Visual perception and signed oral language in deafness.

UNIVERSIDAD DE SEVILLA DEPARTAMENTO DE PSICOLOGÍA EVOLUTIVA Y DE LA EDUCACIÓN VISUAL PERCEPTION AND SIGNED ORAL LANGUAGE IN DEAFNESS Tesis doctoral Eliana Mastrantuono Memoria de investigación presentada para la obtención del Grado de Doctor en Psicología con Mención Internacional Sevilla, 2018 PhD Candidate Eliana Mastrantuono Supervisors Isabel de los Reyes Rodríguez Ortiz David Saldaña Sage UNIVERSIDAD DE SEVILLA DEPARTAMENTO DE PSICOLOGÍA EVOLUTIVA Y DE LA EDUCACIÓN Sevilla, 2018 Acknowledgements At the end of this amazing scientific journey there are many people to thank, who supported me in various stages of the thesis. I am deeply grateful to the supervisors of the thesis, Isabel Rodríguez Ortiz and David Saldaña, who chose me for this project, part of the European LanPercept network, and shared with me ideas and difficulties during the development of the project. Thank you, Isabel, for the brilliant tutoring, the continuous support and the efforts in every phase of the project. A would like to acknowledge Gabriella Vigliocco who gave me the opportunity to spend three months as a visiting student at the Department of Experimental Psychology at University College London, where I was invited to attend the meeting of the Language and Cognition Lab, sharing ideas and thoughts with the members of the Lab regarding my own project and the projects realised in the Lab. I would also like to thank the researchers at DCAL–Deafness Cognition and Language Research Centre–at University College London, who gave me precious suggestions about my research. Furthermore, I would like to express my gratitude to Michele Burigo who supervised me during a visiting period of two months at the Language and Cognition Lab at CITEC, University of Bielefeld. Thanks, Michele, for sharing with me your experience in data analysis. Being my project part of the LanPercept network, there are many amazing people that I regularly met across the three years of the PhD that inspired me, sharing their ideas during workshops and conferences. I am especially grateful to Mila Vulchanova, the coordinator of the ITN LanPercept, and to all PIs and researchers of other universities and private sectors partners involved in the network: Valentin Vulchanov, Joel Talcott, Kenny Coventry, Paul Engelhardt, Pia Knoeferle, Matthew Crocker, Pablo Gagliardo, Tommy Strandvall, Ricardo Matos, Teresa Cadierno, Rolf Zwaan, Katinka Dijkstra, Rik Eshuis. Thanks to all early and experienced researchers within the LanPercept network: Alba, Lara, Yoana, Friederike, Harmen, Dietha, Dorota, Sobh, Ioanna, Brian, Harm, Shu, Zhihan, and Andrea. In particular, I would like to thank Martina who accompanied me during all stages of this journey. I would like to thank all colleagues at the Universidad de Sevilla who gave me their support and friendship during this experience, Pili, Ellie, Coral, Marta, Angela, Conchi, Noelia, Irene, Lidia, Sofia. Thanks to all members of the Laboratorio de Diversidad, Cognicion y Lenguaje that I have not mentioned yet, in particular, Joaquin, Mari, Antonio, Javi, and Ian. I am especially grateful to Coral and Adrian who helped me with sign language and sign-supported speech stimuli recordings. This project would not have been possible without the cooperation of the heads of the schools who granting me permission to approach parents, sharing relevant information with me and facilitating testing of the students. Of course, I would like to thank for their cooperation all students that took part at this project, their parents, teachers and school professionals. Finally, I would like to acknowledge the European Union’s Seventh Framework Programme for research, technological development for funding this project [grant agreement no 316748]. Eliana Mastrantuono Alla mia famiglia, a Riccardo TABLE OF CONTENTS Preface. ....................................................................................................................................................... XI PART 1: INTRODUCTION AND GOALS Chapter 1 Introduction .............................................................................................................................................. 17 1.1 The Education of Deaf Children: Towards an Inclusive Education ...................................................... 17 1.1.2 Deaf education in Spain. ........................................................................................................ 20 1.2 Visual Components of Language .......................................................................................................... 26 1.2.1 Whatever works: The total communication philosophy and the signing systems. ................ 27 1.2.2 The alternating fortunes of the total communication approach and sign-supported speech in education......................................................................................................................................... 30 1.3 The Specificity of Deaf Profiles ............................................................................................................ 37 1.3.1 Children with cochlear implants. ......................................................................................... 39 1.3.2 Native sign language users. ................................................................................................... 47 1.3.3 Deaf native signers with cochlear implants. .......................................................................... 52 1.4 Eye tracking ........................................................................................................................................... 53 1.4.1 Measures of eye movements.................................................................................................. 54 1.4.2. Eye-tracking in deaf studies. ................................................................................................ 55 Chapter 2 Topic and Goals of this Thesis ......................................................................................................... 59 PART 2: EXPERIMENTAL RESEARCH Chapter 3 Study 1: An Eye-tracking Study on the Perception and Comprehension of Unimodal and Bimodal Linguistic Inputs by Deaf Adolescents ........................................................................ 67 Abstract ....................................................................................................................................................... 69 INTRODUCTION 17 Chapter 1 Introduction 1.1 The Education of Deaf Children: Towards an Inclusive Education In recent years, a global shift in educational philosophy is leading to the adoption of a more inclusive education (Knoors, Tang, & Marschark, 2014). The philosophical perspective underlying the phenomenon of inclusion is driven by the idea of egalitarianism among all learners and the role of the institutions of promoting integration (Fernandez-Viader, 2004; Stinson & Antia, 1999). Inclusion is fundamental to prepare individuals for life, giving the opportunity to learners with special educational needs to have normal life experiences and learning from typical peers and, at the same time, to teach and apply democracy at school by challenging social rejection (Stinson & Antia, 1999). This philosophical approach resulted in laws, such as the Individuals with Disabilities Education Act (IDEA), that regulate the issue of inclusion in the wider field of special education (Stinson & Antia, 1999). Inclusive education implies that all learners should attend regular classrooms, and teachers, in collaboration with special educators, should adapt the structure of the classroom to facilitate their learning. In agreement with this currently dominant philosophy, the education for deaf students is also changing direction. Traditionally, when enrolling their children at school, parents of deaf or hard of hearing children had two main options (Stinson & Kluvin, 2014; Tang & Yiu, 2016). The first option, usually preferred for deaf children with greater access to audition, was a mainstream school with oral communication programs. Generally, in public schools, there are only one or two deaf students per VISUAL PERCEPTION AND SIGNED ORAL LANGUAGE IN DEAFNESS 18 classroom. In regular classrooms, deaf students receive consultation or additional instruction through a teacher of the deaf, who in many educational systems is an itinerant teacher. This itinerant teacher can only devote a limited time to each student, having to teach to many deaf students with very diverse profiles in a day (Stinson & Kluvin, 2014). At the best, students in mainstream environments can also benefit of speech language therapy and additional services at high-school level to support communication access and learning, such as notetakers, interpreters, real-time speech-to-text services, might also be supplied (Schirmer, 2001; Stinson et al., 1999; Stinson & Foster, 2000). Mainstream schools are usually fitted with resource rooms and separate classes. The resource rooms are a workable option for mainly orally educated deaf children. In fact, they attend resource rooms only for reviewing specific subjects and spend most of the time in regular classrooms. By contrast, separate classes are a less inclusive option, where deaf students receive their entire instruction from a specialised teacher of deaf education, rarely interacting with hearing students in regular classrooms. The second option was traditionally the special school for deaf, mainly chosen for children with lower or no access to audition. In these special schools, deaf children mainly communicate with each other using natural sign languages or any signed system, separately from the spoken language. Special schools usually provide with a range of special services, such as psychologists, audiologists, and counsellors, and propose a wide variety of academic, vocational courses and athletic and social programs. Recent studies based on large datasets of the United States reveal that students attending special schools are more likely to use sign language and less likely to use spoken language than students attending mainstream institutions (Allen & Anderson, 2010; Shaver, Marschark, Newman, & Marder, 2014), and have major conversational difficulties (Shaver et al., 2014). INTRODUCTION 19 In the 21st century, a consequence of the extension of the philosophy of integration, more inclusive educational placements have become the preferred option, and 80-90% of deaf or hard-of-hearing students now attend mainstream schools (Tang & Yiu, 2016). Nevertheless, average deaf students in regular classrooms still achieve poorer academic outcomes than their hearing peers (Knoors & Marschark, 2015; Marschark & Hauser, 2008). These difficulties are evident even in children with cochlear implants (CIs). Despite substantial evidence that the use of CIs enhances spoken-language acquisition, and improves speech perception and production (Watson, Archbold, & Nikolopoulos, 2006; Watson, Hardie, Archbold, & Wheeler, 2008), a positive impact of cochlear implantation on literacy is still not demonstrated (Harris, 2016). In reading comprehension, deaf children have the same difficulties as hearing poor comprehenders (Kyle & Cain, 2015), and struggle with generating inferences (Miller, 2002). Considering these unsatisfactory outcomes, practitioners in deaf education started to rethink an environment that could be linguistically richer and would facilitate communicative exchanges between deaf and hearing students: models of sign bilingual