Mild Developmental Dyslexia in University Students: Diagnosis and Performance Features in L1, L2, and L3.

Developmental dyslexia, or specific reading and writing difficulties, is a condition persisting into adulthood. In university students, dyslexic problems are generally mild, and research shows that up to half of those who experience dyslexic difficulties in higher education have no official diagnosis upon entering the university. With the high reading and writing demands in university studies, even mild and compensated dyslexia can considerably impede academic performances. The first step in providing dyslexic students with adequate support and specific accommodations is to diagnose their problems. To date, however, no standardized and normed dyslexia tests are available for high-performing students with Finland-Swedish language background. The present thesis addresses this shortage through adaptation, design, testing, and norming of diagnostic instruments for dyslexia in high-performing Finland-Swedish young adults. The basic theoretical assumption adopted in this work is the widely accepted view that weak phonological processing constitutes the core functional deficit in developmental dyslexia. Previous research has shown that certain language-specific features such as the degree of orthographic transparency influence dyslexia manifestations. This adds to the challenge of diagnosing dyslexia in multilingual speakers. To address this issue, the present work explores signs of dyslexia in reading and writing performances of multilingual Finland-Swedish university students in three structurally different languages: English, Swedish, and Finnish. The thesis consists of three studies. In the first study, a Sweden-Swedish dyslexia group screening test (DUVANTM; Lundberg & Wolff, 2003) was adapted to Finland-Swedish (FS-DUVAN). Normative data and relevant background information were collected among a randomly selected sample of Finland-Swedish university freshmen (n = 129) together with data from a group of dyslexic university students (n = 14). The internal reliability of the FS-DUVAN was comparable to that of the original test. Further, a low performance on the FS-DUVAN, indicating poor phonological and orthographic skills, was associated with a positive self-report on familial dyslexia and with a history of special education in school. Due to language background effects on the test performance, separate cut-off values were suggested for monolingual Swedish speakers and early simultaneous Swedish-Finnish bilinguals. For those performing poorly in a screening, further testing is required to specify the deficit. In the second study, an extensive individual test battery was therefore compiled. This test battery was administered to 20 dyslexic Finland-Swedish university students and 20 chronological age-matched and education-matched controls with close to identical language backgrounds. The test battery encompassed reading and writing tasks, cognitive tasks relevant for dyslexia diagnosis, and questionnaires on background information. In this study, the following measures showed to be sensitive to dyslexia: complex speeded naming; multiple phoneme manipulation; error detection in written text; accuracy in reading text aloud, single word writing to dictation, free writing; and speeded segmentation of written input. This study thus reveals several test variables on which high-performing dyslexic university students show impairment when compared to their non-dyslexic peers. In the third study, the reading and the writing performances of the participants in Study II were examined further in their domestic languages Swedish and Finnish, as well as in the foreign language English through both within-group and between-group comparisons. In addition to overall speed and accuracy measures, detailed error analyses were conducted, which focused on features expected to reflect phonological weaknesses. The results demonstrated poorer performances in the dyslexia group in all three languages, in particular in reading and writing accuracy. Furthermore, the dyslexia group exhibited significantly higher proportions of phoneme-to-grapheme errors in writing, especially in English. In addition marginal differences in inflectional errors were observed in the dyslexia group in the morphologically least rich language, English. Hence, the dyslexic problems surfaced most clearly in the less proficient foreign language that was the orthographically most opaque and morphologically poorest language. These results show that language proficiency and orthographic depth affect the appearance of high-performing multilinguals’ dyslexic problems in reading and writing. Taken together, the results are in line with the phonological deficit hypothesis of dyslexia and confirm the existence of pervasive underlying defects in compensated dyslexia through adulthood. The findings demonstrate that dyslexic university students perform differently from their non-dyslexic peers on a number of test measures. The data reveal difficulties in reading and writing performances of dyslexic university students as disclosed in their self-reports. As compared to normal performances, multilinguals’ dyslexic problems in reading and writing tasks were most clearly observed in accuracy, and in particular in English, which was the least well mastered language and also the orthographically most opaque one. The thesis addressed the lack of diagnostic instruments for dyslexia in highperforming Finland-Swedish university students and demonstrated the necessity to carefully modify test materials when borrowing tasks from one language variety and culture to another. The three studies contribute to the development of more sensitive procedures for dyslexia testing in high-performing individuals. In addition to use in Finland-Swedish higher education, the FS-DUVAN should be a valuable dyslexia screening tool in Finland-Swedish secondary education and vocational education. The results highlight the need to take into account the language background of a multilingual individual, as well as the structure of the language(s) involved when testing for signs of dyslexia.