Lost in the Middle
Also called positional bias, U-shaped context performance.
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.
Sources
- Liu et al. (2023). Lost in the Middle: How Language Models Use Long Contexts.
Cite this entry
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/
BibTeX
@misc{protologue_lost_in_the_middle,
title = {Lost in the Middle},
author = {{Protologue}},
year = {2026},
howpublished = {Protologue: A Taxonomy of Prompting and LLM Techniques, v1.0.0},
note = {Entry PTL-0098},
url = {https://protologue.com/t/lost-in-the-middle/}
}