education were implemented in mainstream classrooms. These models are sustained by research on sign bilingualism (Humphries et al., 2012; Marschark, Tang, & Knoors, 2014), which indicate a positive effect of sign language, together with spoken language, on the language development of deaf and hard-of-hearing children. Models of co-enrollment teaching are becoming increasingly popular in many countries. Coenrollment teaching differs from the traditional mainstream teaching in regular classrooms in how it promotes integration between hearing and deaf students. First, in a co-enrollment setting it is necessary to create a real community of bimodal bilingual users. To this aim, hearing students should necessarily be involved in programs to acquire sign language. Crucially, with the aim to create an educational setting in which bimodal languages effectively co-exist, a significant number VISUAL PERCEPTION AND SIGNED ORAL LANGUAGE IN DEAFNESS 20 of deaf signers should attend the same classrooms (at least in a deaf-hearing ratio estimated around 1:3 or 1:4) (Tang & Yiu, 2016). School teachers should engage themselves in collaborating with the teachers for deaf students, team-teaching with them, and they are encouraged to integrate regular education practices with those from special deaf education, with the aim of breaking down barriers to learning and promoting the active participation of deaf students in the classroom. In a co-enrollment classroom much time need to be devoted to the organisation of teaching, as it is provided in two languages. Ground-breaking experiences of co-enrollment were started with the TRIPOD program in California in 1982. Compared to deaf students of the same age, the participating deaf students had improved outcomes in communicative interactions, social acceptance and academic skills, (Kirchner, 2014). Kirchner stressed some aspects that ideally a program of co-enrollment should promote: (a) direct communication of deaf students with hearing peers and teachers, with no mediation of interpreters or special teachers, b) equal access to an ordinary curriculum, (c) involvement of deaf students in academically challenging tasks, and (d) creation of bimodal bilingual peer groups in support of socio-emotional status. 1.1.1 Deaf education in Spain. A recent survey of the Spanish National Health Service of the population over 15 years old provides interesting data on the Spanish deaf population (Gobierno de España, Ministerio de Sanidad, Servicios Sociales e Igualidad, 2014). Spanish population was classified as follows: hearing with no difficulties, hearing with some difficulties (hard of hearing), hearing with many difficulties, and no hearing. A total of 13 % of the Spanish population (5.041.300 individuals) is hard of hearing, of whom 4.3 % (190.900 individuals) is aged between 15 and 24 years. Another 3.6 % (1.418.700 individuals) hears with many difficulties, and of them 0.23% (10.400 individuals) is aged between INTRODUCTION 21 15-24 years. No individuals of the youngest range of age, 15 to 24, are classified with no hearing, thanks to the use of hearing aids. In fact, 3.5 % of the Spanish population uses hearing aids or CIs, and the majority of them are aged between 15 and 24 years (2 %). According to data from the Spanish Department for Education, Culture and Sport, in the year 201415, there were 7531 deaf students in the public educational system, from preschool to high school (4.3% of all students with special needs). The majority of deaf students (a total of 7024) are in public (5388 students) or private (1636) mainstream education, while only 507 deaf students attend special schools for deaf (Gobierno de España, Ministerio de Educación, Cultura y Deporte, 2016). In Spain, bimodal bilingual education was introduced to counter the poor outcomes of deaf students (Valmaseda Balanzategui, 1998). At the end of compulsory education, the performance of deaf adolescents matched the scores of hearing peer in their first years of primary school, especially in reading (Rodríguez-Ortiz, 2005). These poor educational outcomes discouraged the development of oral communication which in turn impacted negatively on social integration (Rodríguez-Ortiz, 2005). This coincided with the advances in sign language studies (Stokoe, 1960) and the advantages in academic achievements of native deaf signers compared to non-native deaf signers that were being reported (Meadow, 1980; Musselman, Lindsay, & Wilson, 1988; Wilbur, 1986). The cognitive and communicative benefits of learning sign language in the early years was apparent. These factors contributed to the adoption of bimodal bilingual education. A first regulation of bimodal bilingual education for deaf students was approved in 1995, within executive regulations for special education (Real Decreto 696/95). With respect to deaf education, these rules required mainstream education to recognise sign language and promote its use and study in schools attended by deaf or hard-of-hearing students. Also, the Real Decreto required appropriate sign-language VISUAL PERCEPTION AND SIGNED ORAL LANGUAGE IN DEAFNESS 22 training for teachers and other practitioners involved in the education of deaf students. Contents referring to both communicative systems, oral communication and sign language, became part of the students’ curriculum (Art.8, ap.6). The next great achievement for Spanish deaf individuals was the legal recognition of the national Spanish Sign Language (LSE), in 2007 (LEY 27/2007 3 ), and, soon after, of Catalan Sign Language (LSC), in 2010 (LEY 17/2010 4 ). In 2011 the Centro de Normalización Lingüística de la Lengua de Signos Española (Institute for the Linguistic Normalisation of Spanish Sign Language) was created, with the purpose of disseminating and standardising LSE. The same year, in Andalusia a law that regulated the use of sign language was approved (LEY 11/2011 5 ). These laws also regulated the issue of oral communication support for deaf individuals. Schools had to provide available bimodal bilingual educational models to deaf students, who should be able to choose their preferred educational approach, oral or signed communication. However, in practice the interpretation of bimodal bilingual education is extremely fuzzy: some schools might be defined as bimodal bilingual, but use signs minimally (Pérez Martin, Valmaseda Balanzategui, & Morgan, 2014). Bimodal bilingual education found some limitations due to the structure of mainstream classrooms: deaf students, even in bimodal bilingual programs, typically attended regular classrooms with a vast majority of hearing students and only one or two deaf students. This made it difficult to carry out a bilingual program involving teachers and hearing classmates and did not help deaf individuals to have a positive perception of bimodal bilingual education. Cabeza-Pereiro 3 Ley 27 /2007, de 23 de octubre, por la que se reconocen las lenguas de signos españolas y se regulan las medias a la comunicación oral de las personas sordas, con discapacidad auditiva y sordociegas (BOE, nº 255, de 24 de octubre de 2007). 4 Ley 17/2010, de 3 de junio, de la lengua de signos catalana (BOE, nº 156, de 28 de junio de 2010). 5 Ley 11/2011, de 5 de diciembre, por la que se regula el uso de la lengua de signos española y los medios de apoyo a la comunicación oral de las personas sordas, con discapacidad auditiva y con sordoceguera en Andalucía (BOE, nº 312, de 28 de diciembre de 2011). INTRODUCTION 23 and Ramallo (2016) carried out a survey on 138 deaf sign-language users about deaf education, among other topics. Participants had more positive opinions of the educational sector than of culture, tourism, healthy system, transports, or access to multimedia information. However, the youngest participants of the survey, aged 18 to 35 —who had attended schools when inclusive education was the more supported option— were the most critical of the educational system. The authors suggested that this might be due to unsuccessful integration of deaf and hearing students in the classroom. Also, as much as 36 % of deaf individuals were unaware of the existence of bilingual schools, and 69% were dissatisfied with the insufficient number of interpreters for deaf students. Bimodal bilingual interpreters, LSE-Oral Spanish, are a key figure for the successful implementation of bilingualism (Rodríguez Ortiz & Mora Roche, 2007). Despite regulations about interpreting, including the 2007 law, and the creation of a professional degree for sign-language interpreters, the deaf community appeared to be dissatisfied with this service. In addition, bimodal bilingual education is rarely applied in its strictest form. A bimodal bilingual educational setting involves the opportunity to use and develop both languages, oral and signed. The proponents of the use of pure natural languages, oral and signed, argued that bimodal bilingual settings should not include the simultaneous use of signs and oral language, because they might impoverish users’ competence in both language modalities (Fernández & Villa, 2017). The guiding principle of this interpretation of bimodal bilingual education is that advanced skills in sign language favour cognitive development and spoken language in deaf children. In reality, various forms of signed communication are usually adopted in bimodal bilingual settings to meet the needs of individual deaf students. Co-enrollment aimed to overcome these difficulties of applying bimodal bilingual teaching in mainstream schools. From nineties, co-enrollment became an option for deaf students, and schools VISUAL PERCEPTION AND SIGNED ORAL LANGUAGE IN DEAFNESS 24 for special deaf education also opened to hearing students (Pérez Martin et al., 2014). These bilingual educational settings are re not an initiative of the educational authorities. It is more of a bottom-up process, which develops in individual schools, teachers, deaf communities, and families of deaf pupils (Morales-López, 2008) and is therefore expanding at a slower pace. Four schools in Madrid are a virtuous example of the passage from being special schools for the deaf to bimodal bilingual centres with co-enrollment. In 2014, 24% of all school-age deaf children in Madrid attended these schools and more than half of them (53% of all students) wore CIs (Pérez Martin et al., 2014). In these bilingual schools, one fourth of the students in a classroom are deaf (5-6 deaf students and 15-20 hearing students). The more balanced proportion of deaf and hearing students than in the past makes it possible to practice and instruct all students in the classroom with bilingual teaching. Bilingual input is already used at the nursery and all pupils, deaf and hearing, share the same curriculum. Classrooms have distinct working areas for mathematics, art, LSE, Spanish, etc. In each area, a group of deaf and hearing students are supported in the study of the specific subject, and teaching is adjusted to their individual levels. Four additional practitioners are involved in co-enrollment in Spain: deaf LSE specialists, co-tutors, speech and language therapists, and interpreters (Pérez Martín et al., 2014). Deaf LSE specialists, often qualified teachers or educators, are primarily required to teach LSE to deaf and hearing students, train families and hearing teachers in LSE and visual communication and promote deaf cultural activities among the school staff. Two co-tutors, participating at the classroom activities nearly all the time, are responsible for facilitating close collaboration in teaching and planning. Speech