ANALYZING THE INTERLANGUAGE OF ASL NATIVES by Litza Stark A thesis submitted to the Faculty of the University of Delaware in partial fulfillment of the requirements for the degree of Honors Bachelor of Arts in Computer and Information Sciences, with Distinction. Spring 2001 Copyright 2001 Litza Stark All Rights Reserved ANALYZING THE INTERLANGUAGE OF ASL NATIVES by Litza A. Stark Approved: Dr. Kathleen McCoy, Ph.D. First Thesis Reader Approved: Dr. William Idsardi, Ph.D. Second Thesis Reader Approved: Dr. Nancy Jordan, Ph.D. Third Thesis Reader Approved: Dr. Ann Ardis, Ph.D. Director of the University Honors Program ACKNOWLEDGMENTS Thanks go to Jacy, my inspiration, partner, and guide for the duration of this work; to my parents, for simply assuming that I could (and would) do anything I wanted to; to Kathy, for steering me through this process and my college career; and to Lisa, for providing consistent and persistent collaboration. TABLE OF CONTENTS LIST OF TABLES vi LIST OF FIGURES vii ABSTRACT viii 1 A tool to aid Deaf language instruction 9 1.1 Overview of the research 9 1.2 Problems facing Deaf learners 9 1.3 A new tool: ICICLE 11 1.3.1 The domain knowledge base 14 1.3.2 The user model 14 1.3.3 Linguistic assumptions behind the system architecture 16 2 Background in interlanguage and acquisition hierarchies 17 2.1 Elements of interlanguage theory and the ZPD 17 2.2 Sources of learners' errors 18 2.3 Research in Deaf acquisition 19 2.4 Implications for ICICLE 21 3 New error analysis of Deaf writing 23 3.1 Motivation for attempting error analysis 23 3.2 Intuitions and expectations 23 3.3 Experimental design 24 3.3.1 Choosing the error measure 24 3.3.2 The samples 25 3.3.3 The error codes 26 3.3.4 The method 26 3.4 Preliminary analysis 27 3.5 The final analysis 29 3.5.1 Refinement of the error codes 30 3.5.2 Coding and intercoder reliability 31 3.5.3 Classification of samples 33 3.5.4 Analysis 34 3.5.4.1 Differences across proficiency levels 34 3.5.4.2 Patterns within proficiency levels 35 4 Conclusions and future work 44 4.1 Conclusions 44 4.2 Limitations of this approach 45 4.3 Towards a full user model 45 A The writing samples 47 A.1 Sample with rating 2 47 A.2 Sample with rating 3 48 A.3 Sample with rating 4 49 A.4 Sample with rating 5 50 B The error codes 52 B.1 The full error set 53 B.2 The reduced error set 56 C Correlations within High-Proficiency Writing Samples 58 Bibliography 65 LIST OF TABLES Table 1 Sample sentence and correction. 26 Table 2 Preliminary analysis of common errors 28 Table 3 Sample correction 1 32 Table 4 Sample correction 2 32 Table 5 Differences in errors between proficiency levels 35 Table 6 Results of factor analysis using reduced set of 21 errors 40 Table 7 SLALOM model based on factor analysis 42 LIST OF FIGURES Figure 1 The ICICLE Architecture (from Michaud 1999) 13 Figure 2 A hypothetical SLALOM hierarchy 15 Figure 3 Projection of vectors onto an axis 38 ABSTRACT Deaf students learning English face a unique and daunting array of challenges because of the vast distance between signed ASL and written English. The ICICLE system would provide an automated tutor to address and remedy some of these difficulties. Central to the ICICLE system is the proposed user modeling component, which would parse input and provide tutorial feedback using (a) knowledge of the universal patterns of language acquisition, and (b) records of the individual user's past behavior. In order to develop a model of the syntax of Deaf students learning written English, we undertook this study. Using writing samples gathered from Deaf students that had been scored according to the Test of Written English, we tabulated individual syntactic errors on the sentence level and conducted MANOVA tests and factor analysis. We found differences in the occurrence of errors across proficiency levels based on the MANOVA test. From the factor analysis, we found classes of errors that were most characteristic of the proficiency levels, and which could be used to build a concrete model of the typical user's syntax. Chapter 1 A TOOL TO AID DEAF LANGUAGE INSTRUCTION 1.1 Overview of the research Along with others on the ICICLE team, I have conducted the following research into the acquisition process of Deaf students learning written English. This research was motivated by the needs of the ICICLE tool, an automated writing tutor designed to assist Deaf students learning English. In order for the system to represent a particular user and the path of his learning process, we need to know what specific stages the typical user passes through. This research took two forms: we looked first at existing literature on Deaf students learning English to see if previous researchers had found patterns of acquisition. Then, having discovered that we still needed more information, we also undertook to find out for ourselves what those problems might be. In this research, we examined the errors that appear in the writing of a sampling of Deaf students at various stages of acqusition in order to characterize the intermediate syntax that they used. 1.2 Problems facing Deaf learners Deaf learners of written English do not have exposure to the language in its natural, spoken state. Instead, they must learn the written form of the language in isolation. During their learning process, they