Large Language Models Lack Understanding of Character Composition of Words
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Abstract (arXiv)
Large language models (LLMs) have demonstrated remarkable performances on a wide range of natural language tasks. Yet, LLMs' successes have been largely restricted to tasks concerning words, sentences, or documents, and it remains questionable how much they understand the minimal units of text, namely characters. In this paper, we examine contemporary LLMs regarding their ability to understand character composition of words, and show that most of them fail to reliably carry out even the simple tasks that can be handled by humans with perfection. We analyze their behaviors with comparison to token level performances, and discuss the potential directions for future research.
Key facts. Cited by 22 papers in the map (data through 14 Oct 2026). Builds on 15 of its 24 references that are in the map. First posted on arXiv 18 May 2024.
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15 of 24 references.
References · 15
- 2023Llama 2: Open Foundation and Fine-Tuned Chat Modelscited by 13,028
- 2018GLUE: A Multi-Task Benchmark and Analysis Platform for Natural Language Understandingcited by 4,899
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- 2019SuperGLUE: A Stickier Benchmark for General-Purpose Language Understanding Systemscited by 1,729
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Citing papers per year: 2024: 5; 2025: 7; 2026: 10.
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- 2026Large Language Model Reasoning Failurescited by 21
- 2024From Introspection to Best Practices: Principled Analysis of Demonstrations in Multimodal In-Context Learningcited by 11
- 2025The Strawberry Problem: Emergence of Character-level Understanding in Tokenized Language Modelscited by 11
- 2025StochasTok: Improving Fine-Grained Subword Understanding in LLMscited by 7
- 2025Subword models struggle with word learning, but surprisal hides itcited by 6
- 2026Measuring Progress Toward AGI: A Cognitive Frameworkcited by 6
- 2025Spelling-out is not Straightforward: LLMs' Capability of Tokenization from Token to Characterscited by 4
- 2025Prompt-Based One-Shot Exact Length-Controlled Generation with LLMscited by 4
- 2024Enhancing Character-Level Understanding in LLMs through Token Internal Structure Learningcited by 3
- 2025Multilingual LLMs Struggle to Link Orthography and Semantics in Bilingual Word Processingcited by 3
- 2025CharBench: Evaluating the Role of Tokenization in Character-Level Taskscited by 3
- 2026ALBA: A European Portuguese Benchmark for Evaluating Language and Linguistic Dimensions in Generative LLMscited by 3
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- 2026From Early Encoding to Late Suppression: Interpreting LLMs on Character Counting Taskscited by 3
- 2024StringLLM: Understanding the String Processing Capability of Large Language Modelscited by 2
- 2024Aligning Generalisation Between Humans and Machinescited by 2
- 2024ChaI-TeA: A Benchmark for Evaluating Autocompletion of Interactions with LLM-based Chatbotscited by 1
- 2026Do multimodal models imagine electric sheep?cited by 1
- 2026Training Language Models with homotokens Leads to Delayed Overfittingcited by 0
- 2026SubTokenTest: A Practical Benchmark for Real-World Sub-token Understandingcited by 0
- 2026Spelling Bee Embeddings for Language Modelingcited by 0
- 2026Beyond Accuracy: Diagnosing Algebraic Reasoning Failures in LLMs Across Nine Complexity Dimensionscited by 0
- 2026SCRIPTIOC-BENCH: A Benchmark for Recognizing Actionable Threat Intelligence from Script-Based Malware using LLMscited by 0
- 2026SCRIPTIOC-BENCH: A Benchmark for Recognizing Actionable Threat Intelligence from Script-Based Malware using LLMs5 Sep 2026
- 2026Measuring Progress Toward AGI: A Cognitive Framework27 May 2026
- 2026Do multimodal models imagine electric sheep?10 May 2026
- 2026Beyond Accuracy: Diagnosing Algebraic Reasoning Failures in LLMs Across Nine Complexity Dimensions8 Apr 2026