and language therapists, in close collaboration with co-tutors, provide children with auditory stimulation to enhance their speech development. Finally, the interpreters, who have an active role in the INTRODUCTION 25 classroom mainly at the level of secondary education, guarantee that classroom contents are fully conveyed in both languages. Practitioners in one of the schools —GAUDEM, in Madrid— also point to project-based teaching (trabajo por proyecto) as a relevant characteristic of co-enrolment a practiced there (Alonso, Rodríguez, & Echeita, 2009). The purpose of the projects is the inclusion and the individual development areas of weakness, with the aim of acquiring basic knowledge. These projects are built around a network involving the family, other classrooms, and even the entire school or pairs of students, not necessary from the same classroom or equal in age. Pérez Martín et al. (2014) has evaluated spoken and sign-language linguistic skills, and socioemotional development in children with CIs, aged 0 to 6 years, enrolled in co-enrollment programs. Children were assessed with chronologicaland hearing-age appropriate tasks. They found their performance was equivalent to typically developing children for spoken language, audition, receptive and expressive vocabulary, and receptive grammar. Contrary to hearing children, deaf participants scored higher in expressive than receptive vocabulary, confirming a trend already detected in prior research (Geers, Moog, Biedenstein, Brenner, & Hayes, 2009) and attributed to language teaching strategies that emphasize naming. Although within normative percentile ranges, receptive grammar scores were in the lower ranges and highly variable among participants even in children with CIs and early bilingual skills, thus confirming its status as one of the most challenging linguistic area for deaf children (Inscoe, Odell, Archbold, & Nikolopoulos, 2009). The evaluation of LSE skills indicated that these children had good developmental trajectories in both comprehension and production, although they had mainly received LSE input from the school. Children also had good socio-emotional skills. In their conclusions, Pérez et al. noted the great VISUAL PERCEPTION AND SIGNED ORAL LANGUAGE IN DEAFNESS 32 bilingualism, as originally conceived in special schools for the deaf in Europe and United Stated in the Seventies-Eighties. They looked at sign language as a fundamental skill for the acquisition of literacy, to be shared by all students and teachers (Hoffmeister, 2000), and a cornerstone of the linguistic and cultural heritage of deaf communities (Padden & Humphries, 1990). From the Nineties and over the 2000s, bilingual education slowly spread across various countries. Deaf education became more inclusive, with the expansion of co-enrolment teaching experiences described above. While the importance of sign languages in deaf education was growing, extraordinary advances in hearing technology and early intervention renewed the discussion about which educational setting provided deaf children “with the best possible opportunities for educational and personal success” (Knoors & Marschark, 2012, p.2). The average age of hearing loss identification has decreased to 2 months in the United Kingdom and to 3 months in the United States. Since the beginning of the 2000s, cochlear implantation was already available in children 18 months old or even younger and, by the mid-Nineties, individually programmed digital hearing aids were available in industrialised countries. Therefore, despite the recognition of the relevance of natural sign language in education of deaf children, many parents of children with CIs preferred to enrol their children in educational programs exclusively based on OC. Between the Nineties and 2000s, additional research has fed into the debate between proponents of OC for children using CI, and advocates of bilingual or TC settings. It has been suggested that SSS has the important function of supporting spoken language in children with CIs with bilingual bimodal skills thanks to the redundant multichannel message that it provides (Knoors & Marschark, 2012). For example, lexemes unfamiliar in one linguistic modality can be known in the other. However, research data are inconsistent in supporting this idea. On one hand, compared to children INTRODUCTION 33 with CIs in TC programs, those enrolled in OC programs have better speech perception (Archbold et al., 2000; Geers, Brenner, & Davidson, 2003), production (Geers, 2004; Geers, Nicholas, & Sedey, 2003; Tobey et al., 2000; Uchanski & Geers, 2003), and overall language (Geers et al., 2003; Kirk, Miyamoto, Ying, Perdew, & Zuganelis, 2000; Svirsky, Robbins, Kirk, Pisoni, & Richard, 2000). However, these improvements in speech were usually only marginal (Archbold et al., 2000; Geers et al., 2003; Svirsky et al., 2000). On the other hand, studies have found significant advantages in vocabulary acquisition for early-implanted children in TC settings compared to those attending OC programs (Connor, Hieber, Arts, & Zwolan, 2000; Yoshinaga-Itano, 2006), which emphasizes early language stimulation (Connor et al., 2000). SSS might have a significant role in the promotion of early communicative exchanges, supporting deaf children’s socio-emotional growth (Yiu & Tang, 2014). SSS receptive skills positively predicted learning in one study (Convertino, Marschark, Sapere, Sarchet, & Zupan, 2009), but in others communicative modes did not impact learning (Robbins, Bollard, & Green, 1999), with deaf students learning in the classroom as much from SSS as from other forms of communication (Cokely, 1990; Marschark, Sapere, Convertino, Seewagen, & Maltzen, 2004). A recent systematic review of studies with children with CIs published between 1999 and 2013 analysed which communicative mode better predicted successful linguistic outcomes. The authors concluded that very limited evidence exists to determine whether the simultaneous use of signs and spoken words is more effective than spoken language alone to foster oral language (Fitzpatrick et al., 2016). Differences in the outcomes from different studies testing the effectiveness of educational approaches can be due to a range of factors. A limited number of participants or comorbid disturbances not diagnosed that might affect participants performance are some. More common complications concern the lack of standardised tests for assessing sign language competence (Mann VISUAL PERCEPTION AND SIGNED ORAL LANGUAGE IN DEAFNESS 34 & Haug, 2016; Spencer, 2016), and inconsistency in the implementation of TC programs (Mayer, 2016), due to the lack of standardisation in the signs used in SSS (Caccamise, Ayers, Finch, & Mitchell, 1997; Mayer, 2016). Deaf learners often found the forms of SSS used by the teachers confusing (Johnson et al., 1989). In turn, they found SSS hard (Bernstein, Maxwell, & Matthews, 1985), because of the limited training in sign language, especially when TC programs were first implemented (Power, 2009). Knoors and Marschark (2012) highlighted the importance of intensive training in SSS of parents and practitioners involved in the education of deaf children; they must acquire the ability to continue to speak fluently and express semantic content with conceptually appropriate signs. More importantly, most of this research assessed children’s language skills either in TC/SSS settings or in OC settings, but rarely within the same group of participants (Giezen, Baker, & Escudero, 2014), and this mostly in case studies (Klatter-Folmer, van Hout, Kolen, & Verhoeven, 2006). The comparison of OC and SSS methods within the same group of individuals with CIs revealed more encouraging and promising results for SSS (Blom & Marschark, 2015; Blom, Marschark, & Machmer, 2016; Giezen et al., 2014; van Berkel-van Hoof, Hermans, Knoors, & Verhoeven, 2016). SSS with students with CIs has been found to impact positively the acquisition of new vocabulary (Giezen et al., 2014) even in learning pseudo words for unfamiliar objects (van Berkel-van Hoof et al., 2016). This was consistent with the Dual Coding Theory (Paivio, 2010; Paivio, Clark, & Lambert, 1988), according to which information processed by dual channel, visual-manual and auditory-oral, creates a stronger connection in memory. SSS had positive results compared to OC also in transmitting information in classroom contexts, when transmitting complex contents (Blom & Marschark, 2015) and during noisy situations (Blom et al., 2016). CIs are INTRODUCTION 35 undoubtedly very efficient in one-to-one interactions, but less so in noisy contexts like classrooms (Battmer et al., 2010). Importantly, there is no evidence that sign language or SSS impede spoken language development in children with or without CIs (Spencer & Marschark, 2010). The redundant information provided by signs can sustain spoken information, conveying meaning even when speech is auditory or visually barely perceived. In this perspective, SSS would not be expected to improve linguistic skills, but it should simply be used as a device to integrate and sustain spoken message. In some contexts, children could greatly benefit from using sign language or SSS. First, because before cochlear implantation, in the first months of life, children will need the richest linguistic environment possible to develop fundamental linguistic and cognitive skills; this will necessarily be visual and can be provided by sign language. Second, signed communication will also be important in the first period after implantation, as a bridge of communication. Third, even when children have completed their training in the use of CIs, they will not always able to profitably use the CIs, for example in noisy contexts, or simply when equipment temporarily malfunctions occur or batteries are dead. Finally, SSS will be especially important when the child is very young or when the student is instructed to carry out a very demanding task (Knoors & Marschark, 2012). There is a substantial agreement in that early identification of hearing loss and early intervention guarantee better outcomes in language and literacy development (Spencer, 2016). Children with early implantation, who are more likely to develop better spoken language than children fitted with CIs at a later age, are usually enrolled in OC programs. Parents of children who barely managed to develop language after cochlear implantation might prefer to enrol their children in TC programs (Archbold et al., 2000). This relationship between the age of implantation and the use of OC clearly emerged in a study by Holt, Svirsky, Neuburger, and Miyamoto (2004), where most children VISUAL PERCEPTION AND SIGNED ORAL LANGUAGE IN DEAFNESS 36 implanted before 12 months of age (88 %), were likely to use OC exclusively, while only 44.3% of children implanted at the 4th year of age did so. However, it has been suggested that all children, with or without CIs, should have an early exposure to signed communication because it can be an additional resource in communication. After an exhaustive review of deaf children development in distinct educational environments — spoken, sign language or sign-supported speech based—, Lederberg, Schick and Spencer (2013) concluded that the ideal strategy for enhancing language in deaf children would be to monitor children needs at various stages of language development and adapt the most fruitful approach for each specific stage and communicative need. Depending on the learner’s needs, signs, in concert with spoken language input, will be used to a greater or less extent, all the way from conveying only some key lexemes to even marking spoken morphology. Children with a full range of options offered by visual and auditory channels benefit from the opportunity to shift across different communicative modalities, especially when implanted at an early stage (Tait, De Raeve, & Nikolopoulos, 2007; Watson et al., 2006). In conclusion, we could rethink the role of TC in terms of how it helps deaf learners to access information. Functional communication, all the way from initial parent-child exchanges, strongly affects quality of life. For deaf individuals, this can be achieved by using the language modality — spoken language, sign language or sign-supported speech— most appropriate for each specific case (Kushalnagar et al., 2011). Knoors and Marschark (2012) encouraged hearing parents of children with CIs to learn and use sign language on regular basis, especially for supporting spoken language. Children with a richer early linguistic input, signed or oral, are more likely to develop better reading skills (Harris & Beech, 1998; Lichtenstein, 1998), improved social exchanges, and linguistic and academic outcomes, at least during the early years (Calderon & Greenberg, 1997). Deaf parents INTRODUCTION 37 mostly choose bilingual-education options for their deaf children. In contrast, hearing parents with deaf children need to carefully evaluate the different educational options for their children. For hearing parents, a sign bilingual education implies the additional effort of learning a sign language and the cultural values involved. 