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Cypriot Greek Down syndrome : their grammar and its interfaces Christodoulou, Christa 2011

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CYPRIOT GREEK DOWN SYNDROME THEIR GRAMMAR AND ITS INTERFACES by Christa Christodoulou B.A., Aristotle University, Thessaloniki, 1999 M.A., University of Essex, 2000 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY in THE FACULTY OF GRADUATE STUDIES (Lingistics) THE UNIVERSITY OF BRITISH COLUMBIA (Vancouver)  August 2011  © Christa Christodoulou, 2011  Abstract This dissertation investigates the linguistic performance of 16 Cypriot Greek individuals diagnosed with Down Syndrome (henceforth, CGDS), aged 19;0 to 45;11, and compares their performance to 17 Cypriot Greek Typically Developing Children (hereafter, CGTDC), aged 7;0 to 8;11. Three hypotheses were tested to determine whether the differences between the two groups, as well as the Grammar of Cypriot Greek adults with typical development (henceforth, CGTD) were: (i) syntactically, (ii) morphologically, or (iii) phonetically and phonologically conditioned. When consulting previous research, a number of shortcomings were observed. Therefore, an innovative methodology was employed to address these issues. Contrary to previous research, which argues for an overall inflectional impairment (either syntactically or morphologically conditioned), this dissertation establishes that the vast majority of differences between the two groups are phonetically conditioned. These differences are due to the distinct physiology of the articulation apparatus in CGDS. Furthermore, a small number of phonologically conditioned differences were either due to (i) the phonological environment (syllable structure and word-position) or (ii) phonological feature underspecification. However, there is also a very small residue of differences that are morphologically conditioned. When a produced feature value does not match the target, CGDS and CGTDC exhibit the same three strategies: (i) use of an alternative feature value (as the default) to the targeted one, (ii) affix drop and (iii) full-word omission. I propose a unified analysis, according to which the morphological differences between CGDS, CGTDC and CGTD are due to a failure of Blocking. The competition between a phonetic exponent that includes (i) all feature values resulting from the syntactic derivation, and (ii) a subset of the features, but no contrasting features, fails to be resolved in favour of the most specified form. I further propose that this may ii  ABSTRACT be extended to phonological features. Finally, I propose that full-word and phoneme omissions suggest a problem with vocabulary or sound insertion, which may be rooted in phonological and verbal short-term memory limitations. In sum, I argue that the adult CGDS Grammar is not an impaired version of the adult CGTD Grammar.  iii  Preface Chapters 5, 6 and 7 are based on data collected from human participants: 16 Cypriot Greek individuals diagnosed with Down Syndrome (ages 19;0 to 45;11), and 17 Cypriot Greek typically developing children (ages 7;0 to 8;11). My application (File: H07-03130) to conduct experimental research on humans (Minimal Risk) was reviewed, by the Behavioural Research Ethics Board at the University of British Columbia on January 28, 2008. Final approval was granted on March 5, 2008, after all requirements were fulfilled and all certificates pertaining to my research were provided. As stated in the confidentiality agreement included in the consent form, for privacy purposes, the names of the participants are not used throughout the Dissertation. Instead, a Participant ID is used to refer to the production of a particular individual. Information on the participants’ Intelligence Quotient (IQ) is given in Appendix B, but once again a Participant ID was used to conceal the identity of participants.  iv  TABLE OF CONTENTS  Table of Contents Abstract ......................................................................................................................................... ii! Preface.......................................................................................................................................... iv! Table of Contents ........................................................................................................................v! List of Tables............................................................................................................................ xiii! List of Figures ........................................................................................................................ xviii! List of Graphs.............................................................................................................................xx! List of Features, Abbreviations and Conventions ........................................................... xxi! Acknowledgements .............................................................................................................. xxvi!  Chapter 1 - Introduction  ....................................................................................................1!  1.1! !Thesis ...................................................................................................................................1! 1.2! !The Significance of Inflectional Impairment in Down Syndrome .......................................3! 1.2.1!  Empirical Contributions ............................................................................................. 4!  1.2.2!  Methodological Contributions ................................................................................... 5!  1.2.3!  Analytical Contributions ............................................................................................ 7!  1.2.4!  Theoretical Contributions .......................................................................................... 8!  1.3! !Theoretical Tools for Testing the Hypotheses ...................................................................10! 1.4! !Overview of the Thesis ......................................................................................................11!  Chapter 2 - Literature Review........................................................................................16! 2.1! Introduction ........................................................................................................................16! 2.2! !Medical and Cognitive Profile of Down Syndrome ...........................................................17! 2.3! Phonetics and Phonology ...................................................................................................20! 2.3.1!  Articulation Difficulties of Down Syndrome .......................................................... 21! v  TABLE OF CONTENTS 2.3.1.1 !! Problems with Specific Sounds ............................................................................21! 2.3.1.2 !! Problems with Phonological Environments .........................................................22! 2.3.2!  Acquisition of Phonology and Phonetics in Typically Developing Children .......... 24!  2.3.3!  Summary .................................................................................................................. 27!  2.4! !The Morpho-syntactic Profile of Down Syndrome ............................................................27! 2.4.1!  English Down Syndrome ......................................................................................... 28!  2.4.2!  German Down Syndrome ........................................................................................ 31!  2.4.3!  Greek Down Syndrome............................................................................................ 33!  2.4.4!  Down Syndrome Studies on Other Languages ........................................................ 36!  2.4.5!  Summary .................................................................................................................. 37!  2.5! !Tense, S/V Agreement, and Case in Typical and Atypical Language Development .........38! 2.5.1!  Tense, S/V Agreement and Case in Typical Child Language Acquisition .............. 39!  2.5.1.1 !! Theories on Language Development....................................................................39! 2.5.1.2 !! Language Development in Greek Typically Developing Children ......................43! 2.5.2!  Language Development in Specific Language Impairment..................................... 45!  2.5.2.1 !! Specific Language Impairment ............................................................................46! 2.5.2.2 !! Studies and Analyses on Greek Specific Language Impairment .........................48! 2.5.3!  Language Development in Williams Syndrome ...................................................... 50!  2.6! What is the Significance of the Inflectional Impairment?..................................................52! 2.6.1!  Empirical Issues ....................................................................................................... 55!  2.6.2!  Methodological Issues ............................................................................................. 59!  2.6.3!  The Significance of Articulatory Limitations and Data Analysis ............................ 61!  Chapter 3 - Greek Morpho-Syntax ..............................................................................64! 3.1! !Introduction ........................................................................................................................64! 3.2! !Verbal Inflection: Tense and S/V Agreement .....................................................................65! 3.2.1!  Verbal Inflection in (Cypriot) Greek ....................................................................... 65! vi  TABLE OF CONTENTS 3.2.2!  Isolating Tense and S/V Agreement ......................................................................... 75!  3.2.2.1 Tense without S/V Agreement .............................................................................76! 3.2.2.2 !! S/V Agreement without Tense .............................................................................76! 3.3! !Nominal Inflection: Case and Agreement ..........................................................................83! 3.3.1!  The Features of Nominal Inflection in (Cypriot) Greek .......................................... 83!  3.3.1.1 !! Nouns ...................................................................................................................85! 3.3.1.2 !! Pronouns and Adjectives ......................................................................................85! 3.3.2!  Distribution of Nominal Inflection .......................................................................... 87!  3.3.2.1 !! Nominal Inflection within a DP ...........................................................................88! 3.3.2.2 Nominal Inflection with Nominal and Adjectival Predicates ..............................89! 3.4.! !Summary ............................................................................................................................89!  Chapter 4 - Methodology of Data Collection and Data Analysis ................91! 4.1! !Introduction ........................................................................................................................91! 4.2! !Participant Groups and Method of Recruitment ................................................................92! 4.3! !Procedure ............................................................................................................................94! 4.3.1!  Recording Equipment .............................................................................................. 95!  4.3.2!  Recording Procedure ................................................................................................ 95!  4.4! !Elicitation Methods ............................................................................................................96! 4.4.1  Experiment #1: Visual Stimuli................................................................................. 97!  4.4.1.1 !! Video I: Targeting the Use of Subjunctive, Present and Dependent ....................98! 