cannot utilize the primary strategy of hearing learners: the correspondence between the written and the spoken word. Hearing children receive a staggering amount of linguistic input from the first moment they enter the world. In addition to the overwhelming quantity of input that they have at their disposal, the quality of this linguistic data may be specifically tailored to assist their language learning process, including special registers such as "motherese" and simplified speech. When it comes time for hearing children to learn written language, they no longer need to acquire all of their vocabulary or grammar, but simply have to transfer their auditory phonological knowledge to a written representation. In contrast, the only input Deaf learners have at their exposure is the written material, which may or may not be at an appropriate level for their stage of acquisition. They have none of the casual, ubiquitous exposure to language that hearing children do. Deaf students with background in American Sign Language at least have the advantage of a solid, native-language background. However, even with this benefit, they still face unique challenges in learning English, resulting from problems inherent in the transfer from a visual and spatial mode to an auditory and written mode, as well as from their native language's linguistic distance from English. As a result, Deaf English education is in a dire situation, with "half of the population of deaf 18-year-olds reading at or below a fourth grade level and only about 10% reading above the eighth grade level" (Strong 1988). Students that already know ASL face the difficult task of transferring linguistic information from one perceptual mode to a completely new one. ASL is a visuo-spatial language in which linguistic features are carried not only by means of hand shape and movement, but also through facial expressions and body shifts. In making the transfer to written English, learners whose first language is ASL must become accustomed to a far more linear system in which simultaneous communication from multiple sources is not possible. Besides the difficulties inherent in transferring between the two modes of speech, ASL is also structurally different from English, with syntactic constructions more akin to Chinese and Navajo (Michaud, Stark, & McCoy 2001). ASL and English differ in when and how certain features are marked (e.g., tense is only marked at the beginning of an utterance, and not on every verb), in the syntactic features present (e.g., there is no subject-verb agreement), and in the correspondence of lexical items (e.g., "other" and "another" are represented by the same sign) (Suri & McCoy 1993). Knowledge of ASL grammar does not in all cases facilitate understanding of English grammar in many basic syntactic categories. 1.3 A new tool: ICICLE ICICLE (Interactive Computer Identification and Correction of Language Errors), a project led by Dr. Kathy McCoy, is a software system designed to be a general-purpose language tutor for acquiring English as a second language. Under its current implementation, however, it is tailored to attend to the particular needs of native speakers of ASL. During an ICICLE session, as shown in Figure 1, the user begins by entering a piece of text and requesting that it be critiqued. The system uses both universal knowledge about the language acquisition process (the domain knowledge base) and specific information about this user's past performance (the user model) to determine which errors the user has made in their writing. These errors are highlighted, and specific commentary and corrections are provided. In its intended implementation, the responses given to particular errors will also be tailored to the user's individual proficiency level. For instance, if the system knows that the user has used a given construction correctly in the past, it may simply need to remind the user of the correction. If, on the other hand, the user has never attempted the construction before, they might need a more in-depth description of the construction. The tutoring can continue indefinitely, with the user altering their text and the system reanalyzing the input and offering additional corrections. Information about a given session will be stored in the system so that it will know what to expect the next time it sees this user. Figure 1 The ICICLE Architecture (from Michaud 1999) The two primary tasks of the system, therefore, are to identify the errors in the inputted text, and then to generate an appropriate response to these errors. Both of these tasks rely on two underlying models: the domain knowledge base and the user model. 1.3.1 The domain knowledge base In order to parse the user's input, the system must be able to parse both correct and incorrect inputs. It must, firstly, have a representation of correct English syntax. In addition, it needs a grammar of typical errors and their relation to correct constructions. Among these errors, some will be problems universal to learners of English as a second language, and some will be specifically related to the transfer of ASL grammar to English grammar. This knowledge base remains static across users, as it represents language universals that should be applicable to any learner. 