Is Argument Structure of Learner Chinese Understandable: A Corpus-Based Analysis

This paper presents a corpus-based analysis of argument structure errors in learner Chinese. The data for analysis includes sentences produced by language learners as well as their corrections by native speakers. We couple the data with semantic role labeling annotations that are manually created by two senior students whose majors are both Applied Linguistics. The annotation procedure is guided by the Chinese PropBank specification, which is originally developed to cover first language phenomena. Nevertheless, we find that it is quite comprehensive for handling second language phenomena. The inter-annotator agreement is rather high, suggesting the understandability of learner texts to native speakers. Based on our annotations, we present a preliminary analysis of competence errors related to argument structure. In particular, speech errors related to word order, word selection, lack of proposition, and argument-adjunct confounding are discussed.Comment: Proceedings of the 2018 International Conference on Bilingual Learning and Teaching (ICBLT-2018

Second language learning from a multilingual perspective

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2018.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Cataloged from student-submitted PDF version of thesis.Includes bibliographical references (pages 119-127).How do people learn a second language? In this thesis, we study this question through an examination of cross-linguistic transfer: the role of a speaker's native language in the acquisition, representation, usage and processing of a second language. We present a computational framework that enables studying transfer in a unified fashion across language production and language comprehension. Our framework supports bidirectional inference between linguistic characteristics of speakers' native languages, and the way they use and process a new language. We leverage this inference ability to demonstrate the systematic nature of cross-linguistic transfer, and to uncover some of its key linguistic and cognitive manifestations. We instantiate our framework in language production by relating syntactic usage patterns and grammatical errors in English as a Second Language (ESL) to typological properties of the native language, showing its utility for automated typology learning and prediction of second language grammatical errors. We then introduce eye tracking during reading as a methodology for studying cross-linguistic transfer in second language comprehension. Using this methodology, we demonstrate that learners' native language can be predicted from their eye movement while reading free-form second language text. Further, we show that language processing during second language comprehension is intimately related to linguistic characteristics of the reader's first language. Finally, we introduce the Treebank of Learner English (TLE), the first syntactically annotated corpus of learner English. The TLE is annotated with Universal Dependencies (UD), a framework geared towards multilingual language analysis, and will support linguistic and computational research on learner language. Taken together, our results highlight the importance of multilingual approaches to the scientific study of second language acquisition, and to Natural Language Processing (NLP) applications for non-native language.by Yevgeni Berzak.Ph. D

Beyond topic-based representations for text mining

A massive amount of online information is natural language text: newspapers, blog articles, forum posts and comments, tweets, scientific literature, government documents, and more. While in general, all kinds of online information is useful, textual information is especially important—it is the most natural, most common, and most expressive form of information. Text representation plays a critical role in application tasks like classification or information retrieval since the quality of the underlying feature space directly impacts each task's performance. Because of this importance, many different approaches have been developed for generating text representations. By far, the most common way to generate features is to segment text into words and record their n-grams. While simple term features perform relatively well in topic-based tasks, not all downstream applications are of a topical nature and can be captured by words alone. For example, determining the native language of an English essay writer will depend on more than just word choice. Competing methods to topic-based representations (such as neural networks) are often not interpretable or rely on massive amounts of training data. This thesis proposes three novel contributions to generate and analyze a large space of non-topical features. First, structural parse tree features are solely based on structural properties of a parse tree by ignoring all of the syntactic categories in the tree. An important advantage of these "skeletons" over regular syntactic features is that they can capture global tree structures without causing problems of data sparseness or overfitting. Second, SyntacticDiff explicitly captures differences in a text document with respect to a reference corpus, creating features that are easily explained as weighted word edit differences. These edit features are especially useful since they are derived from information not present in the current document, capturing a type of comparative feature. Third, Cross-Context Lexical Analysis is a general framework for analyzing similarities and differences in both term meaning and representation with respect to different, potentially overlapping partitions of a text collection. The representations analyzed by CCLA are not limited to topic-based features

Robust Text Correction for Grammar and Fluency

Grammar is one of the most important properties of natural language. It is a set of structural (i.e., syntactic and morphological) rules that are shared among native speakers in order to engage smooth communication. Automated grammatical error correction (GEC) is a natural language processing (NLP) application, which aims to correct grammatical errors in a given source sentence by computational models. Since the data-driven statistical methods began in 1990s and early 2000s, the GEC com- munity has worked on establishing a common framework for its evaluation (i.e., dataset and metric for benchmarking) in order to compare GEC models’ performance quantitatively. A series of shared tasks since early 2010s is a good example of this. In the first half of this thesis, I propose character-level and token-level error correction algorithms. For the character-level error correction, I introduce a semi-character recurrent neural network, which is motivated by a finding in psycholinguistics, called the Cmabrigde Uinervtisy (Cambridge University) effect or typoglycemia. For word-level error correc- tion, I propose an error-repair dependency parsing algorithm for ungrammatical texts. The algorithm can parse sentences and correct grammatical errors simultaneously. However, it is important to note that grammatical errors are not usually limited to mor- phological or syntactic errors. For example, collocational errors such as *quick/fast food and *fast/quick meal are not fully explained by only syntactic rules. This is another im- portant property of natural language, called fluency (or acceptability). Fluency is a level of mastery that goes beyond knowledge of how to follow the rules, and includes know- ing when they can be broken or flouted. In fact, the GEC community has also extended the scope of error types from closed class errors (e.g., noun numbers, verb forms) to the fluency-oriented errors. The second half of this thesis investigates GEC while considering fluency as well as grammaticality. When it comes to “whole-sentence” correction, by extending the scope of errors considering fluency as well as grammaticality, the GEC community has overlooked the reliability and validity of the task scheme (i.e., evaluation metric and dataset for bench- marking). Thus, I reassess the goals of GEC as a “whole-sentence” rewriting task while considering fluency. Following the fluency-oriented GEC framework, I introduce a new benchmark corpus that is more diverse in various aspects such as proficiency, topics, and learners’ native languages. Based on the fluency-oriented metric and dataset, I propose a new “whole-sentence” error correction model with neural reinforcement learning. Unlike conventional maximum likelihood estimation (MLE), the model directly optimizes toward an objective that consid- ers a sentence-level, task-specific evaluation metric. I demonstrate that the proposed model outperforms MLE in human and automated evaluation metrics. Finally, I conclude the thesis and outline ideas and suggestions for future GEC research