Abstract
The Backpack is a Transformer alternative shown to improve interpretability in English language modeling by decomposing predictions into a weighted sum of token sense components. However, Backpacks’ reliance on token-defined meaning raises questions as to their potential for languages other than English, a language for which subword tokenization provides a reasonable approximation for lexical items. In this work, we train, evaluate, interpret, and control Backpack language models in character-tokenized Chinese, in which words are often composed of many characters. We find that our (134M parameter) Chinese Backpack language model performs comparably to a (104M parameter) Transformer, and learns rich character-level meanings that log-additively compose to form word meanings. In SimLex-style lexical semantic evaluations, simple averages of Backpack character senses outperform input embeddings from a Transformer. We find that complex multi-character meanings are often formed by using the same per-character sense weights consistently across context. Exploring interpretability-through control, we show that we can localize a source of gender bias in our Backpacks to specific character senses and intervene to reduce the bias.- Anthology ID:
- 2023.blackboxnlp-1.8
- Volume:
- Proceedings of the 6th BlackboxNLP Workshop: Analyzing and Interpreting Neural Networks for NLP
- Month:
- December
- Year:
- 2023
- Address:
- Singapore
- Editors:
- Yonatan Belinkov, Sophie Hao, Jaap Jumelet, Najoung Kim, Arya McCarthy, Hosein Mohebbi
- Venues:
- BlackboxNLP | WS
- SIG:
- Publisher:
- Association for Computational Linguistics
- Note:
- Pages:
- 106–119
- Language:
- URL:
- https://aclanthology.org/2023.blackboxnlp-1.8
- DOI:
- 10.18653/v1/2023.blackboxnlp-1.8
- Cite (ACL):
- Hao Sun and John Hewitt. 2023. Character-Level Chinese Backpack Language Models. In Proceedings of the 6th BlackboxNLP Workshop: Analyzing and Interpreting Neural Networks for NLP, pages 106–119, Singapore. Association for Computational Linguistics.
- Cite (Informal):
- Character-Level Chinese Backpack Language Models (Sun & Hewitt, BlackboxNLP-WS 2023)
- PDF:
- https://preview.aclanthology.org/naacl24-info/2023.blackboxnlp-1.8.pdf