1.3 The Specificity of Deaf Profiles “Deaf children are not simply hearing children who cannot hear”: the provocative quotation from Marschark and Knoors (2012, p.112) aims to stress the importance for education of bearing in mind the differences in learning and cognition between deaf and hearing students. Prior research had provided evidence of differences in academic performance. Deaf students lag their hearing peers in different areas (Marschark, Sapere, Convertino, & Pelz, 2008), including visual-spatial processing (Blatto-Vallee, Kelly, Gaustad, Porter, & Fonzi, 2007; Marschark, Morrison, Lukomski, Borgna, & Convertino, 2013). This is contrary to the common belief that deaf individuals are more skilful than hearing persons in visual tasks. Despite the reliance on vision for language, deaf learners are not necessarily visual learners (Marschark et al., 2013). Deaf and hearing students show a different organisation and use of concept knowledge, and different cognitive strategies and experiences that can affect academic outcomes (Marschark, 2003). Identifying the ways in which deaf or hard of hearing students differ from hearing students is an essential step to adjust instructional materials and methods (Knoors & Marschark, 2015; Marschark & Knoors, 2012). However, deafness refers to a widely heterogeneous population which differs on many dimensions. Some of the more relevant are aetiology, age of onset of hearing loss, and the degree of the loss. A hearing loss can be genetic or acquired and, in the latter case, can have prenatal, perinatal, or postnatal causes. Language development is critically affected by whether the onset of deafness VISUAL PERCEPTION AND SIGNED ORAL LANGUAGE IN DEAFNESS 38 onset is prior to or follows language acquisition (prelingual or postlingual deafness, respectively) as well as the degree (severity) of hearing loss. A commonly used classification of hearing loss severity is provided by the International Bureau for Audiophonology (BIAP Recommendation 02/1, 1996). In a normal or subnormal hearing, the average tone loss is below 20 dB. A mild hearing loss, with an average tone loss between 21 and 40 dB, causes difficulties if the voice perceived is low-pitched or distant from the subject. A moderate hearing loss of 1st degree, from 41 to 55 dB, and 2nd degree, from 56 to 70 dB, allows to perceive speech if the voice is loud. If the hearing loss is severe, of 1st degree, from 71 to 80 dB, and 2nd degree, from 81 to 90 dB, speech is perceived is the voice is loud and close to the ear. If the hearing loss is between 91 to 119 dB, across three degrees of progressive seriousness, it is classified as very severe hearing loss, also known as profound hearing loss (Clark, 1981). Finally, if the average tone loss is over 120 dB, the individual suffers of a total hearing loss, or cophosis. Based on the combination of these variables, the term deafness is an umbrella-term for a great variety of cases. The variety within deaf population is increased by the technology eventually used to access audition, either hearing aids or CIs, and by the preferred language to communicate, either sign or oral language. Research on language and cognition in deafness mainly focused on individuals severely to profoundly deaf either with CIs or with native knowledge of sign language. Research on children with CIs, in particular children with early access to audition due to early implantation, before 12 months of age, addresses the issue of the effects of language deprivation even if only for the first months after birth. On the other hand, native deaf signers, who are deaf children born from deaf parents, learning sign language as their native first language, give the possibility to study the impact of deprivation of audition, but not language deprivation, on cognitive and linguistic output. INTRODUCTION 39 In the following, research on CI users and native deaf signers will be discussed more in-depth, highlighting the respective role in cognitive and linguistic development of deprivation of audition and native exposure to sign language. In fact, the association between good language skills and higher-level cognitive skills in deaf population (Figueras, Edwards, & Langdon, 2008; Horn, Davis, Pisoni, & Miyamoto, 2005; Kronenberger, Pisoni, Harris, et al., 2013; Kronenberger, Colson, Henning, & Pisoni, 2014) can be explained either referring to the reduced period of auditory deprivation (children with early CIs) or to an early language exposure (native signers). 1.3.1 Children with cochlear implants. A cochlear implant (CI) is an electronic hearing prosthesis, surgically implanted, which replaces hair cells of the cochlea with electrodes. It is not very beneficial if deafness is caused by problems in other parts of the hearing system, such as the brainstem, midbrain, or cortical areas. CIs are effective only in children with a profound or, occasionally, severe degree of hearing loss. As in many other industrialised countries, in Spain cochlear implantation for deaf children became popular from the beginning of the Nineties (Juárez-Sánchez & Monfort, 2010; Manrique & Huarte, 2002). At that time, a large body of research provided evidence for the improved speech perception and linguistic outcomes of children with CIs, compared to children with analogous hearing loss but using hearing aids (Dawson, Blamey, Dettman, Barker, & Clark, 1995; Tomblin, Spencer, Flock, Tyler, & Gantz, 1999). CIs have been demonstrated to be especially effective when activated at an early age, before two years (Connor, Craig, Raudenbush, Heavner, & Zwolan, 2006; Holt & Svirsky, 2008; Manrique, Cervera-Paz, Huarte, & Molina, 2004; Miyamoto, Houston, Kirk, Perdew, & Svirsky, 2003; Nikolopoulos, Dyar, Archbold, & O’Donoghue, 2004; Tomblin, Barker, Spencer, Zhang, & Gantz, 2005). Nevertheless, it is important to bear in mind that CIs do not restore normal hearing and do not involve rapid adaptation, entailing tuning and continuous VISUAL PERCEPTION AND SIGNED ORAL LANGUAGE IN DEAFNESS 40 adjustment of the perceptual processes. The variability in performance of children with CIs is quite high. Even when cochlear implantation is provided early, children born deaf have necessarily to face the earliest months of life with no sound, thus their auditory experience is not equivalent to that of hearing children. Critically, deprivation of sound at early developmental stages might affect processes that are not directly related to hearing and audition systems. Deficient performance in children, regardless of CI devices, might reflect dysfunction of multiple processing systems associated with deafness and language delay (Leigh, 2008). The duration of deprivation of audition, before cochlear implantation, is also associated to delays in socialisation and daily living skills. However, the motor development does not directly correlate to the period of deprivation of audition, although it can be affected by spoken language skills (Horn et al., 2005). In the next sections, the brain cross-modal reorganisation, the executive functions and the linguistic outcomes in children with CIs are presented in greater detail. 1.3.1.1 Brain plasticity. Research on neuroplasticity has consistently reported the impact of sensory deprivation in one modality on the development of the remaining modalities. Deaf individuals show increased tactile accuracy (Levänen & Hamdorf, 2001) and enhanced visual attention, primarily in the peripherally visual field (Bavelier et al., 2000; Dye & Bavelier, 2013; Proksch & Bavelier, 2002). Studies on brain plasticity indicate that primary sensory areas, which normally would serve to process information from the deprived auditory modality, are involved in cross-modal compensatory adaptation, processing information from the remaining modalities. Thus, auditory areas are active during visual and somatosensory processing in deaf individuals (Auer, Bernstein, Sungkarat, & Singh, 2007; Finney, Fine, & Dobkins, 2001). INTRODUCTION 41 Children with CIs offer a unique view from a neurodevelopmental perspective to observe brain and neural reorganisation after a period of auditory deprivation and, consequently language delay (Pisoni et al., 2008). The more effective and extensive cross-modal plasticity is, the less sensory implants —aimed to restore the idle sensory modality— are likely to be successful. Thus, the effectiveness of CIs might be hindered by cross-modal reorganization before implantation, that implies a visual ‘takeover’ of the auditory modality and could compromise the ability of auditory cortex to process spoken language after the activation of CIs (Kral & Sharma, 2012; Lyness, Woll, Campbell, & Cardin, 2013). Campbell, Macsweeney, and Woll (2014), focusing on profound prelingual deaf children who never received acoustic input before cochlear implantation, argued that the exposure to non-auditory signals before implantation distorts the function of the auditory cortex, negatively impacting on CIs effects and speech outcomes. There are critical periods for the phases of sensory development, and experience can significantly modify human behaviour and related aspects of brain functioning during this sensitive period. Cross-modal reorganisation in deaf children implies a visual takeover of the auditory modality, limiting the benefits from the amplification provided by CIs (Kral & Sharma, 2012). For this reason, sign language exposure in the sensitive period of language acquisition has been considered a risk for the preservation of the potential of the auditory cortex to process auditory input in future after cochlear implantation (Giraud & Lee, 2007). Even forms of visual language associated to spoken language, such as speechreading, if used before cochlear implantation, could have an impact on crossmodal plasticity, and hinder the functioning of the auditory modality in favour of the compensatory changes in the visual modality (Hirano et al., 2000). In some implantation programs, training of the auditory modality