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Bias in News Summarization: Measures, Pitfalls and Corpora

Julius Steen, Katja Markert


Abstract
Summarization is an important application of large language models (LLMs). Most previous evaluation of summarization models has focused on their content selection, faithfulness, grammaticality and coherence. However, it is well known that LLMs can reproduce and reinforce harmful social biases. This raises the question: Do biases affect model outputs in a constrained setting like summarization?To help answer this question, we first motivate and introduce a number of definitions for biased behaviours in summarization models, along with practical operationalizations. Since we find that biases inherent to input documents can confound bias analysis in summaries, we propose a method to generate input documents with carefully controlled demographic attributes. This allows us to study summarizer behavior in a controlled setting, while still working with realistic input documents.We measure gender bias in English summaries generated by both purpose-built summarization models and general purpose chat models as a case study. We find content selection in single document summarization to be largely unaffected by gender bias, while hallucinations exhibit evidence of bias.To demonstrate the generality of our approach, we additionally investigate racial bias, including intersectional settings.
Anthology ID:
2024.findings-acl.356
Volume:
Findings of the Association for Computational Linguistics: ACL 2024
Month:
August
Year:
2024
Address:
Bangkok, Thailand
Editors:
Lun-Wei Ku, Andre Martins, Vivek Srikumar
Venue:
Findings
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
5962–5983
Language:
URL:
https://aclanthology.org/2024.findings-acl.356
DOI:
10.18653/v1/2024.findings-acl.356
Bibkey:
Cite (ACL):
Julius Steen and Katja Markert. 2024. Bias in News Summarization: Measures, Pitfalls and Corpora. In Findings of the Association for Computational Linguistics: ACL 2024, pages 5962–5983, Bangkok, Thailand. Association for Computational Linguistics.
Cite (Informal):
Bias in News Summarization: Measures, Pitfalls and Corpora (Steen & Markert, Findings 2024)
Copy Citation:
PDF:
https://aclanthology.org/2024.findings-acl.356.pdf