The language-cognition interface: Executive functions and syntax in atypical development

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Thesis

Reference

The language-cognition interface: Executive functions and syntax in atypical development

STANFORD, Emily Nicole

Abstract

This dissertation reports the findings of five studies investigating he language-cognition interface in various clinical populations. Due to the interdisciplinary nature of the topic, an integrative approach is applied to this research, claiming that both precise syntactic principles and more general cognitive mechanisms can account for phenomena observed in typical and atypical language development. Specifically, it is argued that the acquisition difficulties associated with certain structures in which an object has been moved are due to an interaction between formal syntactic properties, such as intervention effects within a featural Relativized Minimality framework, and processing limitations in attention and working memory.

According to this line of reasoning, both domain-specific and domain-general skills have a role to play in the syntactic development of certain clinical populations, a hypothesis which is tested and validated via two cross-sectional studies, two working memory training studies and one priming study.

STANFORD, Emily Nicole. The language-cognition interface: Executive functions and syntax in atypical development. Thèse de doctorat : Univ. Genève, 2020, no. L. 991

DOI : 10.13097/archive-ouverte/unige:144700 URN : urn:nbn:ch:unige-1447002

Available at:

http://archive-ouverte.unige.ch/unige:144700

Disclaimer: layout of this document may differ from the published version.

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THE LANGUAGE-COGNITION INTERFACE:

EXECUTIVE FUNCTIONS AND SYNTAX IN ATYPICAL DEVELOPMENT

Thèse de doctorat

Présentée à la Faculté des Lettres de l’Université de Genève pour l’obtention du titre de Docteur ès Lettres, mention Linguistique

par

Emily Stanford juin 2020

Juré de thèse Dr. Hélène Delage, directeur Prof. Dr. Luigi Rizzi, co-directeur

Prof. Dr. Ulrich Frauenfelder, membre du juré Prof. Dr. Ur Shlonsky, président

Prof. Dr. Maria Teresa Guasti, membre du juré Prof. Dr. Naama Friedmann, membre du juré

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© Copyright by Emily Nicole Stanford

2020

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Résumé

Ce travail de thèse présente les résultats de cinq études investiguant l'interface langage- cognition dans plusieurs populations cliniques. En raison de la nature interdisciplinaire de ce thème, j’ai choisi une approche intégrative, postulant que des principes syntaxiques spécifiques et des mécanismes cognitifs plus généraux peuvent rendre compte de certains phénomènes observés dans le développement typique et atypique du langage. Plus précisément, je soutiens que les difficultés d'acquisition associées à certaines structures syntaxiques dans lesquelles un objet a été déplacé (par exemple les relatives objets, les structures contenant un pronom clitique objet et les propositions passives) sont dues à une interaction entre les propriétés syntaxiques formelles, telles que les effets d'intervention comme ils sont décrits dans la théorie de la Minimalité Relativisée aux traits, et des limitations de traitement au niveau de l’attention et de la mémoire de travail. Selon ce raisonnement, des compétences spécifiques et générales ont un rôle à jouer dans le développement syntaxique de certaines populations cliniques, telles que les enfants avec un trouble développemental du langage. Cette hypothèse est testée à travers deux études transversales, deux études d’entraînement de la mémoire de travail et une étude d'amorçage. La situation des enfants présentant des difficultés d’apprentissage est mise en lumière au chapitre 2, celle des enfants ayant un trouble développemental du langage aux chapitres 3 et 4, puis celle des enfants avec un trouble du déficit de l’attention avec ou sans hyperactivité dans les chapitres 5 et 6. Considérés dans leur intégralité, les résultats de ces études indiquent que la capacité la capacité à effectuer efficacement des opérations syntaxiques complexes est en effet liée aux performances attentionnelles et en mémoire de travail, mais ils montrent également que des limitations au niveau de ces compétences cognitives plus larges peuvent se produire en l'absence d’altération des compétences syntaxiques. Ces résultats mettent en évidence la complexité des liens syntaxe-cognition, qui ne peuvent pas être entièrement interprétés par les cadres traditionnels se focalisant sur une approche explicative unique.

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Summary

This dissertation reports the findings of five studies investigating the language-cognition interface in various clinical populations. Due to the interdisciplinary nature of the topic, I apply an integrative approach to this research, claiming that both precise syntactic principles and more general cognitive mechanisms can account for phenomena observed in typical and atypical language development. Specifically, I argue that the acquisition difficulties associated with certain structures in which an object has been moved (e.g. object relatives, structures containing object clitic pronouns and passives) are due to an interaction between formal syntactic properties, such as intervention effects as described within a featural Relativized Minimality framework, and processing limitations in attention and working memory. According to this line of reasoning, both domain-specific and domain-general skills have a role to play in the syntactic development of certain clinical populations, such as children with developmental language disorder. This hypothesis is tested via two cross-sectional studies, two working memory training studies and one priming study, with the spotlight moving from children with learning difficulties in Chapter 2 to children with developmental language disorder in Chapters 3 and 4, and then to children with attention deficit hyperactivity disorder in Chapters 5 and 6.

Collectively, the results of these studies indicate that the ability to efficiently perform complex syntactic computations is indeed related to capacity in attention and working memory, but they also provide evidence that limitations in these broader cognitive competences can occur in the absence of impaired syntax. These findings highlight the intricacy of the syntax-cognition link, which cannot be easily interpreted by traditional single-disciplinary frameworks.

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For my grandfather

22 January 1929 – 13 December 2019

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Acknowledgements

This dissertation is the result of three years and three months of hard work and would not exist were it not for the support of a number of people. Below is my modest attempt to piece together a few lines to express my immense gratitude.

First and foremost, I must thank my supervisors, Doctor Hélène Delage and Professor Luigi Rizzi. Hélène, I am indescribably grateful for your dedicated guidance and availability throughout this entire process. Our regular check-ins kept me focused and on track and made the challenge of completing a PhD much more achievable. I cannot thank you enough for the countless hours that you sacrificed, patiently answering my questions and giving me critical feedback on innumerable drafts of written work. Thank you for your encouragement. Luigi, I am honored to call you my mentor. Your calm leadership, wisdom and invaluable experience left me feeling reassured at critical stages of this journey and I feel incredibly fortunate that my education and this dissertation have been enriched by your body of work. At the same time, you always encouraged me to embrace curiosity and to follow my own (somewhat unconventional) path. For this I am so appreciative.

I would also like to thank Professor Ulrich Frauenfelder, Professor Adriana Belletti, Doctor Stephanie Durrleman and Doctor Margaret Kehoe for being influential actors in my academic journey. Ulrich, words cannot express how motivating your continued support has been for me.

Whenever I was feeling down or discouraged, a short conversation with you left me feeling like I could move mountains. There is truly no one else like you. Adriana, thank you for your priceless advice throughout this experience. You have a special way of acknowledging and validating a new researcher, and I cannot describe how much this recognition has meant to me.

Stephanie, thank you for demonstrating what it means to elegantly navigate interdisciplinary research. You undoubtedly understand the challenges of such a path, and I am so grateful for your generous willingness to carve out time for me during what sometimes felt like a solo trek.

As for you, Margaret, I do not know where to begin to adequately communicate my gratitude for your friendship. You uplift others without expecting anything in return, simply because it is part of your sweet spirit. You made me feel heard, seen and accepted and I will truly miss being able to walk down the hall and pop my head into your office.

I am also extremely thankful to Professor Ur Shlonsky for his contribution to my academic cursus. Ur, you have always inspired me to ask difficult questions and to think outside of the box. In particular, your insightful comments following my predoctoral presentation helped form the final shape of this dissertation. I also feel exceptionally lucky that Professor Naama Friedmann and Professor Maria Teresa Guasti accepted to read this work as members of my thesis committee. You represent two of my greatest inspirations and your work has without a doubt influenced my own. Thank you.

This work would not be possible were it not for the families and children who so kindly gave up their time, welcoming unknown students into their homes and allowing us to take over their kitchen tables. The speech-language therapists and other clinicians who helped with the recruitment process must also be thanked, and of course, the 30 MA students with whom I have collaborated over the last three years. To all of the students, thank you for always keeping me

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on my toes. You have been a source of immense frustration at times, but also a source of much happiness. I have surely learned more from you than you have from me, and I wish you all success in your future endeavors.

I feel lucky to have shared this experience with some great doctoral and postdoctoral colleagues in both the Department of Psycholinguistics and the Department of Linguistics at the University of Geneva. Thank you, Maryll Fournet and Eric Ménétré, for your willingness to answer my statistics questions. I was really touched by your kindness. Thanks is also due to Giuseppe Samo and David György. You both gave me invaluable feedback in the final stages of writing this dissertation, taking time away from your own projects to selflessly focus on mine. The two of you embody all that is good about academia and I am so excited to see what the future has in store for you. I cannot forget Virag Csillagh. You have proved to be a kindred spirit in what you so aptly coined “PhD in the Time of Corona”. Our frequent conversations while I was writing this dissertation gave me the morale boost I needed to get over the finish line.

Friendships with colleagues can sometimes be complicated, but you have made it so easy. I also have to credit you, Virag, with the idea of using the image of The Blind Men and the Elephant on page 8.

To my parents, thank you for believing in your wild child and for being my biggest fans. Dad, I inherited my love of languages from you, and I know that you are so proud of how far I have come. Stop talking to strangers on the street about it! Mom, thank you for simply listening. You demonstrate unparalleled empathy and when this pilgrimage felt too difficult or too long or too tiresome, you were the only one I could turn to who would truly listen.

Last but certainly not least, I have to thank Federico, Amo Mio. There are absolutely no words that can express what you mean to me. This success is as much yours as it is mine. Ti amo!

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Preface

As the work presented in Chapters 2 to 6 reports research that was jointly conducted with either Hélène Delage or Hélène Delage and Stephanie Durrleman, the first-person plural has been used in these chapters. Instead, in the introduction and conclusion (Chapters 1 and 7), the first- person singular is used. The studies in Chapters 2 and 3 have been published (in First Language and the American Journal of Speech-Language Pathology respectively), while the studies in Chapters 4 to 6 have been submitted for publication as co-authored articles to refereed journals.

To some degree, the results from each chapter have been presented at various psycholinguistics and linguistics conferences from 2017-2019.

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List of Tables

Table 1.1. Summary of the main points put forward by domain-specific and domain-general

approaches to language acquisition. Source: Botting and Marshall (2017) ... 9

Table 2.1. Overview of participant information: mean age and SDs in years and months, gender of participants, and number of languages spoken by participants ... 27

Table 2.2. Examples of test items for the two tasks... 30

Table 2.3. Comparison of the comprehension accuracy percentages of +/-INT wh-questions and relative clauses in children with SLD ... 32

Table 2.4. Comparison of SLD/TD accuracy percentages when intervention is present (which object questions and object relative clauses)... 32

Table 2.5. Individual SLD scores in the two comprehension tasks and percentile rankings for backward digit span. In bold are scores that are 1.5 SDs or more below the TD mean, while scores highlighted in grey represent performance that is at or below chance level ... 33

Table 2.6. Description of the participants’ language backgrounds with bilingual children highlighted in grey ... 42

Table 3.1. Abbreviated overview of French pronominal forms with the problematic 3p clitics in bold ... 45

Table 3.2. Summary of participant information ... 57

Table 3.3. Summary of Z-scores on standardized tests ... 58

Table 3.4. Summary of composite WM scores and syntax scores on pretests ... 60

Table 3.5. Clitic pronouns elicited by clitics task ... 60

Table 3.6. Summary of pre vs. posttest comparisons for the composite scores for simple and complex span ... 68

Table 3.7. Summary of pre vs. posttest comparisons for all WM tests ... 69

Table 3.8. Summary of correlation analyses performed between gains in 3p clitics and gains in simple and complex span, age and nonverbal reasoning ... 73

Table 3.9. A summary of the DLD participants’ individual data with scores representing impairment in bold ... 82

Table 3.10. A summary of the TD participants’ individual data with scores representing impairment in bold ... 85

Table 4.1. Summary of participant information ... 92

Table 4.2. Summary of Z-scores on standardized tests ... 93

Table 4.3. Summary of the WM measures used in the pre and posttests... 95

Table 4.4. Summary of various sentence types included in the repetition task ... 96

Table 4.5. Summary of composite WM scores and pretest syntax scores ... 97

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Table 4.6. Summary of pretest vs. posttest comparisons for the composite scores for simple and

complex spans ... 99

Table 4.7. Summary of pretest vs. posttest comparisons for the individual WM tests ... 100

Table 4.8. Summary of pretest vs. posttest comparisons for complex sentence repetition measures . 103 Table 4.9. Summary of comparisons made for pretest measures of differing syntactic complexity when the WM and scholastic training participants are put together in each cognitive group ... 104

Table 4.10. Summary of additional pretest vs. posttest comparisons on measures of differing degrees of syntactic complexity ... 105

Table 4.11. A summary of the DLD participants’ individual data with scores representing impairment in bold ... 114

Table 4.12. A summary of the TD participants’ individual data ... 118

Table 5.1. Summary of participant information according to cognitive group ... 133

Table 5.2. Summary of partial correlation analyses results for the six EF and two syntax tasks when all participants are grouped together ... 138

Table 5.3. Partial correlation analyses for the six EF measures and two syntax tasks when the participants are grouped separately ... 138

Table 5.4. Summary of EF scores for the three cognitive groups ... 140

Table 5.5. Descriptive data on participants with ADHD and summary of their performance on the two syntax tasks ... 144

Table 5.6. Summary of EF and syntactic profiles in the ADHD and DLD groups ... 151

Table 6.1. Summary of participant information according to cognitive group ... 167

Table 6.2. Summary of the different experimental conditions ... 171

Table 6.3. Table summarizing the types of target and non-target responses produced by our participants when a patient cue was provided ... 178

Table 6.4. Types of passives produced by our participants ... 179

Table 7.1. Summary of domain-specific and domain-general evidence from the study in Chapter2 197 Table 7.2. Summary of domain-specific and domain-general evidence from the studies in Chapter3 and Chapter4 ... 199

Table 7.3. Summary of domain-specific and domain-general evidence from the studies in Chapter5 and Chapter6 ... 201

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List of Figures

Figure 1.1. Source: Himmelfarb et al 2002: 1526 (artist: G. Renee Guzlas) ... 7

Figure 1.2. Block diagram of thesis outline ... 16

Figure 2.1. Distribution of learning difficulties in the SLD group ... 26

Figure 2.2. Timeline of a right-to-left animation as seen in both comprehension tasks ... 28

Figure 2.3. Response accuracy in comprehension of wh-questions in SLD children ... 31

Figure 2.4. Distribution of percentile rankings for backward digit span for the SLD and TD participants ... 34

Figure 3.1. Illustration corresponding to the example item in (8) ... 61

Figure 3.3. Illustration of a trial containing a sequence of three auditory stimuli from Activity 1, with the storage phase (the image on the left) and the reconstruction phase (the central image and the image on the right) ... 63

Figure 3.4. Illustration of a trial containing a sequence of three auditory stimuli from Activity 3, with the high-speed visual discrimination of quantity task immediately succeeding each stimulus. Participants heard an everyday sound (e.g. a ringing telephone) while looking at a neutral screen (an image of the main character from the application holding a hand to his ear). Immediately following the presentation of the auditory stimulus to be stored, the participants were asked to complete the unrelated visual processing task ... 64

Figure 3.5. Magic Memory performance results from session 1 to session 24 for 20 of the 26 DLD participants on four of the five activities ... 66

Figure 3.6. Magic Memory performance results from session 1 to session 24 for 12 of the 16 TD participants on four of the five activities ... 67

Figure 3.7. Summary of pre and posttest results on the clitics task for both cognitive and training groups with error bars denoting standard deviation ... 71

Figure 3.8. Pre and posttest distribution of responses in the clitics task for children with DLD who followed the WM training ... 72

Figure 3.9. Pre and posttest distribution of responses in the clitics task for children with DLD who followed the scholastic training ... 72

Figure 4.1. A graphical timeline of the study procedure ... 94

Figure 4.2. Screenshots of the Magic Memory design ... 96

Figure 4.3. Distribution of composite WM scores for the pretests, immediate (POST 1) and delayed posttests (POST 2) ... 101

Figure 5.1. An example of an Opposite World condition (Monde à l’envers in French) in which participants had to say the opposite of what they saw (“two” when they saw the digit 1 and “one” when they saw the digit 2) ... 135

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Figure 5.4. Results for the omnibus syntax test for the three cognitive groups... 142

Figure 5.5. Results for the probe syntax task for the three cognitive groups ... 142

Figure 5.6. Response distribution for the probe syntax task... 143

Figure 5.7. Scatterplots for the eight significant partial correlations ... 154

Figure 6.1. Example of an experimental item to which children could respond using an active structure, (i.e. The woman is pushing the girl) or a passive structure (i.e. The girl is being pushed by the lady) ... 168

Figure 6.2. Example of a filler item to which participants would be expected to respond using an intransitive verb (i.e. The man is sleeping) ... 168

Figure 6.3. Example of a referential cue trial in which the agent of the event (the little girl who is pushing the big girl) is cued via an image of the agent in a neutral position that is previewed for 1000ms before the event to be described appears ... 169

Figure 6.4. Example of a perceptual cue trial in which the patient of the event (the little girl who is being pushed by the big girl) appears in color and the agent (the big girl) appears in black and white ... 169

Figure 6.5. Graph showing the effect of cue type ... 174

Figure 6.6. Graph showing the effect of visual cue type ... 175

Figure 6.7. Graph showing the effect of linguistic cue type ... 176

Figure 6.8. Graph summarizing our main results ... 177

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List of abbreviations

+INT Structure/condition containing intervention +RC Structure containing a relative clause 2p(s) Second person (singular)

3p(s) Third person (singular)

ACC Accuracy

ADHD Attention deficit hyperactivity disorder ANOVA Analysis of variance

APA American Psychiatric Association

Bi. Bilingual

BILO Bilan Informatisé de Langage Oral ClLD Clitic left dislocation

CP Complementizer phrase

d Statistical measurement for effect size of two variables DCH Derivational complexity hypothesis

DLD Developmental language disorder

DP Determiner phrase

DSM Diagnostic Statistical Manual EF Executive functions

F Statistic generated by ANOVA fRM Featural Relativized Minimality HSD Honestly significant difference

-INT Structure/condition not containing intervention

L2 Second language

M Mean

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Mo. Monolingual

ms Milliseconds

n Number (subsample)

N Number (full sample)

na Not applicable

NP Noun phrase

ns Not significant

p Level of significance

PCA Parallel combination approach r Correlation coefficient

-RC Structure not containing a relative clause RCD Reading comprehension disorder

RCP Reflexive causative passive

s Seconds

SD Standard deviation

SLD Specific learning difficulties SLT Speech-language therapist

SNSF Swiss National Science Foundation

STM Short-term memory

SVO Subject-verb-object

t Statistic generated by Student’s t-test TD Typically developing

TEA-ch Test of Everyday Attention for Children Tri. Trilingual

U Statistic generated by Mann-Whitney U-test

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WM Working memory

y;m Age in years and months z-score Standardized score

η² Statistical measurement for effect size of multiple variables

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C HAPTER 1

I NTRODUCTION

“Normal speech consists, in large part, of fragments, false starts, blends and other distortions of the underlying idealized forms. Nevertheless…what the child learns is the underlying [idealized form]. This is a remarkable fact. We must also bear in mind that the child constructs this [idealized form] without explicit instruction, that he acquires this knowledge at a time when he is not capable of complex intellectual achievements in many other domains, and that this achievement is relatively independent of intelligence.”

(Chomsky, 1969)

1.1 The relationship between language and cognition: Dissociable or closely intertwined?

1.1.1 Perspectives from linguistic theory

The debate concerning the relationship between language and cognition, especially in the child system, has been ongoing for decades. According to traditional nativist theories (Chomsky, 1959) and modular frameworks (Fodor, 1983) of first language acquisition (henceforth language acquisition), language is supported by domain-specific specialist mechanisms and is separable from other aspects of cognition. Often cited by nativists (see Guasti, 2017 for an overview) as support for language being a specialized faculty, or module, is the observation that infants show astonishingly early sensitivity to complex phonological or syntactic constraints, with no obvious nonlinguistic equivalent. From perhaps even before birth, infants seem to have the means to acquire language without explicit teaching, provided there is sufficient exposure to linguistic input, which itself is prone to errors, hesitations and reformulations. Nonetheless, in typically-developing (TD) children, language develops following a strikingly similar pattern of milestones, regardless of the language(s) the child is exposed to and regardless of varying circumstances: some circumstances, one could imagine, would promote language development (e.g. a household with attentive and engaging parents), and some would be expected to impede it (e.g. a household in which parents are more detached or absent¹). Within the first five years of life, a remarkably competent linguistic system that

1 This is not referring to situations in which children are abused or neglected, as research shows that being raised in such circumstances does have detrimental effects on language acquisition (see meta-analysis by Sylvestre, Bussières, & Bouchard, 2016).

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demonstrates mastery of complex grammatical structures and contains a potentially infinite number of sentences has developed, revealing rich linguistic knowledge and creative expertise that could not have been acquired on the sole basis of the finite number of imperfect speech samples the child has heard.

The development of such an efficient linguistic system at a time in life when children are seemingly not expected to acquire anything else that is comparable in complexity, as pointed out in the quote by Chomsky, is often interpreted by linguists subscribing to nativist-generativist theology as indicating that humans are born genetically programed with the knowledge of a universal set of formal syntactic rules. In other words, language develops innately much in the same way other biological functions develop, and newborns are thus equipped with the language faculty, i.e. mechanisms specialized for computing the complexities of language. The exact nature of the language faculty has been widely debated and various definitions as to its breadth exist (see Hauser, Chomsky, & Fitch, 2002 for an overview), but both narrow and broad definitions typically reject the idea that executive cognitive functions such as attention and working memory (WM) are part of the language module. One argument sometimes put forward by nativists as support for a specialized and separable language module is that functional imaging experiments in neuroscience seem to support the notion of specific brain regions responsible for language (Sakai, 2005), with evidence that the neonatal brain already utilizes distinct neural networks when processing language (e.g. Vannasing et al., 2016). Another main argument for modularization has to do with double dissociations within developmental disorders. Nativists frequently cite reports of patients that show complementary profiles of ability and disability (i.e. patient 1 is impaired on task A while task B is relatively spared, with patient 2 exhibiting the reverse pattern) as a powerful endorsement for the notion of external modularity, i.e. the separability of language and other cognitive capacities. Most commonly, Williams syndrome and developmental language disorder² (DLD) are claimed to be cases of such a double dissociation (e.g. Pinker, 1994). Williams Syndrome is a disorder in which affected individuals are described as demonstrating rather significant cognitive deficits but

2 There is an ongoing debate as to whether this disorder should be called developmental language disorder or specific language impairment and one’s choice of terminology choice often reflects an inclination towards a more linguistic approach (outlined in Section 1.1.1) in which affected individuals demonstrate a discrete impairment in the language module, or a more cognitive approach (outlined in Section 1.1.2) in which impairment in various general mechanisms are at least partially responsible for the observed language difficulties. As the nature of the work presented in this dissertation is built on the premise that selective language problems are rare and that general cognitive weakness is characteristic of children with DLD, I have chosen to adopt the term developmental language disorder, as recommended by the CATALISE consortium (Bishop et al., 2017).

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intact linguistic capacity³ (e.g. Bellugi et al., 1988), whereas individuals with DLD are known to have long-lasting language difficulties, with language performance that falls at the very low end of the distribution, despite intact cognitive functioning (Leonard, 2014). Taking the example of DLD, nativists posit that the disorder is the result of a domain-specific deficit in the specialized language system. This leads us to another argument frequently made by nativists in favor of modularity, which is that various dimensions of the language system can be selectively affected on the basis that some linguists believe that language itself consists of separable components, or internal modularity. Used as evidence to support this claim are reports of subgroups of children with DLD who demonstrate discrete difficulties in the morphosyntactic component of language⁴ (van der Lely, 1998, 2005; Wexler, 1998). In these cases, it is assumed that specific deficits in the grammatical component of the language faculty lead to limitations in grammatical knowledge or prolonged immaturity of the grammar. In other words, it is the inherently complex properties of certain syntactic structures that make them difficult to acquire for such individuals. The next section gives an example of one such structure.

1.1.1.1 Syntactic movement: An example of complexity

Noncanonical structures that do not follow the subject-verb-object (SVO) word order in languages such as English and French offer one example of a complex structure that is frequently associated with late acquisition in TD children and prolonged acquisition difficulties in children with DLD. Although both the subject relative clause in (1) and the object relative clause in (2) consist of the same words and contain an element whose interpretation is specified by means of an antecedent, a robust, crosslinguistic subject-object asymmetry has been repeatedly reported in the acquisition literature. Compared to their subject relative counterparts, object relatives are associated with lower accuracy and longer response times when their comprehension is assessed in young TD children whose syntactic competences are not fully developed and in older children with DLD (Adani, 2011; Adani, Forgiarini, Guasti, & van der Lely, 2014; Arosio, Adani, & Guasti, 2009; Avrutin, 2000; Bentea, Durrleman, & Rizzi, 2016;

Contemori & Belletti, 2014; Delage, Monjauze, Hamann, & Tuller, 2008; de Villiers, de Villiers, & Hoban, 1994; Friedmann, Belletti, & Rizzi, 2009; Friedmann & Novogrodsky, 2004;

3 For arguments against intact language skills in Williams syndrome, see Grant, Valian, and Karmiloff-Smith, 2002; Karmiloff-Smith et al., 1997; Mervis and Becerra, 2007; Mervis and Robinson, 2000; Paterson, Brown, Gsödl, Johnson, and Karmiloff-Smith, 1999.

4 The existence of DLD subgroups with impairment that selectively affects one component of language is still a matter of debate as there is strong evidence that the majority of children with DLD who demonstrate syntactic deficits also show impairment in other areas of language (Bishop, Bright, James, Bishop, & van der Lely, 2000;

Friedmann & Novogrodsky, 2008).

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Goodluck & Tavakolian, 1982; a.o). Similarly, elicitation studies show that young TD children and children with DLD systematically avoid the production of structures containing object relatives (Contemori & Belletti, 2014; Contemori & Garraffa, 2010; Jenson de Lopez, Olsen,

& Chondrogianni, 2014; a.o.).

(1) The mailman that pulled the fireman (2) The mailman that the fireman pulled

In the syntactic literature, the difficulty associated with object relatives is the result of the complex computational requirements that must be satisfied in order to properly derive such a structure. More specifically, these computations consist of extracting the object from its canonical postverbal position and merging it preverbally, thus creating a noncanonical long- distance dependency (also known as a filler-gap dependency) between the fronted object and its base-position gap. In the case of subject relatives, the filler-gap distance is minimal, separated only by the relativizer, and the SVO word order is maintained. By contrast, the filler- gap dependency between the fronted object and its gap must be computed across the intervening subject in object relatives, resulting in an OSV word order. The delayed acquisition of object relatives in young TD children and its impaired acquisition in DLD (e.g. Friedmann et al., 2009) could thus be attributed to the complex syntactic computations involved in the derivation of this structure, such as the creation of a long-distance dependency across an intervening subject, which require more time to master. Indeed, Friedmann et al. use a featural approach to the syntactic principle of Relativized Minimality⁵ (Rizzi, 1990, 2001, 2004, 2013) to argue that assigning thematic roles to noun phrases in structures such as (2) is more difficult when, en route to a preverbal position, a lexically-restricted object crosses over a featurally-similar subject, creating an intervention effect. This will be discussed in more detail in 2.1.2.

An important strength of a nativist approach that is firmly grounded in syntactic theory is that it can make precise predictions about the formal properties and structural operations that render a structure complex, and many of these predictions have been borne out in empirical studies (detailed in subsequent chapters). This approach, however, has little to say about the cognitive mechanisms that subserve these complex syntactic computations, despite the fact that numerous

5 Relativized Minimality (Rizzi, 2013) is a principle given by grammar that aids computational efficiency by reducing the span in which movement operations can occur in a particular structure. It is formulated as follows:

In the configuration …X…Z…Y, a local relation can hold between X and Y only if there is no Z such that a. Z is of the same structural type as X, and

b. Z intervenes between X and Y

A reformulation that defines similarity in terms of feature specifications will be defined in 2.1.2.

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studies have reported co-occurring limitations in general cognitive mechanisms, i.e. WM and attention, in individuals with syntactic impairment, such as children with DLD. In fact, according to Leonard (2014), reports of such nonlinguistic difficulties are “by now so commonplace that no theory of [DLD] can be truly comprehensive without taking them into account (p. 271)”. In the next section, I discuss cognitive approaches to language acquisition, which focus on the role of the environment and how this interacts with cognitive capacities to shape language development.

1.1.2 Perspectives from cognitive science

While nativists believe that infants are born with a language endowment that is unique with respect to other cognitive capacities, some cognitive scientists reject the notion that complex, nonlinguistic cognitive skills are absent in newborns, providing evidence from studies showing that at the perceptual or sensory level, neonates are predisposed to process complex information from all of their senses. For example, neonates can abstract regularities from nonlinguistic information, such as visual and tactile information, (e.g. Streri et al., 2013), with some arguing that young infants are capable of acquiring nonlinguistic analogues in a way that is similar to language acquisition. Thus, in sharp contrast to nativist theories, cognitive approaches to language acquisition, such as constructivist/usage-based models that are founded in the Piagetian tradition (e.g. Tomasello, 2009), highlight cognition, rather than a built-in, specialist module that is passed down by evolution, as the driving force behind language acquisition.

More specifically, subscribers to this school of thought, emphasizing the progressive, experience-dependent emergence of language, believe that language develops through a process of interaction between the environment and the concurrent maturation of a general cognitive system, and that it is driven by a child’s desire to use language for communicative purposes.

Such models are called constructivist or usage-based because children are seen as using their general and social-cognitive skills to build up an inventory of linguistic constructions through imitation of the language(s) they hear around them (Tomasello, 2000). Since language acquisition is assumed to interact closely with the gradual and dynamic development of other cognitive processes within these frameworks, individual differences in cognitive skills, such as WM and attention, should play a non-negligible role in language outcomes.

In what concerns atypical language development, constructivist/usage-based theories tend to dismiss the possibility of a neat dissociation between language and other cognitive capacities (for example, in children with DLD), as it is assumed that language is the product of a single,

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all-purpose learning device rather than a specialized language-learning system. Such theories have been bolstered by the observation that weakness in WM and attention are frequently found alongside language impairment in children with DLD (e.g. Kapa & Plante, 2015), and by a wave of empirical research reporting close links between the mastery of complex syntactic structures and increases in WM resources in both TD children (Delage & Frauenfelder, 2019;

Mateu, 2015; Montgomery, Magimairaj, & O’Malley, 2008; Willis & Gathercole, 2001; a.o.) and children with DLD (Delage & Frauenfelder, 2020; Durrleman & Delage, 2016; Frizelle &

Fletcher, 2015; Marinis & Saddy, 2013; Montgomery & Evans, 2009). These links are in line with the idea put forward by constructivists and usage-based linguists that developmental disorders pinpoint associations across domains rather than dissociations (Bishop, 2002), and provide researchers in this camp with fuel for their main argument, namely that the locus of breakdown in DLD is not situated in the language faculty but in a more general cognitive system. In particular, deficits in phonological (or verbal) WM are consistently reported crosslinguistically for children with DLD, so much so that poor performance on nonword repetition, a measure of phonological WM⁶, is now a commonly recognized clinical marker of the disorder (e.g. Conti-Ramsden, Botting, & Faragher, 2001). Additionally, some studies report more general WM deficits that are not limited to the verbal domain in children with DLD, as well as attention limitations (e.g. Finneran, Francis, & Leonard, 2009).

While processing limitations in children with DLD are empirically validated, there are some inherent problems with an approach that fully attributes the syntactic difficulties observed in DLD to a general impairment in cognitive capacities. As it has been adeptly pointed out (Botting

& Marshall, 2017; Filippi & Karmiloff-Smith, 2013; a.o.), if language is part of a general learning system in which all of the components interact, one would expect to find more widespread cognitive deficits from an earlier age in children who are later diagnosed with DLD, for example in the development of joint attention in infancy or of early nonverbal reasoning skills. While it is true that WM weakness is characteristic of the DLD profile, the presence of such broader limitations is not an essential clinical feature of the disorder. If syntactic development relies exclusively on cognitive capacity, one would expect intact WM to behave as a protective factor, moderating the effect of the language risk factor.