is strongly promoted to the expense of visual support, and sign language, speechreading, or cued speech are banned from the language training of deaf children prior to implantation (Chan, Chan, Kwork, & Yu, 2000; Ingvalson & Wong, 2013; Yoshida, Kanda, & Miyamoto, 2008). VISUAL PERCEPTION AND SIGNED ORAL LANGUAGE IN DEAFNESS 48 1.3.2.1 Brain plasticity. Congenitally deaf native signers are an interesting population for studying neural plasticity. This is because changes in the brain neuroanatomy can be connected to both cognitive factors —related to the learning of a signed language, for example—, and factors related to sensory deprivation. Cognitive factor and sensory deprivation would affect distinct substrates anatomically and functionally. Sign language learning causes plastic changes in the left superior temporal cortex, while auditory deprivation causes plastic effects in the right superior temporal cortex, as emerged by comparing profound deaf native signers to orally educated profound deaf non-signers (Cardin et al., 2013). Functional neuroimaging studies provide evidence for an additional activation of the left parietal lobe during sign language processing that it is not detected in spoken language processing (Emmorey, Mehta, & Grabowski, 2007; MacSweeney, Capek, Campbell, & Woll, 2008). This difference is reported for signers, both deaf and hearing, compared to non-signers, and consequently has been attributed to sign language expertise (Allen, Emmorey, Bruss, & Damasio, 2008). A recent MRI study, comparing profoundly congenitally and genetically deaf persons with native America Sign Language to hearing individuals, detected a network of brain areas with an enhanced responsiveness to peripheral visual stimuli in deaf individuals. In particular, higher responsiveness to peripheral rather than perifoveal visual stimuli was evident in the Heschl’s gyrus regions, were human primary auditory cortex is located, highlighting a functional connection between the primary auditory cortex and the cross-modal compensatory processing (Scott, Karns, Dow, Stevens, & Neville, 2014). INTRODUCTION 49 1.3.2.2 Visual cognition in deaf native signers. With regards to visual cognition in deaf native signers, Bavelier, Dye, and Hauser (2006) pointed out that changes following congenital deafness are highly specific. No differences between deaf and hearing individuals have been found in sensory measures, such as brightness discrimination, visual flicker, aspects of contrast sensitivity, or direction and velocity of motion (Bosworth & Dobkins, 1999, 2002; Brozinsky & Bavelier, 2004; Finney et al., 2001). Deaf native signers have been found to have better visual-spatial skills than hearing individuals in some domains, but not in others. Studies on visual attention, controlling for confounding variables such as language fluency and aetiology of hearing loss, show enhanced visual cognition in deaf native signers with respect to hearing individuals, with faster shifts of visual attention (Rettenbach, Diller, & Sireteanu, 1999) and increased peripheral visual attention (Proksch & Bavelier, 2002). Deaf native signers and hearing controls performed differently especially when visual stimuli, peripheral located or in motion, required attentional selection (Neville & Lawson, 1987a; Neville & Lawson, 1987b). In fact, studies on attentional orienting and executive attention, do not find differences between deaf and hearing participants in the processing of central stimuli. Differences were found when experimental tasks opposed central and peripheral stimuli to each other. In the well-known series of studies by Proksch and Bavelier (2002), using the useful field of view (UFOV) paradigm, deaf and hearing participants were required to identify a shape appearing in the central region, around the locus of fixation. Reactions times revealed that native deaf signers were longer in processing the trials with distractors in the periphery and faster when the distractors appeared in the central region of fixation, contrarily to hearing participants. However, when participants were involved in a peripheral task and were asked to ignore central distractors, hearing individuals were more distracted than deaf individuals. Taken together these findings suggest that the distraction effect does not provide evidence for a deficiency in visual attention in deaf individuals, rather it indicates VISUAL PERCEPTION AND SIGNED ORAL LANGUAGE IN DEAFNESS 50 the emergency of a compensatory mechanism that results in a different distribution of attentional resources across the visual field in deaf and hearing individuals (Bavelier et al., 2006). 1.3.2.3. Executive functioning in deaf native signers. While native and non-native signers have in common the initial deprivation of audition, they do not have equivalent experiences of early linguistic input. In fact, native signers are exposed from birth to the sign language of their parents and family. Around 50% of deaf children of hearing families who qualify for a CIs effectively undergo implantation, unlike children of deaf parents, who a very rarely implanted (Hall, Eigsti, Bortfeld, & Lillo-Martin, 2017b). Exposure to language during the prenatal period and the first months of life, seems to be determinant for the development of child language and cognitive functioning. Native signers are exposed to signs immediately after birth, initially by touch and soon after, also visually (Knoors, 2016). As consequence, the study of deaf native signers allows us to explore the link between language skills and executive functions, controlling for the amount of auditory deprivation. Differences between deaf children with and without native sign language are understood to be the result of an integrated system that includes the auditory system and the cognitive functions, primarily executive functions. Research in this area indicates that early exposure to a language has a strong impact on the development of executive functions, and other cognitive and behavioural functions. Deaf native signers performed similarly to hearing children with respect to theory of mind (Courtin, 2000; Schick, de Villiers, de Villiers, & Hoffmeister, 2007), IQ (Braden, 1987) or sustained attention (Dye & Hauser, 2014). In Hall et al. (2017b), deaf native signers were reported to have age-typical INTRODUCTION 51 executive functions on the BRIEF questionnaire, although with slightly lower scores in working memory and inhibition than a hearing age-equivalent control group. Within executive functions, working memory has been extensively studied. While deaf children with no native sign language have, on average, shorter working memory spans in different tasks (Pisoni et al. 2008), native signers have a comparable working memory to hearing individuals (Boutla, Supalla, Newport, & Bavelier, 2004), and, even a superior visual-spatial memory than individuals with no sign languages (Hall & Bavelier, 2010). Marshall et al. (2015) found that deaf children who experienced a period of language deprivation scored worse than hearing children, while deaf native-signing children had a memory performance comparable to that of hearing controls. The differences in working memory tasks could descend from language-based executive functioning (Marschark, Spencer, et al., 2015; Pisoni et al., 2010). Deaf individuals, regardless of their preferred language modality, have been found to perform similarly to hearing individuals in visual-spatial memory tasks which do not allow easy labelling or verbal-sequential coding. Deaf native signers even outperformed hearing peers in visual-spatial memory tasks, such as the Corsi Blocks task (Wilson, Bettger, Niculae, & Klima, 1997) and showed longer backward memory span than hearing controls —who are usually found to have longer forward than backward memory span (Wilson et al., 1997). The comparable forward and backward spans in deaf native signers could be explained through their use of visual spatial coding, such as visual imagery, in sequential memory tasks (Hall & Bavelier, 2010). On the contrary, non-native deaf signers had major difficulties (Alamargot, Lambert, Thebault, & Dansac, 2007; Marschark et al., 2013). VISUAL PERCEPTION AND SIGNED ORAL LANGUAGE IN DEAFNESS 52 But recent findings suggest that performance on visual-spatial working memory tasks might be more related to the proficiency in a language —spoken or signed—, rather than to the native knowledge of sign language (Marschark, Spencer, et al., 2015). The performance in visual-spatial working memory tasks, comparable in deaf and hearing individuals when not involving linguistic decoding, appears to be independent not only from sign language skills, but also from the hearing status, which is irrelevant whether participants wear CIs (López-Crespo, Daza, & Méndez-López, 2012; Marschark, Sarchet, & Trani, 2016). These results might have important pedagogical implications. In fact, deaf education, especially for native signers, often resorts to the use of visual material and methods, based on the assumption that native signers would be visual learners (Hauser, Lukomski, & Hillman, 2008; Marschark & Hauser, 2012). If visual-spatial working memory is no better in deaf than in hearing students, the advantages of visually oriented teaching methods could be called into question. 1.3.3 Deaf native signers with cochlear implants. Bimodal bilingual deaf children who are native signers and who underwent cochlear implantation are even fewer than non-implanted deaf native signers. Only recently the attitude toward cochlear implant within deaf communities is becoming more positive (Paludneviciene & Leigh, 2011). Encouraging outcomes of deaf native signers with CIs revealed that these children were able to perform similarly to bimodal bilingual hearing controls with native sign language, in a full range of linguistic measures which include vocabulary, articulation, syntax, general language skills, and phonological awareness (Davidson, Lillo-Martin, & Pichler, 2014). Deaf native signers with CIs achieved higher spoken language scores than those predicted for monolingual CI users (Nicholas & Geers, 2008). A longitudinal study on the verbal acquisition of a deaf child with CIs and with deaf signing parents highlighted the positive impact of early exposure to sign language on the INTRODUCTION 53 construction of conceptual representations and spoken language, which reached levels of his hearing peers (Rinaldi & Caselli, 2014). Neuroimaging techniques, together with standardized testing and experimental behavioural research, have been extensively used to explain linguistic outcomes and processing in deaf children, both with CIs and with native sign language. Recently, research on deaf cognition has increasingly also incorporated eye-tracking technology, useful for the observation of visual behaviour in relation to the perception of linguistic inputs. 