Do Androids Know They're Only Dreaming of Electric Sheep?
On the map: Mechanistic interpretability → Hallucination detection from model internals
Abstract (arXiv)
We design probes trained on the internal representations of a transformer language model to predict its hallucinatory behavior on three grounded generation tasks. To train the probes, we annotate for span-level hallucination on both sampled (organic) and manually edited (synthetic) reference outputs. Our probes are narrowly trained and we find that they are sensitive to their training domain: they generalize poorly from one task to another or from synthetic to organic hallucinations. However, on in-domain data, they can reliably detect hallucinations at many transformer layers, achieving 95% of their peak performance as early as layer 4. Here, probing proves accurate for evaluating hallucination, outperforming several contemporary baselines and even surpassing an expert human annotator in response-level detection F1. Similarly, on span-level labeling, probes are on par or better than the expert annotator on two out of three generation tasks. Overall, we find that probing is a feasible and efficient alternative to language model hallucination evaluation when model states are available.
Key facts. Cited by 67 papers in the map (data through 14 Oct 2026). Placed in Hallucination detection from model internals, one of 13 directions in Mechanistic interpretability. Builds on 41 of its 56 references that are in the map. First posted on arXiv 28 Dec 2023.
Builds on
41 of 56 references.
References · 41
- 2017Attention Is All You Needcited by 60,361
- 2014Adam: A Method for Stochastic Optimizationcited by 37,240
- 2017Proximal Policy Optimization Algorithmscited by 15,215
- 2023Llama 2: Open Foundation and Fine-Tuned Chat Modelscited by 13,028
- 2020Retrieval-Augmented Generation for Knowledge-Intensive NLP Taskscited by 9,297
- 2017TriviaQA: A Large Scale Distantly Supervised Challenge Dataset for Reading Comprehensioncited by 2,955
- 2022Locating and Editing Factual Associations in GPTcited by 2,691
- 2022Language Models (Mostly) Know What They Knowcited by 1,856
- 2016Understanding intermediate layers using linear classifier probescited by 1,353
- 2020Transformer Feed-Forward Layers Are Key-Value Memoriescited by 1,336
- 2023FActScore: Fine-grained Atomic Evaluation of Factual Precision in Long Form Text Generationcited by 1,282
- 2018Hierarchical Neural Story Generationcited by 1,193
29 more
- 2015Teaching Machines to Read and Comprehendcited by 1,049
- 2022Mass-Editing Memory in a Transformercited by 1,001
- 2023The Internal State of an LLM Knows When It's Lyingcited by 659
- 2019Evaluating the Factual Consistency of Abstractive Text Summarizationcited by 584
- 2021SummaC: Re-Visiting NLI-based Models for Inconsistency Detection in Summarizationcited by 407
- 2020Asking and Answering Questions to Evaluate the Factual Consistency of Summariescited by 378
- 2020FEQA: A Question Answering Evaluation Framework for Faithfulness Assessment in Abstractive Summarizationcited by 293
- 2017The E2E Dataset: New Challenges For End-to-End Generationcited by 253
- 2021QuestEval: Summarization Asks for Fact-based Evaluationcited by 244
- 2020Reducing conversational agents' overconfidence through linguistic calibrationcited by 210
- 2022Out-of-Distribution Detection and Selective Generation for Conditional Language Modelscited by 197
- 2019Neural Text Summarization: A Critical Evaluationcited by 189
- 2021Annotating and Modeling Fine-grained Factuality in Summarizationcited by 131
- 2020Evaluating Factuality in Generation with Dependency-level Entailmentcited by 122
- 2020GO FIGURE: A Meta Evaluation of Factuality in Summarizationcited by 76
- 2023WikiChat: Stopping the Hallucination of Large Language Model Chatbots by Few-Shot Grounding on Wikipediacited by 67
- 2023Attention Satisfies: A Constraint-Satisfaction Lens on Factual Errors of Language Modelscited by 67
- 2020Knowledge Graph-Augmented Abstractive Summarization with Semantic-Driven Cloze Rewardcited by 66
- 2019Semantic Noise Matters for Neural Natural Language Generationcited by 64
- 2023Cognitive Dissonance: Why Do Language Model Outputs Disagree with Internal Representations of Truthfulness?cited by 62
- 2018UKP-Athene: Multi-Sentence Textual Entailment for Claim Verificationcited by 60
- 2023Understanding and Detecting Hallucinations in Neural Machine Translation via Model Introspectioncited by 44
- 2020Towards Ecologically Valid Research on Language User Interfacescited by 42
- 2021Rome was built in 1776: A Case Study on Factual Correctness in Knowledge-Grounded Response Generationcited by 29
- 2023A Glitch in the Matrix? Locating and Detecting Language Model Grounding with Fakepediacited by 24
- 2023LongDocFACTScore: Evaluating the Factuality of Long Document Abstractive Summarisationcited by 16
- 2022BUMP: A Benchmark of Unfaithful Minimal Pairs for Meta-Evaluation of Faithfulness Metricscited by 7
- 2022Exact Paired-Permutation Testing for Structured Test Statisticscited by 6
- 2023Diversity Measures: Domain-Independent Proxies for Failure in Language Model Queriescited by 4
Built on by
Citing papers per year: 2024: 17; 2025: 28; 2026: 22.
