When large language models (LLMs) hallucinate, developers typically assume the model lacks the required facts. Engineering teams diagnose the error as missing knowledge. The standard response is to increase model size, expand training data, or build complex retrieval architectures.

A new study by researchers at Google Research and Technion demonstrates that the knowledge is often not missing. The model has the information encoded parametrically but fails to surface it during generation. 

Their experiments show that frontier models like GPT-5 and Gemini-3 encode 95-98% of tested facts. This indicates that in many cases, recall, rather than encoding, is the primary bottleneck for factual accuracy. 

By understanding how to unlock existing knowledge through inference-time computation, engineering teams can build more reliable applications without necessarily relying on larger models or external databases.

Knowledge profiling: measuring what models actually know

To map this gap between storage and retrieval, the researchers propose shifting the evaluation focus from question-level accuracy to fact-level profiling. Instead of simply scoring whether an LLM answers an isolated prompt right or wrong, fact-level profiling tests a single underlying piece of information across multiple conditions, evaluating whether the fact is stored in the model's parameters at all, whether it can be queried from different directions and phrasings, and what computational effort is required to retrieve it.

This framework distinguishes between whether a fact is parametrically "encoded" and whether it is "known". A model encodes a fact if it can accurately reproduce it when primed with its original training context. A model knows a fact if it can reliably answer questions about it across varied phrasings and directions.

"Encoding and recall failures are indistinguishable under accuracy metrics, yet they imply different limitations and solutions,” the researchers write. “Encoding failures call for pre-training interventions, such as scaling model size or data coverage. Recall failures suggest post-training interventions that often improve how models utilize what they already encode."

The paper illustrates this using a sample fact: Oasis played their first gig at the Boardwalk club. Based on how models process this information, the study categorizes knowledge into five distinct profiles: