Table Of Content3.3. Overcoming the problems encountered by pervious studies on bilingual AD 83
3.3.1. Complete test batteries ____________________________________ 83
3.3.2. Bilingual versus monolingual mode _________________________ 83
3.3.3. Speakers as their own controls _______________________________ 84
3.3.4. Conversation Analysis (CA) _________________________________ 84
3.4 Summary 89
3.5 Research questions 90
3.6. Hypotheses 91
CHAPTER4: METhODOLOGY____________________ 92
4.1. Research design 92
4.2. Subject selection ______________________________________ 93
4.3. Subject description 95
4.4. Control subjects 98
4.5. Methods 99
4.5.1. Tests and materials ________________________ 99
4.5.1.1. Background information __________ 100
4.5.1.2. Staging dementia and orientation 101
4.5.1.3. Neuropsychological tests ___________ 103
4.5.1.4. Language tests __________________ 108
4.5.1.5. Conversation Analysis 115
4.5.2. Procedures _______________________________ 120
4.5.3. Data processing 122
4.5.3.1 Analysis of formal tests and CA results 122
4.5.3.2 Statistical analysis 124
4.5.4. Pilot study 125
4.6 Summary 127
V
INTRODUCTION TO THE FOLLOWING FIVE CHAPTERS 128
CHAPTER 5: SPEAKER AR 130
5.1. Hypotheses 130
5.2 Results ________________ 132
5.3 Discussion _____________ 148
5.4 Summary 163
CHAPTER 6: SPEAKER BL 165
6.1 Hypotheses 165
6.2 Results _______________ 167
6.3 Discussion _____________ 181
6.4 Summary 194
CHAPTER 7: SPEAKER EB 195
7.1 Hypotheses 195
7.2 Results _______________ 197
7.3 Discussion _____________ 209
7.4 Summary 222
CHAPTER 8: SPEAKERJB 223
8.1 Hypotheses 223
8.2 Results _______________ 224
8.3 Discussion ______________ 232
8.4 Summary 237
CHAPTER 9: SPEAKER JS 238
9.1 Hypotheses __________ 238
9.2 Results _______________ 240
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9.3 Discussion 255
9.4 Summary - 265
CHAPTER 10: GENERAL DISCUSSION_______________ 266
10.1. Pattern and rate of loss compared to monolingual speakers 268
10.1.1 Formal tests _____________________________ 269
10.1.2 CA ________________________________ 273
10.2. Pattern of loss between the speakers two languages 278
10.2.1 Predictions _______________________________ 279
10.2.2 Formal tests _____________________________ 280
10.2.3 CA _________________________________ 285
10.3. Rate of loss ________________________________________ 288
10.3.1 Predictions _______________________________ 288
10.3.2 Formal tests ______________________________ 289
10.3.3 CA _________________________________ 291
10.3.4 Summary 295
10.4. Specific bilingual behaviours _______________________ 295
10.4.1 Predictions _________________________________ 296
10.4.2 Formal tests _____________________________ 296
10.4.3 Sentence translation _______________________ 297
10.4.4 CA _________________________________ 298
10.4.5 Summary 313
10.5 Cognitive decline versus language decline ______________ 314
10.5.1 Findings from the literature _________________ 314
10.5.2 Predictions ______________________________ 315
10.5.3 Language and neuropsychological decline_ 315
10.5.4 Li versus L2 and neuropsychological decline - 319
10.5.5 Summary 323
vii
10.6. Variables (AOA, method of acquisition, pattern of use, proficiency) affecting patterns
and rate of decline ______________________________________________________ 324
10.6.1 Proficiency 325
10.6.2 Age of L2 Acquisition ___________________________________________ 327
10.6.3 Conclusion ____________________________________________________ 328
10.7 Accounting for language profiles in bilingual AD ______________________________ 329
10.7.1 Degree of L2 automatisation ______________________________________ 329
10.7.2 Hierarchy of tasks sensitive to inter-language differences _______________ 330
10.7.3 Previous findings and the schema __________________________________ 340
10.8 Further Research 341
10.8.1 Differences in factors versus equally matched language profiles 342
10.8.2 Effect of AOA on language profiles 343
10.8.3 Effects of proficiency on language profiles 347
10.8.4 Effects of method of acquisition on language profiles 348
10.8.5 Effects of different patterns of use on language profiles 348
10.8.6 Effects of linguistic distance on language profiles 350
10.8.7 Uniformity of task hierarchy ____________________________________ 351
10.8.8 Studies with healthy bilingual speakers 352
10.9 Summary 352
CHAPTER 11: CONCLUSIONS ____ 354
11.1 Methodological issues __________ 354
11.1.1 CA versus formal tests 354
11.1.2 Advantages of CA 358
11.1.3 Time frame ________ 364
11.1.4 Task sensitivity 366
11.1.5 Statistics ______________ 369
11.1.6 Summary 371
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11.2 Clinical implications 372
11.2.1. Assessment issues - 372
11.2.2. Clinical intervention 375
11.2.3 Summary 377
11.3 General Conclusion _________ 377
REFERENCES 381
APPENDIXES
Appendix 1 Afrikaans 396
Appendix 2 Letterof Consent _________________________ 397
Appendix 3 Clinical Dementia Rating __________________ 398
Appendix 4 Language Background Questionnaire 400
Appendix 5 MemoryRecognition Task _______________ 404
Appendix 6 Concept Definition Scoring 405
Appendix 7 Superordinate and Co-ordinate Naming 406
Appendix 8 Sentence Translation Task _________________ 407
Appendix 9 Transcript Symbols and Glossary 408
Appendix 10 Extract from the Conversation Analysis of AR 409
ix
LIST OF TABLES
TABLE 1 DIFFICULTIES ON DIFFERENT LANGUAGE TESTS AT DIFFERENT STAGES
OF DEMENTIA 29
TABLE 2 DEVREESE ET AL: FORMAL TEST RESULTS ________________________ 57
TABLE 3 HYLTENSTAM AND STROUD: NAMING AND REPETITION RESULTS _______ 63
TABLE 4 COOPER: TEST RESULTS _______________________________________ 75
TABLE 5 SUBJECT DESCRIPTION (FROM PREVIOUS STUDIES) 77
TABLE 6 SUBJECTDESCRIPTION ________________________________________ 98
TABLE 7 TESTSADMINISTERED _______________________________________ 99
TABLE 8 STATISTICALTESTS EMPLOYED _________________________________ 124
TABLE 9 AR: SUMMARY OF BACKGROUND DETAILS _______________________ 130
TABLE 10 AR: RESULTS 133
TABLE ha AR: STATISTICALLY SIGNIFICANT INTER-LANGUAGE DIFFERENCES
ATDIFFERENT TIME POINTS _________________________________ 134
TABLE lib AR: STATISTICALLY SIGNIFICANT INTRA-LANGUAGE CHANGES IN SCORES
ACROSS TIME 134
TABLE 12 AR: ERROR TYPES FROM THE CONFRONTATION NAMING TASK________ 135
TABLE 13 AR: AMOUNTS AND TYPES OF CODE SWITCHES MADE ON FORMAL
TEsTs 143
TABLE 14 AR: RESULTS FROM THE SENTENCE TRANSLATION TASK _____________ 144
TABLE 15 AR: AMOUNT OF UTrERANCES CODE SWITCHED IN CONVERSATIONS ____ 144
TABLE 16 AR: TYPES AND TOTALS OF REPAIR FOR EACH LANGUAGE____________ 146
TABLE 17 AR: TRAJECTORY LENGTHS (IN TURNS) FOLLOWING INITIATION OF REPAIR 147
TABLE 18 BL: SUMMARY OF BACKGROUND DETAILS _______________________ 165
TABLE 19 BL: RESULTS 168
TABLE 20a BL: STATISTICALLY SIGNIFICANT INTER-LANGUAGE DIFFERENCES AT