67 papers.
Sort:
By area:
- 2024Don't Hallucinate, Abstain: Identifying LLM Knowledge Gaps via Multi-LLM Collaborationcited by 180
- 2024Do I Know This Entity? Knowledge Awareness and Hallucinations in Language Modelscited by 115
- 2024A Primer on the Inner Workings of Transformer-based Language Modelscited by 85
- 2024Uncertainty Estimation and Quantification for LLMs: A Simple Supervised Approachcited by 76
- 2024Get my drift? Catching LLM Task Drift with Activation Deltascited by 72
- 2024Latent Space Chain-of-Embedding Enables Output-free LLM Self-Evaluationcited by 57
- 2024Insights into LLM Long-Context Failures: When Transformers Know but Don't Tellcited by 36
- 2025Real-Time Detection of Hallucinated Entities in Long-Form Generationcited by 34
- 2025ICR Probe: Tracking Hidden State Dynamics for Reliable Hallucination Detection in LLMscited by 32
- 2025Trust Me, I'm Wrong: LLMs Hallucinate with Certainty Despite Knowing the Answercited by 27
- 2024On the Universal Truthfulness Hyperplane Inside LLMscited by 24
- 2024Towards Uncovering How Large Language Model Works: An Explainability Perspectivecited by 22
38 more
- 2025Representation Engineering for Large-Language Models: Survey and Research Challengescited by 21
- 2025A Head to Predict and a Head to Question: Pre-trained Uncertainty Quantification Heads for Hallucination Detection in LLM Outputscited by 21
- 2024Constructing Benchmarks and Interventions for Combating Hallucinations in LLMscited by 19
- 2025Hallucination Detection in LLMs with Topological Divergence on Attention Graphscited by 19
- 2025Token-Level Density-Based Uncertainty Quantification Methods for Eliciting Truthfulness of Large Language Modelscited by 18
- 2025Probing the Geometry of Truth: Consistency and Generalization of Truth Directions in LLMs Across Logical Transformations and Question Answering Taskscited by 18
- 2025Efficient Hallucination Detection for LLMs Using Uncertainty-Aware Attention Headscited by 16
- 2024Distinguishing Ignorance from Error in LLM Hallucinationscited by 14
- 2025When Models Lie, We Learn: Multilingual Span-Level Hallucination Detection with PsiloQAcited by 14
- 2026HALP: Detecting Hallucinations in Vision-Language Models without Generating a Single Tokencited by 14
- 2024REAL Sampling: Boosting Factuality and Diversity of Open-Ended Generation via Asymptotic Entropycited by 11
- 2024FactCheckmate: Preemptively Detecting and Mitigating Hallucinations in LMscited by 11
- 2025Interpretation Meets Safety: A Survey on Interpretation Methods and Tools for Improving LLM Safetycited by 10
- 2024Unconditional Truthfulness: Learning Unconditional Uncertainty of Large Language Modelscited by 9
- 2025Always Tell Me The Odds: Fine-grained Conditional Probability Estimationcited by 9
- 2025The Geometries of Truth Are Orthogonal Across Taskscited by 9
- 2025LLM Knowledge is Brittle: Truthfulness Representations Rely on Superficial Resemblancecited by 9
- 2024Prompt-Guided Internal States for Hallucination Detection of Large Language Modelscited by 8
- 2026The Truthfulness Spectrum Hypothesiscited by 8
- 2025When Do LLMs Admit Their Mistakes? Understanding The Role Of Model Belief In Retractioncited by 6
- 2025HACK: Hallucinations Along Certainty and Knowledge Axescited by 6
- 2024Shared Imagination: LLMs Hallucinate Alikecited by 5
- 2026Hallucinations Undermine Trust; Metacognition is a Way Forwardcited by 5
- 2025RePPL: Recalibrating Perplexity by Uncertainty in Semantic Propagation and Language Generation for Explainable QA Hallucination Detectioncited by 4
- 2025The Curious Case of Factuality Finetuning: Models' Internal Beliefs Can Improve Factualitycited by 4
- 2025Cross-Layer Attention Probing for Fine-Grained Hallucination Detectioncited by 4
- 2025Localized Calibrated Uncertainty in Code Language Modelscited by 3
- 2025Data-efficient Meta-models for Evaluation of Context-based Questions and Answers in LLMscited by 2
- 2025Shapley Uncertainty in Natural Language Generationcited by 2
- 2026HalluZig: Hallucination Detection using Zigzag Persistencecited by 2
- 2026INTRYGUE: Induction-Aware Entropy Gating for Reliable RAG Uncertainty Estimationcited by 2
- 2026Process Supervision of Confidence Margin for Calibrated LLM Reasoningcited by 2
- 2026From Signals to Transfer: A Factorised Study of Probe-Based Uncertainty Estimation in Large Language Modelscited by 2
- 2026HalluTruthQA: A Fine-Grained Benchmark for Hallucination Detection, Localization, and Explanation in Arabic Question Answeringcited by 2
- 2026Language Models Encode the Contextual Truth of Propositionscited by 2
- 2024Listening to the Wise Few: Query-Key Alignment Unlocks Latent Correct Answers in Large Language Modelscited by 1
- 2025Exploring the generalization of LLM truth directions on conversational formatscited by 1
- 2025ALIEN: Aligned Entropy Head for Improving Uncertainty Estimation of LLMscited by 1
50 most cited of 67 All 67 (JSON)
- 2026Evaluating Persistent Calibration under Evolving Model Knowledge30 Sep 2026
- 2026Language Models Encode the Contextual Truth of Propositions4 Aug 2026
- 2026HalluTruthQA: A Fine-Grained Benchmark for Hallucination Detection, Localization, and Explanation in Arabic Question Answering22 Jul 2026
- 2026SIRIN: A Unified Toolkit for Detecting Contextual Hallucinations in Retrieval-Augmented and Memory-Grounded LLM Systems20 Jul 2026
- 2026ASK-NN: An Asymmetric Nearest-Neighbor Test that detects Distribution Drifts in Natural Language17 Jul 2026
- 2026From Signals to Transfer: A Factorised Study of Probe-Based Uncertainty Estimation in Large Language Models26 Jun 2026
- 2026Pre-Generation Hallucination Detection in Large Language Models via Soft-Target Attention Probing20 Jun 2026
- 2026A Close Look At World Model Recovery In Supervised Fine-Tuned LLM Planners2 Jun 2026
- 2026The Role of Ambiguity in Error Prediction via Uncertainty Quantification1 Jun 2026
- 2026TriLens: Per-Layer Logit-Lens Entropy for White-Box Hallucination Detection31 May 2026
- 2026Causal Tongue-Tie: LLMs Can Encode Causal Direction, But Their Yes/No Outputs Fail to Express25 May 2026
- 2026Hallucinations Undermine Trust; Metacognition is a Way Forward2 May 2026
38 more
- 2026Process Supervision of Confidence Margin for Calibrated LLM Reasoning25 Apr 2026
- 2026RAGognizer: Hallucination-Aware Fine-Tuning via Detection Head Integration17 Apr 2026
- 2026A Robust Evaluation of Probe Robustness: Lessons for Reliable OOD Uncertainty Quantification13 Apr 2026
- 2026INTRYGUE: Induction-Aware Entropy Gating for Reliable RAG Uncertainty Estimation23 Mar 2026
- 2026Leveraging LLM Parametric Knowledge for Fact Checking without Retrieval5 Mar 2026
- 2026HALP: Detecting Hallucinations in Vision-Language Models without Generating a Single Token5 Mar 2026
- 2026The Truthfulness Spectrum Hypothesis23 Feb 2026
- 2026Detecting Overflow in Compressed Token Representations for Retrieval-Augmented Generation12 Feb 2026
- 2026CORVUS: Red-Teaming Hallucination Detectors via Internal Signal Camouflage in Large Language Models19 Jan 2026
- 2026HalluZig: Hallucination Detection using Zigzag Persistence4 Jan 2026
