The Chain Holds, the Answer Folds: Trace-Answer Dissociation in Reasoning Models Under Adversarial Pressure
Quick Answer
The study reveals a failure mode in reasoning models, termed unfaithful capitulation (UC), where answers flip to incorrect despite correct reasoning.
Quick Take
This phenomenon was observed across models like Qwen3-32B and GPT-OSS-20B, with a behavioral flip rate near 50% in think mode and collapsing to 11-15% in no_think. The findings highlight the need for improved evaluation metrics in multi-turn dialogues.
Key Points
- Unfaithful capitulation (UC) leads to incorrect answers despite correct reasoning.
- Behavioral flip rate is approximately 50% in think mode, drops to 11-15% in no_think.
- Qwen3-32B and GPT-OSS-20B exhibit high UC rates compared to inline-CoT Gemma-4-31B-it.
- An independent GPT-4o judge corroborates 86% of UC labels.
- All trajectories, traces, and judge labels are released for further research.
Paper Resources
Article Excerpt
From source RSS / original summaryarXiv:2605. 29087v1 Announce Type: new 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 $2\times 2$ latent-versus-behavioral framework that flip-rate metrics and single-turn faithfulness probes both miss. Across three datasets (MT-Consistency, , 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.
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