Uncertainty in Natural Language Generation: From Theory to Applications
Not on the map. Why?
Abstract (arXiv)
Recent advances of powerful Language Models have allowed Natural Language Generation (NLG) to emerge as an important technology that can not only perform traditional tasks like summarisation or translation, but also serve as a natural language interface to a variety of applications. As such, it is crucial that NLG systems are trustworthy and reliable, for example by indicating when they are likely to be wrong; and supporting multiple views, backgrounds and writing styles -- reflecting diverse human sub-populations. In this paper, we argue that a principled treatment of uncertainty can assist in creating systems and evaluation protocols better aligned with these goals. We first present the fundamental theory, frameworks and vocabulary required to represent uncertainty. We then characterise the main sources of uncertainty in NLG from a linguistic perspective, and propose a two-dimensional taxonomy that is more informative and faithful than the popular aleatoric/epistemic dichotomy. Finally, we move from theory to applications and highlight exciting research directions that exploit uncertainty to power decoding, controllable generation, self-assessment, selective answering, active learning and more.
Key facts. Cited by 61 papers in the map (data through 14 Oct 2026). Builds on 125 of its 201 references that are in the map. First posted on arXiv 28 Jul 2023.
Builds on
125 of 201 references.
References · 125
- 2022Training language models to follow instructions with human feedbackcited by 15,971
- 2019Exploring the Limits of Transfer Learning with a Unified Text-to-Text Transformercited by 14,599
- 2023LLaMA: Open and Efficient Foundation Language Modelscited by 14,132
- 2023Llama 2: Open Foundation and Fine-Tuned Chat Modelscited by 13,028
- 2020Retrieval-Augmented Generation for Knowledge-Intensive NLP Taskscited by 9,297
- 2022ReAct: Synergizing Reasoning and Acting in Language Modelscited by 8,695
- 2019BERTScore: Evaluating Text Generation with BERTcited by 5,512
- 2017On Calibration of Modern Neural Networkscited by 4,960
- 2023Toolformer: Language Models Can Teach Themselves to Use Toolscited by 4,182
- 2017Deep reinforcement learning from human preferencescited by 3,912
- 2021Finetuned Language Models Are Zero-Shot Learnerscited by 3,780
- 2015Neural Machine Translation of Rare Words with Subword Unitscited by 2,918
38 more
- 2019The Curious Case of Neural Text Degenerationcited by 2,916
- 2023Sparks of Artificial General Intelligence: Early experiments with GPT-4cited by 2,592
- 2020Learning to summarize from human feedbackcited by 2,588
- 2022Survey of Hallucination in Natural Language Generationcited by 2,075
- 2022Language Models (Mostly) Know What They Knowcited by 1,856
- 2020BLEURT: Learning Robust Metrics for Text Generationcited by 1,203
- 2018Hierarchical Neural Story Generationcited by 1,193
- 2015A Diversity-Promoting Objective Function for Neural Conversation Modelscited by 1,077
- 2020COMET: A Neural Framework for MT Evaluationcited by 1,033
- 2021An Explanation of In-context Learning as Implicit Bayesian Inferencecited by 938
- 2019Aleatoric and Epistemic Uncertainty in Machine Learning: An Introduction to Concepts and Methodscited by 913
- 2018Personalizing Dialogue Agents: I have a dog, do you have pets too?cited by 828
- 2020A Review of Uncertainty Quantification in Deep Learning: Techniques, Applications and Challengescited by 819
- 2023Semantic Uncertainty: Linguistic Invariances for Uncertainty Estimation in Natural Language Generationcited by 819
- 2021A Gentle Introduction to Conformal Prediction and Distribution-Free Uncertainty Quantificationcited by 792
- 2022Teaching Models to Express Their Uncertainty in Wordscited by 751
