MATCHA通过对比语义对齐提升文本评估精度,有效区分正确与错误内容。
MATCHA: Matching Text via Contrastive Semantic Alignment

- 引入双视角机制:同时衡量与参考文本的语义接近度和对抗生成矛盾句的距离
- 在8个基准上优于ROUGE和BERTScore,TruthfulQA上提升超20%
- 适用于无训练集场景,对模型幻觉检测更敏感,适合评测大模型输出质量
可靠评估对理解大语言模型性能至关重要,但当前主流指标如基于词元重叠的ROUGE和基于嵌入的BERTScore常误判文档间语义相似性。研究表明,这两类指标常对直接矛盾的文本赋予几乎相同的分数,可能掩盖根本性错误。本文提出MATCHA,一种自动评估指标,同时奖励与参考文本的语义一致性并惩罚矛盾。该方法采用双视角设计:(i)测量与标准文本的接近程度;(ii)测量与对抗生成的反事实矛盾句的距离。在八个公开基准上,MATCHA优于主流指标,与人类标注结果一致,涵盖问答、图像描述、自然语言推断、摘要及语义文本相似性任务。在无训练集的TruthfulQA数据集上,相较于ROUGE-L和BERTScore,匹配度提升分别达18.38%和20.82%。定量与定性评估均验证了其有效性,并揭示现有指标的根本缺陷。相比23种嵌入模型(包括最先进模型),MATCHA在仅依赖参考文本的情况下,仍是最准确区分正确与错误陈述的指标。代码与指标已公开(https://github.com/Siran-Li/MATCHA)。
原文摘要 · Abstract (English)
Reliable evaluation is essential for understanding large language model (LLM) performance, yet today's go-to metrics, namely token-overlap scores (e.g., ROUGE) and embedding-based measures (e.g., BERTScore), often misjudge semantic similarity of documents. Our study shows that both token-overlap metrics and embedding-based metrics routinely assign nearly identical scores to texts that directly contradict each other, thereby potentially masking fundamental errors. We introduce MATCHA, an automatic metric that jointly rewards semantic agreement with a reference and penalizes contradictions. MATCHA employs a dual-view perspective that measures (i) proximity to the gold text and (ii) distance from an adversarially generated counterfactual contradiction. In eight public benchmarks, MATCHA outperforms popular metrics, compared with human annotations on question-answering, image caption generation, natural language inference, summarization, and semantic textual similarity tasks. On the TruthfulQA dataset (i.e., a dataset without a training set, where no embedding-based metrics could locally train on), this improvement in terms of matching texts with a reference reaches 18.38% over ROUGE-L and 20.82% over BERTScore. Both quantitative comparison and qualitative human assessments confirm the efficacy and validity of MATCHA and uncover fundamental weaknesses in pre-existing metrics. Compared with 23 embedding models, including top state-of-the-art ones, used as a metric similar to BERTScore, MATCHA remains the most accurate in distinguishing correct from incorrect statements solely based on a reference. Our code and metric are publicly available (https://github.com/Siran-Li/MATCHA).
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