4.4.1.2 !! Video II: Targeting Nominal Inflection and Main-Subordinate Constructions .102! 4.4.1.3 !! Video III: Targeting the Use of Past Tense ........................................................105! 4.4.2  Experiment #2: Repetition ..................................................................................... 109!  4.4.2.1 !! Experiment #2: Task I ........................................................................................109! 4.4.2.2 !! Experiment #2: Task II .......................................................................................114! 4.4.3  Experiment #3: Story Telling (Spontaneous Data) ................................................ 117! vii  TABLE OF CONTENTS 4.4.4  Experiment #4: Interview ...................................................................................... 119!  4.4.4.1 !! Experiment #4: Task I ........................................................................................119! 4.4.4.2 !! Experiment #4: Task II .......................................................................................121! 4.4.5  Summary ................................................................................................................ 122!  4.5 Transcription Analysis .....................................................................................................123! 4.6 Data Analysis and Database Setup ...................................................................................124! 4.6.1 ! General Information ............................................................................................... 124! 4.6.2 ! Constructing the Database ..................................................................................... 126! 4.6.3!  Column Contents ................................................................................................... 127!  4.6.4!  Tagging Conventions ............................................................................................. 128!  4.7! !Statistical Analysis ...........................................................................................................129! 4.8! !Summary ..........................................................................................................................132!  Chapter 5 - Phonetics and Phonology: Results and Analysis ......................133! 5.1! !Introduction ......................................................................................................................133! 5.2! !Consonant Omission ........................................................................................................135! 5.2.1!  Overview of Consonant Omissions ....................................................................... 135!  5.2.2!  Consonant Omissions Affecting Inflectional Features .......................................... 142!  5.3! !Consonant Substitution ....................................................................................................149! 5.3.1!  Overview of Consonant Substitutions ................................................................... 149!  5.3.2!  Substitutions Affecting Inflectional Features ........................................................ 165!  5.4! !Vowel Omission ...............................................................................................................170! 5.5! !Discussion ........................................................................................................................174! 5.5.1!  The Significance of Consonant Omissions with no Morpho-syntactic Effect ....... 176!  5.5.2!  The Significance of Consonant Omissions with Morpho-syntactic Effects .......... 177!  5.5.2.1 !! Disambiguating /t/ Omission..............................................................................177! 5.5.2.2 !! Disambiguating /s/ Omission .............................................................................179! viii  TABLE OF CONTENTS 5.5.2.3 !! Disambiguating /n/ Omission .............................................................................190! 5.5.3!  The significance of Consonant Substitutions with no Morpho-syntactic Effect ... 196!  5.5.4!  The Significance of Consonant Substitutions with Morpho-syntactic Effect ........ 197!  5.5.5!  The Significance of Vowel Omission .................................................................... 200!  5.6 Summary ..........................................................................................................................201!  Chapter 6 - Results on Morpho-Syntactic Features ..........................................203! 6.1! !Introduction ......................................................................................................................203! 6.2! !Overview ..........................................................................................................................205! 6.2.1!  Overall Performance .............................................................................................. 205!  6.2.2!  Evaluation of Produced Feature Values ................................................................. 210!  6.3! !Tense ................................................................................................................................214! 6.3.1!  Tense – Overall Performance................................................................................. 214!  6.3.2!  Productions of the Present Feature Value .............................................................. 220!  6.3.3!  Productions of the Past Feature Value ................................................................... 225!  6.3.4!  Productions of the Dependent Feature Value ........................................................ 229!  6.3.5!  Productions of the Imperative Feature Value ........................................................ 232!  6.3.6!  Summary on Tense Results.................................................................................... 235!  6.3.7!  Traditional Method of Analysis Evaluating Tense ................................................ 235!  6.4! !Subject - Verb Agreement ................................................................................................237! 6.4.1  Overall Results on Person - Number Combinations .............................................. 238!  6.4.2!  Person – Overall Performance ............................................................................... 241!  6.4.2.1 !! Productions of the First Person Feature Value ...................................................247! 6.4.2.2 !! Productions of the Second Person Feature Value ..............................................250! 6.4.2.3 !! Productions of the Third Person Feature Value .................................................253! 6.4.2.4!Summary ...............................................................................................................256! 6.4.3!  Number – Overall Performance ............................................................................. 256! ix  TABLE OF CONTENTS 6.4.3.1 !! Productions of the Singular Feature Value ........................................................260! 6.4.3.2 !! Productions of the Plural Feature Value ............................................................263! 6.4.3.3!Summary ...............................................................................................................266! 6.4.4!  Summary on S/V Agreement Results ..................................................................... 266!  6.5! !Case – Overall Performance .............................................................................................267! 6.5.1  Productions of the Nominative Feature Value ....................................................... 272!  6.5.2  Productions of the Accusative Feature Value ........................................................ 275!  6.5.3  Productions of the Genitive Feature Value ............................................................ 277!  6.5.4!  Productions of the Vocative Feature Value ........................................................... 280!  6.5.5!  Summary ................................................................................................................ 282!  6.6! !Overall Discussion and Comparison of CGDS and CGTDC ...............................................283!  Chapter 7 - Discussion and Theoretical Analysis ..............................................292! 7.1! !Introduction ......................................................................................................................292! 7.2 ! The Differences between CGDS and CGTDC are Phonetically, Phonologically, and Morphologically Conditioned .......................................................................................... 294! 7.2.1!  Differences are mainly Phonetically and Phonologically Conditioned ................. 295!  7.2.2!  Differences are not Syntactically Conditioned ...................................................... 296!  7.2.3!  Differences are partly Morphologically Conditioned ............................................ 307!  7.3! !Towards a Unified Analysis .............................................................................................309! 7.3.1!  Alternatives and the Role of Default Feature Values ............................................ 310!  7.3.2 Theoretial Background............................................................................................... 312! 7.3.2.1 !! Universal and Language Specific Defaults ........................................................313! 7.3.2.1.1 Universal Defaults: Number and Person .................................................... 313 7.3.2.1.2 Language Specific Defaults: Case.............................................................. 315 7.3.2.1.3 Morpho-syntactic Feature Geometry for Greek Nominal Phrases ............. 317 7.3.2.1.4 Language Specific Defaults: Tense ............................................................ 318 x  TABLE OF CONTENTS 7.3.3!  Optionality Derives from Failure of the Subset Principle to Fully Apply ............. 319!  7.3.3.1 !! Morpho-syntactic Features .................................................................................320! 7.3.3.2 !! Phonological Features ........................................................................................328! 7.3.3.3 !! Potential Alternative Analyses ...........................................................................349! 7.4 Conclusions, Predictions and Further Research ...............................................................355!  Bibliography .............................................................................................................................367! Appendices ...............................................................................................................................388! Appendix A - Chapter 3 - Specifics on Greek Morphology and Syntax ..................................388! A.1!  Verbal Inflection .................................................................................................... 389!  A.2!  Nominal Inflection ................................................................................................. 392!  A.3!  Adjectival Inflection .............................................................................................. 393!  A.4!  Phonetic Changes and Phonological Rules ............................................................ 393!  A.4.1! !! The Case of Final /n/ ..........................................................................................393! A.4.2! !! The Case of the Past Prefix e- ............................................................................394! Appendix B - Chapter 4 - Methodology ...................................................................................396! B.1!  Participants............................................................................................................. 396!  B.1.1! !! Down Syndrome Participants – Group A...........................................................396! B.1.2! !! Typically Developing Participants – Group B ...................................................397! B.2!  Experimental Stimuli ............................................................................................. 398!  B.2.1! !! Experiment #1 – Visual Stimuli: Video I – Video Clips Used as Stimuli .........398! B.3!  Column Contents – Example (a Set of Three Columns)........................................ 401!  B.4  Overall Evaluation of Productions (Entire Word) ................................................. 403!  B.4.1! !! No Change ..........................................................................................................403! B.4.2! !! Phonetic or Phonological Change ......................................................................404! B.4.3! !! Morpho-syntactic Change ..................................................................................405! B.4.4! !! Morpho-syntactic and/or Phonetic Change ........................................................406! xi  TABLE OF CONTENTS B.4.5! !! Affix Drop ..........................................................................................................408! Appendix C - Chapter 5 - Phonetics and Phonology Results ...................................................410! C.1  Overall Means - Across Group Comparisions for /s/ and /n/................................. 410!  C.2  Overall Means – Within Group Comparisions for /s/ and /n/ ................................ 411!  C.3.  Across Groups Comparisons for Potential Morpho-syntactic Effects ................... 413!  C.4.  Across Groups Comparisons for Purely Phonetic/Phonological Effects ............... 413!  C.5.  Overall - within Groups Comparisons for Potential Morpho-syntactic Effects .... 414!  C.6.  Overall - across Groups Comparisons for Potential Morpho-syntactic Effects ..... 416!  C.7.  Overall - across Groups Comparisons for Purely Phonetic/Phonological Effects . 417!  Appendix D - Chapter 6 - Morpho-Syntax Results ..................................................................418! D1.  Examples for Extra Evaluation Labels used for Data Evaluation.......................... 418!  D.2  Statistical Comparisions with Participants’ Means with only Alternative Use ..... 420!  D.3  Statistical Comparisions on Participants’ Omission: Overall Features ................. 421!  D.4  Inflectional Feature Values as Alternatives (with Gerund) ................................... 421!  D5.  Results on Inflectional Features, based on Experimental Tasks ............................ 422!  Appendix E - Chapter 7 – Discussion and Analysis .................................................................432! E.1!  Case Defaults in Greek – Diagnostic Tests............................................................ 432!  E.2!  Discussion on Unmarked Greek Case.................................................................... 436!  E.3!  Towards a Unified Analysis – Feature Underspecification ................................... 439!  E.3.1! !! Full P-EX Representation of Derived Feature Bundles ......................................439! E.3.2! !! Feature Bundles and Vocabulary Items for Neuter ............................................439! E.4!  Alternative Syntactic Analysis Based on Caha (2009) .......................................... 440!  xii  List of Tables Table 2.1: Probelmatic Phonemes and Phonological Environments for EngDS ............................ 23! Table 2.2: Phonetic Inventory of Greek Children (based on Mennen and Okalidou (2006)) ...... 25! Table 2.3: Analyses on Child Language Acquisition of Morpho-syntactic Features ................... 43! Table 2.4: Summary of Language Acquisition Stages by EngDS, EngSLI and EngTDC .................. 54! Table 2.5: English Inflectional Paradigm ..................................................................................... 57! Table 2.6: German Inflectional Paradigm ..................................................................................... 58! Table 3.1: Summary of Mood, Tense, S/V Agreement Environments.......................................... 79! Table 3.2: Greek vs. English Verbal Inflection ............................................................................ 82! Table 3.3: Definite Determiner – Inflectional Paradigm .............................................................. 85! Table 3.4: Nouns – Inflectional Paradigm .................................................................................... 85! Table 3.5: Personal Pronouns (Emphatic Forms) – Inflectional Paradigm .................................. 86! Table 3.6: Personal Pronouns (Clitic Forms) – Inflectional Paradigm ......................................... 86! Table 5.1: Distribution of Consonant Omission by CGDS and CGTDC........................................ 137! Table 5.2: Statistical Comparison of Consonant Omissions across Participant Groups............. 139! Table 5.3: Statistical Comparison of Consonant Omissions within Groups: CGDS.................... 140! Table 5.4: Statistical Comparison of Consonant Omissions within Groups: CGTDC .................. 141! Table 5.5: Distribution of /s/ Omission by CGDS and CGTDC ..................................................... 143! Table 5.6: Statistical Comparison of /s/ Omission across Participant Groups ........................... 144! Table 5.7: Statistical Comparison of /s/ Omission within Groups: CGDS .................................. 144! Table 5.8: Statistical Comparison of /s/ Omission within Groups: CGTDC................................. 145! Table 5.9: Distribution of /n/ Omission by CGDS and CGTDC .................................................... 146! Table 5.10: Statistical Comparison of /n/ Omission across Participant Groups ......................... 147! Table 5.11: Statistical Comparison of /n/ Omission within Groups: CGDS ................................ 147! Table 5.12: Statistical Comparison of /n/ Omission within Groups: CGTDC .............................. 147! Table 5.13: Distribution of Consonant Substitutions by CGDS and CGTDC ................................ 150! Table 5.14: Phoneme Substitutions with Consonants by CGDS and CGTDC ............................... 151! Table 5.15: Statistical Comparison of Consonant Substitutions across Groups ......................... 153! xiii  Table 5.16: Statistical Comparison of Consonant Substitutions within Groups: CGDS.............. 153! Table 5.17: Statistical Comparison of Consonant Substitutions within Groups: CGTDC ............ 154! Table 5.18: Distribution of /s/Substitutions by CGDS and CGTDC .............................................. 155! Table 5.19: Statistical Comparison of /s/ Substitutions across Participant Groups .................... 156! Table 5.20: Statistical Comparison of /s/ Substitutions within Groups: CGDS ........................... 156! Table 5.21: Statistical Comparison of /s/ Substitutions within Groups: CGTDC ......................... 156! Table 5.22: Non-Inflectional Phonetic Substitutions with /s/ across Word positions ................ 157! Table 5.23: Distribution of /n/ Substitution by CGDS and CGTDC .............................................. 159! Table 5.24: Statistical Comparison of /n/ Substitutions across Participant Groups ................... 160! Table 5.25: Statistical Comparison of /n/ Substitutions within Groups: CGDS .......................... 160! Table 5.26: Statistical Comparison of /n/ Substitutions within Groups: CGTDC......................... 160! Table 5.27: Non-Inflectional Phonetic Substitutions with /n/ across Word Positions ................ 161! Table 5.28: Sub-categorization of Phonetic Substitutions with /s/ Affecting Inflection ............ 165! Table 5.29: Distribution of /!/Omission by CGDS and CGTDC .................................................... 172! Table 5.30: Distribution of /s/ Omission in Terms of its Nature and Effects for CGDS ............. 180! Table 5.31: Statistical Comparison of /s/ Omission within Groups............................................ 181! Table 5.32: Statistical Comparison of /s/ Substitutions within Groups ...................................... 181! Table 5.33: Distribution of /s/ Omission in Terms of its Nature and Effects CGTDC ................. 182! Table 5.34: Statistical Comparison of /s/ Substitutions within Participant Groups.................... 182! Table 5.35: Statistical Comparison of /s/ Substitutions within Participant Groups .................... 183! Table 5.36: Distribution of /n/ Omission in Terms of its Nature and Effects CGDS ................... 191! Table 5.37: Statistical Comparison of /s/ Substitutions within Participant Groups .................... 192! Table 5.38: Statistical Comparison of /s/ Substitutions within Participant Groups .................... 192! Table 5.39: Distribution of /n/ Omission in Terms of its Nature and Effects CGTDC ................. 192! Table 5.40: Statistical Comparison of /s/ Substitutions within Participant Groups .................... 193! Table 5.41: Statistical Comparison of /s/ Substitutions within Participant Groups .................... 193! Table 5.42: Distribution of the Participants’ Use of the Vowel /!/............................................. 200! Table 6.1: Distribution of Overall Performance by CGDS and CGTDC........................................ 207! Table 6.2: Statistical Comparison of CGDS and CGTDC Overall Performance............................ 208! Table 6.3: Distribution of Overall Productions without Phonetic Analysis ............................... 209! Table 6.4: Confusion Matrix of Tense Production by CGDS and CGTDC .................................... 215! Table 6.5: Distribution of Tense Production with Verbs ............................................................ 216! xiv  Table 6.6: Distribution of Tense Production with Copulas and Auxiliaries ............................... 217! Table 6.7: Distribution of Verb Omissions Targeting Tense ...................................................... 219! Table 6.8: Distribution of Copula and Auxiliary Omissions Targeting Tense ........................... 219! Table 6.9: Statistical Comparison of Omissions Targeting Tense .............................................. 220! Table 6.10: Tense Use by CGDS and CGTDC – Target Based ...................................................... 236! Table 6.11: Distribution of Person– Singular Combinations on Verbs ...................................... 239! Table 6.12: Distribution of Person – Plural Combinations on Verbs ......................................... 240! Table 6.13: Confusion Matrix of Person Production on Verbs by CGDS and CGTDC ................. 242! Table 6.14: Distribution of Person Production on Verbs ............................................................ 243! Table 6.15: Distribution of Person Production on Copulas and Auxiliaries............................... 244! Table 6.16: Distribution of Verb Omissions Targeting Person .................................................. 245! Table 6.17: Copula and Auxiliary Omission Targeting Person .................................................. 245! Table 6.18: Statistical Comparison of Omissions Targeting Person .......................................... 246! Table 6.19: Confusion Matrix of Number Production on Verbs by CGDS and CGTDC............... 257! Table 6.20: Distribution of Number Production with Verbs ...................................................... 257! Table 6.21: Distribution of Number Production with Copulas and Auxiliaries ......................... 258! Table 6.22: Distribution of Verb Omission Targeting Number .................................................. 259! Table 6.23: Distribution of Copula and Auxiliary Omissions Targeting Number ..................... 259! Table 6.24: Statistical Comparison of Omissions Targeting Number ........................................ 260! Table 6.25: Confusion Matrix of Case Production by CGDS and CGTDC ................................... 268! Table 6.26: Distribution of Case Production .............................................................................. 269! Table 6.27: Distribution of Nominal Omissions Targeting Case ............................................... 271! Table 6.28: Statistical Comparison of Omissions Targeting Case ............................................. 