Title
Why Machine Reading Comprehension Models Learn Shortcuts?
Abstract
Recent studies report that many machine reading comprehension (MRC) models can perform closely to or even better than humans on benchmark datasets. However, existing works indicate that many MRC models may learn shortcuts to outwit these benchmarks, but the performance is unsatisfactory in real-world applications. In this work, we attempt to explore, instead of the expected comprehension skills, why these models learn the shortcuts. Based on the observation that a large portion of questions in current datasets have shortcut solutions, we argue that larger proportion of shortcut questions in training data make models rely on shortcut tricks excessively. To investigate this hypothesis, we carefully design two synthetic datasets with annotations that indicate whether a question can be answered using shortcut solutions. We further propose two new methods to quantitatively analyze the learning difficulty regarding shortcut and challenging questions, and revealing the inherent learning mechanism behind the different performance between the two kinds of questions. A thorough empirical analysis shows that MRC models tend to learn shortcut questions earlier than challenging questions, and the high proportions of shortcut questions in training sets hinder models from exploring the sophisticated reasoning skills in the later stage of training.
Year
Venue
DocType
2021
ACL/IJCNLP
Conference
Volume
Citations 
PageRank 
2021.findings-acl
0
0.34
References 
Authors
0
5
Name
Order
Citations
PageRank
Yuxuan Lai101.69
Chen Zhang201.01
Yansong Feng373564.17
Quzhe Huang400.34
Dongyan Zhao599896.35