Still No Lie Detector for Language Models: Probing Empirical and Conceptual Roadblocks
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Abstract (arXiv)
We consider the questions of whether or not large language models (LLMs) have beliefs, and, if they do, how we might measure them. First, we evaluate two existing approaches, one due to Azaria and Mitchell (2023) and the other to Burns et al. (2022). We provide empirical results that show that these methods fail to generalize in very basic ways. We then argue that, even if LLMs have beliefs, these methods are unlikely to be successful for conceptual reasons. Thus, there is still no lie-detector for LLMs. After describing our empirical results we take a step back and consider whether or not we should expect LLMs to have something like beliefs in the first place. We consider some recent arguments aiming to show that LLMs cannot have beliefs. We show that these arguments are misguided. We provide a more productive framing of questions surrounding the status of beliefs in LLMs, and highlight the empirical nature of the problem. We conclude by suggesting some concrete paths for future work.
Key facts. Cited by 78 papers in the map (data through 14 Oct 2026). Builds on 19 of its 63 references that are in the map. First posted on arXiv 30 Jun 2023.
Builds on
19 of 63 references.
References · 19
- 2017Attention Is All You Needcited by 60,361
- 2022Training language models to follow instructions with human feedbackcited by 15,971
- 2023LLaMA: Open and Efficient Foundation Language Modelscited by 14,132
- 2022OPT: Open Pre-trained Transformer Language Modelscited by 3,512
- 2019BoolQ: Exploring the Surprising Difficulty of Natural Yes/No Questionscited by 2,183
- 2022Survey of Hallucination in Natural Language Generationcited by 2,075
- 2016Understanding intermediate layers using linear classifier probescited by 1,353
- 2021An Explanation of In-context Learning as Implicit Bayesian Inferencecited by 938
- 2022Discovering Latent Knowledge in Language Models Without Supervisioncited by 767
- 2016The Mythos of Model Interpretabilitycited by 721
- 2023The Internal State of an LLM Knows When It's Lyingcited by 659
- 2018Recognition in Terra Incognitacited by 658
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- 2020UnifiedQA: Crossing Format Boundaries With a Single QA Systemcited by 476
- 2019Risks from Learned Optimization in Advanced Machine Learning Systemscited by 258
- 2022Talking About Large Language Modelscited by 175
- 2021Truthful AI: Developing and governing AI that does not liecited by 113
- 2022Meaning without reference in large language modelscited by 76
- 2023A Latent Space Theory for Emergent Abilities in Large Language Modelscited by 43
- 2023Operationalising Representation in Natural Language Processingcited by 14
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Citing papers per year: 2023: 9; 2024: 22; 2025: 22; 2026: 25.
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- 2023A Survey on Hallucination in Large Language Models: Principles, Taxonomy, Challenges, and Open Questionscited by 1,601
- 2023The Geometry of Truth: Emergent Linear Structure in Large Language Model Representations of True/False Datasetscited by 712
- 2023A Survey of Confidence Estimation and Calibration in Large Language Modelscited by 256
- 2024LLMs Know More Than They Show: On the Intrinsic Representation of LLM Hallucinationscited by 244
- 2023AI Deception: A Survey of Examples, Risks, and Potential Solutionscited by 188
- 2024Truth is Universal: Robust Detection of Lies in LLMscited by 79
- 2025Detecting High-Stakes Interactions with Activation Probescited by 53
- 2023Honesty Is the Best Policy: Defining and Mitigating AI Deceptioncited by 40
- 2023Challenges with unsupervised LLM knowledge discoverycited by 31
- 2024On the Relationship between Truth and Political Bias in Language Modelscited by 31
- 2024Standards for Belief Representations in LLMscited by 30
- 2025Adaptive Tool Use in Large Language Models with Meta-Cognition Triggercited by 30
38 more
- 2024Linear Probe Penalties Reduce LLM Sycophancycited by 28