DIFFERENT TIME POINTS 169
x
TABLE 20b BL: STATISTICALLY SIGNIFICANT INTRA-LANGUAGE CHANGES IN SCORES
ACROSSTIME_______________________________________________ 169
TABLE 21 BL: ERROR TYPES FROM THE CONFRONTATION NAMING TASK ___________ 170
TABLE 22 BL: AMOUNTS AND TYPES OF CODE SWITCHES MADE ON FORMAL TESTS 176
TABLE 23 BL: RESULTS FROM THE SENTENCE TRANSLATION TASK ________________ 177
TABLE 24 BL: AMOUNT OF UTrERANCES CODE SWITCHED IN CONVERSATIONS _______ 17
TABLE 25 BL: TYPES AND TOTALS OF REPAIR FOR EACH LANGUAGE______________ 179
TABLE 26 BL: TRAJECTORY LENGTHS (IN TURNS) FOLLOWING INITIATION OF REPAIR - 180
TABLE27 EB: SUMMARY OF BACKGROUND DETAILS _________________________ 195
TABLE28 EB: RESULTS _____________________________________________ 198
TABLE 29 EB: STATISTICALLY SIGNIFICANT CHANGES IN SCORES ACROSS TIME______ 199
TABLE 30 EB: ERROR TYPES FROM THE CONFRONTATION NAMING TASK__________ 200
TABLE 31 EB: AMOUNTS AND TYPES OF CODE SWITCHES MADE ON AFRIKAANS
FORMALTESTS __________________________________________ 205
TABLE 32 EB: RESULTS FROM THE SENTENCE TRANSLATION TASK _______________ 206
TABLE 33 EB: AMOUNT OF UTrERANCES CODE SWITCHED IN CONVERSATIONS ______ 206
TABLE 34 EB: TYPES AND TOTALS OF REPAIR FOR EACH LANGUAGE______________ 207
TABLE 35 EB: TRAJECTORY LENGTHS (IN TURNS) FOLLOWING INITIATION OF REPAIR - 208
TABLE 36 JB: SUMMARY OF BACKGROUND DETAILS ________________________ 223
TABLE37 JB: RESULTS ____________________________________________ 225
TABLE 38a JB: STATISTICALLY SIGNIFICANT INTER-LANGUAGE DIFFERENCES AT
DIFFERENTTIME POINTS _____________________________________ 227
TABLE 38b JB: STATISTICALLY SIGNIFICANT INTRA-LANGUAGE CHANGES IN SCORES
ACROSSTIME _______________________________________________ 227
TABLE 39 JB: ERROR TYPES FROM THE CONFRONTATION NAMING TASK__________ 228
TABLE 40 JB: TYPES AND TOTALS OF REPAIR FOR EACH LANGUAGE______________ 229
TABLE 41 JB: TRAJECTORY LENGTHS (IN TURNS) FOLLOWING OTHER-INITIATED REPAIR 230
TABLE 42 JS: SUMMARY OF BACKGROUND DETAILS _________________________ 238
TABLE43 JS: RESULTS ______________________________________________ 241
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TABLE 44 JS: STATISTICALLY SIGNIFICANT CHANGES IN SCORES ACROSS TIME________ 242
TABLE 45 iS: ERROR TYPES FROM THE CONFRONTATION NAMING TASK ____________ 243
TABLE 46 iS: AMOUNTS AND TYPES OF CODE SWITCHES MADE ON FORMAL TESTS _____ 250
TABLE 47 JS: RESULTS FROM THE SENTENCE TRANSLATION TASK _________________ 251
TABLE 48 JS: AMOUNT OF UTFERANCES CODE SWITCHED IN CONVERSATIONS ________ 252
TABLE 49 JS: TYPES AND TOTALS OF REPAIR FOR EACH LANGUAGE_______________ 253
TABLE 50 iS: TRAJECTORY LENGTHS (IN TURNS) FOLLOWING INITIATION OF REPAIR 254
TABLE 51a SUMMARYOF RESULTS: JB, EB _______________________________ 266
TABLE Sib SUMMARYOF RESULTS: BL, iS, AR ________________________________ 267
TABLE 52 SUMMARY: SEVERITY OF IMPAIRMENT (FORMAL TESTS) _________________ 281
TABLE 53 SUMMARY: SEVERITY OF IMPAIRMENT (CA) _________________________ 286
TABLE 54 SUMMARY: RATE OF DECLINE (FORMAL TESTS) ______________________ 289
TABLE 55 SUMMARY: RATE OF DECLINE (CA) ________________________________ 292
TABLE 56 SUMMARY: DIRECTION OF LANGUAGE MIXING BEHAVIOUR ______________ 299
TABLE 57 SUMMARY OF LANGUAGE MIXING PROFILES _________________________ 301
TABLE 58 SUMMARY: LANGUAGE AND NEUROPSYCHOLOCICAL DECLINE (FORMAL TESTS) 316