1.4 Eye tracking Eye tracking is a state-of-the-art research tool increasingly used in a variety of disciplines. Eyetracking technology allows direct and continuous measurement of overt visual attention. Eye movements during language perception might provide behavioural data supplementary to reaction time measures. In the following sections, eye-tracking research in deaf studies will be shortly reviewed to give a general picture of the possibilities offered by this technique and to pinpoint the use that the current research has done of eye movement data. A description of the different measures of eye movements will be outlined. For the current doctoral thesis, eye-movement data were collected with the purpose of obtaining information about where overt attention is driven when a deaf perceiver is attending SSS. VISUAL PERCEPTION AND SIGNED ORAL LANGUAGE IN DEAFNESS 54 1.4.1 Measures of eye movements. Eye-movement events can be described in over a hundred of different measures. Eye-tracking measures can be grouped in four main classes: movement measures, position measures, numerosity measures, and latency and distant measures (Holmqvist et al., 2011). Movement measures, which track eye movements through space, provide information about direction, amplitude, velocity, acceleration, shape, scanpath comparison, areas of interest, and transition. Position measures provide information with respect to where participants are looking (basic position measures), the extent to which gaze data are focused or distributed (position dispersion measures), the similarity in the position of two groups of gaze data (position similarity measures), the duration of the gaze in a determined position (position duration measures), and how pupil dilates looking at a position (position dilation measures). Numerosity measures provide number, proportion or rate of countable eye-movement events, such as saccades, glissades, microsaccades, smooth pursuit, blinks, fixations, dwells, transitions, regressions and some others. Latency and distance measures convey time and space information of an eye-movement event related to another event, respectively. Specifically, latency measures concern time delay, recording the time between the onor the offset of an eye-movement event to the onor offset of another event, while distance measures concern the distance from one point to another at the same time. Two basic eye-tracking events are saccades and fixations. Saccades and fixations can be calculated directly from the raw data samples, through algorithms based on position, velocity and acceleration data. Saccades are rapid movements of the eyes with velocities as high as 500º per second, during which eyes are less sensitive to visual input (saccadic suppression). Between the saccades, the eyes remain approximately in the same position during fixations, when sensitivity to the visual input is high. Fixations are considered reliable when they are longer than a threshold of 70-80 milliseconds INTRODUCTION 55 (ms). The duration of a saccade depends on the distance covered, which usually is shorter in reading tasks and longer in scene perception tasks (Abrams, Meyer, & Kornblum, 1989). Saccades are frequent because of the limitations of the acuity of our visual system. Acuity is very good in the foveal region —the central 2º of vision— and is progressively reduced in the parafoveal region —extending from 2º to 5º from the eye fixation. Acuity is further reduced in the peripheral region, beyond 5º from the fixation point. Depending on its perceptual characteristics, a stimulus in the periphery can require a saccadic movement to be centrally perceived and recognised, or it can be identified through peripheral vision. For example, in reading tasks, a large letter or an object can be peripherally identified (Pollatsek, Rayner, & Collins, 1984), whereas a normal-size word could be more easily discerned by making a saccade and being perceived in the foveal region (Rayner & Morrison, 1981). 1.4.2. Eye-tracking in deaf studies. Eye-tracking studies with deaf observers have investigated how attention is distributed across the visual field when processing language in reading or in sign-language communication. Eye-tracking data provided further evidence for the observations related to the increased peripheral vision of deaf observers, manly native deaf signers, found in visual attention studies (see paragraph 1.3.2.2). In reading tasks, skilled deaf readers, diagnosed with a severe to profound hearing loss, with early onset of deafness, had enhanced perceptual span compared to hearing peers, with longer saccades and less regressions back into the text (Bélanger, Slattery, Mayberry, & Keith, 2012). In sign language communication, a main issue concerns the area that deaf individuals visually attend to when looking at someone signing. In these studies, patterns of gaze fixations of skilled deaf signers with native or nearly native knowledge of sign language are compared to patterns of VISUAL PERCEPTION AND SIGNED ORAL LANGUAGE IN DEAFNESS 56 gaze fixations of late or naïve signers and expert hearing signers. Deaf perceivers have been found to fixate mainly the face area during comprehension of signed communication. This was found both when messages in sign language were produced live by a signer (Emmorey, Thompson, & Colvin, 2009) and when sign language was video-recorded and presented on a screen (Agrafiotis, Canagarajah, Bull, & Dye, 2003; Muir & Richardson, 2005). Differences emerged in the area of the face attended to: it was around the eyes when perceiving sign language produced live by a signer and around the mouth when attending to video-recorded sign language content (Agrafiotis et al., 2003). Furthermore, more frequent fixations towards the mouth were detected in naïve signers, compared to native signers, to pick up additional information conveyed by mouthing (Emmorey et al., 2009). Results of these studies suggest that peripheral vision is adequate to perceive signs and body movements that occur away from the face region of the signer. Similarly, a study that analysed SSS perception (De Filippo & Lansing, 2006) found that signs were mostly peripherally perceived even when they were fundamental to disambiguate the sentence meaning. Importantly, SSS was presented with no sound, meaning that only the variables of the visual linguistic components, signs and lip movements, were included in this experiment. Eye movements have also been explored as a marker of deaf students’ attention in classroom contexts. The preference for visualising a lecture presented on a video-screen by an instructor in SSS or interpreted in sign language was tested across three groups of students, hearing students, skilled deaf signers and new signers and correlated to learning (Marschark et al., 2005). Two conditions of lectures were compared. In the first condition, the lecture was signed by the instructor himself using SSS (simultaneous speech and signing). In the second condition, the lecture was presented by the same instructor, but spoken only and interpreted by an experienced educational sign language interpreter. When the lecture was also interpreted in sign language, skilled signers’ INTRODUCTION 57 visual gaze was mainly allocated to the interpreter region, but new signers split their visual attention between the instructor and the interpreter, and hearing students kept their visual gaze on the instructors, shifting some attention away from the instructor and towards the interpreter. The two groups of deaf students did not differ in their learning under any condition (Marschark et al., 2005): albeit deaf students came into the classroom with less content knowledge and scored lower on learning assessments, they learned just as much, proportionally, as their hearing peers in both conditions. Interestingly, in these latter studies (De Filippo & Lansing, 2006; Marschark, et al., 2005), eye-movement data were related to comprehension and learning. CHAPTER 3 STUDY 1: AN EYE-TRACKING STUDY ON THE PERCEPTION AND COMPREHENSION OF UNIMODAL AND BIMODAL LINGUISTIC INPUTS BY DEAF ADOLESCENTS CHAPTER 4 STUDY 2: INFERENCING IN DEAF ADOLESCENTS DURING SIGNSUPPORTED SPEECH COMPREHENSION CHAPTER 5 STUDY 3: THE ROLE OF MULTIPLE ARTICULATORY CHANNELS OF SIGN-SUPPORTED SPEECH REVEALED BY VISUAL PROCESSING Part 2 Experimental Research Chapter 3 Study 1: An Eye-tracking Study on the Perception and Comprehension of Unimodal and Bimodal Linguistic Inputs by Deaf Adolescents Eliana Mastrantuono, David Saldaña, and Isabel R. Rodríguez-Ortiz Departamento de Psicología Evolutiva y de la Educación, Universidad de Sevilla, Spain This research was supported by the European Union’s Seventh Framework Programme for research, technological development and demonstration under grant agreement no 316748. Reference: Mastrantuono, E., Saldaña, D., & Rodríguez Ortiz, I. (2017). An eye-tracking study with deaf adolescents on the efficacy of sign-supported speech. Frontiers in Psychology, 8(1044). doi:10.3389/fpsyg.2017.01044 EXPERIMENTAL RESEARCH 69 Abstract An eye tracking experiment explored the gaze behaviour of deaf individuals when perceiving language in spoken and sign language only, and in sign-supported speech. Participants were deaf (n = 25) and hearing (n = 25) Spanish adolescents. Deaf students were prelingually profoundly deaf individuals with cochlear implants used by age 5 or earlier, or prelingually profoundly deaf native signers with deaf parents. The effectiveness of sign-supported speech has rarely been tested within the same group of children at discourse-level comprehension. Here, video-recorded texts, including spatial descriptions, were alternately transmitted in spoken language, sign language and sign-supported speech. The capacity of these communicative systems to equalise comprehension in deaf participants with that of spoken language in hearing participants was tested. Within-group analyses of deaf participants tested if the bimodal linguistic input of sign-supported speech favoured discourse comprehension compared to unimodal languages. Deaf participants with cochlear implants achieved equal comprehension to hearing controls in all communicative systems while deaf native signers with no cochlear implants achieved equal comprehension to hearing participants if tested in their native sign language. Comprehension of sign-supported speech was not increased compared to spoken language, even when spatial information was communicated. Eye movements of deaf and hearing participants were tracked and data of dwell times spent looking at the face or body area of the sign model were analysed. Within-group analyses focused on differences between native and non-native signers. Dwell times of hearing participants were equally distributed across upper and lower areas of the face while deaf participants mainly looked at the mouth area; this could enable information to be obtained from mouthings in sign language and from lipreading in sign-supported speech and spoken language. Few fixations were directed towards the signs, although these were more frequent when spatial language was transmitted. Both native and non-native signers looked mainly at the face when perceiving sign language, VISUAL PERCEPTION AND SIGNED ORAL LANGUAGE IN DEAFNESS 70 although non-native signers looked significantly more at the body than native signers. This distribution of gaze fixations suggested that deaf individuals – particularly native signers – mainly perceived signs through peripheral vision. Keywords: eye-tracking, deaf students, cochlear implants, native signers, discourse-level comprehension, sign-supported speech, peripheral vision. Chapter 4 Study 2: Inferencing in Deaf Adolescents during Sign-Supported Speech Comprehension Eliana Mastrantuono, David Saldaña, and Isabel R. Rodríguez-Ortiz Departamento de Psicología Evolutiva y de la Educación, Universidad de Sevilla, Spain This research was supported by the European Union’s Seventh Framework Programme for research, technological development and demonstration under grant agreement no 316748. Reference: Mastrantuono, E., Saldaña, D., & Rodríguez-Ortiz, I. (in press). Inferencing in deaf adolescents during sign-supported speech comprehension. Discourse Processes. DOI: 10.1080/0163853X.2018.1490133 EXPERIMENTAL RESEARCH 73 Abstract We tested the capability of deaf adolescents, including a group of users of cochlear implants, to generate inferences during spoken language comprehension, and whether they benefited from the use of sign-supported speech (SSS). Stimuli consisted of twenty-four short videorecorded texts in spoken language and in SSS. Participants responded to literal and inferential multiple-choice questions. In spoken language, cochlear implant users had more difficulty in processing inferential than literal information and found predictive inferences harder than associative inferences. The level of spoken language proficiency was related to inference generation, especially for predictive inferences. Similarly, deaf native signers had more difficulties in generating predictive inferences, although SSS increased their comprehension. Lipreading skills and working memory were positively related to accuracy in SSS. The inclusion of SSS only had a positive impact on the comprehension of native signers. Results suggest that cochlear implant users would benefit from an intervention to enhance verbal skills. Keywords: spoken language comprehension, sign-supported speech, predictive inferences, associative inferences, native signers, cochlear implant users. VISUAL PERCEPTION AND SIGNED ORAL LANGUAGE IN DEAFNESS 80 Participants were adolescents, aged between 12 and 19 years. This age range allowed the testing of participants who had completed the period of developmental language acquisition. Moreover, all participants who were CI users were long-term users by the time they took part in this study. 