LinguIUTics at PsyDefDetect: Iterative Imbalance-Aware Fine-tuning of Qwen3-8B for Psychological Defense Mechanism Classification
Researchers from LinguIUTics have developed a novel approach to classify psychological defense mechanisms in text, achieving a macro F1-score of 0.3917 in the PsyDefDetect 2026 shared task. Their method involved fine-tuning the Qwen3-8B model using QLoRA, incorporating strategies like grouped stratified cross-validation, minority-class lexical augmentation, and a post-processing pipeline. This iterative, imbalance-aware fine-tuning significantly improved performance, particularly for rare classes, and secured them 4th place among 21 teams. AI
IMPACT Demonstrates advanced fine-tuning techniques for handling imbalanced datasets in specialized NLP tasks, potentially improving clinical text analysis.