Lost in the Middle: How Language Models Use Long Contexts

Liu et al., 2024, Lost in the Middle (Transactions of ACL, vol. 12)

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3 How Well Can Language Models Retrieve From Input Contexts?

  1. What is the synthetic key-value retrieval task, and why use random UUIDs?
    The input is a JSON object of \(k\) key-value pairs (75, 140 or 300), all random 128-bit UUIDs, plus a query key; the model must return its value. Random strings strip away natural-language semantics that could confound the test of pure retrieval.
  2. What did key-value retrieval reveal?
    Claude-1.3 was nearly perfect at all lengths, but other models struggled, again worst when the key was in the middle: even exact-match retrieval of a token string from the context isn’t reliable for all models.

Source

  • Nelson F. Liu, Kevin Lin, John Hewitt, Ashwin Paranjape, Michele Bevilacqua, Fabio Petroni and Percy Liang. 2024. Lost in the Middle: How Language Models Use Long Contexts. In Transactions of the Association for Computational Linguistics, vol. 12, pp. 157–173. License: CC BY 4.0. Flashcards adapted from this work. doi:10.1162/tacl_a_00638 https://aclanthology.org/2024.tacl-1.9/