Edu-MMBias: A Three-Tier Multimodal Benchmark for Auditing Social Bias in Vision-Language Models under Educational Contexts
Organizations: School of Computer Science and Technology, East China Normal University · Shanghai Institute of Artificial Intelligence for Education, East China Normal University · Faculty of Education, East China Normal University
Abstract
As Vision-Language Models (VLMs) become integral to educational decision-making, ensuring their fairness is paramount. However, current text-centric evaluations neglect the visual modality, leaving an unregulated channel for latent social biases. To bridge this gap, we present Edu-MMBias, a systematic auditing framework grounded in the tri-component model of attitudes from social psychology. This framework diagnoses bias across three hierarchical dimensions: cognitive, affective, and behavioral. Utilizing a specialized generative pipeline that incorporates a self-correct mechanism and human-in-the-loop verification, we synthesize contamination-resistant student profiles to conduct a holistic stress test on state-of-the-art VLMs. Our extensive audit reveals critical, counter-intuitive patterns: models exhibit a compensatory class bias favoring lower-status narratives while simultaneously harboring deep-seated health and racial stereotypes. Crucially, we find that visual inputs act as a safety backdoor, triggering a resurgence of biases that bypass text-based alignment safeguards and revealing a systematic misalignment between latent cognition and final decision-making. The contributions of this paper are available at: https://anonymous.4open.science/r/EduMMBias-63B2.
Figures & tables
| Dimension | Modality | CBS * | BBS * | Sig. |
|---|---|---|---|---|
| Race | Text-only | 0.012 | 0.009 | ns |
| VLM | 0.215 | 0.187 | ||
| SES | Text-only | 0.045 | 0.063 | ns |
| VLM | 0.172 | 0.154 | ** | |
| Health | Text-only | 0.038 | 0.045 | ns |
| VLM | 0.141 | 0.128 |
Appendix figures & tables18 assets
Supplementary material from the paper’s appendix.
Appendix
| Model | Full Name | Developer | Size | Language | Category |
| Closed-source Models | |||||
| GPT-4o | gpt-4o-2024-11-20 | OpenAI | N/A | Multilingual | Full-scale |
| GPT-5.2 | gpt-5.2-preview | OpenAI | N/A | Multilingual | Full-scale |
| Gemini-3 | gemini-3-flash-preview-thinking | N/A | Multilingual | Full-scale | |
| Grok-4 | grok-4-fast-reasoning | xAI | N/A | Multilingual | Full-scale |
| Open-source Models | |||||