Nanyun Peng

Existing medical reasoning benchmarks for vision-language models primarily focus on analyzing a patient’s condition based on an image from a *single* visit. However, this setting deviates significantly from real-world clinical practice, where doctors typically refer to a patient’s historical conditions to provide a comprehensive assessment by tracking their changes over time. In this paper, we introduce TemMed-Bench, a multi-task benchmark designed for analyzing changes in patients’ conditions between different clinical visits, which challenges large vision-language models (LVLMs) to reason over **tem**poral **med**ical images. TemMed-Bench consists of a test set comprising three tasks – visual question-answering (VQA), report generation, and image-pair selection – and a supplementary knowledge corpus of over 17,000 instances. With TemMed-Bench, we conduct an evaluation of twelve LVLMs, comprising six proprietary and six open-source models. Our results show that most LVLMs lack the ability to analyze patients’ condition changes over temporal medical images. To enhance the tracking of condition changes, we explore augmenting the input with both retrieved visual and textual modalities in the medical domain. We also show that multi-modal retrieval augmentation yields notably higher performance gains than no retrieval and textual retrieval alone across most models on our benchmark, with the VQA task showing an average improvement of 2.59%. Overall, we compose a benchmark grounded on real-world clinical practice, and it reveals LVLMs’ limitations in temporal medical image reasoning, as well as highlighting the use of multi-modal retrieval augmentation as a potentially promising direction worth exploring to address this challenge.

Multi-turn, multi-modal interaction is a common interaction pattern in human–AI collaborative coding, where users iteratively refine implementations using both language and visual feedback. For example, in front-end development, users often combine textual instructions with visual artifacts such as sketches, mockups, and annotated screenshots. Despite its prevalence, such workflow remains largely overlooked: existing research primarily studied simplified single-turn or text-only settings. To address this gap, we introduce **FronTalk**, a benchmark for **multi-turn, multi-modal code generation** in front-end development. FronTalk has 100 multi-turn dialogues from diverse real-world websites. Each turn includes a textual instruction and an equivalent visual instruction. We further propose a novel *agent-based evaluation framework* that leverages a web agent to simulate user interactions and measure both implementation correctness and user experience of the generated websites. Evaluation of 20 models reveals two fundamental challenges: (1) a *forgetting issue*, where models often overwrite previously implemented features, and (2) a *visual interpretation gap*, where models struggle to translate visual inputs into functional requirements. To address these challenges, we propose ACECoder, which employs a web agent to autonomously critique implementations and verify compliance with prior instructions. This reduces the forgetting rate from 8.0–28.2\% to **nearly zero**. In terms of overall performance, ACECoder improves the textual feedback setting by up to **9.3\%** (56.0\%$\rightarrow$65.3\%) and also mitigates the visual interpretation challenge, boosting performance by up to **5.2\%** (55.0\%$\rightarrow$60.2\%) with visual feedback.

AI systems are used worldwide, but they struggle to serve the needs of culturally diverse populations. Prior work on cultural understanding evaluates AI systems on text-only settings or on visual artifact recognition (e.g. foods, clothing). The ability to reason about visually observable behaviors through local social norms, which we call visual norm understanding, remains unexamined. We introduce NormViz-Bench, a high quality, human-validated benchmark of 3,272 contrastive image pairs (6,544 images) spanning 16 countries. Each pair varies only in the culturally relevant behavior (e.g., objects, attributes, spatial relations, and actions) that alters how each image is interpreted. Each image is labeled as conforming to, violating, or irrelevant to local social norms, and pair-level evaluation requires both images to be correctly classified, thereby preventing reliance on superficial visual shortcuts. Even the strongest VLMs, Gemini 3.0 Flash and Qwen2.5 VL 7B, succeed on only 25.3% and 23.0% of pairs, struggling most with identifying violating and culturally benign visual behaviors. Towards bridging this, we introduce NormViz-Train, a training dataset of 64k images paired with explanations. Though absolute performance remains low (<30%), finetuning on NormViz-Train improves pair accuracy relatively by up to 86% and 36% for Qwen3-VL 4B and 8B respectively, showing a path forward to teach models to connect visual perception to cultural significance. Together, NormViz-Bench and NormViz-Train establish visual norm understanding as a challenging and consequential frontier for multimodal AI.

Group Relative Policy Optimization (GRPO) has emerged as the de facto Reinforcement Learning (RL) objective driving recent advancements in Multimodal Large Language Models. However, extending this success to open-source multimodal generalist models remains heavily constrained by two primary challenges: the extreme variance in reward topologies across diverse visual tasks, and the inherent difficulty of balancing fine-grained perception with multi-step reasoning capabilities. To address these issues, we introduce Gaussian GRPO (G$^2$RPO), a novel RL training objective that replaces standard linear scaling with non-linear distributional matching. By mathematically forcing the advantage distribution of any given task to strictly converge to a standard normal distribution, $\mathcal{N}(0,1)$, G$^2$RPO promotes advantage-scale equity across tasks, mitigates vulnerabilities to heavy-tail outliers, and offers symmetric update for positive and negative rewards. Leveraging the enhanced training stability provided by G$^2$RPO, we introduce two task-level shaping mechanisms to seamlessly balance perception and reasoning. First, response length shaping dynamically elicits extended reasoning chains for complex queries while enforce direct outputs to bolster visual grounding. Second, entropy shaping tightly bounds the model's exploration zone, effectively preventing both entropy collapse and entropy explosion. Integrating these methodologies, we present OpenVLThinkerV2, a highly robust, general-purpose multimodal model. Extensive evaluations across 18 diverse benchmarks demonstrate its superior performance over strong open-source and leading proprietary frontier models.