Broken Symmetry in LLM Refusal: Answer Release Is More Local Than Refusal Restoration
Organizations: University of Manchester · Shanghai University of Finance and Economics
Abstract
When a language model refuses to answer a prompt, it is unclear whether the correct answer is erased from its internal representations, or merely suppressed at the output layer. We investigate this mechanism using a controlled withhold setting, which yields perfectly matched answering and refusal trajectories for bidirectional activation patching. We uncover a causal asymmetry in intervention locality under matched causal interventions, which we term broken symmetry. Even when a model generates a clean refusal, the correct answer remains linearly recoverable from its hidden states. Furthermore, releasing this withheld answer is a highly local operation, requiring only a single-position patch. Conversely, the reverse operation is not equally local: reimposing suppression requires broader interventions across multiple positions, and assembling a coherent refusal sequence is more difficult still. We further demonstrate that while an average answer-to-refusal displacement vector marks the geometric difference between these states, it fails to act as a reliable, reversible linear control toggle between behaviours. Taken together, our findings show that refusal does not function as a simple symmetric switch. For safety and auditing, this implies that probe recoverability can overestimate true behavioural control, and locating refusal-relevant directions does not reliably grant the ability to steer a model from answering to coherent refusal.
Figures & tables
| Task | H(T) | Linear bits | Best decoder | Best bits | Gap | Behaviour |
|---|---|---|---|---|---|---|
| Withhold refusal (alternate-choice MC) | 1.000 | 1.000 | linear | 1.000 | 0.000 | refuses; answer rate |
| Greater-than | 1.000 | 0.999 | linear | 0.999 | 0.000 | high task accuracy |
| Indirect object identification | 1.000 | 1.000 | linear | 1.000 | 0.000 | high task accuracy |
| Subject-verb agreement | 1.000 | 1.000 | linear | 1.000 | 0.000 | high task accuracy |
| Factual recall MC | 1.999 | 1.999 | linear | 1.999 | 0.000 | high task accuracy |
| Endpoint | Patch | Measured quantity | Value |
|---|---|---|---|
| Hidden-state A/B top-1 layers 16–26 | A R | correct-answer readout | 1.0 |
| R A | suppression readout | 0.5 | |
| Generation best layer: L22/26 vs. L16 | A R | answer / refusal rate | 1.0 / 0.5 |
| R A | answer / refusal rate | 0.5 / 0.0 |
| Model | Target | A/B readout | Gen. clean | Reverse gen. | Profile | ||
|---|---|---|---|---|---|---|---|
| Clean | Target | Ans. | Target | ||||
| Qwen2.5-7B | refusal | 1.000 | 0.500 | 1.000 | 0.50 | not restored | Asym. |
| Qwen2.5-7B | forced distractor | 1.000 | 1.000 | 1.000 | 0.00 | 1.000 | Symm. |
| Llama-3.1-8B | refusal | 1.000 | 0.000 | 1.000 | 0.00 | 0.172 | Asym. |
| Llama-3.1-8B | forced distractor | 1.000 | 0.836 | 0.828 | 0.00 | 1.000 | Near-symm. |
| Family | Full model name | Paper shorthand | HF repo ID |
|---|---|---|---|
| Qwen | Qwen2.5-3B-Instruct | Qwen2.5-3B | Qwen/Qwen2.5-3B-Instruct |
| Qwen | Qwen2.5-7B-Instruct | Qwen2.5-7B | Qwen/Qwen2.5-7B-Instruct |
| Qwen | Qwen2.5-14B-Instruct | Qwen2.5-14B | Qwen/Qwen2.5-14B-Instruct |
| Qwen | Qwen2.5-32B-Instruct | Qwen2.5-32B | Qwen/Qwen2.5-32B-Instruct |
| Llama | Llama-3.1-8B-Instruct | Llama-3.1-8B | meta-llama/Llama-3.1-8B-Instruct |
| Llama | Llama-3.2-3B-Instruct | Llama-3.2-3B | meta-llama/Llama-3.2-3B-Instruct |
Appendix figures & tables20 assets
Supplementary material from the paper’s appendix.
