cjvt/WALS-Bench

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WALS-bench: A Metalinguistic Benchmark Based on WALS

Overview

This is a large-scale multilingual benchmark that evaluates metalinguistic knowledge in large language models using typological features from the World Atlas of Language Structures (WALS). The benchmark covers 192 linguistic features across 2,660 languages.

Benchmark Format

The benchmark is available in two formats:

Format 1: 192-question version - one question per feature, under which all languages with a corresponding ground truth value for that feature are listed.

Format 2: 76,475-question version - one question per feature-language pair with a corresponding ground truth value, fully expanded across all languages.

Task Definition

Given a linguistic question derived from a WALS feature with a set of possible answers for a specific language, the model must predict the correct typological category for that language.

Prompt

The benchmark is evaluated using a single prompt. The prompt template used in our experiment: {question} The options are {possible_answers}. Answer by choosing one option. Do not provide an explanation.

Proposed Data Splits

Validation set: 29 features - 5A, 12A, 17A, 21B, 28A, 33A, 35A, 45A, 49A, 56A, 58B, 73A, 80A, 81A, 86A, 89A, 90A, 90D, 92A, 98A, 109B, 111A, 118A, 124A, 131A, 137A, 143A, 144M, 144X Test set: 29 features - 6A, 10A, 15A, 25A, 26A, 36A, 42A, 46A, 55A, 67A, 71A, 77A, 85A, 87A, 90C, 94A, 97A, 106A, 107A, 112A, 117A, 125A, 127A, 130B, 136A, 139A, 143C, 144Q, 144W Training set: 134 features - the remaining features

Data Format

FORMAT 1: Each feature is stored in JSONL format: {"feature_id": "1A", "feature_name": "Consonant Inventories", "domain": "Phonology", "question": "How large is the consonant inventory in the <LANGUAGE> language?", "possible_answers": "Small; Moderately small; Average; Moderately large; Large", "ground_truth": {"Abipón": "Moderately small", "Abkhaz": "Large", "Alabama": "Small", "Aché": "Small" /* additional languages omitted/}}

<LANGUAGE> is replaced with a specific language name at inference time.

FORMAT 2: Each feature is stored in JSONL format: {"feature_id": "1A", "feature_name": "Consonant Inventories", "domain": "Phonology", "question": "How large is the consonant inventory in the Abipón language?", "possible_answers": "Small; Moderately small; Average; Moderately large; Large", "language_name": "Abipón", "ISO639-3": "axb", "ground_truth": "Moderately small"}

Linguistic Feature Coverage

Word Order: 56 features Nominal Categories: 29 features Simple Clauses: 26 features Phonology: 20 features Verbal Categories: 17 features Lexicon: 13 features Morphology: 12 features Nominal Syntax: 8 features Complex Sentences: 7 features Sign Languages: 2 features Clicks (Other): 1 feature Writing System (Other): 1 feature

Language Coverage

Total number of languages covered: 2,660 world languages.

Evaluation

Predictions are evaluated by comparing model outputs to the WALS ground-truth categories.

Dataset authors

Tjaša Arčon, Matej Klemen, Marko Robnik-Šikonja, Kaja Dobrovoljc and Luka Terčon (See http://hdl.handle.net/11356/2083 for the full entry.)

Licence

The original WALS data is licensed under CC BY 4.0. The data has been adapted for use in this benchmark.

Source: Dryer, Matthew S. & Haspelmath, Martin (eds.).
World Atlas of Language Structures Online.
Max Planck Institute for Evolutionary Anthropology.
https://wals.info

Citation information

@misc{arčon2026evaluatingmetalinguisticknowledgelarge,
  title={Evaluating Metalinguistic Knowledge in Large Language Models across the World's Languages},
  author={Tjaša Arčon and Matej Klemen and Marko Robnik-Šikonja and Kaja Dobrovoljc},
  year={2026},
  eprint={2602.02182},
  archivePrefix={arXiv},
  primaryClass={cs.CL},
  url={https://arxiv.org/abs/2602.02182},
}