- 2021Cross-Task Generalization via Natural Language Crowdsourcing Instructionscited by 699
- 2021A Survey of Uncertainty in Deep Neural Networkscited by 680
- 2022PAL: Program-aided Language Modelscited by 652
- 2015Generating Sentences from a Continuous Spacecited by 612
- 2018Wizard of Wikipedia: Knowledge-Powered Conversational agentscited by 530
- 2021MAUVE: Measuring the Gap Between Neural Text and Human Text using Divergence Frontierscited by 470
- 2020How Can We Know When Language Models Know? On the Calibration of Language Models for Question Answeringcited by 445
- 2020Simple and Principled Uncertainty Estimation with Deterministic Deep Learning via Distance Awarenesscited by 389
- 2017A Deep Reinforced Model for Abstractive Summarizationcited by 365
- 2023Robots That Ask For Help: Uncertainty Alignment for Large Language Model Plannerscited by 308
- 2023Generating with Confidence: Uncertainty Quantification for Black-box Large Language Modelscited by 293
- 2020Evaluation of Text Generation: A Surveycited by 277
- 2021Surface Form Competition: Why the Highest Probability Answer Isn't Always Rightcited by 263
- 2022Prompting GPT-3 To Be Reliablecited by 260
- 2020Selective Question Answering under Domain Shiftcited by 238
- 2020Unsupervised Quality Estimation for Neural Machine Translationcited by 211
- 2020Reducing conversational agents' overconfidence through linguistic calibrationcited by 210
- 2017Survey of the State of the Art in Natural Language Generation: Core tasks, applications and evaluationcited by 206
- 2022Out-of-Distribution Detection and Selective Generation for Conditional Language Modelscited by 197
- 2021On Hallucination and Predictive Uncertainty in Conditional Language Generationcited by 176
- 2019Are We Modeling the Task or the Annotator? An Investigation of Annotator Bias in Natural Language Understanding Datasetscited by 175
- 2020Formalizing Trust in Artificial Intelligence: Prerequisites, Causes and Goals of Human Trust in AIcited by 167
50 most cited of 125 All 125 (JSON)
Built on by
Citing papers per year: 2023: 4; 2024: 21; 2025: 23; 2026: 13.
61 papers.
Sort:
By area:
- 2023A Survey of Confidence Estimation and Calibration in Large Language Modelscited by 256
- 2024The Art of Saying No: Contextual Noncompliance in Language Modelscited by 105
- 2024Can Large Language Models Faithfully Express Their Intrinsic Uncertainty in Words?cited by 87
- 2024Calibrating Large Language Models Using Their Generations Onlycited by 65
- 2025A Survey of Uncertainty Estimation Methods on Large Language Modelscited by 62
- 2024Conformal Prediction for Natural Language Processing: A Surveycited by 53
- 2024Multicalibration for Confidence Scoring in LLMscited by 46
- 2024Optimising Calls to Large Language Models with Uncertainty-Based Two-Tier Selectioncited by 33
- 2023Examining LLMs' Uncertainty Expression Towards Questions Outside Parametric Knowledgecited by 32
- 2024Asking the Right Question at the Right Time: Human and Model Uncertainty Guidance to Ask Clarification Questionscited by 32
- 2025Position: Uncertainty Quantification Needs Reassessment for Large-language Model Agentscited by 32
- 2024Cycles of Thought: Measuring LLM Confidence through Stable Explanationscited by 29
38 more
- 2024Introspective Planning: Aligning Robots' Uncertainty with Inherent Task Ambiguitycited by 27
- 2025Trust Me, I'm Wrong: LLMs Hallucinate with Certainty Despite Knowing the Answercited by 27
- 2024Non-Exchangeable Conformal Language Generation with Nearest Neighborscited by 21
- 2024DeLLMa: Decision Making Under Uncertainty with Large Language Modelscited by 21
- 2025Revisiting Uncertainty Quantification Evaluation in Language Models: Spurious Interactions with Response Length Bias Resultscited by 21
- 2025A Head to Predict and a Head to Question: Pre-trained Uncertainty Quantification Heads for Hallucination Detection in LLM Outputscited by 21
