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32 A Comparison of Cut-Off Points for Invalid Cognitive Test Performance Established on Nonclinical Versus Clinical Samples for South African Educationally Disadvantaged Individuals
- Sharon Truter, Ann B Shuttleworth-Edwards
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- Journal:
- Journal of the International Neuropsychological Society / Volume 29 / Issue s1 / November 2023
- Published online by Cambridge University Press:
- 21 December 2023, pp. 444-445
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Objective:
In South Africa, most of the cognitive tests employed for neuropsychological evaluation are those developed in educationally advantaged settings such as the US, but the normative data accompanying the tests are unsuitable for use with South African examinees who have a disadvantaged quality of education, and/or whose primary language is other than English. A recently completed collation of Africa-based normative data (Shuttleworth-Edwards & Truter, 2022) includes a chapter on Performance Validity Tests (PVTs) with proposed cut-off points to assist in the identification of noncredible performance. The aim of this study was to compare the cut-off points established using educationally disadvantaged South African nonclinical normative samples for which only specificity percentages are available, with those established using clinical samples with designated valid and invalid performers for which both specificity and sensitivity data are available. A further aim was to compare the Africa-based cut-off points with age-equivalent cut-off points where available for US-based data on the targeted tests.
Participants and Methods:The collation of Africa-based studies delineates cut-off scores for invalid test performance based on both nonclinical as well as clinical populations for three stand-alone PVTs especially developed to identify invalid performance including the Dot Counting Test (DCT), the Rey Fifteen Item Test (FIT), and the Test of Memory Malingering (TOMM); and three commonly employed cognitive tests for which there are embedded validity indicators including the Digit Span Age-Corrected Scaled Score (ACSS) and Reliable Digit Span (RDS), the Rey Auditory Verbal Learning Test (RAVLT), and the Trail Making Test A and B (TMT A and B). For studies using nonclinical norming data alone, specificity percentages to derive the cut-off points were set at a minimum of 90%. For studies using clinical samples specificity was set at a minimum of 90%, and the associated sensitivity percentages were reported indicating each test’s ability to correctly identify those with an invalid performance. The studies included participants stratified for both child and adult age groups (age 8 to 79 years) from South African educationally disadvantaged backgrounds. The data were tabled together for descriptive comparison purposes, including a column for the US-base cut-off points for equivalent age stages where available.
Results:There was a high level of compatibility between the proposed cut-off points established for the South African nonclinical normative samples compared with those using clinical samples of designated valid and invalid performers. There was a trend for more lenient cut-offs for younger children and older adults compared to older children and younger adults. Compared with US-based data where available, adjustments towards leniency were called-for on all indicators.
Conclusions:Cut-off scores for invalid cognitive test performance can be verified by perusing data derived from nonclinical norming samples as well as those from clinical samples, although the latter have the advantage of providing the sensitivity data to demonstrate the efficacy of a proposed cut-off score for identifying noncredible test performance. Adjustments towards leniency need to be made for cut-off scores for young children and older adults within an educationally disadvantaged population, and for disadvantaged adult populations compared with US-based educationally advantaged populations.
7 A Comparison of Performance of Educationally Disadvantaged Non-English-Speaking Participants on a Category Verbal Fluency Test using English or the First Language
- Sharon Truter, Ann B Shuttleworth-Edwards
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- Journal:
- Journal of the International Neuropsychological Society / Volume 29 / Issue s1 / November 2023
- Published online by Cambridge University Press:
- 21 December 2023, pp. 91-92
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Objective:
South Africa has a multi-lingual population where fewer than 10% of the population speak English as a first language. This poses a challenge regarding language usage for a verbal fluency task. This study investigated the difference in number of words produced by independent groups of non-English examinees required to produce words in English, or in their first language, on a category verbal fluency task.
Participants and Methods:A study on South African non-English first language participants was conducted using the Category Verbal Fluency test (animals) for a sample of nonclinical adults (N = 264) aged 18-60 years with 8-12 years of disadvantaged (poorly resourced) quality of education. Participants either had an African indigenous first language, or Afrikaans (a Dutch derivative) as a first language. The data were derived from one group of either African indigenous or Afrikaans first language participants who were required to use English for word production (Group A English) (n = 159; African indigenous n = 135; Afrikaans n = 24) and another group of participants who were required to use their first language (Group B First Language) (n = 105; African indigenous n = 83; Afrikaans n = 22). The comparative data were stratified for age ranges 18-20, 21-30, 31-40, 41-50 and 51-60 years. Level of education was broadly equivalent across the comparative groups. T-test analyses compared the number of words produced between the English versus indigenous African groups, and English versus Afrikaans first language groups for each age category.
