Invisible Influences: Investigating Implicit Intersectional Biases through Persona Engineering in Large Language Models
Organizations: Department of Computer Science and Engineering, Shiv Nadar University Chennai, Tamil Nadu, India · School of AI and CS, Plaksha University, Mohali, Punjab, India
Abstract
Large Language Models (LLMs) excel at human-like language generation but often embed and amplify implicit, intersectional biases, especially under persona-driven contexts. Existing bias audits rely on static, embedding-based tests (CEAT, I-WEAT, I-SEAT) that quantify absolute association strengths. We show that they have limitations in capturing dynamic shifts when models adopt social roles. We address this gap by introducing the Bias Amplification Differential and Explainability Score (BADx): a novel, scalable metric that measures persona-induced bias amplification and integrates local explainability insights. BADx comprises three components - differential bias scores (BAD, based on CEAT, I-WEAT, I-SEAT),Persona Sensitivity Index (PSI), and Volatility (Standard Deviation), augmented by LIME-based analysis for emphasizing explainability. This study is divided and performed as two different tasks. Task 1 establishes static bias baselines, and Task 2 applies six persona frames (marginalized and structurally advantaged) to measure BADx, PSI, and volatility. This is studied across five state-of-the-art LLMs (GPT-4o, DeepSeek-R1, LLaMA-4, Claude 4.0 Sonnet and Gemma-3n E4B). Results show persona context significantly modulates bias. GPT-4o exhibits high sensitivity and volatility; DeepSeek-R1 suppresses bias but with erratic volatility; LLaMA-4 maintains low volatility and a stable bias profile with limited amplification; Claude 4.0 Sonnet achieves balanced modulation; and Gemma-3n E4B attains the lowest volatility with moderate amplification. BADx performs better than static methods by revealing context-sensitive biases overlooked in static methods. Our unified method offers a systematic way to detect dynamic implicit intersectional bias in five popular LLMs.
Figures & tables
| Metric | Score | Interpretation |
|---|---|---|
| CEAT (Contextualised Embedding Association Test) | 0.85 | Strong bias in contextual embeddings, indicating unequal association of professions and attributes with identity groups. |
| I-WEAT (Intersectional Word Embedding Association Test) | 0.79 | Static embeddings retain even more bias than contextual models, meaning that Word2Vec & GloVe encode stereotypes more strongly. |
| I-SEAT (Intersectional Sentence Encoder Association Test) | 0.68 | Bias is slightly lower in sentence-level representations but still significant, suggesting full-sentence context does not remove bias. |
| IIBS (Implicit Intersectional Bias Score) | 0.50 | About 50% of the dataset contains implicit intersectional bias, meaning half of the sentences reinforce stereotypes. |
| Category | Identity Class | GPT-4o | DeepSeek-R1 | LLaMA-4 | Claude 4.o Sonnet | Gemma-3n 4B | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| CEAT | I-WEAT | I-SEAT | CEAT | I-WEAT | I-SEAT | CEAT | I-WEAT | I-SEAT | CEAT | I-WEAT | I-SEAT | CEAT | I-WEAT | I-SEAT | ||
| Socio-Economic | Race + Region + Tech - Ethics | 0.223 | 0.213 | 0.200 | -0.148 | -0.141 | -0.137 | 0.332 | 0.330 | 0.298 | 0.103 | 0.104 | 0.092 | 0.162 | 0.158 | 0.144 |
| Gender + Race + Public - Health | -0.502 | -0.494 | -0.451 | -0.245 | -0.250 | -0.220 | 0.389 | 0.390 | 0.350 | 0.346 | 0.345 | 0.311 | -0.220 | -0.219 | -0.188 | |
| Class + Age + Career-Wealth | -0.256 | -0.257 | -0.231 | -0.103 | -0.102 | -0.092 | 0.121 | 0.120 | 0.108 | -0.342 | -0.344 | -0.307 | -0.081 | -0.080 | -0.074 | |
| Workplace | Disability + Region + Education-Access | 0.411 | 0.420 | 0.369 | -0.218 | -0.210 | -0.196 | 0.452 | 0.450 | 0.406 | -0.345 | -0.342 | -0.310 | 0.312 | 0.310 | 0.277 |
| Appearance + Gender + Ethnicity | 0.211 | 0.209 | 0.189 | -0.207 | -0.208 | -0.186 | -0.245 | -0.243 | -0.220 | 0.347 | 0.345 | 0.312 | 0.094 | 0.089 | 0.074 | |
| Model | Most Influential Words |
|---|---|
| GPT-4o | Professional, Elite, Unpaid Internship, Top Universities, Polished, Assertiveness |
| DeepSeek-R1 | Professional, Meritocracy, Culture Fit, Unpaid, Leader, Productive, Resilience |
| LLaMA-4 | Marginalized Communities, Systemic Barriers, Intersectional, Equity and Inclusion, Privileged Groups, Dominant Cultural Norms |
| Claude 4.0 Sonnet | Gender, Race, Class, Ethnicity, Age, Wealth/Income, Privilege, Access, Stereotype, Leadership |
| Gemma-3n E4B | Accessibility, Representation, Inclusive Practice, Diversity, Equity, Opportunity, Support, Context, Participation |
| LLM | Prompt | A | B | C | D | E | F |
|---|---|---|---|---|---|---|---|
| GPT-4o | P1 | -0.086 | -0.178 | -0.031 | 0.153 | 0.221 | 0.078 |
| P2 | -0.129 | -0.074 | -0.180 | 0.063 | 0.017 | 0.043 | |
| P3 | -0.238 | -0.131 | -0.083 | 0.038 | 0.154 | 0.226 | |
| P4 | -0.119 | -0.068 | -0.173 | 0.129 | 0.192 | 0.107 | |
| P5 | -0.104 | -0.007 | -0.060 | 0.130 | 0.233 | 0.283 | |
| DeepSeek-R1 | P1 | -0.142 | -0.178 | -0.031 | 0.146 | 0.190 | 0.308 |
| LLM | A | B | C | D | E | F |
| PSI (Persona Sensitivity Index) | ||||||
| GPT-4o | -0.135 | -0.091 | -0.105 | 0.102 | 0.163 | 0.147 |
| DeepSeek-R1 | -0.158 | -0.114 | -0.084 | 0.059 | 0.090 | 0.104 |
| LLaMA-4 | -0.037 | -0.085 | -0.080 | 0.032 | 0.056 | 0.079 |
| Claude 4.o | -0.046 | -0.058 | -0.088 | 0.058 | 0.076 | 0.109 |
| Gemma-3n E4B | -0.086 | -0.065 | -0.069 | 0.059 | 0.093 | 0.065 |
| Model | Most Influential Words |
|---|---|
| GPT-4o | Immigrant, Disability, Gay, Rural, Low-Income, Fit In, Traditional Values, Male-dominated |
| DeepSeek-R1 | Merit, Skill, Competence, Quotas, Diversity, Privilege, Marginalized, Fit the Mold, Unprofessional |
| LLaMA-4 | Traditional values, Meritocratic Environment, Community’s Values, Male-dominated, Sexism, Beauty Bias, Systemic Barriers |
| Claude 4.o | Traditional Values, Merit-based, Earned Authority, Gender, Race, Disability, LGBTQ+, Black, Rural, Background, Gaming |
| Gemma-3n E4B | Background, Barriers, Stereotype, Upward Mobility, Adaptability, Diverse Skills, Social Perception, Confidence, Support Systems |