Lost in the Prompt Order: Revealing the Limitations of Causal Attention in Language Models

Fuente: arXiv
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Auteurs principaux: Ok, Hyunjong, Lee, Jaeho
Format: Preprint
Publié: 2026
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author Ok, Hyunjong
Lee, Jaeho
author_facet Ok, Hyunjong
Lee, Jaeho
contents Large language models exhibit surprising sensitivity to the structure of the prompt, but the mechanisms underlying this sensitivity remain poorly understood. In this work, we conduct an in-depth investigation on a striking case: in multiple-choice question answering, placing context before the questions and options (CQO) outperforms the reverse order (QOC) by over 14%p, consistently over a wide range of models and datasets. Through systematic architectural analysis, we identify causal attention as the core mechanism: in QOC prompts, the causal mask prevents option tokens from attending to context, creating an information bottleneck where context becomes invisible to options.
format Preprint
id arxiv_https___arxiv_org_abs_2601_14152
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Lost in the Prompt Order: Revealing the Limitations of Causal Attention in Language Models
Ok, Hyunjong
Lee, Jaeho
Computation and Language
Artificial Intelligence
Machine Learning
Large language models exhibit surprising sensitivity to the structure of the prompt, but the mechanisms underlying this sensitivity remain poorly understood. In this work, we conduct an in-depth investigation on a striking case: in multiple-choice question answering, placing context before the questions and options (CQO) outperforms the reverse order (QOC) by over 14%p, consistently over a wide range of models and datasets. Through systematic architectural analysis, we identify causal attention as the core mechanism: in QOC prompts, the causal mask prevents option tokens from attending to context, creating an information bottleneck where context becomes invisible to options.
title Lost in the Prompt Order: Revealing the Limitations of Causal Attention in Language Models
topic Computation and Language
Artificial Intelligence
Machine Learning
url https://arxiv.org/abs/2601.14152