Text Modification for Bulgarian Sign Language Users

Text Modification for Bulgarian Sign Language Users Slavina Lozanova∗ Ivelina Stoyanova† Svetlozara Leseva† [email protected] [email protected] [email protected] Svetla Koeva† Boian Savtchev‡ [email protected] [email protected] ∗ AssistNet, Sofia, Bulgaria † Department of Computational Linguistics, IBL, BAS, Sofia, Bulgaria ‡ Cambridge Language Assessment Centre BG015, Sofia, Bulgaria Abstract cation devices (Paul, 1998; Conrad, 1979; Mussel- man, 2000; Traxler, 2000; Vermeulen AM, 2007), The paper discusses the main issues re- which shows that reading skills are influenced garding the reading skills and compre- by complex social, linguistic and communication- hension proficiency in written Bulgarian related factors rather than by the sensory disability of people with communication difficulties, alone. and deaf people, in particular. We consider The paper explores reading comprehension of several key components of text compre- Deaf people1 who use Bulgarian Sign Language hension which pose a challenge for deaf (BulSL) as their primary language. Various re- readers and propose a rule-based system search studies both in Bulgaria and abroad have for automatic modification of Bulgarian shown that hearing-impaired BulSL users have texts intended to facilitate comprehension poorer reading skills than their hearing peers. Var- by deaf people, to assist education, etc. In ious methods for text modification have been ex- order to demonstrate the benefits of such a plored to the end of obtaining texts that corre- system and to evaluate its performance, we spond to the proficiency of the readers. Most of have carried out a study among a group of the modification methodologies have been focused deaf people who use Bulgarian Sign Lan- on simplifying the original texts and decreasing guage (BulSL) as their primary language their complexity (Inui et al., 2003). Our approach, (primary BulSL users), which compares however, focuses not on simplification, but on the the comprehensibility of original texts and adaptation of the structure of the original texts to their modified versions. The results shows the linguistic properties of BulSL. a considerable improvement in readability The paper is organized as follows. Section 2 when using modified texts, but at the same discusses the reading skills of BulSL users, paying time demonstrates that the level of com- attention to children’s and adult education in Bul- prehension is still low, and that a complex garia focused on the acquisition of Bulgarian and set of modifications will have to be imple- the relationship between BulSL and verbal Bulgar- mented to attain satisfactory results. ian. After outlining the main principles which un- 1 Introduction derlie text adaptation aimed at fostering text comprehensibility in the target population, we present The individual development of deaf people de- a rule-based method for automatic modification of pends on a complex of factors, which include the Bulgarian written texts. The method applies a set cause and the degree of hearing loss, the age of of linguistic transformations and produces modi- hearing loss onset, educational background, lan- fied versions of the texts, which are better suited guage and communication methods, cultural iden- to the needs of BulSL users (Section 3). Section tification, disability preconceptions. Hearing loss 4 describes an experiment devised to explore the leads to a limited spoken language input, delays reading comprehension of BulSL users of original in language acquisition and communication dif- and modified texts. Section 5 draws conclusions ficulties. Deaf children and adults demonstrate lower reading achievements than hearing people 1Capitalized ’Deaf’ is used to denote the community of deaf people who use Sign Language as their primary lan- regardless of the degree of hearing loss, and the guage. The term emphasizes the socio-cultural model of use (or lack) of high-performing hearing amplifi- Deafness rather than the medical view of hearing impairment. 39 Proceedings of the 2nd Workshop on Predicting and Improving Text Readability for Target Reader Populations, pages 39–48, Sofia, Bulgaria, August 4-9 2013. c 2013 Association for Computational Linguistics and outlines some directions for future work. provide the basis for developing advanced methods for automatic text modification directed to im- 2 Reading Skills of Hearing-Impaired proving text readability for deaf BulSL users. People 2.2 Sign Language and Verbal Language 2.1 Education Research has shown that Deaf children of Deaf Previous research has shown that deaf students lag parents (DCDP) with sign language as their pri- behind their hearing peers in reading comprehen- mary mode of communication outperform their sion, because they experience difficulties with vo- deaf