Token-Level Entropy Reveals Demographic Disparities in Language Models

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1. Verfasser: Lee, Messi H. J.
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Veröffentlicht: 2025
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author Lee, Messi H. J.
author_facet Lee, Messi H. J.
contents We ask whether demographic identity, signaled by a name alone, systematically reshapes the generative distribution of a language model. Measuring full-vocabulary Shannon entropy at temperature zero across six open-weight base models and 5,760 implicit sentence-completion prompts (e.g., "Tanisha walked into the office on a Monday morning and"), we find that Black-associated names produce higher first-token entropy than White-associated names across all six architectures - opposite to the output-level homogeneity bias documented under explicit demographic prompting (Lee et al., 2024) - and Black-associated names always produce greater entropy above identity-neutral baselines than White-associated names ($ΔΔ> 0$ in all six models). Women-associated names co-occur with lower first-token entropy (DL-pooled $\hatβ= -0.041, p = .019$) and more homogeneous outputs ($\hatα= +0.024, p < .001$) than men-associated names - a pattern convergent with homogeneity bias; race and gender effects are additive. Instruction tuning does not attenuate the race gap (matched-format DL-pooled $\hatβ=+0.153$). Running the same templates with explicit group labels instead of names yields null race effects in 10 of 12 models where implicit probing is significant - establishing that probing methodology is a primary determinant of which distributional structure is recovered.
format Preprint
id arxiv_https___arxiv_org_abs_2501_19337
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Token-Level Entropy Reveals Demographic Disparities in Language Models
Lee, Messi H. J.
Computation and Language
Computer Vision and Pattern Recognition
We ask whether demographic identity, signaled by a name alone, systematically reshapes the generative distribution of a language model. Measuring full-vocabulary Shannon entropy at temperature zero across six open-weight base models and 5,760 implicit sentence-completion prompts (e.g., "Tanisha walked into the office on a Monday morning and"), we find that Black-associated names produce higher first-token entropy than White-associated names across all six architectures - opposite to the output-level homogeneity bias documented under explicit demographic prompting (Lee et al., 2024) - and Black-associated names always produce greater entropy above identity-neutral baselines than White-associated names ($ΔΔ> 0$ in all six models). Women-associated names co-occur with lower first-token entropy (DL-pooled $\hatβ= -0.041, p = .019$) and more homogeneous outputs ($\hatα= +0.024, p < .001$) than men-associated names - a pattern convergent with homogeneity bias; race and gender effects are additive. Instruction tuning does not attenuate the race gap (matched-format DL-pooled $\hatβ=+0.153$). Running the same templates with explicit group labels instead of names yields null race effects in 10 of 12 models where implicit probing is significant - establishing that probing methodology is a primary determinant of which distributional structure is recovered.
title Token-Level Entropy Reveals Demographic Disparities in Language Models
topic Computation and Language
Computer Vision and Pattern Recognition
url https://arxiv.org/abs/2501.19337