5.1 Summary of results In Experiment 1, comprehension of SSS was compared to comprehension of spoken language only and sign language only. Comprehension of deaf participants in the different modalities was compared to comprehension of spoken language by hearing-age peers. The use of eye tracking aimed to reveal where deaf participants allocated their overt attention when attending to language in different modalities. Although SSS did not negatively affect comprehension, compared to spoken language, the results did not indicate improved comprehension either, both for participants of the CI or the LSE groups. CI users achieved the same comprehension scores as hearing students in spoken language and SSS, while participants in the LSE group scored below hearing-age peers in these two modalities, although they achieved the same level of comprehension when attending to stimuli in their native sign language. These results highlighted the benefits in spoken language comprehension gained by using CIs, while no effects were evidenced for the use of SSS. We had hypothesized that SSS, because of its spatial nature, would especially favour the comprehension of spatial descriptions included in the texts. Contrary to expectations, the use of SSS did not enhance comprehension compared to spoken language when focusing the analysis on spatial information either. The eye tracking data provided however interesting results. They confirmed previous research in which the face of the sign model was the area primarily attended to by all deaf perceivers — not only native signers—, during sign language perception (Emmorey et al., 2009), while the signs were attended to via peripheral vision. Greater focus on the lower area of the face of the SUMMARY AND DISCUSSION OF RESULTS 81 sign model was detected, consistent with other studies in which sign language was transmitted through video recordings (Agrafiotis et al., 2003; Muir & Richardson, 2005). Although all deaf participants mainly looked at the face area during sign language perception, native signers significantly differed from non-native signers in that they looked towards the signs for a shorter overall period. This difference between native and non-native signers was not detected in SSS, during which native signers looked at the hand longer than they did when perceiving sign language. This was attributed to the fact that SSS is an artificial system and cannot be automatized as a natural language, so the use of peripheral vision to perceive signs presented some differences in the two modalities. Experiment 2 extended the investigation on discourse comprehension by deaf adolescents and the effectiveness of SSS to the comprehension of literal and inferential information, specifically associative and predictive inferences. Cognitive functions, nonverbal IQ and working memory, as well as linguistic variables, lipreading and proficiency in spoken and sign language, were analysed as possible predictors of language comprehension. In previous studies (Cleary, Pisoni, & Geers, 2001; Pisoni et al., 2008; Pisoni & Geers, 2000), cognitive functioning, in particular executive functions, has been used to explain individual differences among deaf children who are non-native signers —and who, inevitably, suffered from an early deprivation of linguistic input— compared to deaf children who are native signers. Consistent with findings related to hearing individuals (Currie & Cain, 2015), participants with CIs processed inferential information less accurately than literal information. Predictive inferences were less accurate than associative inferences in participants from both the CI and the LSE group. Proficiency in spoken language contributed to explain predictive inference generation in CI users. It was suggested that predictive inferences were more challenging as they require a more complete comprehension of the text than associative inferences. In fact, predictive inferences involve the integration of more pieces of information in the text, while for generating associative inferences VISUAL PERCEPTION AND SIGNED ORAL LANGUAGE IN DEAFNESS 82 it might be sufficient to only grasp a key piece of information in the text and connect it to prior world knowledge. The use of SSS did not increase comprehension in CI users, suggesting that these participants were mainly focused on the orally transmitted message. On the contrary, SSS did enhance the performance of native LSE signers, compared to spoken language. Working memory capacity positively affected comprehension of SSS but did not have effects on spoken language. Lipreading played a significant role in comprehension of literal and inferential information across all groups of participants. In the first two experiments, our main purpose was to evaluate the effectiveness of SSS in increasing discourse comprehension and inferential processing by deaf adolescents. Experiments 3 and 4 were more essentially centred on gathering evidence for the respective contribution of lip movements and signs in transmitting information during SSS perception, and on clarifying whether signs are actually attended to, even if it is peripherally. Eye-tracking data in the previous experiments had revealed a strong preference for looking at the face when attending to discourse in SSS, similarly to what has been found in sign language (Experiment 1). This gaze behaviour might be a consequence of the major perceptual difficulty of discerning lip movements compared to signs, something that would lead one to focus overt attention towards the lip movements, perceiving information from signs via peripheral vision (i). Alternatively, it might be that signs are simply overridden rather than peripherally perceived, and all information is obtained from spoken/lipread words (ii). In Experiment 3, the visual presentation of SSS on a screen was manipulated and adopted two modes to test these hypotheses. For testing the perceptual hypothesis (i), the lip area was magnified compared to the chest area (magnified condition). This way, lip movement perception was facilitated, and overt attention could be more balanced between the face/lip area and chest/signing area. For testing the effective use of peripheral vision in perceiving signs (ii), SUMMARY AND DISCUSSION OF RESULTS 83 an interactive gaze-contingent application of the eye tracker that limited the useful field of vision was implemented. The gaze-contingent display only allowed the area of the screen around the participant’s locus of fixation to be visible (gaze-contingent condition). At any time, participants were able to obtain information from one linguistic channel only, either the face/lip movements area or the chest/signing area. In the magnified condition (i), participants of the LSE group and, more generally, participants with poorer lipreading skills and CI users with lower scores in working memory capacity, looked more frequently towards the signs, compared to what they did in normal visual conditions. On the other hand, the gaze-contingent window (ii) affected gaze behaviour and accuracy of all groups of participants, with an increased number of fixations towards the signing area, lower accuracy, and longer reaction times than in normal visual conditions. These latter results might suggest that deaf participants benefit from the bimodal channel of information and that they resort to signs to integrate, confirm or substitute information from spoken/lipread words. When the sources of information from SSS are not concurrently available, comprehension is hindered. However, these results must be carefully interpreted: they might have been driven by the experimental video presentation of the stimuli, which led participants to visualise the unfamiliar display differently, regardless of the linguistic channel from which they actually get information. Experiment 4 aimed to clarify whether deaf perceivers really resorted to signs to obtain information, beyond spoken/lipread words. This objective was pursued by designing stimuli where speech and sign information was mismatched, with signs carrying a different meaning from the spoken words. Although they were instructed to pay attention to the orally transmitted message, participants of the CI group allocated overt attention more frequently towards the signs in the mismatch than in the matching condition. There were also slower and less accurate, because they often selected the representation referring to the sign. Native LSE signers had a dramatic drop in accuracy in the mismatching condition, mostly referring to the signs, even if VISUAL PERCEPTION AND SIGNED ORAL LANGUAGE IN DEAFNESS 84 their gaze behaviour and reaction times did not significantly change across conditions. These results might suggest that signs were processed by all participants: longer reaction times and more fixations towards the sign in CI users in the mismatching condition indicate that they processed the inconsistency between speech and signs, and that they occasionally relied on the signs when missing information from spoken/lipread words. When perceiving SSS in normal conditions, CI users might therefore be engaged in the semantic integration of signs and speech. As for native signers, the lack of effects in gaze behaviour and reaction times, despite the decrease in accuracy when processing the mismatching condition, showed that participants obtained information mostly from signs, ignoring spoken words. 