- 2025Localized Calibrated Uncertainty in Code Language Models31 Dec 2025
- 2025TrueBrief: Faithful Summarization through Small Language Models12 Dec 2025
- 2025Polarity-Aware Probing for Quantifying Latent Alignment in Language Models21 Nov 2025
- 2025HACK: Hallucinations Along Certainty and Knowledge Axes28 Oct 2025
- 2025LLM Knowledge is Brittle: Truthfulness Representations Rely on Superficial Resemblance13 Oct 2025
- 2025When Models Lie, We Learn: Multilingual Span-Level Hallucination Detection with PsiloQA6 Oct 2025
- 2025Training-free Truthfulness Detection via Sparse MLP Value Vectors22 Sep 2025
- 2025Cross-Layer Attention Probing for Fine-Grained Hallucination Detection4 Sep 2025
- 2025Real-Time Detection of Hallucinated Entities in Long-Form Generation26 Aug 2025
- 2025Shapley Uncertainty in Natural Language Generation29 Jul 2025
- 2025ICR Probe: Tracking Hidden State Dynamics for Reliable Hallucination Detection in LLMs22 Jul 2025
- 2025The Curious Case of Factuality Finetuning: Models' Internal Beliefs Can Improve Factuality11 Jul 2025
- 2025Probabilistic distances-based hallucination detection in LLMs with RAG11 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
- 2025Data-efficient Meta-models for Evaluation of Context-based Questions and Answers in LLMs29 May 2025
- 2025Efficient Hallucination Detection for LLMs Using Uncertainty-Aware Attention Heads26 May 2025
- 2025When Do LLMs Admit Their Mistakes? Understanding The Role Of Model Belief In Retraction22 May 2025
- 2025ALIEN: Aligned Entropy Head for Improving Uncertainty Estimation of LLMs21 May 2025
- 2025RePPL: Recalibrating Perplexity by Uncertainty in Semantic Propagation and Language Generation for Explainable QA Hallucination Detection21 May 2025
- 2025Exploring the generalization of LLM truth directions on conversational formats14 May 2025
- 2025A Head to Predict and a Head to Question: Pre-trained Uncertainty Quantification Heads for Hallucination Detection in LLM Outputs13 May 2025
- 2025Always Tell Me The Odds: Fine-grained Conditional Probability Estimation2 May 2025
- 2025Hallucination Detection in LLMs with Topological Divergence on Attention Graphs14 Apr 2025
- 2025Representation Engineering for Large-Language Models: Survey and Research Challenges24 Feb 2025
- 2025Token-Level Density-Based Uncertainty Quantification Methods for Eliciting Truthfulness of Large Language Models20 Feb 2025
- 2025Trust Me, I'm Wrong: LLMs Hallucinate with Certainty Despite Knowing the Answer18 Feb 2025
50 newest of 67 All 67 (JSON)
- 2024Get my drift? Catching LLM Task Drift with Activation Deltascited by 72
- 2025Data-efficient Meta-models for Evaluation of Context-based Questions and Answers in LLMscited by 2
- 2026INTRYGUE: Induction-Aware Entropy Gating for Reliable RAG Uncertainty Estimationcited by 2
- 2025Probabilistic distances-based hallucination detection in LLMs with RAGcited by 1
- 2026Detecting Overflow in Compressed Token Representations for Retrieval-Augmented Generationcited by 1
- 2026RAGognizer: Hallucination-Aware Fine-Tuning via Detection Head Integrationcited by 1
- 2026SIRIN: A Unified Toolkit for Detecting Contextual Hallucinations in Retrieval-Augmented and Memory-Grounded LLM Systemscited by 0
- 2026SIRIN: A Unified Toolkit for Detecting Contextual Hallucinations in Retrieval-Augmented and Memory-Grounded LLM Systems20 Jul 2026
- 2026RAGognizer: Hallucination-Aware Fine-Tuning via Detection Head Integration17 Apr 2026
- 2026INTRYGUE: Induction-Aware Entropy Gating for Reliable RAG Uncertainty Estimation23 Mar 2026