- 2026From Early Encoding to Late Suppression: Interpreting LLMs on Character Counting Tasks1 Apr 2026
- 2026ALBA: A European Portuguese Benchmark for Evaluating Language and Linguistic Dimensions in Generative LLMs27 Mar 2026
- 2026Large Language Model Reasoning Failures5 Feb 2026
- 2026Spelling Bee Embeddings for Language Modeling25 Jan 2026
- 2026SubTokenTest: A Practical Benchmark for Real-World Sub-token Understanding14 Jan 2026
- 2026Training Language Models with homotokens Leads to Delayed Overfitting6 Jan 2026
- 2025Prompt-Based One-Shot Exact Length-Controlled Generation with LLMs19 Aug 2025
- 2025CharBench: Evaluating the Role of Tokenization in Character-Level Tasks4 Aug 2025
10 more
- 2025Spelling-out is not Straightforward: LLMs' Capability of Tokenization from Token to Characters12 Jun 2025
- 2025StochasTok: Improving Fine-Grained Subword Understanding in LLMs2 Jun 2025
- 2025The Strawberry Problem: Emergence of Character-level Understanding in Tokenized Language Models20 May 2025
- 2025Subword models struggle with word learning, but surprisal hides it18 Feb 2025
- 2025Multilingual LLMs Struggle to Link Orthography and Semantics in Bilingual Word Processing15 Jan 2025
- 2024ChaI-TeA: A Benchmark for Evaluating Autocompletion of Interactions with LLM-based Chatbots24 Dec 2024
- 2024Enhancing Character-Level Understanding in LLMs through Token Internal Structure Learning26 Nov 2024
- 2024Aligning Generalisation Between Humans and Machines23 Nov 2024
- 2024StringLLM: Understanding the String Processing Capability of Large Language Models2 Oct 2024
- 2024From Introspection to Best Practices: Principled Analysis of Demonstrations in Multimodal In-Context Learning1 Jul 2024
- 2025The Strawberry Problem: Emergence of Character-level Understanding in Tokenized Language Modelscited by 11
- 2025StochasTok: Improving Fine-Grained Subword Understanding in LLMscited by 7
- 2025Subword models struggle with word learning, but surprisal hides itcited by 6
- 2026Measuring Progress Toward AGI: A Cognitive Frameworkcited by 6
- 2025Spelling-out is not Straightforward: LLMs' Capability of Tokenization from Token to Characterscited by 4
- 2025Prompt-Based One-Shot Exact Length-Controlled Generation with LLMscited by 4
- 2024Enhancing Character-Level Understanding in LLMs through Token Internal Structure Learningcited by 3
- 2025Multilingual LLMs Struggle to Link Orthography and Semantics in Bilingual Word Processingcited by 3
- 2025CharBench: Evaluating the Role of Tokenization in Character-Level Taskscited by 3
- 2026ALBA: A European Portuguese Benchmark for Evaluating Language and Linguistic Dimensions in Generative LLMscited by 3
- 2024StringLLM: Understanding the String Processing Capability of Large Language Modelscited by 2
- 2024Aligning Generalisation Between Humans and Machinescited by 2
12 most cited of 17 All 17 (JSON)
- 2026SCRIPTIOC-BENCH: A Benchmark for Recognizing Actionable Threat Intelligence from Script-Based Malware using LLMs5 Sep 2026
- 2026Measuring Progress Toward AGI: A Cognitive Framework27 May 2026
- 2026Do multimodal models imagine electric sheep?10 May 2026
- 2026ALBA: A European Portuguese Benchmark for Evaluating Language and Linguistic Dimensions in Generative LLMs27 Mar 2026
- 2026Spelling Bee Embeddings for Language Modeling25 Jan 2026
- 2026Training Language Models with homotokens Leads to Delayed Overfitting6 Jan 2026
- 2025Prompt-Based One-Shot Exact Length-Controlled Generation with LLMs19 Aug 2025
- 2025CharBench: Evaluating the Role of Tokenization in Character-Level Tasks4 Aug 2025
- 2025Spelling-out is not Straightforward: LLMs' Capability of Tokenization from Token to Characters12 Jun 2025
- 2025StochasTok: Improving Fine-Grained Subword Understanding in LLMs2 Jun 2025
- 2025The Strawberry Problem: Emergence of Character-level Understanding in Tokenized Language Models20 May 2025
- 2025Subword models struggle with word learning, but surprisal hides it18 Feb 2025
12 newest of 17 All 17 (JSON)