peers of hearing parents (DCHP) on differ- cabulary (Paul, 1996), syntax (Kelly, 1996), and ent academic tests, including reading tests (May- the use of prior knowledge and metacognition berry, 2000). Several studies have found a positive (Trezek et al., 2010). In addition, reading com- correlation between the advanced American Sign prehension difficulties are often linked to lack of Language (ASL) skills of deaf students and their general knowledge due to inadequate education higher reading skills (Hoffmeister, 2000; Padden and limited access to information (Lewis and Jack- and Ramsey, 2000). Evidence is not conclusive as son, 2001). Two independently performed studies to how sign languages relate to verbal languages (Albertini and Mayer, 2011; Parault and William, and what influence they have on the acquisition 2010) have found out that deaf college students’ of general communication skills and knowledge reading skills are below those of six-graders2. about the world. MacAnally et al. (1999) support the hypothe- The extensive research on sign languages in the sis that using less complicated and more accessi- last fifty years worldwide has shown that they are ble reading materials, consisting of language con- independent linguistic systems which differ from structions close or similar to sign language struc- verbal languages (Stokoe, 1960; Stokoe, 1972; ture can facilitate reading comprehension and mo- Sutton-Spence and Woll, 2003). Being an inde- tivate deaf people to read. In support of this claim pendent language, a sign language affects the way Berent (2004) points out that deaf students would in which its users conceptualize the world, accord- read more smoothly if the subject, verb, and object ing to the principle of linguistic relativity, first for- are in a simple SVO (subject-verb-object) word mulated by Sapir and Whorf (Lee, 1996). Due order. These studies provide evidence in favour to the fact that sign languages are very different of text adaptation that reflects features of the sign from verbal ones, many Deaf people attain a cer- language and the development of modified teach- tain level of proficiency in a verbal language at the ing materials. state of interlanguage4 (Selinker, 1972) but that Bulgarian education for the deaf is based en- level is not sufficient to ensure successful social tirely on the oral approach and no systematic effort integration. has been invested into exploring total communi- 2.3 Readability of Written Texts for Native cation and bilingual approaches (Lozanova, 2002; Users of Sign Language Saeva, 2010). Even in the specialized schools for the deaf, where sign language communication Readability is measured mainly on the basis of vo- occurs naturally, BulSL has not been integrated cabulary and sentence complexity, including word into the school curriculum. Besides, the linguis- length and sentence length: the higher the letter, tic analysis of BulSL has been limited to mere syllable and word count of linguistic units, the descriptions and presentation of signs: Bulgar- greater the demand on the reader. Some syntactic ian Sign Language dictionaries (1966, 1996); Sign structures also affect readability – negative and in- Language Dictionary in Civil Education (Stoy- terrogative constructions, passive voice, complex anova et al., 2003); Specialized Multimedia BulSL sentences with various relations between the main dictionary3 (2005). clause and the subordinates, long distance depen- In order to improve education and the reading dencies, etc. Besides, readability improves if the and communication skills of deaf people, a com- information in a text is well-organized and effec- prehensive study of BulSL is necessary, that will 4The term ’interlanguage’ denotes the intermediate state in second language acquisition characterized by insufficient 211-12-year-olds. understanding and grammatical and lexical errors in language 3http://www.signlanguage-bg.com production. 40 tively presented so that its local and global dis- close in meaning to the original. course structure is obvious to the reader (Swann, 1992). • Modified text should be grammatically cor- Text modification is often understood as simpli- rect and structurally authentic by preserving fication of text structure but this may result in an as much as possible of the original textual and inadequately low level of complexity and loss of syntactic structure. relevant information. Moreover, using a limited • In general, modified text should be character- vocabulary, avoiding certain syntactic structures, ized by less syntactic complexity compared such as complex sentences, is detrimental to the with the original text. However, the purpose communication and learning skills. of the modification is not to simplify the text The efforts towards providing

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