- 2023Localizing Lying in Llama: Understanding Instructed Dishonesty on True-False Questions Through Prompting, Probing, and Patchingcited by 24
- 2024Noise Injection Reveals Hidden Capabilities of Sandbagging Language Modelscited by 24
- 2024A Survey on the Honesty of Large Language Modelscited by 23
- 2024A Survey on Large Language Model-Based Social Agents in Game-Theoretic Scenarioscited by 23
- 2024Language Models in Dialogue: Conversational Maxims for Human-AI Interactionscited by 21
- 2025Representation Engineering for Large-Language Models: Survey and Research Challengescited by 21
- 2023Weakly Supervised Detection of Hallucinations in LLM Activationscited by 20
- 2024Constructing Benchmarks and Interventions for Combating Hallucinations in LLMscited by 19
- 2025Benchmarking Deception Probes via Black-to-White Performance Boostscited by 19
- 2025Probing the Geometry of Truth: Consistency and Generalization of Truth Directions in LLMs Across Logical Transformations and Question Answering Taskscited by 18
- 2024Does ChatGPT Have a Mind?cited by 14
- 2024Distinguishing Ignorance from Error in LLM Hallucinationscited by 14
- 2024CtrlA: Adaptive Retrieval-Augmented Generation via Inherent Controlcited by 13
- 2025Difficulties with Evaluating a Deception Detector for AIscited by 13
- 2023Self-Consistency of Large Language Models under Ambiguitycited by 12
- 2024Are Language Models More Like Libraries or Like Librarians? Bibliotechnism, the Novel Reference Problem, and the Attitudes of LLMscited by 11
- 2025Interpretation Meets Safety: A Survey on Interpretation Methods and Tools for Improving LLM Safetycited by 10
- 2026Linear representations in language models can change dramatically over a conversationcited by 10
- 2025LLLMs: A Data-Driven Survey of Evolving Research on Limitations of Large Language Modelscited by 9
- 2025The Geometries of Truth Are Orthogonal Across Taskscited by 9
- 2025LLM Knowledge is Brittle: Truthfulness Representations Rely on Superficial Resemblancecited by 9
- 2025The Impact of Off-Policy Training Data on Probe Generalisationcited by 9
- 2026One Probe Won't Catch Them All: Towards Targeted Deception Detectioncited by 9
- 2024Prompt-Guided Internal States for Hallucination Detection of Large Language Modelscited by 8
- 2025Mechanistic Indicators of Understanding in Large Language Modelscited by 8
- 2026The Truthfulness Spectrum Hypothesiscited by 8
- 2024Truth-value judgment in language models: 'truth directions' are context sensitivecited by 7
- 2026Detecting Multi-Agent Collusion Through Multi-Agent Interpretabilitycited by 7
- 2026Position: Anthropomorphic Misalignment Research Needs Stronger Evidencecited by 7
- 2025When Do LLMs Admit Their Mistakes? Understanding The Role Of Model Belief In Retractioncited by 6
- 2025HD-NDEs: Neural Differential Equations for Hallucination Detection in LLMscited by 6
- 2025Mechanistic Interpretability Needs Philosophycited by 6
- 2024An Assessment of Model-On-Model Deceptioncited by 5
- 2024Meta-Models: An Architecture for Decoding LLM Behaviors Through Interpreted Embeddings and Natural Languagecited by 5
- 2026Hallucinations Undermine Trust; Metacognition is a Way Forwardcited by 5
- 2025Representation-based Broad Hallucination Detectors Fail to Generalize Out of Distributioncited by 4
- 2025Unraveling Token Prediction Refinement and Identifying Essential Layers in Language Modelscited by 3
50 most cited of 78 All 78 (JSON)
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- 2026Stress-Testing LLM Lie Detectors: Role-Play Failures and Spurious Correlations30 Sep 2026
- 2026Can AI systems have free will?14 Sep 2026
- 2026A Systematic Evaluation of Cross-Lingual Consistency Enhancement Methods in Multilingual Language Models3 Sep 2026
- 2026Investigating Linear Probe Robustness to Linguistic Register, Medical Specialty, and Corpus Shifts in Medical QA1 Sep 2026
- 2026Recognition-Refusal Misalignment in LLMs: Why Models Answer Structurally Unanswerable Questions29 Aug 2026
- 2026The Hallucination Signal Is a Mean Shift: Why Simple Probes Suffice28 Aug 2026
- 2026Belief Cascades Drive Persuasion in LLM Agent Networks25 Aug 2026
- 2026Language Models Encode the Contextual Truth of Propositions4 Aug 2026
