Characterizing Selective Refusal Bias in Large Language Models

Fuente: arXiv
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Main Authors: Khorramrouz, Adel, Levy, Sharon
Format: Preprint
Published: 2025
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author Khorramrouz, Adel
Levy, Sharon
author_facet Khorramrouz, Adel
Levy, Sharon
contents Safety guardrails in large language models(LLMs) are developed to prevent malicious users from generating toxic content at a large scale. However, these measures can inadvertently introduce or reflect new biases, as LLMs may refuse to generate harmful content targeting some demographic groups and not others. We explore this selective refusal bias in LLM guardrails through the lens of refusal rates of targeted individual and intersectional demographic groups, types of LLM responses, and length of generated refusals. Our results show evidence of selective refusal bias across gender, sexual orientation, nationality, and religion attributes. This leads us to investigate additional safety implications via an indirect attack, where we target previously refused groups. Our findings emphasize the need for more equitable and robust performance in safety guardrails across demographic groups.
format Preprint
id arxiv_https___arxiv_org_abs_2510_27087
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Characterizing Selective Refusal Bias in Large Language Models
Khorramrouz, Adel
Levy, Sharon
Computation and Language
Computers and Society
Safety guardrails in large language models(LLMs) are developed to prevent malicious users from generating toxic content at a large scale. However, these measures can inadvertently introduce or reflect new biases, as LLMs may refuse to generate harmful content targeting some demographic groups and not others. We explore this selective refusal bias in LLM guardrails through the lens of refusal rates of targeted individual and intersectional demographic groups, types of LLM responses, and length of generated refusals. Our results show evidence of selective refusal bias across gender, sexual orientation, nationality, and religion attributes. This leads us to investigate additional safety implications via an indirect attack, where we target previously refused groups. Our findings emphasize the need for more equitable and robust performance in safety guardrails across demographic groups.
title Characterizing Selective Refusal Bias in Large Language Models
topic Computation and Language
Computers and Society
url https://arxiv.org/abs/2510.27087