1.3.2 The user model Alongside the static knowledge base, the system must develop a model of each user. This user model should provide information for the dual functions of interpretation and feedback. In the case of ambiguous constructions in the input, a user model allows the system to choose the parse most likely to occur at the user's current stage of acquisition. And in designing feedback for the user, the user model can indicate both what corrections should be emphasized and the particular phrasing that should be used in the text of the feedback. The user model will be a hierarchical representation of the user's linguistic development, referred to as SLALOM: Steps of Language Acquisition in a Layered Organization Model (McCoy et. al. 1996, Michaud 1999, Michaud et. al. 2001). Progress can be charted in specific areas, such as morphology, sentence structure, relative clause formation, or determiner use. Each one of these areas will constitute an individual hierarchy, in which elements are organized according to increasing complexity (See Figure 2 for a conjecture of how the SLALOM model might appear). For instance, within the morphology hierarchy, the "+ing" construction is learned before the "+s" plural construction, which in turn is learned before the "+ed" past tense construction. Individual vertical hierarchies will also be linked to one another horizontally; object noun relative clauses might be learned at the same stage as the SVO sentence construction, and the two hierarchies would thus correspond at this level. Much research has been done tracing the acquisition process of individual syntactic categories. However, not much has been done to link the hierarchies horizontally in order to describe which features are concurrently acquired. To develop a full SLALOM model, it is necessary to discover where the individual hierarchies are linked. Figure 2 A hypothetical SLALOM hierarchy Having such a model containing information about specific syntactic constructions would allow us to extrapolate predictions about one class of error based on observed errors of an entirely different sort. The system, based on SLALOM information, could designate a user as functioning at a particular level, and would expect their errors to come from the current level and (perhaps) the level above. It could assume that all constructions falling below the current level had already been learned. Having the information that SLALOM would provide could expedite the process of parsing a user's input and improve the specificity of the feedback offered to the user. 1.3.3 Linguistic assumptions behind the system architecture In order for the ICICLE system to be feasible, its assumptions about the nature of language acquisition must have a valid theoretical basis. In the domain knowledge base, we must be able to formulate specific errors that will be likely to occur in the writing of ASL natives learning English. This module assumes that the errors made by second-language learners come in part from interference from their native language, and in part from the structure of their target language. The user model assumes that learners pass through fairly discrete and consistent stages in language acquisition, such that the errors in their writing will be predictable. In the following section I will provide evidence from existing research to suggest that we may safely operate under these assumptions. Chapter 2 BACKGROUND IN INTERLANGUAGE AND ACQUISITION HIERARCHIES 2.1 Elements of interlanguage theory and the ZPD Interlanguage theory, first proposed by Selinker in 1972, has become an increasingly accepted principle of second language acquisition. The theory describes the process of learning a second language as an evolutionary one, in which a learner passes through a sequence of intermediate grammars, or interlanguages, on the way to the target language (Selinker 1972). These interlanguages constitute the learner's working hypotheses concerning the grammar of the target language. The initial hypothesis is based largely on the grammar of the first language (L1). As the learner is exposed to more examples of the target language (L2), she revises her ideas about the L2 grammar. An ideal end state is reached when there is no mismatch between the language that she produces and the language that she is exposed to (Dulay & Burt 1974). Along the way, each interlanguage constitutes a grammar in its own right, rather than simply a scattershot attempt to mimic the L2. Each interlanguage consists of varying proportions of L1 grammar, L2 grammar, and hypothesized constructions that don't appear in either language. During a learning process, there is always some material that has already been learned and some that is beyond the learner's grasp, but in between these two domains falls material that the learner is currently in the process of acquiring. Russian psychologist Lev Vygotsky called this material the Zone of Proximal Development (ZPD), and suggested that this material constitutes a set of hypotheses that the learner is in the process of testing (Vygotsky 1986). She will make attempts to utilize her new concepts, and her usage will be full of errors that are not always consistent. It is this set of knowledge that an instructor should focus on; instruction on material beneath the ZPD is pointless, and instruction on that material beyond the ZPD will not take hold. The instructor should work with the student's natural learning process and help them conquer that material which is challenging them at a given moment. By using the SLALOM model, we attempt to pinpoint that material which is most likely to appear in the ZPD, and focus on instruction in that realm. The interlanguage model of language acquisition provides the theoretical framework behind the SLALOM model, and Vygotsky's concept of the ZPD provides the instructional basis for ICICLE. Essentially, SLALOM's hierarchical levels represent different interlanguages, in which the earliest interlanguages contain the least complex structures. There is "an apparent predilection on the part of the learner for interlanguage structure which poses the fewest possible difficulties for mental processing" (Rutherford 1984). ICICLE seeks to take advantage of the natural hierarchical nature of language acquisition to facilitate its language instruction. 2.2 Sources of learners' errors Traditional theories of second language acquisition hold that there are two sources for a learner's errors: language transfer and the influence of universal grammar. Thus, the errors arise out of interference from the first language and a learner's instinctual syntactical hypotheses. However, most of the sequence of the acquisition of any language, according to some researchers, is determined by the L2 itself. Studies on the acquisition of particular structures have found that the problems that learners of English as a second language have are frequently similar to those that young first-language learners of English have (Gass 1979). In addition, "regardless of first language background, children reconstruct English syntax in similar ways" (Dulay & Burt 1974). The native language causes variations on the standard sequence of learning a given language, but it is the target language that has the strongest influence on a learner's path of acquisition. Universal grammar is another source of learners' difficulties. Some hierarchies of acquisition are not unique to a particular target language, but arise from universal cognitive limitations on the complexity of structures. Certain structures are inherently more complex than others, and thus take longer to be acquired cross- linguistically. Some research on individual syntactic structures (such as relative clauses) describes the particular hierarchy of difficulty for these structures. These hierarchies hold true not only cross-linguistically, in that more complex structures will never be present without also having the less complex ones, but also within an individual's learning process. Simple structures will be learned before more complex ones are attempted (Keenan & Comrie 1977, Keenan & Hawkins 1987). 2.3 Research in Deaf acquisition The English acquisition process for Deaf students is not significantly different from that of a learner with any other first language (Swisher 1989). However, the influence of ASL and the lack of auditory information available to this population might offer some distinct difficulties. Berent, for instance, even concludes that there is a ceiling to Deaf students' capabilities brought about because of their processing limitations (Berent 1988). Whether or not there are such limitations, we are clearly dealing with a unique population of learners. In describing the details of the SLALOM model, I had initially hoped to find existing research on the acquisition sequence of Deaf learners. A number of researchers have indeed focused on Deaf students learning English, but their research leaves some crucial gaps. Some studies reproduced acquisition research that had been done on first-language English learners and applied it to the learning process of Deaf students. These supported the claims of language universals in showing that Deaf learners undergo much the same processes as first-language English learners (Dulay & Burt 1973, Bailey et. al. 1974, Gass 1979). Some researchers conclude that, unlike learners with other first languages, Deaf learners have a ceiling to their possible language acquisition. They suggest that instructors should focus primarily on those structures that are most successfully acquired by Deaf learners, rather than wasting time on inherently difficult concepts (Bochner 1978, Berent 1988). Quigley, et. al., have conducted the most comprehensive research concerning Deaf students' acquisition of English syntactic structures. His studies provide a fairly thorough picture of the timing of acquisition of individual structures. Interestingly, they focus exclusively on prelinguistically Deaf students, but don't investigate possible influences from ASL, nor do they specify what, if any, experience the subjects have had with ASL (though the majority of the subjects do come from residential schools for the Deaf). It is questionable, then, whether his research would be wholly reliable for making conclusions about the transfer from ASL to English (Quigley et. al. 1974, Quigley et. al. 1976, Wilbur et. al. 1976, Wilbur 1977, Quigley & King 1992). Quigley tries to establish sequences of acquisition for a number of structures in the English of Deaf learners. He and his colleagues find rough sequences for questions, complement structures, verb tenses, and pronominalization. They find that