Empty Shelves or Lost Keys? Recall Is the Bottleneck for Parametric Factuality

Fuente: arXiv
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Autores principales: Calderon, Nitay, Ben-David, Eyal, Gekhman, Zorik, Ofek, Eran, Yona, Gal
Formato: Preprint
Publicado: 2026
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author Calderon, Nitay
Ben-David, Eyal
Gekhman, Zorik
Ofek, Eran
Yona, Gal
author_facet Calderon, Nitay
Ben-David, Eyal
Gekhman, Zorik
Ofek, Eran
Yona, Gal
contents Standard factuality evaluations of LLMs treat all errors alike, obscuring whether failures arise from missing knowledge (empty shelves) or from limited access to encoded facts (lost keys). We propose a behavioral framework that profiles factual knowledge at the level of facts rather than questions, characterizing each fact by whether it is encoded, and then by how accessible it is: cannot be recalled, can be directly recalled, or can only be recalled with inference-time computation (thinking). To support such profiling, we introduce WikiProfile, a new benchmark constructed via an automated pipeline with a prompted LLM grounded in web search. Across 4 million responses from 13 LLMs, we find that encoding is nearly saturated in frontier models on our benchmark, with GPT-5 and Gemini-3 encoding 95--98% of facts. However, recall remains a major bottleneck: many errors previously attributed to missing knowledge instead stem from failures to access it. These failures are systematic and disproportionately affect long-tail facts and reverse questions. Finally, we show that thinking improves recall and can recover a substantial fraction of failures, indicating that future gains may rely less on scaling and more on methods that improve how models utilize what they already encode.
format Preprint
id arxiv_https___arxiv_org_abs_2602_14080
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Empty Shelves or Lost Keys? Recall Is the Bottleneck for Parametric Factuality
Calderon, Nitay
Ben-David, Eyal
Gekhman, Zorik
Ofek, Eran
Yona, Gal
Computation and Language
Artificial Intelligence
Standard factuality evaluations of LLMs treat all errors alike, obscuring whether failures arise from missing knowledge (empty shelves) or from limited access to encoded facts (lost keys). We propose a behavioral framework that profiles factual knowledge at the level of facts rather than questions, characterizing each fact by whether it is encoded, and then by how accessible it is: cannot be recalled, can be directly recalled, or can only be recalled with inference-time computation (thinking). To support such profiling, we introduce WikiProfile, a new benchmark constructed via an automated pipeline with a prompted LLM grounded in web search. Across 4 million responses from 13 LLMs, we find that encoding is nearly saturated in frontier models on our benchmark, with GPT-5 and Gemini-3 encoding 95--98% of facts. However, recall remains a major bottleneck: many errors previously attributed to missing knowledge instead stem from failures to access it. These failures are systematic and disproportionately affect long-tail facts and reverse questions. Finally, we show that thinking improves recall and can recover a substantial fraction of failures, indicating that future gains may rely less on scaling and more on methods that improve how models utilize what they already encode.
title Empty Shelves or Lost Keys? Recall Is the Bottleneck for Parametric Factuality
topic Computation and Language
Artificial Intelligence
url https://arxiv.org/abs/2602.14080