The objectives of this study were to examine if pre-stroke proficiency predicts post-stroke lexical semantic performance in Spanish-English bilingual persons with aphasia (PWA) and identify patterns of impairment in this population. A language use questionnaire was administered to 27 Spanish-English bilingual PWA to measure pre-stroke proficiency in both languages. Standardized language assessments in Spanish and English were administered to measure post-stroke lexical semantic performance in both languages. A principal component analysis was conducted on the language use questionnaire measures, revealing Daily Usage, Education, Exposure, and Language Ability Rating as factors that contribute to a person’s proficiency in their first language (L1), and Age of Acquisition, Daily Usage, Family Proficiency, Education, Exposure, Confidence and Language Ability Rating as factors that contribute to a person’s proficiency in their second language (L2). Regression analyses revealed that pre-stroke proficiency significantly predicted post-stroke lexical semantic performance, most strongly in English than in Spanish. Two distinct patterns of impairment emerged within the participants: parallel impairment and differential impairment. Overall, these results confirm that pre-stroke language proficiency is a key determiner of performance on standardized language assessments post-stroke, such that the higher proficiency pre-stroke, the higher performance on standardized tests post stroke. This pattern was more clear when English was L1 or L2 relative to when Spanish was L1 or L2. These results have important implications for assessment and diagnosis of aphasia in bilingual individuals particularly when clinicians need to select the language of assessment.

Background: The Samoan population is a growing population and one with an estimated high incidence of aphasia. Language assessment with bilingual individuals is said to be a challenging area of Speech-Language Therapy practice. Language assessment of bilingual Samoan-English speakers with aphasia is a field with limited research, and the specific experience of the individuals involved is an important factor to consider in improving SLT practice with this population. Aims: The current thesis aimed to explore the experience of language assessment of bilingual Samoan-English speakers with aphasia as perceived by those involved in the assessment process. Method: Two qualitative studies were utilised to address the aims, the first was a single case study observing the process of language assessment of a bilingual Samoan-English speaker with aphasia and follow-up interviews with other participants involved. The second study was a focus group with Speech-Language Therapists who had experience with language assessment of bilingual Samoan-English speakers with aphasia. Outcome and results: The results of the case study revealed eight themes: language assessment of bilingual Samoan-English speakers with aphasia is a hard process for the individuals involved; language assessment of bilingual Samoan-English speakers with aphasia is a team process; differences in understanding of communication impairments and the assessment process; time; preparation; appropriateness of assessment tasks, resources, and processes; uncertainty; and flexibility. The results of the focus group indicated eight categories: Speech-Language Therapists’ background, using interpreters, family involvement, Samoan language and culture, getting an initial impression of and building rapport with the individual with aphasia, assessment tasks and resources, determining which language(s) to assess and logistics of assessment. Conclusion: Language assessment of bilingual Samoan-English speakers with aphasia is a challenging area of Speech-Language Therapy practice. Challenges are multifaceted and although some challenges may be present in all language assessment with individuals with aphasia, they are further exacerbated by the addition of multiple languages, people, and culture. Helpful strategies identified in this study may aid in improving the overall experience.

The research on bilingual language processing explores two main avenues of relevance to the present study: lexico-semantic access and cognitive control. Lexico-semantic access research investigates the manner in which bilingual individuals retrieve single words from their lexical system. Healthy bilingual individuals can manipulate their lexico-semantic access to accommodate settings in which code- or language-switching is expected. Alternatively, they can manipulate their lexico-semantic access to speak only their first (L1) or second (L2) languages. Cognitive control, also known as executive functioning, is closely related to lexico-semantic access. Specifically, bilingual individuals maintain and switch between their languages through a mechanism known as cognitive control. Both cognitive control and lexico-semantic access are important for language processing in healthy bilingual individuals as well as bilingual persons with aphasia (BPWA). However, the extent to which BPWA utilize each of these processes in the production of single words is still unknown. The present study used a method of verbal fluency in the form of a novel modified category generation task to assess the relative contributions of lexico-semantic access and cognitive control in bilingual healthy controls and BPWA.

The aims of this study were to determine if various treatment, item, and patient-level factors could be used to predict probe naming accuracy in a bilingual Spanish-English SFA treatment study. At the treatment-level, variables included phase (baseline vs. treatment), training condition (trained set 1 items vs. translations), and time (session). At the item-level, psycholinguistic variables were investigated including lexical frequency, phonological length in phones, and phonological neighborhood density. Finally, at the patient-level, impairment measures were used including aphasia severity (as measured by WAB AQ) naming impairment (represented by a composite naming score from pre-treatment assessments). Mixed-effects logistic regression methods were used to fit the data with fixed effects for the variables of interest as well as random effects for subject and item. The regression analyses revealed significant main effects of phase, time, and interactions with training condition such that naming accuracy on probes was higher for the treatment language during the treatment phase and over time in general. Significant effects were also noted for each of the psycholinguistic variables such that increased frequency, shorter length, and a larger neighborhood increased the likelihood of correct naming responses. Finally, overall aphasia severity and naming impairment both correlated with naming outcomes.

<p>This thesis examines the performance of non-impaired Tamil-English speaking bilinguals on the Tamil-English version of the Bilingual Aphasia Test (BAT) (Paradis and Libben, 1987). The test was administered to 25 participants, 15 women and 10 men. The results show that, on average, participants achieved an overall score of 97%. However, participants did not do well on two subtests on the English version, specifically sections on derivational morphology and morphological opposites. Also, a more detailed analysis indicates that years of education significantly correlates with performance, even though it is claimed that years of education should not affect performance on this test. This study makes suggestions for how to improve the Tamil-English version, in view of the findings from this study, and provides a cautionary note on the role played by years of education in test performance. If the latter factor is not taken into account, the test could possibly lead to an inaccurate assessment of a patient’s language abilities, and could potentially result in misdiagnosis. In an effort to increase the test’s validity and reliability, this study recommends a series of modifications to the Tamil-English version of the BAT, based both on participants’ comments and on statistical analyses.</p> / Master of Science (MSc)