Artifacts or Abduction: How Do LLMs Answer Multiple-Choice Questions Without the Question?

Fuente: arXiv
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Main Authors: Balepur, Nishant, Ravichander, Abhilasha, Rudinger, Rachel
Format: Preprint
Published: 2024
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author Balepur, Nishant
Ravichander, Abhilasha
Rudinger, Rachel
author_facet Balepur, Nishant
Ravichander, Abhilasha
Rudinger, Rachel
contents Multiple-choice question answering (MCQA) is often used to evaluate large language models (LLMs). To see if MCQA assesses LLMs as intended, we probe if LLMs can perform MCQA with choices-only prompts, where models must select the correct answer only from the choices. In three MCQA datasets and four LLMs, this prompt bests a majority baseline in 11/12 cases, with up to 0.33 accuracy gain. To help explain this behavior, we conduct an in-depth, black-box analysis on memorization, choice dynamics, and question inference. Our key findings are threefold. First, we find no evidence that the choices-only accuracy stems from memorization alone. Second, priors over individual choices do not fully explain choices-only accuracy, hinting that LLMs use the group dynamics of choices. Third, LLMs have some ability to infer a relevant question from choices, and surprisingly can sometimes even match the original question. Inferring the original question is an impressive reasoning strategy, but it cannot fully explain the high choices-only accuracy of LLMs in MCQA. Thus, while LLMs are not fully incapable of reasoning in MCQA, we still advocate for the use of stronger baselines in MCQA benchmarks, the design of robust MCQA datasets for fair evaluations, and further efforts to explain LLM decision-making.
format Preprint
id arxiv_https___arxiv_org_abs_2402_12483
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Artifacts or Abduction: How Do LLMs Answer Multiple-Choice Questions Without the Question?
Balepur, Nishant
Ravichander, Abhilasha
Rudinger, Rachel
Computation and Language
Multiple-choice question answering (MCQA) is often used to evaluate large language models (LLMs). To see if MCQA assesses LLMs as intended, we probe if LLMs can perform MCQA with choices-only prompts, where models must select the correct answer only from the choices. In three MCQA datasets and four LLMs, this prompt bests a majority baseline in 11/12 cases, with up to 0.33 accuracy gain. To help explain this behavior, we conduct an in-depth, black-box analysis on memorization, choice dynamics, and question inference. Our key findings are threefold. First, we find no evidence that the choices-only accuracy stems from memorization alone. Second, priors over individual choices do not fully explain choices-only accuracy, hinting that LLMs use the group dynamics of choices. Third, LLMs have some ability to infer a relevant question from choices, and surprisingly can sometimes even match the original question. Inferring the original question is an impressive reasoning strategy, but it cannot fully explain the high choices-only accuracy of LLMs in MCQA. Thus, while LLMs are not fully incapable of reasoning in MCQA, we still advocate for the use of stronger baselines in MCQA benchmarks, the design of robust MCQA datasets for fair evaluations, and further efforts to explain LLM decision-making.
title Artifacts or Abduction: How Do LLMs Answer Multiple-Choice Questions Without the Question?
topic Computation and Language
url https://arxiv.org/abs/2402.12483