Evaluating Language Model Context Windows: A "Working Memory" Test and
  Inference-time Correction
Authors: name: Amanda Dsouza; name: Christopher Glaze; name: Changho Shin; name: Frederic Sala
Published: 2024-07-04 05:46:20

Abstract: Large language models are prominently used in real-world applications, often
tasked with reasoning over large volumes of documents. An exciting development
in this space is models boasting extended context capabilities, with some
accommodating over 2 million tokens. Such long context model capabilities
remain uncertain in production systems, motivating the need to benchmark their
performance on real world use cases. We address this challenge by proposing
SWiM, an evaluation framework that addresses the limitations of standard tests.
Testing the framework on eight long context models, we find that even strong
models such as GPT-4 and Claude 3 Opus degrade in performance when information
is present in the middle of the context window (lost-in-the-middle effect).
Next, in addition to our benchmark, we propose medoid voting, a simple, but
effective training-free approach that helps alleviate this effect, by
generating responses a few times, each time randomly permuting documents in the
context, and selecting the medoid answer. We evaluate medoid voting on single
document QA tasks, achieving up to a 24% lift in accuracy.