Bryan Chen Zhengyu Tan
2026
BLEnD-Vis: Benchmarking Multimodal Cultural Understanding in Vision Language Models
Bryan Chen Zhengyu Tan | Weihua Zheng | Zhengyuan Liu | Nancy F. Chen | Hwaran Lee | Kenny Tsu Wei Choo | Roy Ka-Wei Lee
Proceedings of the 19th Conference of the European Chapter of the Association for Computational Linguistics (Volume 1: Long Papers)
Bryan Chen Zhengyu Tan | Weihua Zheng | Zhengyuan Liu | Nancy F. Chen | Hwaran Lee | Kenny Tsu Wei Choo | Roy Ka-Wei Lee
Proceedings of the 19th Conference of the European Chapter of the Association for Computational Linguistics (Volume 1: Long Papers)
As vision-language models (VLMs) are deployed globally, their ability to understand culturally situated knowledge becomes essential. Yet, existing evaluations largely assess static recall or isolated visual grounding, leaving unanswered whether VLMs possess robust and transferable cultural understanding. We introduce ‘BLEnD-Vis‘, a multimodal, multicultural benchmark designed to evaluate the robustness of everyday cultural knowledge in VLMs across linguistic rephrasings and visual modalities. Building on the BLEnD dataset, ‘BLEnD-Vis‘ constructs 313 culturally grounded question templates spanning 16 regions and generates three aligned multiple-choice formats: (i) a text-only baseline querying from Region → Entity, (ii) an inverted text-only variant (Entity → Region), and (iii) a VQA-style version of (ii) with generated images. The resulting benchmark comprises 4,916 images and over 21,000 multiple-choice questions (MCQ) instances, validated through human annotation. ‘BLEnD-Vis‘ reveals significant fragility in current VLM cultural knowledge; models exhibit performance drops under linguistic rephrasing. While visual cues often aid performance, low cross-modal consistency highlights the challenges of robustly integrating textual and visual understanding, particularly in lower-resource regions. ‘BLEnD-Vis‘ thus provides a crucial testbed for systematically analysing cultural robustness and multimodal grounding, exposing limitations and guiding the development of more culturally competent VLMs. Code is available at https://github.com/Social-AI-Studio/BLEnD-Vis.
MMAC: A Multilingual, Multimodal Alignment Framework for Cultural Grounding Evaluation
Weihua Zheng | Zhengyuan Liu | Tanmoy Chakraborty | Weiwen Xu | Xiaoxue Gao | Bryan Chen Zhengyu Tan | Bowei Zou | Chang Liu | Yujia Hu | Xing Xie | Xiaoyuan Yi | Jing Yao | Chaojun Wang | Long Li | Rui Liu | Huiyao Liu | Koji Inoue | Ryuichi Sumida | Tatsuya Kawahara | Fan Xu | Lingyu Ye | Wei Tian | Dongjun Kim | Jimin Jung | Jaehyung Seo | Nadya Yuki Wangsajaya | Pham Minh Duc | Ojasva Saxena | Palash Nandi | Xiyan Tao | Wiwik Karlina | Tuan Luong | Keertana Arun Vasan | Roy Ka-Wei Lee | Nancy F. Chen
Proceedings of the 64th Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers)
Weihua Zheng | Zhengyuan Liu | Tanmoy Chakraborty | Weiwen Xu | Xiaoxue Gao | Bryan Chen Zhengyu Tan | Bowei Zou | Chang Liu | Yujia Hu | Xing Xie | Xiaoyuan Yi | Jing Yao | Chaojun Wang | Long Li | Rui Liu | Huiyao Liu | Koji Inoue | Ryuichi Sumida | Tatsuya Kawahara | Fan Xu | Lingyu Ye | Wei Tian | Dongjun Kim | Jimin Jung | Jaehyung Seo | Nadya Yuki Wangsajaya | Pham Minh Duc | Ojasva Saxena | Palash Nandi | Xiyan Tao | Wiwik Karlina | Tuan Luong | Keertana Arun Vasan | Roy Ka-Wei Lee | Nancy F. Chen
Proceedings of the 64th Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers)
The global deployment of Large Language Models (LLMs) underscores the urgent need to evaluate their cultural alignment. However, assessing genuine "cultural awareness" across modalities (text, vision, speech) and languages remains a significant challenge. To comprehensively investigate this domain, we propose MMAC, a systematic framework that encompasses a tri-modally aligned cultural benchmark creation pipeline and a five-dimensional evaluation protocol to assess cross-country awareness disparities, evaluate cross-lingual and cross-modal consistency, and verify cultural knowledge generalization and grounding validity. Given the prevailing Western cultural bias in current models, we focus on 8 Asian countries as our dataset foundation to more acutely reveal potential cultural deficiencies in LLMs. Our dataset, MMAC-bench, features 27,000 human-curated questions across 10 languages. Crucially, it is the first dataset aligned at the input level across text, image, and speech, enabling direct cross-modal transfer tests. Each question consists of multiple-choice options accompanied by open-ended generated explanations, where 79% require multi-step reasoning grounded in cultural context, moving beyond simple memorization. We probe the causes of modal divergence, offering insights into fostering culturally robust MLLMs.