the sequences closely match those found in first-language learners, although the acquisition is frequently delayed in Deaf learners. They do not seek to attribute errors to transfer from ASL, even when it might be appropriate. For instance, they note that the Deaf students have difficulty understanding the need to mark tense in both verbs of a conjoined sentence, but fail to mention that ASL does not require repeated tense marking within an utterance referring to a single topic. Quigley provides a wealth of information about the acquisition of English by Deaf students with respect to individual constructions. His research supports the claim for a hierarchical sequence of second language acquisition with respect to Deaf learners. Many of his individual studies provide us with information about the sequence of acquisition within a given syntactic category. For the SLALOM model, however, we are seeking to link the acquisition processes of these constructions, and his data contain no temporal markers by which to compare the different processes. While his research is useful, we need to look elsewhere in order to describe the ways in which various structures interact during the acquisition process. 2.4 Implications for ICICLE ICICLE and the SLALOM model rest heavily on the concepts delineated by interlanguage theory and the ideas of language transfer. The system will come equipped with expectations about rules derived from both English and ASL, in the form of the grammar and the rules defined for incorrect constructions. Based on the theory of language transfer outlined above, it would be unlikely for a user to use constructions that do not resemble either ASL or English grammar. Within the system, we seek to place a given user in a stage of acquisition that reflects an approximation of her current interlanguage. We try to emphasize those constructions that are being used erratically, as would be expected by Vygotsky's ZPD. Research in second language acquisition provides ample evidence to support the current design of ICICLE and the SLOLEM model. Chapter 3 NEW ERROR ANALYSIS OF DEAF WRITING 3.1 Motivation for attempting error analysis In order to create a useful SLALOM model, we need concrete data about the order of acquisition of syntactic structures by Deaf learners. Existing research, as outlined above, provides data concerning order of acquisition for independent structures, but we want to build a model that can express the interconnectedness of diverse syntactic structures. We need data that shows us what kinds of structures and errors tend to co-occur during the learning process, and whether they occur more frequently in writing from a learner at a particular stage of acquisition. We undertook to conduct a new study to examine the acquisition of English syntax by Deaf students, paying close attention to the influence of ASL on their syntax. By conducting a broad study of the specific errors conducted by Deaf writing students, and comparing their fine-grained syntax with the overall proficiency of their writing, we hoped to establish a general outline for the SLOLEM model. 3.2 Intuitions and expectations Upon first attempting this analysis, we had little idea how much to expect. We intended to count the errors found in the samples, to divide the samples according to a more global measure of proficiency, and then to look for distinctive patterns that would differentiate the various proficiency levels. These patterns would take the form of differences in the number or kinds of errors that occur at different levels. We then hoped that we could further examine these differences in order to find out what errors were particularly correlated with one another, and what errors were particularly distinctive to a given proficiency level. 3.3 Experimental design 3.3.1 Choosing the error measure In examining the acquisition process and describing interlanguages, there are a number of indicators that might shed light on a writer's level of linguistic competence. The errors committed by a writer provide one of the most apparent indicators of the learning process, especially considering the assumptions behind the ZPD. Nevertheless, it is also important to examine those structures that are used correctly and those that are not attempted at all. Together, these three measures provide a complete portrait of a learner's interlanguage, and could potentially show us exactly where in the SLALOM hierarchy the learner falls. However, identifying those structures that are used successfully, or those structures that are not used at all, is a daunting task, and subject to much interpretation. In an unconstrained set of writing, it may be impossible to determine those structures that are not attempted. However, it should be feasible to parse sentences either by hand or automatically in order to gauge which syntactic structures are being used successfully. At some point we hope to use the ICICLE parser to identify the correctly used structures, but now, while the parser is still under development, we are beginning by examining simply the errors committed in our corpus of data. To enumerate the errors found in a given sample, we marked the errors that appeared sentence by sentence. We also grouped the samples according to their levels of proficiency. At this point, we could test to find any similarities in the error profiles among students at some proficiency level, or differences between the profiles of students at different proficiency levels. Assuming that the error profiles change along with the proficiency levels, this analysis should give us insight into which structures are being acquired at a given level. 