The automatic evaluation of natural language generation (NLG) systems presents a long-lasting challenge. Recent studies have highlighted various neural metrics that align well with human evaluations. Yet, the robustness of these evaluators against adversarial perturbations remains largely under-explored due to the unique challenges in obtaining adversarial data for different NLG evaluation tasks. To address the problem, we introduce AdvEval, a novel black-box adversarial framework against NLG evaluators. AdvEval is specially tailored to generate data that yield strong disagreements between human and victim evaluators. Specifically, inspired by the recent success of large language models (LLMs) in text generation and evaluation, we adopt strong LLMs as both the data generator and gold evaluator. Adversarial data are automatically optimized with feedback from the gold and victim evaluator. We conduct experiments on 12 victim evaluators and 11 NLG datasets, spanning tasks including dialogue, summarization, and question evaluation. The results show that AdvEval can lead to significant performance degradation of various victim metrics, thereby validating its efficacy.

通过引入黑盒对抗性评估框架AdvEval，利用强大的语言模型作为数据生成器和金标评估器，自动优化对抗数据并产生强烈的人工评估与受害评估之间的不一致性，实现了对自然语言生成系统进行鲁棒性评估的研究。在12个受害评估器和11个自然语言生成数据集上的实验证明了AdvEval的有效性。

揭示NLG评估器的致命弱点：由大型语言模型驱动的统一对抗框架