271! Table 6.29: Distribution of Overall performance per Feature by CGDS and CGTDC ................... 283! Table 6.30: Distribution of Verbal, Copula and Auxiliary Omission by CGDS and CGTDC ....... 285! Table 6.31: Default Use of Verbal Tense, S/V Agreement and Case by CGDS and CGTDC ........ 288! Table 7.1: Summary of Most Frequent Alternative Value Productions by CGDS and CGTDC .... 311! Table 7.2: Default Case Environments for English, SG, CG and CGDS ..................................... 316! Table 7.3: Non-match Productions based on Target/Expected Forms ....................................... 326! Table 7.4: Place and Manner Specifications of Selected Obstruents.......................................... 331! Table 7.5: Confusion Matrix for Consonant Substitutions and Omissions by CGDS ................. 333! Table 7.6: Confusion Matrix for Consonant Substitutions and Omissions by CGTDC ............... 335! xv  Table A.1: The Standard Greek Inflectional Paradigm for the Two Verb Conjugations ........... 389! Table A.2: The Cypriot Greek Inflectional Paradigm for the Two Verb Conjugations ............. 390! Table A.3: The (Auxiliary) Verb ‘exo’ for SG and CG .............................................................. 391! Table A.4: The Copula Verb ‘ime’ for SG and CG .................................................................... 391! Table A.5: The Cypriot Greek Auxiliary .................................................................................... 391! Table A.6: Examples of Irregular Roots ..................................................................................... 391! Table A.7: Most Common Noun Endings – Masculine.............................................................. 392! Table A.8: Most Common Noun Endings -Feminine ................................................................. 392! Table A.9: Most Common Noun Endings -Neuter ..................................................................... 392! Table A.10: Inflectional Endings for Adjectives – all Genders .................................................. 393! Table B.1: Down Syndrome Participants.................................................................................... 396! Table B.2: Typically Developing Children Participants ............................................................. 397! Table C.1: Statistical Comparison -/s/ Omission across Groups (Overall Means) .................... 410! Table C.2: Statistical Comparison - /s/ Substitution across Groups (Overall Means) ............... 410! Table C.3: Statistical Comparison -/n/ Omission across Groups (Overall Means) ................... 411! Table C.4: Statistical Comparison -/n/ Substitution across Groups (Overall Means) ................ 411! Table C.5: CCV vs. CV Statistical Comparison -/s/ Omission: CGDS (Overall Means) ............ 411! Table C.6: CCV vs. CV Statistical Comparison - /s/ Omission: CGTDC (Overall Means) ......... 411! Table C.7: CCV vs. CV Statistical Comparison - /n/ Omission: CGDS (Overall Means) ........... 411! Table C.8: CCV vs. CV Statistical Comparison - /n/ Omission: CGTDC (Overall Means) ......... 412! Table C.9: CCV vs. CV Statistical Comparison -/s/ Substitution: CGDS (Overall Means) ........ 412! Table C.10: CCV vs. CV Statistical Comparison-/s/ Substitution: CGTDC (Overall Means) ..... 412! Table C.11: CCV vs.CV Statistical Comparison-/n/ Substitution: CGDS (Overall Means) ....... 412! Table C.12: CCV vs. CV Statistical Comparison-/n/ Substitution: CGTDC (Overall Means) ..... 412! Table C.13: Potential Morpho-syntactic Effects-/s/ Omission (Production-Omission) ............. 413! Table C.14: Potential Morpho-syntactic Effects -/s/ Substitution (Production-Substitution) .... 413! Table C.15: Potential Morpho-syntactic Effects - /n/ Omission (Production-Omission) ........... 413! Table C.16: Potential Morpho-syntactic Effects -/n/ Substitution (Production-Substitution) .... 413! Table C.17: Purely Phonetic/Phonological Effects - /s/ Omission (Production-Omission) ....... 413! Table C.18: Purely Phonetic/Phonological Effects - /s/ Substitution (Production-Substitution) 414! Table C.19: Purely Phonetic/Phonological Effects - /n/ Omission (Production-Omission) ....... 414! Table C.20: Purely Phonetic/Phonological Effects - /n/ Substitution (Production-Substitution) 414! xvi  Table C.21: Statistical Comparison - /s/ Omissions within Groups: CGDS (Overall Means) ..... 414! Table C.22: Statistical Comparison - /s/ Omissions within Groups: CGTDC (Overall Means) ... 414! Table C.23: Statistical Comparison - /s/ Substitutions within Groups: CGDS (Overall Means) . 415! Table C.24: Statistical Comparison - /s/ Substitutions within Groups: CGTDC (Overall Means) 415! Table C.25: Statistical Comparison - /n/ Omissions within Groups: CGDS (Overall Means) .... 415! Table C.26: Statistical Comparison - /n/ Omissions within Groups: CGTDC (Overall Means)... 415! Table C.27: Statistical Comparison - /n/ Substitutions within Groups: CGDS (Overall Means) 415! Table C.28: Statistical Comparison - /n/ Substitutions within Groups: CGTDC (Overall Means)415! Table C.29: Potential Morpho-syntactic Effects - /s/ Omission (Overall Means) ...................... 416! Table C.30: Potential Morpho-syntactic Effects - /s/ Substitution (Overall Means) .................. 416! Table C.31: Potential Morpho-syntactic Effects - /n/ Omission (Overall Means) ..................... 416! Table C.32: Potential Morpho-syntactic Effects -/n/ Substitution (Overall Means) .................. 416! Table C.33: Purely Phonetic/Phonological Effects - /s/ Omission (Overall Means) .................. 417! Table C.34: Purely Phonetic/Phonological Effects - /s/ Substitution (Overall Means) .............. 417! Table C.35: Purely Phonetic/Phonological Effects - /n/ Omission (Overall Means) ................. 417! Table C.36: Purely Phonetic/Phonological Effects - /n/ Substitution (Overall Means) ............. 417! Table D.1: Statistical Comparison: Alternative Use only on Overall Inflectional Features ....... 420! Table D.2: Statistical Comparison of Tense: Alternative Use only ............................................ 420! Table D.3: Statistical Comparison of Person: Alternative Use only .......................................... 420! Table D.4: Statistical Comparison of Number: Alternative Use only ........................................ 420! Table D.5: Statistical Comparison of Case: Alternative Use only.............................................. 421! Table D.6: Statistical Comparison: Omission on Overall Inflectional Features ......................... 421! Table D.7: Default Use of Verbal Tense, S/V Agreement and Case (Includes Gerund) ............ 421! Table D.8: Tense, S/V Agreement and Case Performance for Experiment #1 – Video I ........... 423! Table D.9: Tense, S/V Agreement and Case Performance for Experiment #1 – Video II .......... 424! Table D.10: Tense, S/V Agreement and Case Performance for Experiment #1 – Video III ...... 425! Table D.11: Tense, S/V Agreement and Case Performance for Experiment #2 – Task I ........... 426! Table D.12: Tense, S/V Agreement and Case Performance for Experiment #2 – Task II .......... 427! Table D.13: Tense, S/V Agreement and Case Performance for Experiment #3 – Task I ........... 428! Table D.14: Tense, S/V Agreement and Case Performance for Experiment #3 – Task II .......... 429! Table D.15: Tense, S/V Agreement and Case Performance for Experiment #4 – Task I ........... 430! Table D.16: Tense, S/V Agreement and Case Performance for Experiment #4 – Task II .......... 431! xvii  List of Figures Figure 2.1: Trisomy of Chromosome 21....................................................................................... 18! Figure 4.1 – Video Clip 1: Example B – Video II ........................................................................ 99! Figure 4.2 –Video Clip 2: Example B – Video I .......................................................................... 99! Figure 4.3 –Video Clip 3: Introducing the Characters (I) ........................................................... 101! Figure 4.4 –Video Clip 4: Introducing the Characters (II) ......................................................... 101! Figure 4.5 –Video Clip 5: Video II – Example A ....................................................................... 103! Figure 4.6 –Video Clip 6: Video II – Example B ....................................................................... 104! Figure 4.7 – Video Clip 7: Video III – Example A .................................................................... 107! Figure 4.8 –Video Clip 8: Video III – Example B ...................................................................... 107! Figure 4.9: Example of Word Tagging in the Database ............................................................. 125! Figure 7.1: Morpho-syntactic Feature Geometry (Harley and Ritter 2002) ............................... 314! Figure 7.2: Morpho-syntactic Feature Geometry for Greek Nominals....................................... 317! Figure B.1: Video Clip 1: Example A ...................................................................................... 398 Figure B.2: Video Clip 2: Example B......................................................................................... 398! Figure B.3: Video Clip 3 - Introductions ................................................................................... 398 Figure B.4: Video Clip 4 - Introductions ................................................................................... 398! Figure B.5: Video Clip 5 - Introductions ................................................................................... 411 Figure B.6: Video Clip 6 - Introductions .................................................................................... 399! Figure B.7: Video Clip 7 – Experimental Stimulus 1 ................................................................. 399! Figure B.8: Video Clip 8 – Exp. Stimulus 2 .............................................................................. 399 Figure B.9: Video Clip 9 – Exp. Stimulus 3 ............................................................................... 399! Figure B.10: Video Clip 10 – Exp. Stimulus 4 ......................................................................... 399 Figure B.11: Video Clip 11 – Exp. Stimulus 5 ........................................................................... 400! Figure B.12: Video Clip 12 – Exp. Stimulus 6 ......................................................................... 400 Figure B.13: Video Clip 13 – Exp. Stimulus 7 ........................................................................... 400! Figure B.14: Video Clip 14 – Exp. Stimulus 8 ……………………………………………. …..400  xviii  LIST OF FIGURES Figure B.15: Video Clip 15 – Exp. Stimulus 9 ........................................................................... 400! Figure B.16: Video Clip 16 – Exp. Stimulus 10 ........................................................................ 400 Figure B.17: Video Clip 17 – Exp. Stimulus 11 ......................................................................... 401! Figure B.18: Video Clip 18 – Exp. Stimulus 12 ......................................................................... 401 Figure B.19: Video Clip 19 – Exp. Stimulus 13 ......................................................................... 401!  xix  List of Graphs Graph 6.1: Comparison of Overall Production with and without Phon. Analysis ......................... 209! Graph 6.2: Distribution of Present Verbal Inflection by CGDS and CGTDC .................................. 221 Graph 6.3: Distribution of Present Copula by CGDS and CGTDC ................................................... 221! Graph 6.4: Distribution of Past Verbal Inflection by CGDS and CGTDC ........................................ 226! Graph 6.5: Distribution of the Dependent Value by CGDS and CGTDC .......................................... 229! Graph 6.6: Distribution of the Imperative Value by CGDS and CGTDC .......................................... 232! Graph 6.7: Distribution of 1st Person Inflection by CGDS and CGTDC ........................................... 247! Graph 6.8: Distribution of 2nd Person Inflection by CGDS and CGTDC .......................................... 