{
  "id": "lost-in-the-middle",
  "code": "PTL-0098",
  "term": "Lost in the Middle",
  "aliases": [
    "positional bias",
    "U-shaped context performance"
  ],
  "category": "failure-modes",
  "definition": "Lost in the middle is the finding that language models use information at the beginning or end of a long context much more reliably than information placed in the middle.",
  "description": "Liu et al. observed a U-shaped performance curve on multi-document question answering as the position of the relevant document varied. A practical takeaway is to place key material and instructions at the start or end of long prompts.",
  "example": null,
  "broader": [],
  "narrower": [],
  "related": [
    "context-window",
    "needle-in-a-haystack",
    "context-engineering",
    "thread-of-thought"
  ],
  "introduced": 2023,
  "sources": [
    {
      "title": "Lost in the Middle: How Language Models Use Long Contexts",
      "authors": "Liu et al.",
      "year": 2023,
      "url": "https://arxiv.org/abs/2307.03172"
    }
  ],
  "url": "https://protologue.com/t/lost-in-the-middle/",
  "citation": "Protologue. (2026). Lost in the Middle. In Protologue: A Taxonomy of Prompting and LLM Techniques (v1.0.0, PTL-0098). https://protologue.com/t/lost-in-the-middle/"
}