- 2025Token-Level Density-Based Uncertainty Quantification Methods for Eliciting Truthfulness of Large Language Modelscited by 18
- 2024Contextualized Sequence Likelihood: Enhanced Confidence Scores for Natural Language Generationcited by 16
- 2025Efficient Hallucination Detection for LLMs Using Uncertainty-Aware Attention Headscited by 16
- 2025MetaFaith: Faithful Natural Language Uncertainty Expression in LLMscited by 16
- 2024Interpreting Predictive Probabilities: Model Confidence or Human Label Variation?cited by 15
- 2024From Loops to Oops: Fallback Behaviors of Language Models Under Uncertaintycited by 14
- 2025Anthropomimetic Uncertainty: What Verbalized Uncertainty in Language Models is Missingcited by 14
- 2025When Models Lie, We Learn: Multilingual Span-Level Hallucination Detection with PsiloQAcited by 14
- 2024Reconfidencing LLMs from the Grouping Loss Perspectivecited by 11
- 2024Through the Lens of Split Vote: Exploring Disagreement, Difficulty and Calibration in Legal Case Outcome Classificationcited by 9
- 2024Unconditional Truthfulness: Learning Unconditional Uncertainty of Large Language Modelscited by 9
- 2024"I Never Said That": A dataset, taxonomy and baselines on response clarity classificationcited by 9
- 2024Text-to-SQL Calibration: No Need to Ask -- Just Rescale Model Probabilitiescited by 7
- 2025COPU: Conformal Prediction for Uncertainty Quantification in Natural Language Generationcited by 6
- 2025HACK: Hallucinations Along Certainty and Knowledge Axescited by 6
- 2025Black-Box Hallucination Detection via Consistency Under the Uncertain Expressioncited by 5
- 2023LUNA: A Model-Based Universal Analysis Framework for Large Language Modelscited by 4
- 2024Unanswerability Evaluation for Retrieval Augmented Generationcited by 4
- 2025Comparing Uncertainty Measurement and Mitigation Methods for Large Language Models: A Systematic Reviewcited by 4
- 2025Statistical Methods in Generative AIcited by 4
- 2025Towards Reliable LLM-based Robot Planning via Combined Uncertainty Estimationcited by 4
- 2026The Yes-Man Syndrome: Benchmarking Abstention in Embodied Robotic Agentscited by 4
- 2025Embracing Diversity: A Multi-Perspective Approach with Soft Labelscited by 3
- 2025Don't Throw Away Your Beams: Improving Consistency-based Uncertainties in LLMs via Beam Searchcited by 3
- 2026Calibration Is Not Enough: Evaluating Confidence Estimation Under Language Variationscited by 3
- 2026VLM-UQBench: A Benchmark for Modality-Specific and Cross-Modality Uncertainties in Vision Language Modelscited by 3
- 2026Uncertainty Decomposition for Clarification Seeking in LLM Agentscited by 3
- 2024Variability Need Not Imply Error: The Case of Adequate but Semantically Distinct Responsescited by 2
- 2025References Matter: Investigating the Impact of Reference Set Variation on Summarization Evaluationcited by 2
- 2025ESI: Epistemic Uncertainty Quantification via Semantic-preserving Intervention for Large Language Modelscited by 2
- 2026Learning When to Sample: Confidence-Aware Selective Sampling for Efficient Chain-of-Thought Reasoningcited by 2
- 2023Human-in-the-loop: Towards Label Embeddings for Measuring Classification Difficultycited by 1
50 most cited of 61 All 61 (JSON)
- 2026Characterizing Overconfident Failure in LLM-Based Code Generation8 Oct 2026
- 2026Uncertainty Quantification for LLM Agents: A Taxonomy, an Evaluation Protocol, and an Empirical Study7 Sep 2026
- 2026Uncertainty Decomposition for Clarification Seeking in LLM Agents17 Jun 2026
- 2026Epistemic Uncertainty Is Not the Reducible Kind10 Jun 2026
- 2026Shared Doubt: Zero-Shot Cross-Lingual Confidence Estimation for Language Models29 May 2026
- 2026Clarify, Abstain or Answer? Strategising in Conversation with Belief-Augmented Generation25 May 2026
- 2026The Yes-Man Syndrome: Benchmarking Abstention in Embodied Robotic Agents19 May 2026