250! Graph 6.9: Distribution of 3rd Person Verbal Inflection by CGDS and CGTDC ............................... 253! Graph 6.10: Distribution of Singular Verbal Inflection by CGDS and CGTDC ............................... 261! Graph 6.11: Distribution of Plural Verbal Inflection by CGDS and CGTDC ................................... 263! Graph 6.12: Distribution of Nominative Inflection by CGDS and CGTDC ...................................... 272! Graph 6.13: Distribution of Accusative Inflection by CGDS and CGTDC ....................................... 275! Graph 6.14: Distribution of Genitive Inflection by CGDS and CGTDC ........................................... 277! Graph 6.15: Distribution of Vocative Inflection by CGDS and CGTDC .......................................... 280!  xx  List of Features, Abbreviations and Conventions I.  GLOSSING – INFLECTIONAL FEATURES AND FUNCTION WORDS  ACC  =  Accusative  GEN  =  Genitive  NOM  =  Nominative  VOC  =  Vocative  PRES  =  Present  PAST  =  Past  DEP  =  Dependent  FUT  =  Future  PL  =  Plural  SG  =  Singular  SG/PL  =  Singular or Plural  1/1st  =  1st Person  2/2nd  =  2nd Person  3/3rd  =  3rd Person  IMPF  =  Imperfective  PRF  =  Perfective  FEM  =  Feminine  MASC  =  Masculine  NEU  =  Neuter  SUBJ  =  Subjunctive  IMP  =  Imperative  OPT  =  Optative xxi  LIST OF FEATURES, ABBREVIATIONS AND CONVENTIONS OPT  =  Optative  NEG  =  Negation  PREP  =  Preposition  CONJ  =  Conjunction  II.  PHONOLOGICAL FEATURES  Cons  =  Consonantal  Contin  =  Continuant  Sonor  =  Sonorant  Spread gl  =  Spread glottis  III.  ABBREVIATIONS FOUND IN TEXT  AGR  =  agreement  AgrP  =  agreement Phrase  AgrSP  =  agreement Subject Phrase  ATOM  =  agreement/Tense Omission Model  CHAT  =  CHILDES format for transcription and coding  CHILDES  =  Child Language Data Exchange System  CGDS  =  Cypriot Greek individuals diagnosed with Down Syndrome  CGTDC  =  Cypriot Greek Typically Developing Children  CGTD  =  Cypriot Greek adults with Typical Development  CG  =  Cypriot Greek  CP  =  Complementizer Phrase  CV  =  Consonant-Vowel  CVC  =  Consonant-Vowel-Consonant  (C)CVC  =  (Consonant-)Consonant-Vowel-Consonant  D  =  Determiner  DET  =  Determiner  DP  =  Determiner Phrase  DS  =  Down Syndrome  EngDS  =  English individuals diagnosed with Down Syndrome xxii  LIST OF FEATURES, ABBREVIATIONS AND CONVENTIONS EngSLI  =  English individuals diagnosed Specific Language Impairment  EngTD  =  English adults with Typical Development  EngTDC  =  English Typically Developing Children  EOI  =  Extended Optional Infinitive Hypothesis  FS  =  False start or stuttering  GerDS  =  German individuals diagnosed with Down Syndrome  GerTDC  =  German Typically Developing Children  GreekDS  =  Greek individuals diagnosed with Down Syndrome  GreekSLI  =  Greek individuals diagnosed Specific Language Impairment  GreekTD  =  Greek adults with Typical Development  GreekTDC  =  Greek Typically Developing Children  GreekWS  =  Greek individuals diagnosed with Williams Syndrome  IIH  =  Inflectional Impairment Hypothesis  INF  =  Infinitive  INFL  =  Infinitival  IP  =  Inflectional Phrase  IQ  =  Intelligence Quotient  ItDS  =  Italian individuals diagnosed with Down Syndrome  ItSLI  =  Italian individuals diagnosed with Specific Language Impairment  ItTDC  =  Italian Typically Developing Children  NC(X)  =  Category of noun, adjective, determiner, pronoun, etc. The Subscript  C  followed by a Latin numeral indicates the nominal class a noun or adjective belongs to. X marks the relevant given Inflectional class. NP  =  Noun Phrase  OI  =  Optional Infinitive  P-EX  =  Phonetic exponent (phonological representation of morpho-syntactic features)  PhI  =  Productions with phonetic (or phonological) issues affecting inflectional features  PP  =  Prepositional Phrase  P-SEG  =  Phonological Segment  RDBMS  =  DataBase Management System xxiii  LIST OF FEATURES, ABBREVIATIONS AND CONVENTIONS SLI  =  Specific Language Impairment  SG  =  Standard Greek  SGTD  =  Standard Greek Typical Developing Adults  Subj  =  Subjunctive  S/V agreement =  Subject/Verb agreement  TP  =  Tense Phrase  TD  =  Typically Developing  UG  =  Universal Grammar  V  =  Vowel  VC  =  Vowel-Consonant  VP  =  Verb Phrase  IV.  ABBREVIATIONS  AND  CONVENTIONS  FOUND IN  TABLES  AND  FIGURES (OTHER  THAN  THE ONES MENTIONED ABOVE)  %  =  Percentage  !  =  Omission of a word or phoneme/sound  " use  =  Feature use (only for a specific feature value)  Alt  =  Alternative Use (Use of a form other than the one targeted or expected based on the experimental stimulus or experimental target)  Alternative  =  Use of a form other than the one targeted or expected based on the experimental stimulus or experimental target  Alternative INC % = Percentage of incorrect Productions based only on the use of a feature values as an alternative to other feature values Aug  =  Augment (Past Prefix)  CGDS Gl %  =  Global Use (includes every utterance produced by CGDS)  CGTDC Gl %  =  Global Use (includes every utterance produced by CGTDC)  CGDS Prod % =  CGDS productions (excluding omissions, incomplete utterances and fillers)  CGTDC Prod % =  CGTDC productions (excluding omissions, incomplete utterances and fillers)  CI (or other)  =  Inflectional paradigms a nominal belongs to, based on Ralli (1998)  COR %  =  Percentage of correct Productions xxiv  LIST OF FEATURES, ABBREVIATIONS AND CONVENTIONS Gl %  =  Calculated based on percentage of global use (the production of every single utterance targeted– whether a full word, incomplete utterance or fillers)  Global  =  Overall use of a specific feature or feature value regardless of whether it was produced as targeted or as an alternative to another feature value, based on the experimental task  Global INC % =  Percentage of incorrect Productions based on the participants’ overall production of a specific feature of feature value  INC %  =  Percentage of incorrect Productions  LF  =  Logical Form  Match  =  Use of a form as targeted or expected based on the experimental stimulus or experimental target)  N  =  Number of Tokens  NM  =  Non-Match (produced utterances which did not match the target)  NM %  =  Percentage of Non-Match (percentage of produced utterances which did not match the target)  Obg  =  Obligatory  Opt  =  Optional  Overall Performance = the production of every single utterance targeted– whether a full word, incomplete utterance of a filler PF  =  Phonetic Form  Prod%  =  Production Percentage (overall productions excluding omissions and incomplete utterances or fillers  V.  TRANSCRIPTION CONVENTIONS  //  =  Underlying phonological form of a phoneme  []  =  Actual production of a phoneme  !  =  Omission  ()  =  Optional  xxv  Acknowledgements At the age of 14, I was first faced with the dilemma of what career I wanted to pursue. I responded with an approximate description of the qualifications needed to be a (neuro)linguist, but I was told that the goals I was setting for the future were unrealistic and I should try to think of a more conventional profession like a doctor, a teacher or a lawyer. This dissertation is an answer to those who questioned that anything is possible. Thank you for the motivation you gave me to prove otherwise. I owe a huge debt of gratitude to everyone who took part in the study; thanks to the CGTD children and their parents, who were extremely cooperative, and thanks to the CGDS, who welcomed me with open arms and incredible willingness to “help me help them out”, as some of them put it. Their love, warmth, and readiness to participate in this research study made the process of data collection much easier than I could have ever imagined. I would also like to thank the authorities and personnel of the Foundation, where the CGDS participants were tested, for being so accommodating, and allowing me to conduct research on their premises. Thanks to the Behavioural Research Ethics Board at the University of British Columbia, and the Cyprus Ministry of Education and Culture which granted approval of the research, as well as the Elementary school for assisting with the selection of participants and contacting the parents of potential participants. I owe a huge debt of gratitude to everyone on my supervisory committee. Thanks to Jessica De Villiers for making sure that the experimental part of the research and data analysis were clear and comprehensible. Thanks to Joseph Stemberger for encouraging me to pursue a phonological analysis in addition to the phonetic and morpho-syntactic one, which led to the discovery of facts about Down Syndrome (and perhaps UG) that no other study in the past has ever addressed. I also thank him for always responding promptly to my panic emails. Last but certainly not least, I would like to thank my supervisor Martina Wiltschko, the most extraordinary supervisor anyone could ever have. It was the excitement in her eyes every time I went to her with a new piece of xxvi  fascinating data that kept me going. She has been my mentor, my best friend, my sister, my mother, my counsellor, the person I wanted to make proud, more than anyone else. I feel I have gained more than I could ever say from having the privilege of working with her. She is perhaps the only person I know who fulfills the role of !"!#$%&'(). Thanks to my external examiner Prof. Tom Roeper for his insightful comments and questions on my research and analysis. I hope I was able to address them in the best possible way. Also, thanks to the two university examiners, Prof. Geoff Hall and Dr. Carla Hudson for their invaluable comments and advice, especially on the statistical analysis. Thanks to Prof. Kenneth Wexler for the intellectually stimulating and challenging conversation on this research’s data and results. I would like to thank all of my professors at UBC over the years. Thanks to Henry Davis Bryan Gick, Gunnar Ólafur Hansson, Lisa Matthewson, Hotze Rullmann and Eric Vatikiotis Bateson, for teaching me the value of global linguistic knowledge and Guy Carden, Rose-Marie Déchaine, Carla Hudson, Michael Rochemont, Patricia Shaw, Molly Babel for teaching me something important about their respective fields over the years. Thanks to Penolope Bacsfalvi for her encouraging words and useful comments and information on EngDS. Thanks to the Post Doctoral Fellows Emily Curtis and Matthew Bauer, who encouraged my interest with Cypriot Greek phonetics and phonology, and Susannah Kirby, for our long discussions on child language acquisition. Thanks to my two Grad advisors while at UBC: Douglas Pulleybank for being an excellent Grad advisor and for our interesting discussion on the phonological analysis pursed in Chapter 7, and Bryan Gick for being the caring person that he is, for not letting me quit on my second year, when I wanted to do everything at the speed of light, and for his help with phonetic issues over the years. Financially, I was supported by the Canadian Commonwealth Scholarship Program (Ministry of Foreign Affairs and International Trade, Canada) with a four-year Doctoral Fellowship. I would like to thank the Canadian Bureau for International Education (CBIE), especially my program advisor, Ms. Diane Cyr, who did not only take care of all the administrative issues for me, but was also there when I needed a friend. I am also extremely grateful to Jessica De Villiers, Joseph Stemberger and Martina Wiltschko for their financial support towards the last stages of my Doctorate. Also, thanks to the Canadian Order of American Hellenic Educational Progressive xxvii  Association (AHEPA) District #26 for honouring me with the 2009 Award for Academic Excellence. A number of people have generously contributed their services, time and advice on technical and analytical issues. First, thanks to Strang Burton, who helped me with ideas for experimental testing and contributed some of his valuable time in helping me substantialise those ideas, but mostly for advising me to import my data into a Relational DataBase Management System (RDBMS). I would like to thank Donald Derrick and Anita Szakay for their help with Statistics prior to the Doctoral examination. I would also like to thank Nadya Modyanova for all her time and help with the post-defence statistical analysis. Lena Patsa is one of the people