6 It should be noted that nonword repetition tasks have been criticized as measuring more than phonological WM as performance on such tasks may be influenced by factors such as lexical knowledge (Munson, Kurtz, & Windsor, 2005), phonotactic frequency (Coady, Evans, & Kluender, 2010) and phonological structure (Marshall & van der Lely, 2009).

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1.1.3 Combining perspectives: Divergent theories working together in a common enterprise

The two stances on language acquisition that have been described reflect very different ideologies: the nativist stance is rooted in formal linguistic theory while the constructivist stance has its origins in the tradition of developmental psychology. How does one adjudicate between these divergent views? As aptly pointed out by Frauenfelder and Delage (2013, p. 375), “the investigation of language acquisition is an interdisciplinary enterprise involving such disciplines as psycholinguistics, linguistics, cognitive psychology, anthropology and the neurosciences”. Bearing this in mind, is it possible to adequately describe a phenomenon that is as complex as language acquisition with a single-disciplinary perspective? One recalls the well-known metaphor of The Blind Men and the Elephant (depicted in Figure 1.1) that highlights a recurrent feature of research: large and multifaceted problems are approached from a limited angle with unintentional “blind spots”. The risk of such an approach is that a description bounded to a narrow standpoint can only offer a piecemeal account of the issue.

Examining a complex problem through a single lens does not do the phenomenon justice.

Figure 0.1. Source: Himmelfarb et al 2002: 1526 (artist: G. Renee Guzlas)

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One way to bring attention to potentially overlooked information and to obtain a more holistic perspective of language acquisition is to integrate expertise from various branches of research by using an interdisciplinary approach, as suggested by Frauenfelder and Delage (2013). In reality, nativist and constructivist/usage-based positions on language acquisition have rather more in common than what appears on the surface, with sharp divisions of labor becoming less clear cut. Many linguists firmly grounded in the nativist tradition acknowledge that cognitive capacities play a role in language acquisition. For example, Chomsky (2005, p. 12) writes, “It could be that unbounded Merge, and whatever else in involved in [Universal Grammar], is present at once, but only manifested in limited ways for extraneous reasons (memory and attention limitations and the like)”. Similarly, van der Lely (2005, p. 55) states, “Most researchers in the domain-specific camp would agree that both domain-general and domain- specific mechanisms are likely to contribute to specialized systems, such as syntax”. In the same vein, it is not uncommon for cognitive scientists, especially within the neuroconstructivist⁷ tradition, to accept the idea that language acquisition requires innate abilities. According to Newport (2011, p. 281), “Most nonmodularists, thanks to the profound importance of Chomsky’s work and its enormous impact on our field, believe that there are striking universal principles that constrain language structure and also that there are innate abilities of humans that are foundational for language acquisition and language processing”.

Recently, Botting and Marshall (2017) argued that one potential way forward would be to build on the strengths of nativist and constructivist/usage-based models in order to develop what could be viewed as a hybrid model of language acquisition. According to these authors (p. 153), in what concerns research on language acquisition and development, domain-specific approaches have the advantage of bringing “detailed analysis and a sense of careful measurement that is sometimes lacking in other work” while domain-general approaches “push a more empirical and developmental agenda [and] emphasize the fact that ‘pure’ impairments are somewhat of a misnomer”. Summarizing the main theoretical points of domain-specific and domain-general accounts (Table 0.1), Botting and Marshall propose three possible hybrid theories in what they have named a Parallel Combination Approach (PCA).

7 Neuroconstructivism refers to an approach in developmental psychology in which domain specificity is considered to gradually take place as domain-general functions become more modularized with time (Karmiloff- Smith, 1998, 2009).

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Table 0.1. Summary of the main points put forward by domain-specific and domain-general approaches to language acquisition. Source: Botting and Marshall (2017)

Domain-specific Domain-general Typical development (a) Individual cognitive skills

and language are modular⁸ from start

(c) Individual cognitive skills and language are built from domain-relevant but

generalized skills Atypical development (b)⁹ Specific impairments in

cognition and language are the result of an impaired or poorly encapsulated module

(d)¹⁰ Specific impairments in cognition and language are the result of a particular combination of inefficient domain-general skills

As the combination of (a) and (b) represents an exclusively domain-specific position and the combination of (c) and (d) represents that of the domain-general camp, these specific pairings are logically ignored when attempting to merge the two stances. The first hybrid option, Theory 1, combines (a) and (d) and describes a scenario in which language capacity is innate but fails to function efficiently (or is not properly triggered) in a system with significant limitations in more general cognitive skills. Theory 2, instead, combines (c) and (b) to create a neuroconstructivist picture in which language is initially part of a general cognitive system but gradually becomes domain specific in TD children. Within this conception of cognitive architecture, atypical development would be the result of inefficient modularization. Finally, Theory 3 combines all four possibilities. In this set-up, language is an innate, fast-tracked faculty (a) but is underpinned by general cognitive skills (c), such as WM or attention.

Limitations in these general skills (d) could have a knock-on effect on how linguistic information is modularized (b) or could occur comorbidly with modularization deficits. A third possibility, according to Botting and Marshall, is that a specific impairment in the modularization process exists and that weak (but not necessarily impaired) skills in (d) are not strong enough to protect against it.

8Although Botting and Marshall (2017) do not explicitly define what they mean by language being modular, I interpret it here along the lines of “demonstrating neural circuitry that is specialized for language”.

