Fine-tuning and adaptation

LoRA, PEFT, instruction tuning and domain adaptation — adapting a pretrained model without paying to train one.

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arXiv Machine Learning
Oct 7

A Systematic Study of Small Language Models on Abstract Reasoning Tasks

The paper investigates how small language models acquire abstract reasoning skills on the ARC‑TGI benchmark, which groups grid‑transformation tasks into controllable families and allows resampling, spatial shifts, and cross‑benchmark transfer. Over 1,000 supervised fine‑tuning runs across decoder‑only, encoder‑decoder, and mixture‑of‑experts families, the study finds that high in‑distribution accuracy is possible but depends heavily on optimization and is uneven across task families. Performance drops sharply outside the training distribution, and gains from larger training sets or additional in‑context examples vary by model family; attention diagnostics reveal distinct patterns but do not explain causal mechanisms.

By Nur A Zarin Nishat, Jens Lehmann, Andrei Aioanei, Sahar Vahdati
arXiv Machine Learning
Oct 7

Skillful Data-Driven Subseasonal Soil Moisture Forecasting: Prospects and Limits for Flash Drought Prediction

The paper presents a Vision Transformer-based model for subseasonal soil‑moisture forecasting over Europe, showing that forecast skill depends heavily on how the prediction problem is formulated. By using residual learning and forecasting root‑zone soil moisture in physical units, the model outperforms persistence and existing deep‑learning and ECMWF baselines, providing well‑calibrated probabilistic predictions. However, predicting flash drought onset—defined by rapid multi‑pentad intensification—remains a challenge shared by all current subseasonal‑to‑seasonal systems.

By Noelia Otero, Atahan \"Ozer, Miguel-\'Angel Fern\'andez-Torres, Jackie Ma
arXiv Machine Learning
Oct 7

What pass@k Cannot Measure: Evaluating Diversity and Capability Retention after Post-Training

The paper critiques the use of pass@$k$ as a sole metric for evaluating reinforcement‑learning post‑training on language models, showing that it ignores diversity in model outputs. Experiments on Qwen2.5‑1.5B‑Instruct trained with Group Relative Policy Optimization (GRPO) and rejection‑sampling fine‑tuning (RFT) reveal that these methods shift token‑level, answer‑level, and unique‑answer diversity in opposite directions, yet pass@$k$ fails to capture these differences. Even when restricting to verifier‑correct completions, diversity gaps persist, and pass@$k$ does not consistently identify the better performing arm on hard problem subsets, indicating that the metric can mask true capability changes.

By Subham Rath, Raj Dandekar, Rajat Dandekar, Sreedath Panat
arXiv Machine Learning
Oct 7

Rethinking Fine-Tuning: Unlocking Hidden Capabilities in Vision-Language Models

The paper introduces Mask Fine‑Tuning (MFT), a new approach for adapting Vision‑Language Models that avoids modifying backbone weights. MFT learns masks to selectively route information through existing pretrained connections, dynamically uncovering subnetworks that better align with downstream tasks. Experiments demonstrate that MFT consistently outperforms both Full Fine‑Tuning and Parameter‑Efficient Fine‑Tuning across multiple benchmarks, while also offering insights into how pretrained VLMs reorganize their internal pathways during adaptation.

By Mingyuan Zhang, Yue Bai, Yifan Wang, Yiyang Huang, Yun Fu
arXiv Computation and Language
Oct 7

The Failure Is in the Readout: Fine-Grained Emotion Recognition Benchmarks Measure Elicitation, Not Perception

The paper introduces EmoNet‑Face‑HQ, a fine‑grained emotion recognition benchmark that uses generated portraits and a 40‑category taxonomy to evaluate vision‑language models (VLMs). It finds that VLMs perform poorly when asked to generate responses but can match or surpass a fine‑tuned model (Empathic‑Insight‑Face) when their logits are read directly as binary queries. The study shows that the benchmark’s difficulty lies in the readout process rather than in perception, and that graded probability outputs yield better performance than simple yes/no questions.

By Tobias Hallmen, Fabian Deuser, Robin-Nico Kampa, Norbert Oswald, Elisabeth Andr\'e
arXiv Computer Vision
Oct 7

Towards benchmarking Western Bluebird detection in the wild

The paper introduces a new benchmark dataset of over 6,000 high‑resolution images for detecting and segmenting Western bluebirds in natural, cluttered scenes. Experiments show that supervised detectors such as Faster R‑CNN and RT‑DETR outperform open‑vocabulary models in zero‑shot settings, though fine‑tuned YOLO‑World can compete. Segmentation results favor Mask R‑CNN for mask quality, while YOLOv8‑Seg offers the best precision and speed. The study also identifies multiple factors—scale, brightness, contrast, clutter, blur, crowding, and session variation—as contributors to detection failures.

By Estela Monserrat Arriaga Santana, Julian Rosas Scull, Ibeth P. Alarc\'on, Bibiana Montoya, Aylin Sosa Mej\'ia, Hugo Jair Escalante
arXiv Computer Vision
Oct 7

Multitask Conditional Generative Adversarial Network Enables Automatic Whole Knee Cartilage and Menisci Segmentation and Reliable $T_{1\rho}$ and $T_2$ Quantification Without High-Resolution Morphological Images

The study introduces a multitask conditional generative adversarial network (MT‑cGAN) that simultaneously synthesizes high‑resolution DESS‑like images and segments knee cartilage and menisci directly from quantitative MRI echo images. Evaluated on 508 knee MRIs from 361 subjects, MT‑cGAN achieved a mean Dice score of 0.84 for segmentation and the lowest coefficient of variation for T1ρ (1.84%) and T2 (1.81%) quantification, outperforming existing conditional GAN approaches. By eliminating the need for separate high‑resolution morphological scans, the method shortens scan times and supports clinical adoption of quantitative MRI.

By Ahmed Tahseen Minhaz, Richard Lartey, Zhiyuan Zhang, Jeehun Kim, Kunio Nakamura, Mingrui Yang, Jiasen Zhang, Weihong Guo, Naveen Subhas, Carl S. Winalski, Xiaojuan Li