without whom the completion of my data analysis would have taken twice as long. She generously contributed her time to help me construct a database for my research data and patiently taught me how to use the software. Thanks to my “models” (Katie Calloway, Laura Estrata and Kyle Harland), who helped me create the experimental stimuli for Experiment #1 by patiently posing for me. Last but certainly not least I would like to thank Dan Bewley (a.k.a. problem solver) for all his help with Excel, in organising my data and results and answering my endless computer-related questions. Managing Excel would have been even harder without his promptness and willingness to help. On a personal and professional level, there were a few people who made this journey more tolerable. First and foremost, I would like to thank Solveiga Armoskaite for being the best my officemate I could ever ask for. I will never forget our quite unconventional discussions (about linguistics, the paranoia of research, and other issues) during our short breaks and our late night walks home from the Department. Thanks to Sonja Thoma for teaching me a million things, but most of all for teaching me that you mosly learn by asking questions and that human beings have immense strength to help them “recover” and move on, but are able to use it only if they chose to do so. Thanks to Amelia Reis Silva, for making me laugh and for sometimes boosting my selfesteem when all I saw was a dead end. Also thanks to Jennifer Glougie; she has often given me kind words of encouragement and for proof-reading my dissertation. She has been an excellent friend over the years. Thanks to my academic family, the Thesis Anonymous group: Solveiga Armoskaite, Mike Barrie, Heather Bliss, Peter Jacobs, Atsushi Fujimori, Olga Steriopolo, Sonja Thoma, James Thompson. They have been my greatest source of interesting and challening xxviii  ideas, questions and comments on my research, as well as support, and encouragement over the past three years. I thank each of them for different reasons: Atsushi for always inspiring me think or look deeper and see things from a different perspective/angle, Heather for always inspiring me to do better, James for his funny remarks, laid back style, great questions and great hugs, Olga for listening, and talking at the right moment, Peter for his sensibility and encouragement, Mike for all the helpful ideas and comments on syntactic issues, Solveiga for making me feel that I am not alone and for being one of my greatest sources of reflection, and Sonja for her many interesting questions. I would also like to thank my colleagues Martin Oberg, and Hudu Fusheini, who along with Sonja Thoma helped me survive the first two years of coursework (a.k.a. UBC Linguistics boot-camp) with lots of team-work, support and respect for one another. Thanks to everyone else who shared the experience with me, with whom I shared intellectually stimulating discussions: Ruby Arkoh, Jason Brown, Marion Caldecott, Carrie Gillon, Mario Chávez-Peón, Seok Koon Chin, Chen-Hao Chiu, Joel Dunham, Elizbeth Ferch, Rafael Girard, Hannah Greene, Analia Gutiérrez, Yoko Ikegami, Kristin Johannsdottir, Masaru Kiyota, Karsten Koch, Patrick Littell, John Lyon, Calisto Mudzingwa, Tyler Peterson, Beth Rogers, Murray Schellenberg, Mark Scott, Carmella Towes, Ryan Waldie, and Noriko Yamane. There is not really enough to say about the Department Administrator, the kind-hearted Enda Dharmaratne, who has been my mum since I moved to Vancouver and always had a word of kindness and encouragement for everyone who found their way into her office. All I can say is that I have never met a person who is so capable of solving any emergency or any problem she is presented. Finally, there was a group of people outside of linguistics, who played a vital role in me staying sane throughout this process. I owe a huge debt of gratitude to my dear parents Maria and Niko, who supported me throughout this journey, even though they still have no idea what I am doing any why. Thanks to my sister Dora and my brother Costa who, along with their families, tried to the best of their abilities to make me feel that I was never alone and dealt with a number of administrative issues on my behalf. Thanks to my little Stylianos, who makes me feel that the word *(+*& (‘godmother’ in CG, produced clearly at 13 months!) could never sound so sweet! It is really hard to express my gratitude to those who were there for me and helped me stay strong and sane every step of the way, who listened to me and argued with me, who stayed up late to xxix  listen to all my data analysis problems and cared enough to pay attention when I talked about my work. These people were my second family in Vancouver and without them I have no idea how different things would be. I would like to thank Vanora Miller, Alexandra Moreno, Andres Varhola, Ruth Moreno, and Thomas Beckman, for always being my fun group, trying to drag me out of my cave and into a more relaxing, laid back lifestyle. Sorry for disappointing you most of the time, but thank you for never giving up. Especially, thanks to Ale and Vanora, who always had an interesting way of putting things into perspective and for the most sane-insane conversations I have ever had. Thanks to Jaclyn and Scott Widenmaier, Katie Calloway, David Bergeron, Laura Estrata and Andrew Hill for some of the most valuable and meaningful friendships I have ever had. I would like to also thank my “Greek family” in Vancouver: Georgios Giannelis, Diomidis Michalopoulos, Lena Patsa and Andreas Sotirakopoulos. Thanks for the words of encouragement, love, and support, for always caring and being willing to help, for the most amazing road-trips and best homemade pizza I have ever had in my life. Last, but not least, there is someone who has always been there for me and there are hardly any words to express my love and gratitude. Thanks to Dan Bewley for offering me every possible help and positive emotion a human being is capable of, without thinking twice. Without him, I doubt I would have been able to complete this work. In the moment of crisis, he was always levelheaded to keep me sane and calm. In the moment of happiness he was there to celebrate with me. In difficult moments he was there to support me and keep me safe. I feel blessed to have him in my life, especially through the most difficult journey, I had to complete so far, ,-* ./0%- µ(1.  xxx  To my family (for all their support)  and To my mentor (for believing in me)  xxxi  Chapter 1  Introduction  1.1  THESIS  The goal of this dissertation is to examine the linguistic performance of Cypriot Greek individuals diagnosed with Down Syndrome (henceforth, CGDS). Previous research has reported that English individuals diagnosed with Down Syndrome (henceforth, EngDS) use Tense1 and Subject/Verb (hereinafter, S/V) agreement differently than English Typically Developing (hereinafter, EngTD) adults and children (Laws and Bishop 2003, Eadie et al. 2002, Chapman and Hesketh 2000, Chapman et al. 1998, inter alia).2 This difference in use is generally taken to indicate impairment of the inflectional system, and I will refer to it as the Inflectional Impairment Hypothesis (henceforth, IIH). In this dissertation, I investigate whether the same is also true for CGDS adults; namely, whether CGDS adults also display inflectional impairment and if so what the conditioning factors are. I will test three hypotheses to determine what conditions the differences between CGDS adults and 7- to 8-year old Cypriot Greek Typically Developing Children (henceforth, CGTDC): I.  The differences in the production of the inflectional system are morphologically conditioned  II.  The differences in the production of the inflectional system are syntactically conditioned  1  When referring to inflectional features, words are capitalised. No extensive/substantial study of Case marking in Down Syndrome (henceforth, DS) is available to date. 23 From this point forward study I will of refer to marking these grammatical differences as the CGDS Grammar; the to term not actually No extensive/substantial Case in Down Syndrome (henceforth, DS) is available date. 2  1  CHAPTER 1 – INTRODUCTION III.  The differences in the production of the inflectional system are phonetically and phonologically conditioned.  Naturally, the possibility remains that differences between the two groups are a result of a combination of factors.  Note that the source of the hypothesised impairment (morphology, syntax, or phonology) cannot be determined on the basis of previous work. This is due to several factors. First, previous analyses lack extensive morphological, syntactic, phonetic and phonological analyses of the experimental results. Second, the majority of the existing studies are conducted on EngDS where poor morphology limits the testing ground. Finally, factors, external to morpho-syntax, are not controlled for. In this dissertation, I will show that the differences found between the CGDS and Cypriot Greek adults with Typical Development (henceforth, CGTD) result from: (i) mainly articulatory and phonological restrictions associated with Down Syndrome (hereafter, DS), (ii) use of default forms, and (iii) restrictions with vocabulary insertion. This leads me to conclude that the so-called inflectional impairment is not due to a defective Grammar, but instead points towards a different realisation of some grammatical aspects of the CGTD Grammar.3  In the remainder of this chapter I give an overview of this Thesis. In Section 1.2, I explain the motivations for this research and list the contributions of the current study to the fields of Linguistics, Neurolinguistics, and Speech-Language Pathology, as well as research on DS in general. In Section 1.3, I discuss the background on which the three hypotheses are evaluated. Finally, I give a brief summary of each chapter (Section 1.4). I conclude with a final note on what makes this research different from previous work and discuss avenues for future research.  3  From this point forward I will refer to these grammatical differences as the CGDS Grammar; the term not actually meaning a different Grammar per se, but rather differences with certain grammatical functions analysed and discussed throughout this dissertation.  2  CHAPTER 1 – INTRODUCTION  1.2  THE  SIGNIFICANCE  OF  INFLECTIONAL  IMPAIRMENT  IN  DOWN  SYNDROME The main characteristic of the hypothesised impairment (IIH) is affix drop, i.e. the optional realisation of inflectional marking. The core question I address in this dissertation is, whether the adult CGDS productions can indeed be characterised by and inflectional impairment, and if they can, what conditions this hypothesised inflectional impairment in DS?  A question to ask is whether the alleged impairment is specific to Tense and S/V agreement or whether it affects all types of inflection? A review of the existing literature is not conclusive. For instance, Ring and Clahsen (2005) show problems with inflectional morphology (including optional inflection of Tense-marking, Comparative and Plural marking). In contrast, Eadie et al. (2002) report problems with verbal inflection (Tense and S/V agreement), especially regular Past inflection –ed, but no problems with plurals and the gerund. A study by Laws and Bishop (2003) reports accurate use of Tense (regular and irregular), but problems with 3rd Person Singular. Moreover, while Chapman and Hesketh (2000) argue for an overall inflectional impairment, Eadie et al. (2002) find minimal problems (approximately 20%) with Plural, -ing, determiners and the possessive. Moreover, results appear to differ across languages; while the above studies report that inflectional impairment in EngDS affects both Tense and S/V agreement, SchanerWolles (2004) shows that German DS (henceforth, GerDS) surpass 98% accuracy in their use of S/V agreement. If this is indeed the case, then we may conclude that DS has different effects, depending on the target language, and perhaps the choice of experimental methods and stimuli.  