Columbia EMNLP paper: dense retrievers are systematically biased by identity signals in queries

vishalmisra · x · 2026-10-28

A Columbia University team presented at EMNLP2026 that dense (embedding-based) retrievers — the core of many RAG systems — are systematically skewed by identity signals in queries. Key findings from the poster: retrievers favor the asker's ideology in both synthetic and real queries; they perform significantly worse on Asian-American health queries, with gaps of 17+ percentage points on real queries, larger than in synthetic tests; and lexical control (hybrid BM25) only partially mitigates bias, suggesting deeper representation-level causes beyond token features. Evaluated across politics/religion/health domains with synthetic and naturalistic experiments.

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