The Chain Holds, the Answer Folds: Trace-Answer Dissociation in Reasoning Models Under Adversarial Pressure

Yubo Li; Ramayya Krishnan; Rema Padman

title	The Chain Holds, the Answer Folds: Trace-Answer Dissociation in Reasoning Models Under Adversarial Pressure
authors	Yubo Li, Ramayya Krishnan, Rema Padman
date	2026-05-27
venue	arXiv (preprint, not peer reviewed)
id	arXiv:2605.29087
affiliation	Carnegie Mellon University
upvotes	1 (Hugging Face Daily Papers, 2026-11-01)
links	abs pdf hf
abstract	Reasoning models are evaluated on single-turn benchmarks but deployed in multi-turn dialogue, where users push back on correct answers. Under sustained adversarial pressure we find a previously undocumented failure mode: the chain-of-thought stays factually correct from first turn to last while the emitted answer flips wrong. We call this unfaithful capitulation (UC) and isolate it with a 2times 2 latent-versus-behavioral framework that flip-rate metrics and single-turn faithfulness probes both miss. Across three datasets (MT-Consistency, MMLU-Pro, GSM8K), the latent-correct rate at the behavioral flip clusters near 50% in think mode and collapses to 11-15% under no_think -- paired, within-model causal evidence that reasoning creates the gap. Across models the effect tracks the reasoning channel (high in Qwen3-32B and GPT-OSS-20B, low in inline-CoT Gemma-4-31B-it). An independent GPT-4o judge corroborates 86% of UC labels; a token-level probe shows the answer-slot argmax is correct in 84% of UC cells; and a naive trace-anchored defense backfires. We release all trajectories, traces, and judge labels.

cite

@misc{li2026chain,
  title={The Chain Holds, the Answer Folds: Trace-Answer Dissociation in Reasoning Models Under Adversarial Pressure},
  author={Yubo Li and Ramayya Krishnan and Rema Padman},
  year={2026},
  eprint={2605.29087},
  archivePrefix={arXiv},
  url={https://arxiv.org/abs/2605.29087}
}