TABLE 59 SUMMARY: NEUROPSYCHOLOGICAL DECLINE AND L2 COMPLEX TASKS 320
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LIST OF FIGURES
FIGURE 1 AR: NUMBER OF ITEMS NOT NAMED ON CONFRONTATION NAMING TASK_____ 135
FIGURE 2 AR: PREDICTED VERSUS OBSERVED L1/L2 RATE OF DECLINE_____________ 155
FIGURE 3 BL: NUMBER OF ITEMS NOT NAMED ON CONFRONTATION NAMING TASK _____ 171
FIGURE 4 BL: PREDICTED VERSUS OBSERVED LIIL2 RATE OF DECLINE_____________ 185
FIGURE 5 EB: NUMBER OF ITEMS NOT NAMED ON CONFRONTATION NAMING TASK _____ 200
FIGURE 6 EB: PREDICTED VERSUS OBSERVED LIIL2 RATE OF DECLINE ____________ 212
FIGURE 7 JB: PREDICTED VERSUS OBSERVED L1IL2 RATE OF DECLINE_____________ 234
FIGURE 8 JS: NUMBER OF ITEMS NOT NAMED ON CONFRONTATION NAMING TASK _____ 243
FIGURE 9 JS: PREDICTED VERSUS OBSERVED L1/L2 RATE OF DECLINE _____________ 260
FIGURE 10 HIERARCHY OF LANGUAGE ASPECTS IN TERMS OF SENSITIVITY TO INTER-
LANGUAGE AUTOMATISATION DIFFERENCES _________________________ 331
FIGURE 11 EB AND AR PROFILES AS A FUNCTION OF L2 LEVEL OF AUTOMATISATION AND
RESOURCEAVAILABILITY _____________ _________________________ 338
xiii
INTRODUCTION
The psycholinguistic and neurolinguistic organisation of two languages in one brain has
fuelled intensive investigation for many years now. Researchers have delved into issues such
as which aspects of language functioning are language universal, and which are language
specific; whether there are two separate language systems or one larger system; whether
languages are localised in the same area of the brain or are diffusely represented; how
different ages of language acquisition may affect the organisation of languages; and the
relationship between language and cognition. Various population groups such as healthy
bilingual speakers and bilingual speakers with aphasia have been studied to answer these
questions, and, in the case of pathology, to provide an indication of what the most effective
intervention methods might be.
It is only recently that researchers have begun to investigate the effect that dementia has on a
bilingual speaker's two languages. The progressive nature of deterioration with dementia
facilitates a longitudinal investigation into language attrition. By tracking the long term
progressive dissolution of language skills, we can find out what aspects are most vulnerable,
and by comparing attrition in one language to the other, we can begin to infer how they might
have been organised in the first place. Such insights into the organisation of two languages in
one brain is precluded from the study of aphasia, which results from a sudden, focal lesion. In
addition, since dementia also involves cognitive decline, it affords an opportunity to closely
examine the relationship between language and cognition. However, only a handful of studies
have been reported on bilingual speakers with dementia thus far, all of which can be criticised
on a number of accounts, including use of ambiguous and conflicting terminology, and
abundant methodological concerns.
The aim of this work was to begin a systematic investigation into the area of bilingual
dementia. Since there are many types of dementia (for instance multi-infarct dementia, Lewy
Body Disease, Alzheimer's Disease) - all unlikely to exercise the same influence on language -
Description:Language attrition in healthy bilingual speakers. 21 .. progressive dissolution of language skills, we can find out what aspects are most vulnerable,.
