Polarization by Default: Auditing Recommendation Bias in LLM-Based Content Curation

Fuente: arXiv
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Autori principali: Pagan, Nicolò, Barrie, Christopher, Bail, Chris Andrew, Törnberg, Petter
Natura: Preprint
Pubblicazione: 2026
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author Pagan, Nicolò
Barrie, Christopher
Bail, Chris Andrew
Törnberg, Petter
author_facet Pagan, Nicolò
Barrie, Christopher
Bail, Chris Andrew
Törnberg, Petter
contents Large Language Models (LLMs) are increasingly deployed to curate and rank human-created content, yet the nature and structure of their biases in these tasks remains poorly understood: which biases are robust across providers and platforms, and which can be mitigated through prompt design. We present a controlled simulation study mapping content selection biases across three major LLM providers (OpenAI, Anthropic, Google) on real social media datasets from Twitter/X, Bluesky, and Reddit, using six prompting strategies (\textit{general}, \textit{popular}, \textit{engaging}, \textit{informative}, \textit{controversial}, \textit{neutral}). Through 540,000 simulated top-10 selections from pools of 100 posts across 54 experimental conditions, we find that biases differ substantially in how structural and how prompt-sensitive they are. Polarization is amplified across all configurations, toxicity handling shows a strong inversion between engagement- and information-focused prompts, and sentiment biases are predominantly negative. Provider comparisons reveal distinct trade-offs: GPT-4o Mini shows the most consistent behavior across prompts; Claude and Gemini exhibit high adaptivity in toxicity handling; Gemini shows the strongest negative sentiment preference. On Twitter/X, where author demographics can be inferred from profile bios, political leaning bias is the clearest demographic signal: left-leaning authors are systematically over-represented despite right-leaning authors forming the pool plurality in the dataset, and this pattern largely persists across prompts.
format Preprint
id arxiv_https___arxiv_org_abs_2604_15937
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Polarization by Default: Auditing Recommendation Bias in LLM-Based Content Curation
Pagan, Nicolò
Barrie, Christopher
Bail, Chris Andrew
Törnberg, Petter
Social and Information Networks
Artificial Intelligence
Computation and Language
Computers and Society
Multiagent Systems
Large Language Models (LLMs) are increasingly deployed to curate and rank human-created content, yet the nature and structure of their biases in these tasks remains poorly understood: which biases are robust across providers and platforms, and which can be mitigated through prompt design. We present a controlled simulation study mapping content selection biases across three major LLM providers (OpenAI, Anthropic, Google) on real social media datasets from Twitter/X, Bluesky, and Reddit, using six prompting strategies (\textit{general}, \textit{popular}, \textit{engaging}, \textit{informative}, \textit{controversial}, \textit{neutral}). Through 540,000 simulated top-10 selections from pools of 100 posts across 54 experimental conditions, we find that biases differ substantially in how structural and how prompt-sensitive they are. Polarization is amplified across all configurations, toxicity handling shows a strong inversion between engagement- and information-focused prompts, and sentiment biases are predominantly negative. Provider comparisons reveal distinct trade-offs: GPT-4o Mini shows the most consistent behavior across prompts; Claude and Gemini exhibit high adaptivity in toxicity handling; Gemini shows the strongest negative sentiment preference. On Twitter/X, where author demographics can be inferred from profile bios, political leaning bias is the clearest demographic signal: left-leaning authors are systematically over-represented despite right-leaning authors forming the pool plurality in the dataset, and this pattern largely persists across prompts.
title Polarization by Default: Auditing Recommendation Bias in LLM-Based Content Curation
topic Social and Information Networks
Artificial Intelligence
Computation and Language
Computers and Society
Multiagent Systems
url https://arxiv.org/abs/2604.15937