3  CHAPTER 1 – INTRODUCTION 1.2.1 Empirical Contributions CGDS allows us to test the three hypotheses concerning the nature of the hypothesised inflectional impairment. Three types of inflectional marking (the inflectional features of Tense, Person and Number (making up S/V agreement) for verbs and Case for nominal expressions) are examined in a variety of environments with all possible feature combinations. We observe that in case one type of inflection is not used as targeted (e.g. Tense), we do not necessarily see a simultaneous effect on the other types of inflection (S/V agreement and Case). Having examined a considerable number of factors external to morpho-syntax, like surrounding structure, elicitation methodology, and phonetic and phonological effects, the CGDS Grammar and its interfaces (i.e., articulatory restrictions and vocabulary insertion) cannot be characterised by a general impairment of their inflectional system. Rather, it appears that inflection is in fact not impaired at all. This raises the question as to what is responsible for the differences between the adult CGDS on the one hand and adult and child CGTD productions on the other hand. I show that these differences are mostly due to articulatory restrictions and a different phonological system found in DS. In particular, the articulatory restrictions lead to different pronunciations of various inflected forms. The difference in pronunciation (either phoneme omission or substitution) causes the produced form to be homophonous with another form with different inflectional features. Thus, to a large extent the apparent inflectional impairment is phonetically and phonologically conditioned.  There is however a residue of cases (approximately 12% for Tense, 5% for Person, 3.5% for Number and 3% for Case for CGDS), which cannot be accounted for in this way. These percentages consist of forms that exhibit a systematic use of an alternative form across all CGDS participants. I argue that these cases instantiate the use of a default form. I propose that this can 4  CHAPTER 1 – INTRODUCTION be understood on the assumption that Blocking (a filtering device regulating the output generated from a derivation (Wunderlich 1996)) may not always be at work in the Grammar of DS.  Extensive morphological, syntactic, phonetic and phonological analyses verify that there are three main differences between the CGDS and the adult CGTD Grammar. First, articulatory limitations restrict the production of certain phonemes regardless of whether the phoneme occurs in inflectional or non-inflectional environments. Omission or substitution of phonemes in inflectional environments causes ambiguity. Second, Blocking failure allows the selection of the default form; a given morpho-syntactic or phonological feature is used in the place of the expected or targeted feature. Third, higher percentages of full-word and inflectional affix omission, especially with auxiliaries and copulas, were observed with CGDS. I hypothesise that these result from problems with Vocabulary Insertion.  1.2.2  Methodological Contributions  The methodological goal of this study was to collect data involving all possible feature combinations available in the language in a large number of syntactic environments: simplex clauses and complex clauses in Indicative as well as Subjunctive Mood). More explicitly, I used simple one-clause stimuli as well as more complex main-subordinate clause stimuli with one or more subordinate clauses, and conjoined main clauses. Clauses included both the Indicative and Subjunctive in declarative, negative, and interrogative structures. In all the aforementioned structure types, I ensured there was a relatively even distribution of the tested features: Tense, Person, and Number for verbs and Case for nouns, determiners, adjectives, pronouns, etc.  5  CHAPTER 1 – INTRODUCTION To elicit the type of data needed for this study, I used several different methods of data collection. I used both controlled and free elicitation tasks. For controlled elicitation tasks, participants needed to either produce an utterance based on a visual stimulus or repeat a structure given to them. For free elicitation tasks, participants were only given a context (e.g. describe a typical weekday) and were free to construct the story and their utterances in any way they wanted, using vocabulary of their choice. This did not only aim in covering all grounds but also in eliminating the methodology of testing as a contributing factor to the differences observed between the two groups and with adult CGTD. The choice of experimental stimuli was based on a pilot study (with five participants: three CGDS and two CGTDC), which was conducted prior to this study, to assess the level of the participants’ linguistic skills.  This type of data collection differs from previous ones in the following way. First, it combines a variety of both free elicitation tasks and controlled elicitation tasks, whereas previous studies mostly used only controlled elicitation tasks. Results, however, verified that this combination is absolutely necessary. More explicitly, participants were more comfortable producing certain structures in free elicitation (e.g. Subjunctive clauses), while other structures and feature combinations were specifically absent in free elicitation, even though they were used accurately in controlled elicitation. This is possibly due to the restrictions imposed by the targeted topic.  As a result of eliciting data in this way, we benefit from the collection of a large and diverse corpus of data. Elicited productions allowed for a greater variety of syntactic environments, while free elicitation tasks provided a clearer picture of what is and what is not possible in the CGDS Grammar. This allowed for more generalised conclusions, since it eliminated factors external to my research question, such those of (i) structural environment, (ii) phonetic and phonological restrictions, (iii) elicitation method and (iv) effects from specific feature 6  CHAPTER 1 – INTRODUCTION combinations (dis-)favoured due to either more or less frequent use. Additionally, throughout my dissertation I offer a large number of examples (over 150 examples) exhibiting the methodology employed and the participants’ performance. This is systematically absent in previous work on DS, (apart from Schaner-Wolles (2004) and Tsakiridou (2006)); neither examples of experimental stimuli nor examples of the participants’ productions are presented.  1.2.3  Analytical Contributions  To date, this is the first study that pursues a morpho-syntactic analysis of the DS Grammar taking into account phonetic and phonological effects on morpho-syntactic marking. This turns out to be significant, because we find that a large number of what has previously been assumed to be syntactically or morphologically conditioned differences between CGDS and CGTD Grammar are in fact the result of articulatory and phonological restrictions. Moreover, I argue that what appears to be inconsistent for one linguistic domain (i.e. phonological differences which cannot be explained by a set of phonological processes like devoicing or consonant harmony), when examined from a different perspective (i.e. morpho-syntactic), they are indeed part of a systematic pattern. This mainly concerns the hypothesised inconsistencies concerning the phonological limitations reported in previous work on EngDS (Dodd 1976, Kumin 2006), as well as the contradictions in morpho-syntactic results found in the DS literature within and across languages noted above. Finally, the separate phonetic and phonological analysis (in addition to the morpho-syntactic one) offers independent evidence for the proposed analysis. In particular, I show that CGDS exhibit the same strategy of using phonological default features in non-expected or targeted environments, just as they do with morpho-syntactic features. One of the major contributions of this study is that, though an utterance may not be produced as targeted by CGDS, this does not mean that it is used incorrectly. Specifically, evidence from 7  CHAPTER 1 – INTRODUCTION previous work (Schaner-Wolles 2004) has shown that GerDS may alter the syntactic environment to accommodate an unexpected production. This environment may facilitate the new form. Therefore, the evaluation of productions is based on two criteria: (i) what is targeted but also (ii) the syntactic environment it is produced in. Hence, the focus of evaluation falls on what is actually produced, rather than only on what is targeted. I show that CGDS are in fact able to (i) produce the targeted utterance accurately at a very high percentage and (ii) accommodate an alternative use of a feature through re-organization of the inflectional and syntactic environment in which it is produced.  Furthermore, after the participants’ performance of the entire word is assessed, each feature inflected on a word is evaluated separately. The methodology of evaluating each individual feature helped to provide evidence against a syntactic impairment. If the functional category Tense/Infl was impaired we would assume that all features are simultaneously affected. However, this is not what I find. Instead, features are affected individually. In particular, I show that features that are associated with a single syntactic head, i.e. Tense/Infl, are simultaneously affected only at percentages lower than 5% of the entire incorrect use of inflectional features.  1.2.4  Theoretical Contributions  This dissertation shows that CGDS present problems at the Spell Out level. In particular, the Blocking mechanism sometimes fails for CGDS (and CGTDC to a lesser extent) and the Subset Principle4 (a more refined version of Blocking) fails to resolve the competition in favour of the most specified form. As a result, a form carrying default feature value(s) and no contrasting 4  According to the Subset Principle, the appropriate phonological representation of a bundle of features resulting from a syntactic derivation is chosen if the vocabulary item matches all OR a subset of the features specified in that position. If more than one Vocabulary Items match the criteria for insertion, the item matching the greatest number of features must be chosen (Halle 1997).  8  CHAPTER 1 – INTRODUCTION features is used instead of the targeted one. Moreover, production of the phonological features by CGDS exhibits similarities to the morphological features. That is, at the Spell Out level, we observe that the Subset Principle occasionally fails to apply, with both morpho-syntactic and phonological features. Finally, what is striking is that all the morphological, syntactic, phonetic, and phonological processes observed with CGDS are also part of both CGTD and CGTDC Grammars. The difference is that they are (i) used at a greater extent by CGDS and (ii) based on the CGTD Grammar, they are sometimes found in unexpected environments.  Hence, the  differences between the two Grammars are unquestionably not syntactically conditioned.  Finally, I propose a unified analysis in progress under which all differences with morphosyntactic and phonological features, as well as full-word omission, between the CGDS and CGTD Grammar, can be accounted for. Though at present the proposed analysis accounts for all the phenomena observed with CGDS there is still need to test the proposed analysis across different languages, and different stages of language acquisition. Hence, these may suggest that (a) this is the full language acquisition CGDS master and (b) CGTDC at the tested ages present some morphological restrictions, at the vocabulary insertion place, which may extend to parallel restrictions, at higher percentages with younger CGTDC.  All the above-mentioned facts clearly show that, when comparing the adult CGDS and CGTD productions, we do not conclude that the CGDS Grammar is an impaired version of the CGTD Grammar. Rather, what we find is that CGDS is parallel to the CGTD (and CGTDC) Grammar with differentiating characteristics resulting from (i) articulatory restrictions, (ii) phonological difficulties, and (iii) occasional failure of the Subset Principle to filter the targeted form, or more generally, failure of the Blocking mechanism to rank Expressiveness over Economy, leading to the omission of the phonetic content of a word, but maintenance of the syntactic information. 