3.3.2 The samples All of our data come from an existing corpus of writing samples from Deaf students at Gallaudet University (GU), the National Technical Institute of the Deaf (NTID), the Pennsylvania School for the Deaf, and the Bicultural Center. Most of these samples (the bulk of them from GU and NTID) were written by entering college freshmen. These samples were collected completely confidentially; we do not know the writers' names or any identifying information. However, we screened out all samples except those most likely written by native ASL speakers [In some situations, this was determined by a self-rating by the student; in other cases characteristics such as other Deaf family members or Deaf boarding school at an early age were used. ], as we are particularly interested in examining the language transfer from ASL to English without interference from other signed communication systems. Our final corpus consists of 106 samples, with an average length of 17 sentences (228 words). (See Appendix A for a selection of writing samples.) 3.3.3 The error codes We began with a set of 75 error codes, encompassing both syntactic and semantic problems. Each one of these codes could be identified at the sentence level, so that we could associate a list of codes with each sentence in a sample. In order to find the broadest results possible, the codes reflected many different syntactic structures, on the sentence level, on the phrase level, and on the word level. 3.3.4 The method Each sentence was coded as a discrete unit, considering only the syntactic context of that sentence. Coders began their examination of a sentence by deciding which alterations were necessary to make the sentence grammatical by changing as few words in the sentence as possible. Once they had written a corrected form of the sentence, coders listed those error codes that described what led to the alterations, in the order in which they occurred. In the case of multiple interpretations for a given sentence, coders could list more than one correction and rate them as to their likelihood. Table 1 Sample sentence and correction. Note that the error codes are listed in the order in which they occur in the sentence. Original People here are helpful and they make me to be self-confidence, mature. Codes ev adjf mc Correction People here are helpful and they make me self-confident and mature Codes: ev = extra verb; adjf = adjective formation; mc = missing conjunction Our final data consisted of the count of how many errors of each type occurred in each of the samples. Thus, we had a table of 106 entries (for each of the samples), each of which had 67 associated values (for each of the error codes). 3.4 Preliminary analysis After the writing samples were completely coded using the set of 75 errors, we ran a preliminary set of statistical tests to look for patterns of errors. A single native-speaker judge classified the samples into four levels of proficiency based on subjective global assessment of the samples. The very worst samples verged on "word salad," showing very little grasp of English grammar; these were assigned a score of 1. Those that were slightly better -- not quite unintelligible, with only rudimentary sentence structures -- were assigned a score of 2. Samples with a score of 3 were intelligible, though full of grammatical and organizational problems. Sophisticated structures were occasionally attempted but not usually accurate. The best of the samples, which showed very few errors and were completely intelligible, were assigned a score of 4. After these ratings were given to the samples, the error occurrences within and across the informal levels were tabulated. Under this very casual analysis, we found an indication that there was a progression in the occurrences of errors across the proficiency levels (see Table 2). Table 2 Preliminary analysis of common errors showed some trends towards differences among the four proficiency levels Establishing that there was indeed some difference among the levels was not sufficient, however. It was also important to determine whether these errors were somehow related within the levels. Finding relations between errors at a given proficiency level will provide us with information about a particular horizontal cross-section of the SLALOM model, by showing us which syntactic categories are under acquisition simultaneously. To find those syntactic constructions which are in the ZPD at the same time, we looked for pairwise correlations of the occurrences of errors in the samples within each proficiency level. Eventually, if there were strong correlations between specific errors or error groups at a given proficiency level, the known presence of one error could help predict what other errors might be present, thus helping the user model to inference the full picture of the interlanguage on the basis of a few examples. Indeed, there were a number of error pairs that were significantly correlated (p<0.05, with 0.40