Browsing by Author "Gouse, Hetta-Mari"

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    Executive function in adolescents with fetal alcohol spectrum disorders: a developmental perspective
    (2025) Pomario, Tania; Gouse, Hetta-Mari; Thomas, Kevin
    Objective: Children with fetal alcohol spectrum disorders (FASD) have well-documented deficits in executive function. However, few previous studies have examined executive deficits displayed by children with FASD within a developmental framework. This longitudinal study explored the manifestation of executive function in both alcohol-exposed and typically developing adolescents from a low socioeconomic community in a low-and middle-income country. Method: 110 participants (48 with FASD, mean age 14.65 years, SD = 0.65 and 62 controls, mean age 14.49 years, SD = 0.44) were assessed at two time points, 18 months apart. Participants completed a battery of neuropsychological tests to measure executive function. Parents and teachers provided ratings of participants' everyday executive function on the Behavior Inventory of Executive Function (BRIEF). Principal component analysis examined the underlying components of the neuropsychological measures of executive function in the control group. Composite executive function test scores were computed for both groups, and ANCOVA was used to examine whether a) cognitive performance of the FASD group differed from that of the control group, and b) whether there was a change in scores across the two time points. Chi-square and ANCOVA analyses assessed group differences on the BRIEF. Finally, correlations and regressions investigated whether composite cognitive scores were significant predictors of behaviour, as measured by the BRIEF. Results: Neuropsychological measures of executive function clustered into four distinct factors reflecting the domains of Generativity, Attentional Control, Working Memory, and Processing Speed. The FASD group performed significantly worse than the control group on the Working Memory domain (p < .01). On the BRIEF, a significantly higher proportion of the FASD group was rated as having scores in the clinically impaired range by both parents (p < .001) and teachers (p < .01) compared to controls. Significant differences were found between the FASD and control groups on the Emotional Control and Organization of Materials scales of the BRIEF Teacher. Significant differences were found for the Global Executive Composite and the Plan/Organize and Monitor scales on the BRIEF Parent. The cognitive composites Attentional Control and Generativity were significantly negatively correlated with scores on several of the BRIEF Teacher clinical scales for the FASD group. Conclusion: Performance on working memory tasks emerged as the only domain of executive function that distinguished the FASD group from the control group. There was no notable developmental change in executive abilities over the course of the 18- month period in either group. Both parents and teachers reported that the FASD group displayed significantly more executive deficits, but only teacher ratings were correlated with neuropsychological test results. This suggests that children with FASD have more difficulties with executive functioning in their everyday lives than what is being detected on neuropsychological measures alone.
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    Language effects on semantic fluency test performance among South African adults
    (2021) Kwinana, Anathi; Thomas, Kevin; Gouse, Hetta-Mari
    Issues around the cultural fairness of cognitive tests and their administration are becoming increasingly important as the global spread of neuropsychological practice quickens. Most of these tests are developed and standardized in high-income countries of the global north, and so when used in low- and middle-income countries (LAMICs) of the global south they are susceptible to influence by non-organic factors. Of relevance for this thesis is that these factors include language of test administration (e.g., whether the test is administered in the participant's home language or language of education) and the language profile of the test-taker (e.g., whether the person is multilingual). Semantic fluency tests are a standard component of many neuropsychological test batteries (e.g., those used to detect various forms of dementia), and are commonly administered in LAMICs without due regard for language influences on performance. Hence, the aim of this research was to investigate the influence of language of test administration on semantic fluency test performance in a sample of multilingual students from an English-medium South African university. Participants were 75 balanced English-isiXhosa bilinguals who were administered singlelanguage and forced-switching semantic fluency tests in both languages, as well as a freeswitching semantic fluency test. Results showed that, across test conditions, participants generated more words when administered the tests in English than in isiXhosa. Analyses also showed that, during the isiXhosa but not English administration, participants performed better under free-switching than forced-switching or single-language conditions. The strongest conclusion one can draw from these observations is that test administrators must ensure that test takers are assessed in a language that allows them to demonstrate their optimal cognitive capacity, and that therefore a determination of language proficiency in each of the test-taker's languages is a necessary prerequisite for assessment. This step is especially important in countries, like South Africa, that are home to many multilingual individuals.