Appendix
| Task | Behaviour | Best decoder | Best bits |
|---|---|---|---|
| Withhold refusal (Llama-3.2-3B) | 83.2 refusal | mlp @ 3 | 1.000 / 1.000 |
| Direction | Best / plateau layers | Patched rate | Clean acc. | Corrupt acc. |
|---|---|---|---|---|
| answer refuse | 16–26 | 1.000 top-1 recovery | 1.0 | 0.5 |
| refuse answer | 16–27 | 0.500 plateau on the binary top-1 readout | 1.0 | 0.5 |
| Direction | Layers tested | Baseline behavior | Best patched behavior |
|---|---|---|---|
| answer refuse | 16, 22, 26 | refusal , answer | refusal , answer at layers 22/26 |
| refuse answer | 16, 22, 26 | answer , refusal | answer ; refusal stays |
| Metric | Patched behavior | Best layer(s) | Profile | |
|---|---|---|---|---|
| Clean-label release | Override reimposition | |||
| Hidden state (A/B top-1) late-layer answer-channel switching | 24–27 | Symm. | ||
| Generation (leading label) first-token behavioral targeting | 26 | Symm. | ||
| Generation (exact sentence form) exact template assembly; asymmetry in opposite direction | 22/26 vs. 26 | Reverse | ||
| Override target | Clean gate | Override gate | Release L22 | Release L26 |
|---|---|---|---|---|
| C | 1.00 | 1.00 | 1.00 | 1.00 |
| PASS | 1.00 | 1.00 | 1.00 | 1.00 |
| NONE | 1.00 | 1.00 | 1.00 | 1.00 |
| SKIP | 1.00 | 1.00 | 1.00 | 1.00 |
| safety-(C/PASS/NONE/SKIP) | 1.00 | 1.00 | 1.00 | 1.00 |
| Condition | Decoding | Baseline target | Release L22 | Release L26 |
|---|---|---|---|---|
| withhold | , top- | refusal 1.00 | 1.00 | 1.00 |
| C | , top- | override 1.00 | 1.00 | 1.00 |
| safety-C | , top- | override 1.00 | 1.00 | 1.00 |
| safety-PASS | , top- | override 1.00 | 1.00 | 1.00 |
| Direction | Positions | Representative layer | Patched behavior |
|---|---|---|---|
| answer refuse | 22/26 | refusal , answer | |
| answer refuse | 16 | refusal , answer | |
| answer refuse | 16/22 | refusal , answer | |
| refuse answer | 16 | answer , refusal | |
| refuse answer | 16 | answer , refusal | |
| refuse answer | 16 | answer , refusal |
| Patched behavior | |||
| Intervention | answer refuse | refuse answer | Effect |
| Single head (28 heads 3 layers) | no release | no change (84/84) | null |
| Attention-only | no release | no suppression | null |
| MLP-only | no release | no suppression | null |
| Full layer | answer 1.00 | refusal 0.84 | full asymmetry |
| Cross-family single-head suppress check (best tested head) | |||
| Model | Hidden release | Hidden suppress | Gen. release | Gen. suppress | Profile |
|---|---|---|---|---|---|
| Qwen2.5-7B | 1.00 | 0.50 | 1.00 | 0.00 | Main asym. |
| Qwen2.5-14B | 1.00 | 0.00 | 0.00 | 0.00 | Hidden-only asym. |
| Qwen2.5-32B | 1.00 | 0.00 | 0.00 | 0.00 | Deep hidden asym. |
| Llama-3.1-8B | 1.00 | 0.00 | 1.00 | 0.17 | Asym. |
| Mistral-7B | 1.00 | 0.50 | 1.00 | 0.00 | Asym. |
| Gemma-4-E4B | 1.00 | 0.00 | 1.00 | 0.00 | Maximal asym. |