- 2026Gradients with Respect to Semantics Preserving Embeddings Tell the Uncertainty of Large Language Models6 May 2026
- 2026Credal Concept Bottleneck Models for Epistemic-Aleatoric Uncertainty Decomposition27 Apr 2026
- 2026Why Don't You Know? Evaluating the Impact of Uncertainty Sources on Uncertainty Quantification in LLMs12 Apr 2026
- 2026Learning When to Sample: Confidence-Aware Selective Sampling for Efficient Chain-of-Thought Reasoning9 Mar 2026
- 2026VLM-UQBench: A Benchmark for Modality-Specific and Cross-Modality Uncertainties in Vision Language Models9 Feb 2026
38 more
- 2026Calibration Is Not Enough: Evaluating Confidence Estimation Under Language Variations12 Jan 2026
- 2025Don't Throw Away Your Beams: Improving Consistency-based Uncertainties in LLMs via Beam Search10 Dec 2025
- 2025HACK: Hallucinations Along Certainty and Knowledge Axes28 Oct 2025
- 2025ESI: Epistemic Uncertainty Quantification via Semantic-preserving Intervention for Large Language Models15 Oct 2025
- 2025Towards Reliable LLM-based Robot Planning via Combined Uncertainty Estimation9 Oct 2025
- 2025When Models Lie, We Learn: Multilingual Span-Level Hallucination Detection with PsiloQA6 Oct 2025
- 2025Black-Box Hallucination Detection via Consistency Under the Uncertain Expression26 Sep 2025
- 2025Learning to vary: Teaching LMs to reproduce human linguistic variability in next-word prediction22 Sep 2025
- 2025Statistical Methods in Generative AI8 Sep 2025
- 2025Anthropomimetic Uncertainty: What Verbalized Uncertainty in Language Models is Missing11 Jul 2025
- 2025References Matter: Investigating the Impact of Reference Set Variation on Summarization Evaluation17 Jun 2025
- 2025Mind the Gap: Benchmarking LLM Uncertainty and Calibration with Specialty-Aware Clinical QA and Reasoning-Based Behavioural Features12 Jun 2025
- 2025MetaFaith: Faithful Natural Language Uncertainty Expression in LLMs30 May 2025
- 2025Position: Uncertainty Quantification Needs Reassessment for Large-language Model Agents28 May 2025
- 2025Efficient Hallucination Detection for LLMs Using Uncertainty-Aware Attention Heads26 May 2025
- 2025A Head to Predict and a Head to Question: Pre-trained Uncertainty Quantification Heads for Hallucination Detection in LLM Outputs13 May 2025
- 2025Comparing Uncertainty Measurement and Mitigation Methods for Large Language Models: A Systematic Review25 Apr 2025
- 2025Revisiting Uncertainty Quantification Evaluation in Language Models: Spurious Interactions with Response Length Bias Results18 Apr 2025
- 2025Your Model is Overconfident, and Other Lies We Tell Ourselves3 Mar 2025
- 2025Embracing Diversity: A Multi-Perspective Approach with Soft Labels1 Mar 2025
- 2025A Survey of Uncertainty Estimation Methods on Large Language Models28 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
- 2025COPU: Conformal Prediction for Uncertainty Quantification in Natural Language Generation18 Feb 2025
- 2024Variability Need Not Imply Error: The Case of Adequate but Semantically Distinct Responses20 Dec 2024
- 2024Unanswerability Evaluation for Retrieval Augmented Generation16 Dec 2024
- 2024Text-to-SQL Calibration: No Need to Ask -- Just Rescale Model Probabilities23 Nov 2024
- 2024"I Never Said That": A dataset, taxonomy and baselines on response clarity classification20 Sep 2024
- 2024Unconditional Truthfulness: Learning Unconditional Uncertainty of Large Language Models20 Aug 2024
- 2024From Loops to Oops: Fallback Behaviors of Language Models Under Uncertainty8 Jul 2024
- 2024The Art of Saying No: Contextual Noncompliance in Language Models2 Jul 2024
- 2024Cycles of Thought: Measuring LLM Confidence through Stable Explanations5 Jun 2024
- 2024Contextualized Sequence Likelihood: Enhanced Confidence Scores for Natural Language Generation3 Jun 2024
- 2024Can Large Language Models Faithfully Express Their Intrinsic Uncertainty in Words?27 May 2024
