What Makes Reading Comprehension Questions Difficult?

TL;DR

This study investigates what makes reading comprehension questions difficult, finding that passage source and readability do not significantly impact difficulty, but diverse passage selection influences question types and reasoning requirements.

Contribution

It provides empirical insights into factors affecting question difficulty and reasoning types, guiding better selection of passages for benchmark datasets.

Findings

Passage source and readability do not significantly affect difficulty

Diverse passages lead to a variety of question types and reasoning

Logical reasoning is more common in technical passages

Abstract

For a natural language understanding benchmark to be useful in research, it has to consist of examples that are diverse and difficult enough to discriminate among current and near-future state-of-the-art systems. However, we do not yet know how best to select text sources to collect a variety of challenging examples. In this study, we crowdsource multiple-choice reading comprehension questions for passages taken from seven qualitatively distinct sources, analyzing what attributes of passages contribute to the difficulty and question types of the collected examples. To our surprise, we find that passage source, length, and readability measures do not significantly affect question difficulty. Through our manual annotation of seven reasoning types, we observe several trends between passage sources and reasoning types, e.g., logical reasoning is more often required in questions written for technical passages. These results suggest that when creating a new benchmark dataset, selecting a diverse set of passages can help ensure a diverse range of question types, but that passage difficulty need not be a priority.