Teaching with Lies: Curriculum DPO on Synthetic Negatives for
  Hallucination Detection
Authors: name: Shrey Pandit; name: Ashwin Vinod; name: Liu Leqi; name: Ying Ding
Published: 2025-05-23 07:05:09

Abstract: Aligning large language models (LLMs) to accurately detect hallucinations
remains a significant challenge due to the sophisticated nature of hallucinated
text. Recognizing that hallucinated samples typically exhibit higher deceptive
quality than traditional negative samples, we use these carefully engineered
hallucinations as negative examples in the DPO alignment procedure. Our method
incorporates a curriculum learning strategy, gradually transitioning the
training from easier samples, identified based on the greatest reduction in
probability scores from independent fact checking models, to progressively
harder ones. This structured difficulty scaling ensures stable and incremental
learning. Experimental evaluation demonstrates that our HaluCheck models,
trained with curriculum DPO approach and high quality negative samples,
significantly improves model performance across various metrics, achieving
improvements of upto 24% on difficult benchmarks like MedHallu and HaluEval.
Additionally, HaluCheck models demonstrate robustness in zero-shot settings,
significantly outperforming larger state-of-the-art models across various
benchmarks.