- 2024Optimising Calls to Large Language Models with Uncertainty-Based Two-Tier Selection3 May 2024
- 2024Conformal Prediction for Natural Language Processing: A Survey3 May 2024
- 2024Multicalibration for Confidence Scoring in LLMs6 Apr 2024
- 2024Calibrating Large Language Models Using Their Generations Only9 Mar 2024
50 newest of 61 All 61 (JSON)
- 2024Cycles of Thought: Measuring LLM Confidence through Stable Explanationscited by 29
- 2024Introspective Planning: Aligning Robots' Uncertainty with Inherent Task Ambiguitycited by 27
- 2025Towards Reliable LLM-based Robot Planning via Combined Uncertainty Estimationcited by 4
- 2026Learning When to Sample: Confidence-Aware Selective Sampling for Efficient Chain-of-Thought Reasoningcited by 2
- 2025Mind the Gap: Benchmarking LLM Uncertainty and Calibration with Specialty-Aware Clinical QA and Reasoning-Based Behavioural Featurescited by 1
- 2026Learning When to Sample: Confidence-Aware Selective Sampling for Efficient Chain-of-Thought Reasoning9 Mar 2026
- 2025Towards Reliable LLM-based Robot Planning via Combined Uncertainty Estimation9 Oct 2025
- 2025Mind the Gap: Benchmarking LLM Uncertainty and Calibration with Specialty-Aware Clinical QA and Reasoning-Based Behavioural Features12 Jun 2025
- 2024Cycles of Thought: Measuring LLM Confidence through Stable Explanations5 Jun 2024
- 2024Introspective Planning: Aligning Robots' Uncertainty with Inherent Task Ambiguity9 Feb 2024
- 2023A Survey of Confidence Estimation and Calibration in Large Language Modelscited by 256
- 2024The Art of Saying No: Contextual Noncompliance in Language Modelscited by 105
- 2024Can Large Language Models Faithfully Express Their Intrinsic Uncertainty in Words?cited by 87
- 2024Calibrating Large Language Models Using Their Generations Onlycited by 65
- 2025A Survey of Uncertainty Estimation Methods on Large Language Modelscited by 62
- 2024Conformal Prediction for Natural Language Processing: A Surveycited by 53
- 2024Multicalibration for Confidence Scoring in LLMscited by 46
- 2024Optimising Calls to Large Language Models with Uncertainty-Based Two-Tier Selectioncited by 33
- 2023Examining LLMs' Uncertainty Expression Towards Questions Outside Parametric Knowledgecited by 32
- 2024Asking the Right Question at the Right Time: Human and Model Uncertainty Guidance to Ask Clarification Questionscited by 32
- 2025Trust Me, I'm Wrong: LLMs Hallucinate with Certainty Despite Knowing the Answercited by 27
- 2024Non-Exchangeable Conformal Language Generation with Nearest Neighborscited by 21
12 most cited of 50 All 50 (JSON)
- 2026Characterizing Overconfident Failure in LLM-Based Code Generation8 Oct 2026
- 2026Epistemic Uncertainty Is Not the Reducible Kind10 Jun 2026
- 2026Shared Doubt: Zero-Shot Cross-Lingual Confidence Estimation for Language Models29 May 2026
- 2026Clarify, Abstain or Answer? Strategising in Conversation with Belief-Augmented Generation25 May 2026
- 2026Gradients with Respect to Semantics Preserving Embeddings Tell the Uncertainty of Large Language Models6 May 2026
- 2026Credal Concept Bottleneck Models for Epistemic-Aleatoric Uncertainty Decomposition27 Apr 2026
- 2026Why Don't You Know? Evaluating the Impact of Uncertainty Sources on Uncertainty Quantification in LLMs12 Apr 2026
- 2026Calibration Is Not Enough: Evaluating Confidence Estimation Under Language Variations12 Jan 2026
- 2025Don't Throw Away Your Beams: Improving Consistency-based Uncertainties in LLMs via Beam Search10 Dec 2025
- 2025HACK: Hallucinations Along Certainty and Knowledge Axes28 Oct 2025
- 2025ESI: Epistemic Uncertainty Quantification via Semantic-preserving Intervention for Large Language Models15 Oct 2025
- 2025When Models Lie, We Learn: Multilingual Span-Level Hallucination Detection with PsiloQA6 Oct 2025
12 newest of 50 All 50 (JSON)