3. Electronic Theses and Dissertations (ETDs) - All submissions
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Item A comparison of working memory profiles in HIV-infected and HIV-exposed uninfected children(2016) Milligan, RobynConventional psychometric measures, such as the IQ score, have significant limitations in addressing the assessment needs of linguistically and culturally diverse communities. In response, working memory assessment has been identified as a promising alternative to these constraints. It is a better predictor of scholastic success than IQ, and is essential in the acquisition of fundamental literacy and numeracy concepts in school beginners. While there is a lot of theoretical and empirical support for working memory performance in typically developing populations, less is known about its functioning in the context of atypical development; particularly in children who are infected with, or exposed to HIV in utero. This study compared the working memory (AWMA) and general neuropsychological functioning (NEPSY-II) of 273 South African school beginners (6-8 years). The sample consisted of both HIV-infected (n = 95), and HIV-exposed (n = 86) children, as well as an uninfected, unexposed typically developing control group (n = 92). Significant differences were found between the three groups on measures of working memory and general neurocognitive functioning, where the processing component of working memory appeared to be particularly impaired in the two HIV-affected atypical groups. A within-group analysis of the relative strengths and weaknesses of each of the three groups showed that both storage and processing skills in the verbal domain appeared to be general weaknesses, while visuospatial working memory was a relative strength. The former is believed to be influenced by issues of linguistic test bias in the multilingual sample, while the latter is posited to be a consequence of this very multilingualism, which affords these children an executive functioning advantage. The two HIV-affected samples also showed significant deviations in the structure of their working memory when compared to the typically developing control group. However, within-group structural comparisons of a number of working memory models showed that the four factor model comprising separate components of the verbal and visuospatial simple and processing components of working memory was still favoured, even in conditions of atypical development. The study contributes to the growing body of working memory research by presenting the working memory profiles of HIV-infected and HIV-exposed, uninfected children. It also assists in identifying HIV-exposed, uninfected children as a vulnerable and under-researched clinical group which could benefit from further intervention, as well as foregrounding working memory as a less biased alternative in the assessment of paediatric cognitive functioning.Item The relationship between cognitive functioning and early childhood factors in children with speech and language impairment.(2012-02-28) Milligan, RobynIt has long been the quest of developmental theorists to understand the mechanisms behind cognitive functioning and the acquisition of language. Studies have identified that there is an interdependent, dialectical relationship between cognitive development and language acquisition. The development of language, in typical populations, is therefore dependent on a baseline cognitive skill, which, once acquired, capacitates the further development of cognition. However, very little is known about this process within atypical populations, particularly those with speech and language impairment. This study examined the relationship between cognitive functioning and early predictive factors in an atypical population of pre-school children with speech and language impairment using three measures of cognitive functioning (as measured by the WPPSI (Wechsler Pre-School and Primary Intelligence Scale), the Griffiths and the JSAIS (Junior South African Individual Scale)) and a range of demographic, diagnostic and early developmental childhood factors. Results identify factors such as parental levels of education, family structure, gender and pregnancy and early childhood health as the main influences of cognitive performance. They also highlight the pervasive influence of speech and language impairment on non-verbal and processing speed abilities. The presence of genetic conditions as well as multiple diagnoses was frequently found to have significant associations with poor cognitive performance. The study also highlighted two things of unexpected interest. The first refers to the role of handedness (particularly undifferentiated handedness) in identifying cognitive difficulty which is related to hemispheric lateralisation, and its relationship to the various diagnostic groups represented within the sample. The second considers the high proportion of diagnostic co-morbidity and the common cognitive profiling patterns across diagnostic categories in abilities outside of the verbal range to highlight potential directions for future research. The implications of these overlaps are considered within existing research on brain laterality, hemispheric dominance and neurological immaturity.