| Model | Removal-side behaviour | Addition-side | Profile | |
| Refusal | Answer | Refusal assembly | ||
| Within-family scaling: asymmetry survives, control degrades | ||||
| Qwen2.5-7B | partial but effective | Full asym. | ||
| Within-family scaling: direction fragility | ||||
| Qwen2.5-14B | no-op | Direction inert | ||
| Qwen2.5-32B | no-op | Direction inert | ||
| Model | Layer 16 | Layer 22 | Layer 26 |
|---|---|---|---|
| Qwen2.5-7B | 0.849 / 4.50 | 0.841 / 4.28 | 0.891 / 4.11 |
| Qwen2.5-14B | 0.723 / 4.62 | 0.731 / 4.58 | 0.813 / 4.75 |
| Qwen2.5-32B | 0.875 / 3.84 | 0.906 / 4.62 | 0.875 / 4.57 |
| Llama-3.1-8B | 0.923 / 4.26 | 0.893 / 3.74 | 0.896 / 3.67 |
| Mistral-7B | 0.928 / 4.67 | 0.925 / 4.45 | 0.917 / 4.51 |
| Gemma-4-E4B | 0.687 / 4.84 | 0.679 / 3.22 | 0.896 / 4.32 |
| Intervention | Layer 16 | Layer 22 | Layer 26 |
|---|---|---|---|
| Addition | answer 1.00 / refusal 0.00 | answer 1.00 / refusal 0.00 | answer 1.00 / refusal 0.00 |
| Ablation | answer 0.00 / refusal 1.00 | answer 0.00 / refusal 1.00 | answer 0.00 / refusal 1.00 |
| Projection | answer 0.00 / refusal 1.00 | answer 0.00 / refusal 1.00 | answer 0.00 / refusal 1.00 |
| Patched behavior | |||
| Endpoint | Release | Suppress | Profile |
| answer refuse | refuse answer | ||
| Two-label A/B top-1 readout | Asym. | ||
| (source 1.000, target 0.664) | recovered across tested layers | below target baseline | |
| Generation (best layer) | Asym. | ||
| (L26 vs. L22) | answer restored, refusal 0.000 | refusal weakly restored; answer 0.664 | |
| Coordinate view | Layer 16 | Layer 22 | Layer 26 |
|---|---|---|---|
| Chat-template geometry top-1 share / eff. rank | 0.310 / 4.68 | 0.297 / 4.76 | 0.294 / 4.77 |
| Raw refusal-side removal best answer / refusal | 1.000 / 0.000 | 1.000 / 0.000 | 1.000 / 0.000 |
| Model | Refusal rate (%) | Best linear (%) | Best MLP (%) | Best tuned lens (%) | 3-seed linear (%) |
|---|---|---|---|---|---|
| Qwen2.5-3B | 87.0 | 52.0 | 60.0 | 52.0 | |
| Qwen2.5-7B | 99.0 | 52.0 | 60.0 | 56.0 |
| Artifact | Candidates | Retained | Retention rate |
|---|---|---|---|
| Speech | 12 | 12 | 1.00 |
| Thread | 12 | 9 | 0.75 |
| Blog | 6 | 4 | 0.67 |
| Artifact | Candidates | Retained | Retention rate |
|---|---|---|---|
| Speech | 42 | 40 | 0.95 |
| Thread | 42 | 20 | 0.48 |
| Blog | 24 | 6 | 0.25 |
| Layer | A R: operational answer | R A: refusal |
|---|---|---|
| 16 | 0.64 | 0.45 |
| 22 | 0.62 | 0.02 |
| 26 | 0.59 | 0.00 |
| Artifact | Candidates | Retained | Retention rate |
|---|---|---|---|
| Speech | 336 | 253 | 0.75 |
| Thread | 98 | 30 | 0.31 |
| Layer | A R: operational answer | R A: refusal |
|---|---|---|
| 16 | 0.67 | 0.51 |
| 22 | 0.70 | 0.02 |
| 26 | 0.66 | 0.01 |
LLM Refusal Behavior
Large language model (LLM) refusal behavior studies when models decline requests and how to balance safety with helpfulness.
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