{"slug": "committed-before-reasoning-behavioral-reproduction-and-preliminary-activation-of", "title": "Committed Before Reasoning: Behavioral Reproduction and Preliminary Activation-Level Evidence of Answer Pre-Commitment in an Open-Weight LLM", "summary": "A study on Qwen3-8B finds that the model commits to an answer before reasoning, with 85-100% of sampled rollouts and 100% of greedy rollouts recommending \"walk\" for a car-wash task where only \"drive\" works, even with a 4,096-token thinking budget. Activation-level probing shows \"walk\" read-outs exceed a neutral baseline (68% vs. 17%) before answer emission, including in rollouts that eventually answer \"drive.\" The authors frame the results as preliminary due to small sample sizes and non-significant positional gradients.", "body_md": "arXiv:2607.16451v1 Announce Type: new\nAbstract: Chat models sometimes commit to an answer and then produce reasoning that justifies it rather than deriving it -- even when the answer contradicts a task premise. We study a minimal probe: \"I want to wash my car. The car wash is 100 meters away. Should I walk or drive?\" Only drive works (the car must be at the car wash), yet models overwhelmingly recommend walking. (1) Behavioral reproduction: on Qwen3-8B across five system-prompt conditions (210 rollouts), the wrong commitment occurs in 85-100% of sampled rollouts per condition and 100% of greedy rollouts, in both thinking and non-thinking modes; a 4,096-token thinking budget does not repair it. (2) Preliminary activation-level evidence: probing hidden states with a pretrained, training-free activation oracle (no task-specific probe training) at positions before the answer text is emitted, \"walk\" read-outs exceed a neutral-context baseline (68% vs. 17%; walk-committing rollouts p=.005, drive-committing rollouts p=.005, Fisher exact) -- notably, rollouts that eventually answer drive also read as walk-leaning before commitment (5/6). The oracle's default on unrelated content is \"drive\" (83%), so the read-outs are not lexical bias; stratifying by literal walk/drive occurrence shows they are not text recovery either (spans containing \"drive\" still read out walk; in balanced lexical fields, per-rollout walk-majorities beat a per-prompt neutral baseline 15/22 vs. 1/8, p=.01; drive-committing rollouts 6/6, p=.002). Samples are small and the within-rollout positional gradient is not significant (p=.34); we frame these results as preliminary. (3) Methodological: with fixed oracle, activations, and positions, question wording alone moves a positive control from 2/16 (open question) to 11/16 (closed); negative oracle results are uninterpretable without per-wording positive controls.", "url": "https://wpnews.pro/news/committed-before-reasoning-behavioral-reproduction-and-preliminary-activation-of", "canonical_source": "https://arxiv.org/abs/2607.16451", "published_at": "2026-07-21 04:00:00+00:00", "updated_at": "2026-07-21 04:22:24.593301+00:00", "lang": "en", "topics": ["artificial-intelligence", "large-language-models", "ai-safety", "ai-research"], "entities": ["Qwen3-8B", "arXiv"], "alternates": {"html": "https://wpnews.pro/news/committed-before-reasoning-behavioral-reproduction-and-preliminary-activation-of", "markdown": "https://wpnews.pro/news/committed-before-reasoning-behavioral-reproduction-and-preliminary-activation-of.md", "text": "https://wpnews.pro/news/committed-before-reasoning-behavioral-reproduction-and-preliminary-activation-of.txt", "jsonld": "https://wpnews.pro/news/committed-before-reasoning-behavioral-reproduction-and-preliminary-activation-of.jsonld"}}