9  CHAPTER 1 – INTRODUCTION  1.3  THEORETICAL TOOLS FOR TESTING THE HYPOTHESES  In this section, I give a brief overview of the theoretical background considered to evaluate the three hypotheses. More explicitly, I investigate the following features: Tense, Person and Number in S/V agreement, as well as Case. I not only examine the expression of these features by means of overt morphology, but also the syntactic environment in which they occur as well as the syntactic relations that they enter during the syntactic derivation. This approach allows us to determine whether the differences between the CGDS and CGTD are syntactically, morphologically, phonetically or phonologically conditioned.  It is often assumed that the inflectional differences between CGDS and CGTD are triggered by an impairment of the functional category TENSE. According to this analysis, the differences are syntactically conditioned. However, if we only look at the overt manifestation of Tense inflection, we cannot determine whether these differences are indeed syntactically or morphologically conditioned. If these differences are syntactically conditioned, we would expect that not only the morphological manifestation of Tense is affected, but also the syntax of Tense. In particular, it is often assumed that the syntactic head TENSE does not only host Tense but also S/V agreement (Chomsky 1995, among many others).  In addition, it is often assumed that there is a connection between Tense and Case such that only tensed verbs can assign Nominative Case (Pesetsky and Torrego 2004, Rouveret and Vergnaud 1980, Vergnaud 1982, inter alia). Thus, if the differences in the morphological realisation of Tense are syntactically conditioned, we would expect that they should correlate with differences in S/V agreement as well as Nominative Case. Moreover, it has been argued Case is assigned to the entire DP. Therefore, Case features not only manifest themselves on the noun but also on the determiner head (henceforth, D) of a DP (Chomsky 1995). Hence, syntactically conditioned 10  CHAPTER 1 – INTRODUCTION difficulties with Case would mean that if problems with Case marking on a noun are observed then, we would expect to also observe effects on the determiner as well (D being the head of the phrase). I refer to this as bundling effects.  1.4  OVERVIEW OF THE THESIS  In this section, I give a brief overview of each chapter. In Chapter 2, I introduce the background that informs this dissertation. What do we gain by studying the language of atypical populations such as DS?  I present and discuss previous research on the phonetic, phonological and morpho-syntactic characteristics of typical language development and atypical populations in English, Greek and other languages. I conclude by raising a number of empirical, methodological and analytical issues resulting from previous work. First, contradictions between studies within and across languages are identified. Second, I argue for the necessity to study DS in a language with richer inflectional morphology than English. Third, I show that there is need for a greater variety (both in quantity and quality) of experimental stimuli and comprehensive methodology, than used in previous research, to address the research question. Fourth, I argue that we need an analysis that does not focus entirely on the target utterance (as previous studies do) but in addition, considers the structural and inflectional environment in which the productions are found. Fifth, I argue for the necessity to investigate the phonetic and phonological system of CGDS, alongside with their inflectional system, to determine the nature of differences between the target and produced form. In following chapters, I show how these issues are addressed through my dissertation research.  11  CHAPTER 1 – INTRODUCTION In Chapter 3, I summarise the specifics of the verbal and nominal inflection in Greek. I then discuss the specific environments examined for the present study and I explain how these allow me to address the empirical issues raised in Chapter 2. The main purpose of Chapter 3 is to provide the most relevant generalizations pertaining to Tense, S/V agreement and Case, and how these interact with each other. In particular, I show that Cypriot Greek (hereafter, CG) has the following properties which make it an ideal testing ground for our purposes: (i) there are environments where Tense and S/V agreement are fused (morphological dependency) and other environments where they surface independently, (ii) there are environments where S/V agreement and Tense co-occur (syntactic dependency) and others where S/V agreement alone is found, and (iii) nominal expressions are overtly morphologically marked for Case, along with Gender, Number and Person (for pronouns), creating a large variety of feature combinations.  In Chapter 4, I explain the methodology employed for data collection and data analysis. I give a detailed presentation of the four experiments and explain (i) the grammatical constructions targeted, (ii) the goal, (iii) the experimental design and how it served the purpose of each experiment, and (iv) how each experiment contributes to answering the research question. Furthermore, I provide information on the transcription conventions, data analysis, database construction and statistical analysis. In Chapter 5, I discuss the phonetic and phonological results of the collected data. I show that certain sounds appear to be challenging for DS and are frequently either omitted or substituted. I conclude that the main differences between the CGDS and the CGTDC Grammar are phonetically and phonologically conditioned. I develop the argument as follows.  12  CHAPTER 1 – INTRODUCTION First, examining the phonological environments in which consonants are omitted or substituted, I show that CGDS have a general problem with /s/, /#/, /n/, /v/, /$/, /t/ as well as other consonants, regardless of whether these are found in inflectional or non-inflectional environments. These are either omitted or, through a phonological process, substituted for other sounds. This is important not only because the same sounds are reported problematic in phonetic and phonological studies on EngDS but also because these are the sounds used for inflectional marking in English. Second, almost all substitutions are systematic in both groups. In particular, the target sounds share phonological features with the substituting sounds. Third, these results contradict previous claims about EngDS where the phonological patterns produced by EngDS are characterised as “inconsistent” (Dodd 1976, Kumin 2006). It is shown that non-consistent substitutions are morpho-syntactically, phonetically or phonologically conditioned and still display systematicity. The phonetic and phonological analysis is particularly important, as it is used as the foundation of the morpho-syntactic analysis. That is, phonetic and phonological restrictions are factored into the morpho-syntactic analysis.  In Chapter 6, I present the morpho-syntactic results. I start with a presentation of the participants’ overall performance of standard and non-standard productions as well as omissions, and discuss the difference between considering and disregarding phonetically and phonologically triggered changes on produced forms. In particular, I show how results can be misinterpreted if phonetic and phonological problems are not considered. Moreover, I present the results on the participants’ overall performance with Tense, S/V agreement and Case, as well as a detailed analysis of their performance of each feature value for Tense, Person, Number and Case. First, I show that overall – with almost all features or feature values – CGDS and CGTDC productions are almost at ceiling with accuracy of over 99%. Second, I observe and report three options when the 13  CHAPTER 1 – INTRODUCTION target is not met: (i) systematic use of feature values alternative to those targeted (based on controlled elicitation stimuli) or expected (based on the context and goal of free elicitation tasks) by experimental tasks; (ii) affix drop, and (iii) entire-word omission. Third, statistical comparison revealed non-significant differences (i.e. similar performance) between CGDS and CGTDC with Tense on verbs. Concerning individual feature values on verbs, I found nonsignificant differences with Present, Past, Imperative, 1st Person, and Plural, and Vocative for nominal expressions. Accusative revealed a marginally significant difference. However, with other features and feature values the two groups differ significantly. Therefore, based on the aforementioned facts, and a number of evidence from factors external to morpho-syntax, I argue that CGDS do not exhibit a delayed version of the adult CGTD Grammar, parallel to a specific stage of language acquisition. Rather, they exhibit a different development in particular aspects of their Grammar, that only slightly differ from the adult CGTD Grammar morphologically, phonetically and phonologically.  Chapter 7 is divided into three parts: (i) a discussion on what conditions the differences between CGDS and the CGTDC by examining three hypotheses, (ii) a proposal for a unified analysis for morpho-syntactic and phonological features, as well as full-word omission and (iii) conclusions, predictions and my agenda for future research. Three main findings are reported in this chapter. First, the results from this research contradict the idea that the inflectional impairment described in previous work on EngDS is syntactically conditioned, or even morphologically conditioned to the degree that has been argued in previous work. Second, based on the analysis of the morphosyntactic features provided, I explain that the residue of differences not phonetically or phonologically conditioned observed between the CGDS and the CGTD Grammar are not due to a breakdown during the syntactic derivation, but rather a failure of the Subset Principle to fully 14  CHAPTER 1 – INTRODUCTION apply after Spell Out. This results in the most underspecified (default) form for each feature becoming a probable choice. Third, I propose that a different realisation of the CGDS Grammar is due to a breakdown at Spell Out where the phonological representation of the features resulting from the syntactic (or phonological) derivation occurs at the stage after features are derived. Specifically, phonological features of voiceless stop and fricative consonants exhibit the same phenomenon as morpho-syntactic features, due to underspecified phonological features. Fourth, the same analysis applies for the morphological differences found between the CGTDC and the CGTD Grammar, though differences are smaller than those seen with CGDS. I propose that fullword and inflectional affix omissions also occur at this level. Finally, I conclude.  Throughout all steps undertaken for the realisation of this research, CGDS Grammar is not studied with the notion that it is an impaired or incomplete version of the CGTD Grammar and it is never characterised as such. Rather, I study and treat the CGDS Grammar as one which (i) has a strikingly similar inflectional system to that of the CGTD Grammar, (ii) has numerous common elements with CGTDC Grammar, (iii) has morphologically conditioned differences with the CGTD Grammar, where default values are used where not expected, and (iv) exhibits differences in its phonetic and phonological system; mostly structured differences, based on the articulatory restrictions characterising DS.  This dissertation offers a proposal for a unified analysis, which captures the morphology, syntax, phonetics and phonology of the CGDS Grammar. In addition, this is the first study to consider interacting factors across different linguistic domains (morphology, syntax, phonetics and phonology), which allows for a more comprehensive analysis.  15  Chapter 2  Literature Review  2.1  INTRODUCTION  The main focus of this dissertation is the study of 19- to 45-year old adult CGDS. The speech of individuals with Down Syndrome (henceforth, DS) has been reported to be characterised by specific problems with Tense and S/V agreement. I compare their performance with 7- to 8- year old CGTDC at (or past) the final stage of language acquisition. The differences between Typically Developing (henceforth, TD) language and atypical language development have