@inproceedings{stearns-etal-2026-cross,
title = "Cross-Corpus {CEFR} Classification through Artificial Learners Perplexities",
author = "Stearns, Bernardo and
McCrae, John P. and
Gaillat, Thomas",
editor = "Piperidis, Stelios and
Bel, N{\'u}ria and
van den Heuvel, Henk and
Ide, Nancy and
Krek, Simon and
Toral, Antonio",
booktitle = "Proceedings of the Fifteenth Language Resources and Evaluation Conference",
month = may,
year = "2026",
address = "Palma de Mallorca, Spain",
publisher = "ELRA Language Resource Association",
url = "https://aclanthology.org/2026.lrec-1.62/",
doi = "10.63317/2bvpcczgao2t",
pages = "828--837",
abstract = "The complexity of neural methods for automatic proficiency assessment often sacrifices interpretability and robustness. This paper presents a competitive alternative for CEFR classification using optimized statistical models with a novel perplexity-based feature engineering pipeline. We introduce LLM-derived perplexity features as a proxy for how unexpected a learner{'}s word choices are: native model perplexity measures unexpectedness relative to native language use, while Artificial Learner model perplexity quantifies relative to a specific proficiency level. While recent work favors end-to-end neural architectures, we demonstrate that traditional pipelines enhanced with these interpretable perplexity features can achieve comparable performance on established benchmarks. We evaluate two transfer scenarios: zero-shot (trained on EFCAMDAT, tested on external corpora) and 90-10 split (same features, in-domain classifier training). On KUPA-KEYS, perplexity features achieve RMSE 0.707 (zero-shot) and 0.660 (90-10 split), outperforming fine-tuned BERT and prompt-based LLMs. On CELVA-SP, zero-shot perplexity shows limited generalization (RMSE 1.437 vs. LLM{'}s 1.016), but statistical models close this gap in the 90-10 split (RMSE 0.872). Across all three evaluation datasets, perplexity-based models achieve the best average macro F1 in the 90-10 split (0.446 vs. 0.287 for BERT and 0.175 for prompting), demonstrating that interpretable features paired with domain-adapted classifiers provide the most robust cross-domain representations. We contribute: (1) state-of-the-art KUPA-KEYS results with interpretable models, (2) the first comprehensive CELVA-SP benchmark, and (3) evidence that feature-level transfer outperforms both end-to-end fine-tuning and zero-shot prompting."
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<abstract>The complexity of neural methods for automatic proficiency assessment often sacrifices interpretability and robustness. This paper presents a competitive alternative for CEFR classification using optimized statistical models with a novel perplexity-based feature engineering pipeline. We introduce LLM-derived perplexity features as a proxy for how unexpected a learner’s word choices are: native model perplexity measures unexpectedness relative to native language use, while Artificial Learner model perplexity quantifies relative to a specific proficiency level. While recent work favors end-to-end neural architectures, we demonstrate that traditional pipelines enhanced with these interpretable perplexity features can achieve comparable performance on established benchmarks. We evaluate two transfer scenarios: zero-shot (trained on EFCAMDAT, tested on external corpora) and 90-10 split (same features, in-domain classifier training). On KUPA-KEYS, perplexity features achieve RMSE 0.707 (zero-shot) and 0.660 (90-10 split), outperforming fine-tuned BERT and prompt-based LLMs. On CELVA-SP, zero-shot perplexity shows limited generalization (RMSE 1.437 vs. LLM’s 1.016), but statistical models close this gap in the 90-10 split (RMSE 0.872). Across all three evaluation datasets, perplexity-based models achieve the best average macro F1 in the 90-10 split (0.446 vs. 0.287 for BERT and 0.175 for prompting), demonstrating that interpretable features paired with domain-adapted classifiers provide the most robust cross-domain representations. We contribute: (1) state-of-the-art KUPA-KEYS results with interpretable models, (2) the first comprehensive CELVA-SP benchmark, and (3) evidence that feature-level transfer outperforms both end-to-end fine-tuning and zero-shot prompting.</abstract>
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%0 Conference Proceedings
%T Cross-Corpus CEFR Classification through Artificial Learners Perplexities
%A Stearns, Bernardo
%A McCrae, John P.
%A Gaillat, Thomas
%Y Piperidis, Stelios
%Y Bel, Núria
%Y van den Heuvel, Henk
%Y Ide, Nancy
%Y Krek, Simon
%Y Toral, Antonio
%S Proceedings of the Fifteenth Language Resources and Evaluation Conference
%D 2026
%8 May
%I ELRA Language Resource Association
%C Palma de Mallorca, Spain
%F stearns-etal-2026-cross
%X The complexity of neural methods for automatic proficiency assessment often sacrifices interpretability and robustness. This paper presents a competitive alternative for CEFR classification using optimized statistical models with a novel perplexity-based feature engineering pipeline. We introduce LLM-derived perplexity features as a proxy for how unexpected a learner’s word choices are: native model perplexity measures unexpectedness relative to native language use, while Artificial Learner model perplexity quantifies relative to a specific proficiency level. While recent work favors end-to-end neural architectures, we demonstrate that traditional pipelines enhanced with these interpretable perplexity features can achieve comparable performance on established benchmarks. We evaluate two transfer scenarios: zero-shot (trained on EFCAMDAT, tested on external corpora) and 90-10 split (same features, in-domain classifier training). On KUPA-KEYS, perplexity features achieve RMSE 0.707 (zero-shot) and 0.660 (90-10 split), outperforming fine-tuned BERT and prompt-based LLMs. On CELVA-SP, zero-shot perplexity shows limited generalization (RMSE 1.437 vs. LLM’s 1.016), but statistical models close this gap in the 90-10 split (RMSE 0.872). Across all three evaluation datasets, perplexity-based models achieve the best average macro F1 in the 90-10 split (0.446 vs. 0.287 for BERT and 0.175 for prompting), demonstrating that interpretable features paired with domain-adapted classifiers provide the most robust cross-domain representations. We contribute: (1) state-of-the-art KUPA-KEYS results with interpretable models, (2) the first comprehensive CELVA-SP benchmark, and (3) evidence that feature-level transfer outperforms both end-to-end fine-tuning and zero-shot prompting.
%R 10.63317/2bvpcczgao2t
%U https://aclanthology.org/2026.lrec-1.62/
%U https://doi.org/10.63317/2bvpcczgao2t
%P 828-837
Markdown (Informal)
[Cross-Corpus CEFR Classification through Artificial Learners Perplexities](https://aclanthology.org/2026.lrec-1.62/) (Stearns et al., LREC 2026)
ACL