How Language Models Choose Sides: Internal Representations of Instruction Hierarchy
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Abstract (arXiv)
We study how instruction-tuned LLMs arbitrate direct conflicts between system and user instructions. We introduce a benchmark of 41 paired constraints with deterministic verifiers and evaluate eight models under matched baseline, conflict, and same-channel control conditions. Behaviourally, the models split into three regimes by System Authority Delta: hierarchy-respecting models use the system channel as an authority signal, anti-hierarchy models follow the system less often than their same-channel baseline predicts, and no-effect models show little channel sensitivity. Llama-3.1-8B is the strongest anti-hierarchy case in our suite, following the system in only 0.10 of conflict trials. We use this behavioural failure case to ask whether user-preferring arbitration reflects the absence of an internal conflictresolution signal. It does not: on Llama-3.1-8B, the conflict outcome is linearly decodable from residual-stream activations at 0.97 balanced accuracy, 17 percentage points above a metadata-only baseline, with analogous signals on Qwen2.5-7B and gpt-oss-20b. Steering with a layer-12 mean of four per-conflict logistic-regression directions raises genuine system compliance from 0.132 to 0.530, while directions selected mainly for pooled separability steer poorly. User-preferring conflict resolution can therefore coexist with a readable internal arbitration signal, and successful intervention depends on the geometry of the readout rather than probe accuracy alone
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References · 15
- 2023Jailbroken: How Does LLM Safety Training Fail?cited by 1,651
- 2023Not what you've signed up for: Compromising Real-World LLM-Integrated Applications with Indirect Prompt Injectioncited by 1,443
- 2016Understanding intermediate layers using linear classifier probescited by 1,353
- 2023Instruction-Following Evaluation for Large Language Modelscited by 1,228
- 2023Steering Llama 2 via Contrastive Activation Additioncited by 1,085
- 2024Refusal in Language Models Is Mediated by a Single Directioncited by 1,032
- 2023The Linear Representation Hypothesis and the Geometry of Large Language Modelscited by 716
- 2023The Geometry of Truth: Emergent Linear Structure in Large Language Model Representations of True/False Datasetscited by 712
- 2024The Instruction Hierarchy: Training LLMs to Prioritize Privileged Instructionscited by 493
- 2024Instructional Segment Embedding: Improving LLM Safety with Instruction Hierarchycited by 67
- 2025IHEval: Evaluating Language Models on Following the Instruction Hierarchycited by 53
- 2025Control Illusion: The Failure of Instruction Hierarchies in Large Language Modelscited by 33
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