- 2026Detecting Overflow in Compressed Token Representations for Retrieval-Augmented Generation12 Feb 2026
- 2025Probabilistic distances-based hallucination detection in LLMs with RAG11 Jun 2025
- 2025Data-efficient Meta-models for Evaluation of Context-based Questions and Answers in LLMs29 May 2025
- 2024Get my drift? Catching LLM Task Drift with Activation Deltas2 Jun 2024
- 2024Don't Hallucinate, Abstain: Identifying LLM Knowledge Gaps via Multi-LLM Collaborationcited by 180
- 2024A Primer on the Inner Workings of Transformer-based Language Modelscited by 85
- 2024Uncertainty Estimation and Quantification for LLMs: A Simple Supervised Approachcited by 76
- 2024Latent Space Chain-of-Embedding Enables Output-free LLM Self-Evaluationcited by 57
- 2024Insights into LLM Long-Context Failures: When Transformers Know but Don't Tellcited by 36
- 2025Real-Time Detection of Hallucinated Entities in Long-Form Generationcited by 34
- 2025ICR Probe: Tracking Hidden State Dynamics for Reliable Hallucination Detection in LLMscited by 32
- 2025Trust Me, I'm Wrong: LLMs Hallucinate with Certainty Despite Knowing the Answercited by 27
- 2024On the Universal Truthfulness Hyperplane Inside LLMscited by 24
- 2025A Head to Predict and a Head to Question: Pre-trained Uncertainty Quantification Heads for Hallucination Detection in LLM Outputscited by 21
- 2024Constructing Benchmarks and Interventions for Combating Hallucinations in LLMscited by 19
- 2025Hallucination Detection in LLMs with Topological Divergence on Attention Graphscited by 19
12 most cited of 48 All 48 (JSON)
- 2026Evaluating Persistent Calibration under Evolving Model Knowledge30 Sep 2026
- 2026Language Models Encode the Contextual Truth of Propositions4 Aug 2026
- 2026HalluTruthQA: A Fine-Grained Benchmark for Hallucination Detection, Localization, and Explanation in Arabic Question Answering22 Jul 2026
- 2026ASK-NN: An Asymmetric Nearest-Neighbor Test that detects Distribution Drifts in Natural Language17 Jul 2026
- 2026From Signals to Transfer: A Factorised Study of Probe-Based Uncertainty Estimation in Large Language Models26 Jun 2026
- 2026Pre-Generation Hallucination Detection in Large Language Models via Soft-Target Attention Probing20 Jun 2026
- 2026The Role of Ambiguity in Error Prediction via Uncertainty Quantification1 Jun 2026
- 2026TriLens: Per-Layer Logit-Lens Entropy for White-Box Hallucination Detection31 May 2026
- 2026Causal Tongue-Tie: LLMs Can Encode Causal Direction, But Their Yes/No Outputs Fail to Express25 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
- 2026The Truthfulness Spectrum Hypothesis23 Feb 2026
12 newest of 48 All 48 (JSON)
Similar, not cited
Close in wording, no citation either way
- 2026Detection Without Correction: A Robust Asymmetry in Activation-Based Hallucination Probing
- 2025A Single Direction of Truth: An Observer Model's Linear Residual Probe Exposes and Steers Contextual Hallucinations
- 2026External Observers May See More Clearly: Cross-Model Span-Level Hallucination Detection in Large Language Models via Hidden State Probing
- 2026VIB-Probe: Detecting and Mitigating Hallucinations in Vision-Language Models via Variational Information Bottleneck
- 2025MTRE: Multi-Token Reliability Estimation for Hallucination Detection in VLMs
- 2026HalluScope: Fine-grained Hallucination Diagnosis for Multimodal Large Language Models
- 2026HalluSAE: Detecting Hallucinations in Large Language Models via Sparse Auto-Encoders
- 2026Grounding Probes: Generator-Independent Hallucination Detection from Observer Model Hidden States