Results:The comparison for the indigenous African first language participants, revealed no significant differences in word production for words produced in English or first language regardless of age. In the comparison for the Afrikaans first language participants there was a highly consistent tendency for better word production in Afrikaans than in English. These results indicate that socio-cultural factors may be influential for English language proficiency on a verbal fluency task, rather than the effect of first language usage “per se”.
Conclusions:Since the dismantling of the Apartheid system in South Africa thirty years ago, English has become the main language used in government and business and is the preferred language of tuition in schools for those speaking English or an African indigenous language, whereas during the Apartheid era, two official languages were used for government, business, and schooling (Afrikaans and English). Currently, many Afrikaans speaking individuals continue to have Afrikaans as the preferred primary language of tuition in the schools and it persists as the preferred language for use in many Afrikaans dominated business arenas. This study attests to a high level of English fluency amongst those South Africans with an indigenous African first language, who clearly are as fluent in word production using English as they are when using their first language, in contrast to the indications for Afrikaans speaking individuals. Practitioners need to be alert to sociocultural factors that can impact on the optimal use of language in test situations, which may not necessarily be the first language.
2 - WAIS-III test performance in the South African context: extension of a prior cross-cultural normative database
- from Section One - Cognitive tests: conceptual and practical applications
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- By A. B. Shuttleworth-Edwards, Rhodes University, E. K. Gaylard, practises as a clinical psychologist in Johannesburg, focusing on child assessment and psychotherapy, S. E. Radloff, Rhodes University
- Edited by Sumaya Laher, Kate Cockcroft
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- Book:
- Psychological Assessment in South Africa
- Published by:
- Wits University Press
- Published online:
- 21 April 2018
- Print publication:
- 31 December 2013, pp 17-32
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Summary
The focus of this chapter is on the Wechsler Adult Intelligence Scale – Third Edition (WAIS-III) and its application within the South African context. While there is now a fourth edition of the Wechsler Adult Intelligence Scale, WAIS-IV (Wechsler, 2008), the only cross-cultural research within the South African context to date is in respect of the WAIS-III, the normative implications of which continue to have crucial relevance for practitioners wishing to employ a WAIS in this country.
Importantly, two distinct categories of norms have been delineated in the psychometric assessment literature: (i) population-based norms (standardisation data) representative of the general population that are typically derived on large samples and presented in association with a newly developed test; and (ii) norms that closely approximate the subgroup to which an individual belongs (withingroup norms), such as form the basis of the leading normative guidebooks in clinical neuropsychology (Mitrushina, Boone, Razani & D'Elia, 2005; Strauss, Sherman & Spreen, 2006).
The objective of standardisation data is to allow for the location of an individual's ability relative to the general population, for purposes such as institutional placement. In contrast, the purpose of within-group norms is to allow for comparisons of an individual's level of performance with the subgroup that best approximates his or her unique demographic characteristics for diagnostic purposes, and is the impetus behind the data for presentation in this chapter.
Within-group norms with fine levels of stratification are regularly reported descriptively in terms of means and standard deviations, and may be based on small sample numbers (for example, n < 10, and in some instances the sample numbers may be as low as n = 1 or 2). Nevertheless, such normative indicators are considered less prone to the false diagnostic conclusions that may accrue via comparisons with population-based standardisation data that are not demographically applicable in a particular case (Lezak, Howieson & Loring, 2004; Mitrushina et al., 2005; Strauss et al., 2006).
The history of the Wechsler Adult Intelligence Scales
Historically, the various WAIS in current usage have their origins in the release of the Wechsler-Bellevue Intelligence Scale Forms I and II in 1939 and 1944, respectively (Wechsler, 1939; 1944). Over the years, the adult Wechsler tests in their various refined and updated versions, currently covering the age range from 16 to 89 years, have accumulated a wealth of endorsement through clinical and research experience.
