🤖 AI Summary
This work addresses the long-overlooked challenge of negation understanding in neural information retrieval (IR), where language models (LMs) exhibit significant deficiencies. We propose a systematic evaluation framework and conduct a comprehensive assessment of mainstream IR models’ ranking performance on negated queries, using the NevIR and ExcluIR benchmarks. Our findings reveal that most models perform near-randomly; although listwise large language model (LLM) re-rankers achieve the best and most robust performance across both negation tasks, they still substantially underperform human-level capability. Moreover, distributional discrepancies between ExcluIR and NevIR hinder cross-dataset generalization. This study provides the first empirical evidence of the relative advantages—and fundamental limitations—of listwise LLM re-rankers in negation-aware retrieval, offering critical insights and concrete directions for advancing negation-sensitive IR modeling.
📝 Abstract
Negation is a fundamental aspect of human communication, yet it remains a challenge for Language Models (LMs) in Information Retrieval (IR). Despite the heavy reliance of modern neural IR systems on LMs, little attention has been given to their handling of negation. In this study, we reproduce and extend the findings of NevIR, a benchmark study that revealed most IR models perform at or below the level of random ranking when dealing with negation. We replicate NevIR's original experiments and evaluate newly developed state-of-the-art IR models. Our findings show that a recently emerging category - listwise Large Language Model (LLM) rerankers - outperforms other models but still underperforms human performance. Additionally, we leverage ExcluIR, a benchmark dataset designed for exclusionary queries with extensive negation, to assess the generalizability of negation understanding. Our findings suggest that fine-tuning on one dataset does not reliably improve performance on the other, indicating notable differences in their data distributions. Furthermore, we observe that only cross-encoders and listwise LLM rerankers achieve reasonable performance across both negation tasks.