SubmissionNumber#=%=#14 FinalPaperTitle#=%=#VISHC at PsyDefDetect: Mitigating Data Scarcity in Psychological Defense Classification with Context-Aware Synthetic Augmentation ShortPaperTitle#=%=# NumberOfPages#=%=# CopyrightSigned#=%=# JobTitle#==# Organization#==# Abstract#==#Psychological defense mechanisms (PDMs) are unconscious cognitive processes that modulate how individuals perceive and respond to emotional distress. Automatically classifying PDMs from text is clinically valuable but severely hindered by data scarcity and class imbalance, challenges which generative augmentation alone cannot resolve without psychological grounding. In this work, we address these challenges in the PsyDefDetect shared task (BioNLP @ ACL 2026) by proposing a context-aware synthetic augmentation framework combined with a hybrid classification model. Our hybrid model integrates contextual language representations with basic clinical features, including I-pronoun density and open-up ratio, along with 150 annotated defense items. Experiments demonstrate that definition quality in prompting directly governs generation fidelity and downstream performance. Our approach outperforms DMRS Co-Pilot, improving accuracy by 0.37 and macro-F1 by 0.19, establishing a strong baseline for psychologically grounded defense mechanism classification in low-resource settings. Source code is available at: https://github.com/htdgv/CASA-PDC. Author{1}{Firstname}#=%=#Hoang-Thuy-Duong Author{1}{Lastname}#=%=#Vu Author{1}{Orcid}#=%=# Author{1}{Email}#=%=#26duong.vht@vinuni.edu.vn Author{1}{Affiliation}#=%=#VinUni-Illinois Smart Health Center, College of Engineering and Computer Science, VinUniversity Author{2}{Firstname}#=%=#Quoc-Cuong Author{2}{Lastname}#=%=#Pham Author{2}{Orcid}#=%=# Author{2}{Email}#=%=#24cuong.pq@vinuni.edu.vn Author{2}{Affiliation}#=%=#VinUni-Illinois Smart Health Center, College of Engineering and Computer Science, VinUniversity Author{3}{Firstname}#=%=#Huy-Hieu Author{3}{Lastname}#=%=#Pham Author{3}{Orcid}#=%=# Author{3}{Email}#=%=#hieu.ph@vinuni.edu.vn Author{3}{Affiliation}#=%=#VinUni-Illinois Smart Health Center, College of Engineering and Computer Science, Center for Innovations in Health Sciences, VinUniversity ========== èéáğö