30 - The ImPACT neurocognitive screening test: a survey of South African research including current and projected applications
- from Section Three - Assessment approaches and methodologies
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- By A. B. Shuttleworth-Edwards, Rhodes University, V. J. Whitefield-Alexander, Crescent Clinic in Kenilworth, Cape Town, S. E. Radloff, Rhodes University
- Edited by Sumaya Laher, Kate Cockcroft
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- Book:
- Psychological Assessment in South Africa
- Published by:
- Wits University Press
- Published online:
- 21 April 2018
- Print publication:
- 31 December 2013, pp 443-460
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Summary
In recent decades, the development of computerised neurocognitive screening has revolutionised medical management in the sports concussion arena by making possible preseason (baseline) testing of large numbers of athletes, and repeat follow-up testing of the concussed athlete, to monitor recovery and facilitate safe return-to-play decisions (Moser et al., 2007). The aim of this chapter is to introduce the most widely employed instrument of this genre, the ImPACT (Immediate Postconcussion Assessment and Cognitive Testing) test (Iverson, Lovell & Collins, 2002), and to review the available South African normative research data in respect of the instrument to date. While the test has potential for wide application beyond the sports concussion arena (as discussed in the concluding section of this chapter), its development within the sports injury context calls for background detail in this regard.
Mild traumatic brain injury (concussion) in sport
Mild traumatic brain injury (MTBI), typically referred to as ‘concussion’ in the sports arena, is a common feature amongst both amateur and professional sports alike (Cassidy, Carroll, Peloso, Borg & Von Holst, 2004). While once considered to be a ‘routine risk’ associated with participation in the game, the impact of these injuries has gained significant international interest and concern amongst sports and health professionals in the past three decades (Barth et al., 1989; Collins, Lovell & McKeag, 1999; Shuttleworth-Edwards, Border, Reid & Radloff, 2004), and is currently considered by the Centers for Disease Control and Prevention (CDC, 1997) to be of epidemic proportions. The incidence of the concussive injury varies widely depending on the sport, such that in one comparative high school study US football accounted for 63 per cent of all cases, wrestling for 10.5 per cent, girls’ soccer for 6.2 per cent, boys’ soccer for 5.7 per cent, girls’ basketball for 5.2 per cent, boys’ basketball for 4.2 per cent, softball for 2.1 per cent, baseball for 1.2 per cent, field hockey for 1.1 per cent and volleyball for 0.5 per cent (Powell & Barber-Foss, 1999).
3 - WISC-IV test performance in the South African context: a collation of cross-cultural norms
- from Section One - Cognitive tests: conceptual and practical applications
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- By A. B. Shuttleworth-Edwards, Rhodes University, A. S. van der Merwe, Rhodes University, P. van Tonder, Rhodes University, S. E. Radloff, Rhodes University
- Edited by Sumaya Laher, Kate Cockcroft
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- Book:
- Psychological Assessment in South Africa
- Published by:
- Wits University Press
- Published online:
- 21 April 2018
- Print publication:
- 31 December 2013, pp 33-47
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Summary
The Wechsler Intelligence Scales have led the way in assessment of intelligence for almost seven decades, since the release of the original Wechsler-Bellevue Intelligence Scale in 1939 (Saklofske, Weiss, Beal & Coalson, 2003). Despite exemplary characteristics of other new and revised versions of intelligence tests, the Wechsler tests remain, and in the foreseeable future are likely to remain, the most widely used standardised measures for individual testing of children and adults worldwide, covering the age range from 2.5 to 89 years (Flanagan & Kaufman, 2009). The intermediate age ranges are catered for by the Wechsler Intelligence Scale for Children (WISC) which, when first released in 1949, marked the division of the Wechsler Intelligence Scales into separate tests for children and adults (Saklofske et al., 2003).
The WISC has gone through two previous revisions (WISC-R, 1974; WISCIII, 1991) prior to the most recently released version of the WISC-IV (Wechsler, 2003; 2004) that is intended for use with children aged 6 years to 16 years 11 months. The current version of the test was revised to keep up with changes in norms as population scores become inflated over time (known as the Flynn effect), as well as to ensure that test items remain current and unbiased (Prifitera, Weiss, Saklofske & Rolfhus, 2005). It also encompasses a fundamental theoretical shift, as it was designed with current trends in factor analysis theories in mind and thereby is considered to have introduced stronger psychometric properties (Baron, 2005). The test remains a good measure of g (the general intelligence factor) and consistently measures the same constructs across age groups 6 to 16 (Keith, Fine, Taub, Reynolds & Kranzler, 2006). The results of the US standardisation confirmed that the WISC-IV achieved high levels of reliability, with test-retest reliability being at least .76, but mostly in the .80s, and with subtest scores being less stable compared to Index scores and the Full Scale Intelligence Quotient (FSIQ); convergent validity with preceding editions of the Wechsler tests, including the WISC-III, yielded correlations from at least .73, but mostly in the high .70s and high .80s (Wechsler, 2003).
Based on new neurological models of cognitive function, the WISC-IV's main departure from the traditional Wechsler model is that it improves on the test's ability to evaluate perceptual reasoning, working memory and processing speed (Wechsler, 2003).