- 2026Belief-reality separation lives in routing over a shared value slot in language models11 Jul 2026
- 2026Comparing Linear Probes with Mahalanobis Cosine Similarity17 Jun 2026
- 2026The Impossibility of Eliciting Latent Knowledge10 Jun 2026
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- 2026Hallucinations Undermine Trust; Metacognition is a Way Forward2 May 2026
- 2026A Robust Evaluation of Probe Robustness: Lessons for Reliable OOD Uncertainty Quantification13 Apr 2026
- 2026Testing the Limits of Truth Directions in LLMs4 Apr 2026
- 2026Detecting Multi-Agent Collusion Through Multi-Agent Interpretability1 Apr 2026
- 2026Think Before You Lie: How Reasoning Leads to Honesty10 Mar 2026
- 2026Leveraging LLM Parametric Knowledge for Fact Checking without Retrieval5 Mar 2026
- 2026The Truthfulness Spectrum Hypothesis23 Feb 2026
- 2026Probing the Limits of the Lie Detector Approach to LLM Deception16 Feb 2026
- 2026Indications of Belief-Guided Agency and Meta-Cognitive Monitoring in Large Language Models2 Feb 2026
- 2026One Probe Won't Catch Them All: Towards Targeted Deception Detection1 Feb 2026
- 2026Linear representations in language models can change dramatically over a conversation28 Jan 2026
- 2025Difficulties with Evaluating a Deception Detector for AIs27 Nov 2025
- 2025Polarity-Aware Probing for Quantifying Latent Alignment in Language Models21 Nov 2025
- 2025The Impact of Off-Policy Training Data on Probe Generalisation21 Nov 2025
- 2025LLM Probing with Contrastive Eigenproblems: Improving Understanding and Applicability of CCS3 Nov 2025
- 2025LLM Knowledge is Brittle: Truthfulness Representations Rely on Superficial Resemblance13 Oct 2025
- 2025Representation-based Broad Hallucination Detectors Fail to Generalize Out of Distribution19 Sep 2025
- 2025Explainability Through Systematicity: The Hard Systematicity Challenge for Artificial Intelligence29 Jul 2025
- 2025Benchmarking Deception Probes via Black-to-White Performance Boosts16 Jul 2025
- 2025Mechanistic Indicators of Understanding in Large Language Models7 Jul 2025
- 2025Mechanistic Interpretability Needs Philosophy23 Jun 2025
- 2025Detecting High-Stakes Interactions with Activation Probes12 Jun 2025
- 2025The Geometries of Truth Are Orthogonal Across Tasks10 Jun 2025
- 2025Interpretation Meets Safety: A Survey on Interpretation Methods and Tools for Improving LLM Safety5 Jun 2025
- 2025Probing the Geometry of Truth: Consistency and Generalization of Truth Directions in LLMs Across Logical Transformations and Question Answering Tasks1 Jun 2025
- 2025HD-NDEs: Neural Differential Equations for Hallucination Detection in LLMs30 May 2025
- 2025LLLMs: A Data-Driven Survey of Evolving Research on Limitations of Large Language Models25 May 2025
- 2025When Do LLMs Admit Their Mistakes? Understanding The Role Of Model Belief In Retraction22 May 2025
- 2025Exploring the generalization of LLM truth directions on conversational formats14 May 2025
- 2025Representation Engineering for Large-Language Models: Survey and Research Challenges24 Feb 2025
- 2025Adaptive Tool Use in Large Language Models with Meta-Cognition Trigger18 Feb 2025
- 2025Unraveling Token Prediction Refinement and Identifying Essential Layers in Language Models25 Jan 2025
- 2025Representation in large language models1 Jan 2025
- 2024HalluCana: Fixing LLM Hallucination with A Canary Lookahead10 Dec 2024
- 2024A Survey on Large Language Model-Based Social Agents in Game-Theoretic Scenarios5 Dec 2024
- 2024Noise Injection Reveals Hidden Capabilities of Sandbagging Language Models2 Dec 2024
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- 2025Adaptive Tool Use in Large Language Models with Meta-Cognition Triggercited by 30
- 2024A Survey on Large Language Model-Based Social Agents in Game-Theoretic Scenarioscited by 23
- 2026Detecting Multi-Agent Collusion Through Multi-Agent Interpretabilitycited by 7
- 2026Leveraging LLM Parametric Knowledge for Fact Checking without Retrievalcited by 1
- 2026Belief Cascades Drive Persuasion in LLM Agent Networkscited by 0
- 2026Silent Dissent: LLM Agents That Yield to the Majority Still Represent Their Original Premisecited by 0
- 2026Silent Dissent: LLM Agents That Yield to the Majority Still Represent Their Original Premise2 Oct 2026
