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The Pursuit of Empathy: Evaluating Small Language Models for PTSD Dialogue Support
Preprint   Open access

The Pursuit of Empathy: Evaluating Small Language Models for PTSD Dialogue Support

Suhas BN, Yash Mahajan, Dominik Mattioli, Andrew M Sherrill, Rosa I Arriaga, Chris W Wiese and Saeed Abdullah
ArXiv.org
Cornell University
09/20/2025
DOI: 10.48550/arxiv.2505.15065
url
https://doi.org/10.48550/arxiv.2505.15065View
Preprint (Author's original)This preprint has not been evaluated by subject experts through peer review. Preprints may undergo extensive changes and/or become peer-reviewed journal articles. Open Access

Abstract

This paper investigates the capacity of small language models (0.5B-5B parameters) to generate empathetic responses for individuals with PTSD. We introduce Trauma-Informed Dialogue for Empathy (TIDE), a novel dataset comprising 10,000 two-turn conversations across 500 diverse, clinically-grounded PTSD personas (https://huggingface.co/datasets/yenopoya/TIDE). Using frontier model outputs as ground truth, we evaluate eight small LLMs in zero-shot settings and after fine-tuning. Fine-tuning enhances empathetic capabilities, improving cosine similarity and perceived empathy, although gains vary across emotional scenarios and smaller models exhibit a "knowledge transfer ceiling." As expected, Claude Sonnet 3.5 consistently outperforms all models, but surprisingly, the smaller models often approach human-rated empathy levels. Demographic analyses showed that older adults favored responses that validated distress before offering support (p = .004), while graduate-educated users preferred emotionally layered replies in specific scenarios. Gender-based differences were minimal (p > 0.15), suggesting the feasibility of broadly empathetic model designs. This work offers insights into building resource-efficient, emotionally intelligent systems for mental health support.
Computer Science - Artificial Intelligence Computer Science - Computation and Language Computer Science - Computers and Society

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