "Lee, Hung-Yi and
Dev, Sunipa and
Li, Jessy and
Elliott, Desmond",
booktitle = "Findings of the {A}ssociation for {C}omputational {L}inguistics: {EMNLP} 2026",
month = oct,
year = "2026",
address = "Budapest, Hungary",
publisher = "Association for Computational Linguistics",
url = "https://aclanthology.org/2026.findings-emnlp.1324/",
doi = "10.18653/2026.findings-emnlp.1324",
pages = "28066--28091",
ISBN = "979-8-89176-462-0",
abstract = "When answering factual questions, language models may respond correctly, hallucinate, or abstain. We investigate whether this epistemic disposition is encoded in hidden states before any answer token is generated. Using a balanced Wikipedia QA corpus with pre/post article-date splits and rollout-consensus labels, we analyze prompt-only MLP activations from four instruction-tuned 7{--}9B models. PCA reveals a dominant pre-generation epistemic routing axis that orders outcomes as ABSTAIN, HALLUCINATION, and CORRECT. We then apply activation steering as a bounded causal stress test. Dense residual-write edits can shift many hallucinations toward abstention or correctness, while sparse MLP-intermediate edits localize the steering signal. These results frame the axis as a steering audit: it identifies where fixed edits improve factual behavior and where correct loss or broken outputs call for conditional controllers."
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<abstract>When answering factual questions, language models may respond correctly, hallucinate, or abstain. We investigate whether this epistemic disposition is encoded in hidden states before any answer token is generated. Using a balanced Wikipedia QA corpus with pre/post article-date splits and rollout-consensus labels, we analyze prompt-only MLP activations from four instruction-tuned 7–9B models. PCA reveals a dominant pre-generation epistemic routing axis that orders outcomes as ABSTAIN, HALLUCINATION, and CORRECT. We then apply activation steering as a bounded causal stress test. Dense residual-write edits can shift many hallucinations toward abstention or correctness, while sparse MLP-intermediate edits localize the steering signal. These results frame the axis as a steering audit: it identifies where fixed edits improve factual behavior and where correct loss or broken outputs call for conditional controllers.</abstract>
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%0 Conference Proceedings
%T A Pre-Generation Epistemic Routing Axis in Language Models
%A Bakos, Steve
%A Davoudi, Heidar
%A An, Aijun
%Y Lee, Hung-Yi
%Y Dev, Sunipa
%Y Li, Jessy
%Y Elliott, Desmond
%S Findings of the Association for Computational Linguistics: EMNLP 2026
%D 2026
%8 October
%I Association for Computational Linguistics
%C Budapest, Hungary
%@ 979-8-89176-462-0
%F bakos-etal-2026-pre
%X When answering factual questions, language models may respond correctly, hallucinate, or abstain. We investigate whether this epistemic disposition is encoded in hidden states before any answer token is generated. Using a balanced Wikipedia QA corpus with pre/post article-date splits and rollout-consensus labels, we analyze prompt-only MLP activations from four instruction-tuned 7–9B models. PCA reveals a dominant pre-generation epistemic routing axis that orders outcomes as ABSTAIN, HALLUCINATION, and CORRECT. We then apply activation steering as a bounded causal stress test. Dense residual-write edits can shift many hallucinations toward abstention or correctness, while sparse MLP-intermediate edits localize the steering signal. These results frame the axis as a steering audit: it identifies where fixed edits improve factual behavior and where correct loss or broken outputs call for conditional controllers.
%R 10.18653/2026.findings-emnlp.1324
%U https://aclanthology.org/2026.findings-emnlp.1324/
%U https://doi.org/10.18653/2026.findings-emnlp.1324
%P 28066-28091
Markdown (Informal)
[A Pre-Generation Epistemic Routing Axis in Language Models](https://aclanthology.org/2026.findings-emnlp.1324/) (Bakos et al., Findings 2026)
ACL