- 2026Belief Cascades Drive Persuasion in LLM Agent Networks25 Aug 2026
- 2026Detecting Multi-Agent Collusion Through Multi-Agent Interpretability1 Apr 2026
- 2026Leveraging LLM Parametric Knowledge for Fact Checking without Retrieval5 Mar 2026
- 2025Adaptive Tool Use in Large Language Models with Meta-Cognition Trigger18 Feb 2025
- 2024A Survey on Large Language Model-Based Social Agents in Game-Theoretic Scenarios5 Dec 2024
- 2023Localizing Lying in Llama: Understanding Instructed Dishonesty on True-False Questions Through Prompting, Probing, and Patchingcited by 24
- 2025Representation Engineering for Large-Language Models: Survey and Research Challengescited by 21
- 2026One Probe Won't Catch Them All: Towards Targeted Deception Detectioncited by 9
- 2025Mechanistic Interpretability Needs Philosophycited by 6
- 2026Comparing Linear Probes with Mahalanobis Cosine Similaritycited by 1
- 2026Investigating Linear Probe Robustness to Linguistic Register, Medical Specialty, and Corpus Shifts in Medical QAcited by 0
- 2026Investigating Linear Probe Robustness to Linguistic Register, Medical Specialty, and Corpus Shifts in Medical QA1 Sep 2026
- 2026Comparing Linear Probes with Mahalanobis Cosine Similarity17 Jun 2026
- 2026One Probe Won't Catch Them All: Towards Targeted Deception Detection1 Feb 2026
- 2025Mechanistic Interpretability Needs Philosophy23 Jun 2025
- 2025Representation Engineering for Large-Language Models: Survey and Research Challenges24 Feb 2025
- 2023Localizing Lying in Llama: Understanding Instructed Dishonesty on True-False Questions Through Prompting, Probing, and Patching25 Nov 2023
- 2023Self-Consistency of Large Language Models under Ambiguitycited by 12
- 2026Think Before You Lie: How Reasoning Leads to Honestycited by 2
- 2026Think Before You Lie: How Reasoning Leads to Honesty10 Mar 2026
- 2023Self-Consistency of Large Language Models under Ambiguity20 Oct 2023
- 2023A Survey on Hallucination in Large Language Models: Principles, Taxonomy, Challenges, and Open Questionscited by 1,601
- 2023The Geometry of Truth: Emergent Linear Structure in Large Language Model Representations of True/False Datasetscited by 712
- 2023A Survey of Confidence Estimation and Calibration in Large Language Modelscited by 256
- 2024LLMs Know More Than They Show: On the Intrinsic Representation of LLM Hallucinationscited by 244
- 2023AI Deception: A Survey of Examples, Risks, and Potential Solutionscited by 188
- 2024Truth is Universal: Robust Detection of Lies in LLMscited by 79
- 2025Detecting High-Stakes Interactions with Activation Probescited by 53
- 2023Honesty Is the Best Policy: Defining and Mitigating AI Deceptioncited by 40
- 2023Challenges with unsupervised LLM knowledge discoverycited by 31
- 2024Standards for Belief Representations in LLMscited by 30
- 2024Noise Injection Reveals Hidden Capabilities of Sandbagging Language Modelscited by 24
- 2024Language Models in Dialogue: Conversational Maxims for Human-AI Interactionscited by 21
12 most cited of 58 All 58 (JSON)
- 2026Stress-Testing LLM Lie Detectors: Role-Play Failures and Spurious Correlations30 Sep 2026
- 2026Can AI systems have free will?14 Sep 2026
- 2026A Systematic Evaluation of Cross-Lingual Consistency Enhancement Methods in Multilingual Language Models3 Sep 2026
- 2026Recognition-Refusal Misalignment in LLMs: Why Models Answer Structurally Unanswerable Questions29 Aug 2026
- 2026The Hallucination Signal Is a Mean Shift: Why Simple Probes Suffice28 Aug 2026
- 2026Language Models Encode the Contextual Truth of Propositions4 Aug 2026
- 2026Belief-reality separation lives in routing over a shared value slot in language models11 Jul 2026
- 2026The Impossibility of Eliciting Latent Knowledge10 Jun 2026
- 2026Position: Anthropomorphic Misalignment Research Needs Stronger Evidence29 May 2026
- 2026When Answers Stray from Questions: Hallucination Detection via Question-Answer Orthogonal Decomposition14 May 2026
- 2026Hallucinations Undermine Trust; Metacognition is a Way Forward2 May 2026
- 2026A Robust Evaluation of Probe Robustness: Lessons for Reliable OOD Uncertainty Quantification13 Apr 2026
12 newest of 58 All 58 (JSON)