Can Persona-Prompted LLMs Emulate Subgroup Values? An Empirical Analysis of Generalisability and Fairness in Cultural Alignment
Bryan Chen Zhengyu Tan | Zhengyuan Liu | Xiaoyuan Yi | Jing Yao | Xing Xie | Nancy F. Chen | Roy Ka-Wei Lee
Proceedings of the 64th Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers)
Bryan Chen Zhengyu Tan | Zhengyuan Liu | Xiaoyuan Yi | Jing Yao | Xing Xie | Nancy F. Chen | Roy Ka-Wei Lee
Proceedings of the 64th Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers)
Despite their global prevalence, many Large Language Models (LLMs) are aligned to a monolithic, often Western-centric set of values. This paper investigates the more challenging task of fine-grained value alignment: examining whether LLMs can emulate the distinct cultural values of demographic subgroups. Using Singapore as a case study and the World Values Survey (WVS), we examine the value landscape and show that even state-of-the-art models like GPT-4.1 achieve only 57.4% accuracy in predicting subgroup modal preferences. We construct a dataset of over 20,000 samples to train and evaluate a range of models. We demonstrate that simple fine-tuning on structured numerical preferences yields substantial gains, improving accuracy on unseen, out-of-distribution subgroups by an average of 17.4%. These gains partially transfer to open-ended generation. However, we find significant pre-existing performance biases, where models better emulate young, male, Chinese, and Christian personas. Furthermore, while fine-tuning improves average performance, it widens the disparity between subgroups when measured by distance-aware metrics. Our work offers insights into the limits and fairness implications of subgroup-level cultural alignment.
2025
Unmasking Implicit Bias: Evaluating Persona-Prompted LLM Responses in Power-Disparate Social Scenarios
Bryan Chen Zhengyu Tan | Roy Ka-Wei Lee
Proceedings of the 2025 Conference of the Nations of the Americas Chapter of the Association for Computational Linguistics: Human Language Technologies (Volume 1: Long Papers)
Bryan Chen Zhengyu Tan | Roy Ka-Wei Lee
Proceedings of the 2025 Conference of the Nations of the Americas Chapter of the Association for Computational Linguistics: Human Language Technologies (Volume 1: Long Papers)
Large language models (LLMs) have demonstrated remarkable capabilities in simulating human behaviour and social intelligence. However, they risk perpetuating societal biases, especially when demographic information is involved. We introduce a novel framework using cosine distance to measure semantic shifts in responses and an LLM-judged Preference Win Rate (WR) to assess how demographic prompts affect response quality across power-disparate social scenarios. Evaluating five LLMs over 100 diverse social scenarios and nine demographic axes, our findings suggest a “default persona” bias toward middle-aged, able-bodied, native-born, Caucasian, atheistic males with centrist views. Moreover, interactions involving specific demographics are associated with lower-quality responses. Lastly, the presence of power disparities increases variability in response semantics and quality across demographic groups, suggesting that implicit biases may be heightened under power-imbalanced conditions. These insights expose the demographic biases inherent in LLMs and offer potential paths toward future bias mitigation efforts in LLMs.
Persuasion Dynamics in LLMs: Investigating Robustness and Adaptability in Knowledge and Safety with DuET-PD
Bryan Chen Zhengyu Tan | Daniel Wai Kit Chin | Zhengyuan Liu | Nancy F. Chen | Roy Ka-Wei Lee
Proceedings of the 2025 Conference on Empirical Methods in Natural Language Processing
Bryan Chen Zhengyu Tan | Daniel Wai Kit Chin | Zhengyuan Liu | Nancy F. Chen | Roy Ka-Wei Lee
Proceedings of the 2025 Conference on Empirical Methods in Natural Language Processing
Large Language Models (LLMs) can struggle to balance gullibility to misinformation and resistance to valid corrections in persuasive dialogues, a critical challenge for reliable deployment. We introduce **DuET-PD** (**Du**al **E**valuation for **T**rust in **P**ersuasive **D**ialogues), a framework evaluating multi-turn stance-change dynamics across dual dimensions: persuasion type (corrective/misleading) and domain (knowledge via MMLU-Pro, and safety via SALAD-Bench). We find that even a state-of-the-art model like GPT-4o achieves only 27.32% accuracy in MMLU-Pro under sustained misleading persuasions. Moreover, results reveal a concerning trend of increasing sycophancy in newer open-source models. To address this, we introduce Holistic DPO, a training approach balancing positive and negative persuasion examples. Unlike prompting or resist-only training, Holistic DPO enhances both robustness to misinformation and receptiveness to corrections, improving Llama-3.1-8B-Instruct’s accuracy under misleading persuasion in safety contexts from 4.21% to 76.54%. These contributions offer a pathway to developing more reliable and adaptable LLMs for multi-turn dialogue. Code is available at https://github.com/Social-AI-Studio/DuET-PD.
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Co-authors
- Roy Ka-Wei Lee 5
- Nancy Chen 4
- Zhengyuan Liu 4
- Xing Xie 2
- Jing Yao 2
- Xiaoyuan Yi 2
- Weihua Zheng 2
- Tanmoy Chakraborty 1
- Daniel Wai Kit Chin 1
- Kenny Tsu Wei Choo 1
- Pham Minh Duc 1
- Xiaoxue Gao 1
- Yujia Hu 1
- Koji Inoue 1
- Jimin Jung 1
- Wiwik Karlina 1
- Tatsuya Kawahara 1
- Dongjun Kim 1
- Hwaran Lee 1
- Long Li 1
- Chang Liu 1
- Huiyao Liu 1
- Rui Liu 1
- Tuan Luong 1
- Palash Nandi 1
- Ojasva Saxena 1
- Jaehyung Seo 1
- Ryuichi Sumida 1
- Xiyan Tao 1
- Wei Tian 1
- Keertana Arun Vasan 1
- Chaojun Wang 1
- Nadya Yuki Wangsajaya 1
- Fan Xu (徐凡) 1
- Weiwen Xu 1
- Lingyu Ye 1
- Bowei Zou (邹博伟) 1