SubmissionNumber#=%=#26 FinalPaperTitle#=%=#DAL Team at PsyDefDetect: From Supervised Encoders to Hierarchical LLM-RAG for Psychological Defense Detection ShortPaperTitle#=%=# NumberOfPages#=%=# CopyrightSigned#=%=# JobTitle#==# Organization#==# Abstract#==#We propose a hierarchical framework for psychological defense mechanism detection in multi-turn dialogues, integrating large language models, retrieval-augmented generation, and heuristic calibration. Our approach decomposes prediction into coarse-to-fine reasoning stages and incorporates dialogue reconstruction, explanation-enhanced retrieval, and hybrid LLM–supervised filtering to address severe label imbalance and implicit, context-dependent labeling. Experiments on the PsyDefDetect dataset show that LLM-based RAG improves performance on minority and ambiguous classes, achieving a Macro F1 of 0.31, while also revealing persistent challenges in fine-grained discrimination of latent psychological constructs. Author{1}{Firstname}#=%=#Anh Phuong Author{1}{Lastname}#=%=#Chu Author{1}{Username}#=%=#pa_vnu_uet Author{1}{Orcid}#=%=# Author{1}{Email}#=%=#23020324@vnu.edu.vn Author{1}{Affiliation}#=%=#VNU University of Engineering and Technology, Hanoi, Vietnam Author{2}{Firstname}#=%=#Luong Duc Author{2}{Lastname}#=%=#Tran Author{2}{Orcid}#=%=# Author{2}{Email}#=%=#22021148@vnu.edu.vn Author{2}{Affiliation}#=%=#Faculty of Information Technology, VNU University of Engineering and Technology, Vietnam Author{3}{Firstname}#=%=#Dat Hoang Author{3}{Lastname}#=%=#Do Author{3}{Orcid}#=%=# Author{3}{Email}#=%=#24020060@vnu.edu.vn Author{3}{Affiliation}#=%=#Faculty of Information Technology, VNU University of Engineering and Technology, Vietnam Author{4}{Firstname}#=%=#Phuong Tu Author{4}{Lastname}#=%=#Mai Author{4}{Orcid}#=%=# Author{4}{Email}#=%=#21020552@vnu.edu.vn Author{4}{Affiliation}#=%=#Faculty of Information Technology, VNU University of Engineering and Technology, Vietnam Author{5}{Firstname}#=%=#Quynh Hoang Author{5}{Lastname}#=%=#Le Author{5}{Orcid}#=%=# Author{5}{Email}#=%=#lhquynh@vnu.edu.vn Author{5}{Affiliation}#=%=#Faculty of Information Technology, VNU University of Engineering and Technology, Vietnam Author{6}{Firstname}#=%=#Cat Duy Author{6}{Lastname}#=%=#Can Author{6}{Orcid}#=%=# Author{6}{Email}#=%=#duy-cat.can@chuv.ch Author{6}{Affiliation}#=%=#Faculty of Biology and Medicine, University of Lausanne, Switzerland ========== èéáğö