9 Botting and Marshall (2017) do not describe it as such, but I interpret (b) to indicate a computational (i.e. syntax) deficit.

10 I interpret (d) to indicate a processing (i.e. attention/WM) deficit.

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In addition to the obvious advantage¹¹ of uniting two influential approaches with unique merits, Botting and Marshall reason that the descriptive power of such a combinatory approach has the potential to help illuminate some of the key issues in the DLD literature, including but not limited to the questions of (i) heterogeneity in children with DLD and (ii) comorbidity of different deficits. For example, individuals who have been identified as demonstrating selective deficits in grammar may represent children with minor cognitive limitations and a main locus of impairment at (b). In this case, because general cognitive skills, such as WM and attention, are relatively unimpaired and can offer compensation for problems with modularization, language impairment is expected to be milder. Conversely, in children with comorbid deficits at (b) and (d), language impairment should be more severe.

1.1.3.1 The Derivational Complexity Hypothesis

Despite the conceivable ability of an integrated approach to propel research on DLD, frameworks that situate themselves between the two seeming poles (linguistic vs. cognitive) are rare. However, one could argue that one proposal that fits nicely into this relatively unexplored middle region is Jakubowicz’s (2004, 2005, 2011) Derivational Complexity Hypothesis (DCH), which aims to account for the syntactic impairment in DLD by linking domain-specific syntactic principles with domain-general behavioral variables. In the same vein as nativist theories, the DCH considers children to be biologically endowed for language, but the development of language, in particular syntax, is determined by a combination of factors, namely the computational complexity of a certain structure and the maturation of domain- general cognitive capacities. More specifically, structures with inherently less complex morphosyntactic properties emerge before those whose derivations require more complex operations, which are at least partially bound by an individual’s capacity to temporarily store and manipulate verbal information. According to the DCH, the preverbal merging of an object

11 There are also some obvious shortcomings to the PCA proposed by Botting and Marshall (2017). Firstly, if the locus of impairment in DLD can theoretically occur at (i) the more general processing level, (ii) the more specific computational level or (iii) both the processing and computational levels, and if all three cases result in similar outcomes (syntactic impairment), how does one tell apart children with DLD who fall into categories (i) and (iii)?

In both cases, one would expect to find general cognitive limitations and syntactic difficulties. Also, if the locus of breakdown is different, as would clearly be the case for (i) and (ii), does this truly constitute the same disorder?

Secondly, if general mechanisms underpin the efficient modularization of language, how does such an approach account for situations in which children demonstrate weakness in general cognitive skills but selectively spared syntax? This is the same question that has been often asked by nativists citing Williams syndrome as a flagship case of broad cognitive deficits with an intact grammatical system. While most researchers now accept that Williams syndrome is not the best example of this particular pattern of strengths and weaknesses (Brock, 2007), another disorder that may be better suited for the task is attention deficit hyperactivity disorder (discussed in more detail in Chapter5 and Chapter6). These remaining questions should be resolved in order for this approach to hold water.

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(as described in Section 1.1.1.1 and also referred to as object movement or object fronting) is an example of a complex syntactic operation that is costly for an immature cognitive system, with computational complexity being principally defined by the number of movement operations that may (or must) be performed in order to derive a particular structure according to Jakubowicz’s (2004, 2005, 2011) metric¹². Based on this metric, young TD children whose WM capacity is not fully developed will preferentially produce more economical structures with fewer movement operations, a prediction that fits with empirical data (discussed in the following chapters). This prediction also holds for older children with DLD whose WM capacity remains limited. Thus, the DCH can be considered an approach that integrates domain- specific and domain-general principles: general cognitive capacities have a role to play in a specialized language system as they are recruited to help develop domain-specific language predispositions.

While the DCH gives broader cognitive mechanisms a leading role in the development of syntax and assumes that the syntactic impairment observed in DLD is at least partially related to the underdevelopment of these mechanisms, it does not specify the precise details of this relationship. For example, within the DCH framework, it is not clear if the locus of the breakdown in DLD is at the processing level only (i.e. a WM deficit), or if more specific computational impairments are also characteristic of DLD (i.e. a joint deficit in both general and specialized mechanisms). However, the DCH, along with more tentative theories, such as the one put forward by Botting and Marshall (2017), has opened the door for researchers to apply elements from both formal linguistics and cognitive science to their work on language acquisition and development, as it is becoming increasingly recognized that mutual exclusivity between the two positions is unnecessary. Two studies adopting such a combined, integrative approach set the groundwork for what is presented in this dissertation, namely work conducted by Delage and Frauenfelder (2019, 2020) showing that multiple components of WM are not only linked to syntactic performance but also predict it in French-speaking children with and without DLD. These studies ultimately led to the writing of a federally funded research project that is at the core of my doctoral research and which aims to contribute to the investigation of the language-cognition relationship in various developmental disorders.

12 Derivational Complexity Metric (Jakubowicz, 2011):

a. Merging αi n times gives rise to a less complex derivation than merging αi (n + 1) times b. Internal Merge of α gives rise to a less complex derivation than Internal Merge of α + β

The language-cognition interface: Executive functions and syntax in atypical development

Thesis

Reference

The language-cognition interface: Executive functions and syntax in atypical development

THE LANGUAGE-COGNITION INTERFACE:

EXECUTIVE FUNCTIONS AND SYNTAX IN ATYPICAL DEVELOPMENT

Résumé

Summary

Acknowledgements

Preface

Table of Contents

List of Tables

List of Figures

List of abbreviations

C HAPTER 1

I NTRODUCTION