5.2 Discussion 5.2.1 Discussion of the findings for cochlear implant users. Overall, in CI users, discourse comprehension was not significantly improved with SSS compared to the use of spoken language only (Experiment 1), even when it involved the higherlevel cognitive processes required by inference generation (Experiment 2). Although these participants, implanted before the age of five, had good-to-proficient skills in sign language and educational experiences with SSS, they did not benefit from the reinforced information provided by the bimodal linguistic channel of SSS. Comprehension by CI users of spoken language and SSS was equivalent to comprehension by hearing peers of spoken language (Experiment 1). It might be the case that there was little room left for improving comprehension using SSS, possibly due to the general difficulty of the task, which involved the construction of spatial situation models. Despite the lack of favourable results for the use of SSS with CI users, eye-tracking data during processing atomic sentences in visual conditions constraining the peripheral vision indicated that these participants allocated attentional resources toward signs (Experiment 3) and, when lexical items were conflicting, they frequently relied on signs, even though instructed to refer to spoken words (Experiment 4). Jointly considered, these findings SUMMARY AND DISCUSSION OF RESULTS 85 reveal that CI users do resort to the visual linguistic source offered by signs in SSS. The attention to the signed lexicon found in the experiments using atomic sentences as stimuli, together with the longer reaction times in the comprehension task when the bimodal input of SSS was experimentally disrupted, can be related to the cognitive phenomenon that has been identified as code-blending facilitation (Emmorey et al., 2012 ), redundant signals effects (Miller, 1986) or the dual coding theory (Paivio, 2010; Paivio et al., 1988). This phenomenon is observed when two stimuli with the same meaning simultaneously presented via bimodal channels involve a semantic integration that leads perceivers to process two stimuli more easily and quickly than they would a single stimulus, because the redundant information is combined and coactivates a response. The coactivation of functionally independent but interconnected multimodal systems would create a stronger connection in memory and the information would be better retained (Paivio, 2010). This effect has been found in hearing-impaired individuals who are used to connecting auditory and visual linguistic stimuli through lipreading or signs, but it has not been detected in normal-hearing individuals or in individuals with specific language impairment (van Berkel-van Hoof et al., 2016). Recent findings related to single-word acquisition, have found that bimodal input provides a support for vocabulary acquisition or comprehension of novel or pseudowords (Giezen, 2011; Giezen et al., 2014; van Berkel-van Hoof et al., 2016). Why did we not find this advantage at a discourse level (Experiment 1) or in short texts (Experiment 2)? The explanation might be connected to the greater number of variables (grammar knowledge, short-term memory, working memory, or sustained attention) that are involved in discourse comprehension, and the heterogeneity in cognitive and linguistic performance within the students with CIs. Discourse and long-sentence comprehension require mastery of the grammar of a language and SSS does not support this goal. The grammatical skills of CI users are frequently below age-appropriate standards, even when vocabulary size is VISUAL PERCEPTION AND SIGNED ORAL LANGUAGE IN DEAFNESS 86 equated to that of hearing-age peers (Caselli et al., 2012; Duchesne et al., 2009). For this thesis, due to time limitations, participants’ grammatical skills were not assessed. Only a few measures of linguistic and cognitive skills were collected and correlated to language comprehension: nonverbal IQ, working memory, spoken receptive vocabulary size, lipreading skills, and proficiency in spoken and sign language comprehension. With respect to the receptive vocabulary measure, no variance among participants, with and without CIs, was found, with only few of them performing above baseline. Due to the lack of variance, in most of the experiments (Experiments 2, 3, and 4), the measure of spoken receptive vocabulary could not be included as a predictor of comprehension. Given the poor performance across all participants, spoken receptive vocabulary represented a substantial common difficulty for this population, and resorting to sign vocabulary would appear to be well-motivated. Other linguistic skills affected comprehension in CI users. Proficiency in spoken language comprehension was especially relevant in increasing the generation of predictive inferences that, more than other types of inference, require a full understanding of the text and depend on the integration of more pieces of information across the entire text (Experiment 2). Lipreading was also an important predictor of comprehension across all participants, not only CI users, with more proficient lipreaders achieving higher levels of comprehension (Experiments 2 and 4) and poorer lipreaders fixating more on the signs in the magnified condition (Experiment 3). Along with linguistic skills, CI users were also influenced by working memory: participants with a smaller working memory capacity looked more frequently at signs in the magnified visual condition, as poor lipreaders did (Experiment 3). Furthermore, these participants relied more frequently than their peers with greater working memory on signs, compared to speech, to obtain information when sign and speech mismatched (Experiment 4). It might be that the participants with poorer working memory in this sample recalled items in the visual-manual SUMMARY AND DISCUSSION OF RESULTS 87 modality more easily than in the auditory-oral modality. Despite the effective reinforcement that signs in SSS provided to participants with CIs with poorer linguistic skills and with working memory, the overall amount of information gained by CI users did not improve with SSS. These results are in contrast with some recent findings related to the successful use of SSS with CI users in classroom contexts (Blom & Marschark, 2015; Blom, Marschark, & Machmer, 2016). SSS was found to be more effective than spoken language when materials with greater complexity of content were proposed, but not with materials with simpler content (Blom & Marschark, 2015). Furthermore, SSS increased comprehension in comparison to spoken language in noisy contexts, such as classroom contexts with multi-talker babble, where much auditory information can easily be missed or misheard (Blom, Marschark, & Machmer, 2016). In our studies, testing materials were not differentiated for content complexity and stimuli were presented via video recordings in quiet rooms with good acoustic accessibility to ensure that participants, individually tested, perceived the same stimuli in analogous conditions. However, given the attention that participants devoted to signs, especially participants with poorer linguistic skills and working memory, it is plausible that SSS may make a difference in supporting comprehension in tasks with complex content and topic-specific vocabulary, and in noisy contexts. 5.2.2 Discussion of the findings for native LSE signers. For native signers, comprehension was expected improve in SSS compared to spoken language only, thanks to the signs. Indeed, native signers had better production of predictive inferences, which entail a more complete comprehension of the overall context compared to other inferential processes (Experiment 2). The relevance of signs for these participants was confirmed by the orientation of visual attention towards them when visual conditions were manipulated (Experiment 3). Moreover, when speech and sign mismatched, native signers showed their reliance on signs, frequently referring to them rather than to spoken /lipread words VISUAL PERCEPTION AND SIGNED ORAL LANGUAGE IN DEAFNESS 88 (Experiment 4). However, in Experiment 1, SSS did not impact significantly on comprehension compared to spoken language only. This might be due to the difficulty and to the specificity of the task, which could be more suitably transmitted in sign language, as the text comprehension required the construction of a spatial situation model. While SSS did not make comprehension by native signers equivalent to the comprehension of spoken language by hearing peers, sign language did (Experiment 1). In conclusion, although various results of our thesis indicate that SSS increases the comprehension of native signers compared to spoken language, it is important to stress that SSS is not a natural language and can hardly guarantee the same comprehension that native signers can achieve in their native sign language. Differences in processing SSS and sign language were not only revealed by accuracy scores, but also by the spatial distribution of visual attention in native and non-native signers. 5.2.3 Spatial distribution of visual attention during SSS perception. The most innovative aspect of this thesis concerns the combination of comprehension and eyetracking data during language perception in SSS. As in sign language perception, deaf participants mostly fixated on the face area when attending to SSS (Experiment 1). In sign language, there is clear evidence that participants are perceiving signs peripherally. In SSS, however, where a bimodal channel of information is available, it was not clear that participants —particularly those with functional hearing— perceive signs via peripheral vision. It might be that they are just ignoring the signs and obtaining all the information from speech and lipreading. The use of a moving window that limited the useful field of vision to either the face or the signing area (Experiment 3), and the implementation of a paradigm with inconsistent meanings between sign and speech (Experiment 4), provided evidence to support the hypothesis that participants with CIs are also actively attending to the information from signs. SUMMARY AND DISCUSSION OF RESULTS 89 The findings of these experiments also draw attention to differences in visual processing of SSS and sign language, and between native and non-native signers. Deaf native signers, when perceiving sign language, had fewer gaze deviations towards the signs than deaf non-native signers (Experiment 1). This is consistent with earlier findings that attributed this difference to a more developed peripheral vision in native signers (Agrafiotis et al., 2003). On the other hand, no differences were detected between native and non-native signers’ gaze behaviour in SSS (Experiment 1). This was attributed to the artificiality of SSS, which cannot be acquired as a natural language. Native signers have not automatized the use of peripheral vision in complex long texts as in sign language perception. However, eye movement data from Experiment 1 referred to long time windows, which tracked the eyes across the entire length of the stimuli, approximately 100 seconds each. However, when reviewing fixations over shorter time windows and texts, differences between native and non-native signers did emerge in SSS: native signers looked less towards signs than non-native signers when attending to the basic sentences presented in the baseline visual condition (Experiment 3) and in the time window of a critical word (Experiment 4). Although fixating on the face area, native signers, who were found to be significantly less expert lipreaders that their peers with CIs, seemed not to pay attention to lip movements, retrieving most information from the peripherally perceived signs. This occurred even when participants were explicitly instructed to retain orally transmitted information (Experiment 4). This account would confirm the division of labour hypothesis proposed in Mitchell (1996), which contemplates a limited-resource model for attentional resources. 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