What the [MASK]? Making Sense of Language-Specific BERT Models

TL;DR

This paper surveys language-specific BERT models, comparing them to multilingual BERT, to evaluate their performance across different languages, domains, and tasks, and provides an interactive platform for exploration.

Contribution

It offers a comprehensive overview of language-specific BERT models, highlighting their differences from mBERT and assessing their effectiveness in various NLP scenarios.

Findings

Language-specific BERT models often outperform mBERT on their respective languages.

Differences in architecture and training data significantly impact model performance.

An interactive website is provided for ongoing comparison and analysis.

Abstract

Recently, Natural Language Processing (NLP) has witnessed an impressive progress in many areas, due to the advent of novel, pretrained contextual representation models. In particular, Devlin et al. (2019) proposed a model, called BERT (Bidirectional Encoder Representations from Transformers), which enables researchers to obtain state-of-the art performance on numerous NLP tasks by fine-tuning the representations on their data set and task, without the need for developing and training highly-specific architectures. The authors also released multilingual BERT (mBERT), a model trained on a corpus of 104 languages, which can serve as a universal language model. This model obtained impressive results on a zero-shot cross-lingual natural inference task. Driven by the potential of BERT models, the NLP community has started to investigate and generate an abundant number of BERT models that are trained on a particular language, and tested on a specific data domain and task. This allows us to evaluate the true potential of mBERT as a universal language model, by comparing it to the performance of these more specific models. This paper presents the current state of the art in language-specific BERT models, providing an overall picture with respect to different dimensions (i.e. architectures, data domains, and tasks). Our aim is to provide an immediate and straightforward overview of the commonalities and differences between Language-Specific (language-specific) BERT models and mBERT. We also provide an interactive and constantly updated website that can be used to explore the information we have collected, at https://bertlang.unibocconi.it.