The Tower of London-DX 2nd Edition test: Preliminary norms for educationally disadvantaged Xhosa-speaking individuals

Abstract

This study aimed to construct preliminary normative indications for educationally disadvantaged, Xhosa-speaking South African individuals on the Tower of London-Drexel University 2nd Edition test (TOL-DX 2nd Edition). The TOL-DX 2nd Edition is a commonly employed neurocognitive measure of executive function across seven indicators. The study sample included 39 Xhosa-speaking participants proficient in English, aged 19 to 40 years, with a Grade 11 or Grade 12 education attained at a poorly resourced school. Descriptive statistics in the form of means and standard deviations were used to describe the TOL-DX 2nd Edition scaled score normative indicators for the present sample. These preliminary norms were broadly equivalent to the United States standardisation for all seven test indexes. Larger studies with wider age, educational, and geographical distributions are suggested to generate norms that may be usable for clinical case interpretations among educationally disadvantaged South African individuals.

Keywords:

• cross-cultural
• disadvantaged education
• norms
• Tower of London-DX 2nd Ed
• Xhosa

Notes

1 During the period between 1948 and 1994, all South Africans were classified according to the Population Registration Act (Act No. 30 of 1950) into four main divisions including ‘white’, ‘black, ‘coloured’, and ‘Asian’. These terms are thus utilised here on the understanding that they are socially constructed racial signifiers, which have had particular pertinence and continue to be salient in a complex relationship with each other within the South African society, and therefore have salience within the local research context (Van Ommen, 2013).

2 Two distinct categories of norms have been delineated in the psychometric assessment literature, including: (i) population-based norms (standardisation data) that aim to be generally representative of the population in a country, are derived on large countrywide samples, and are typically presented in association with a newly developed test; and (ii) demographically focused norms (within-group norms) that have the aim of closely approximating the subgroup to which an individual belongs within a country-wide population, sometimes on relatively small sample groups. Within-group norms characterise two prominent normative guidebooks in clinical neuropsychology (Mitrushina et al., 2005; Strauss et al., 2006). Additionally, they also form the basis of the South African norming data of Shuttleworth- Edwards and colleagues, cited in this article. In accord- ance with this literature, the terms “norm”, ‘’norms”, and ‘’normative data’’ are applied here for within-group normative indications; the term “standardisation” is used to describe population-based normative data.