Low cognitive test results in the Global South: Artifact or reality? Evidence from everyday life

Abstract

Developing countries show weak results in international cognitive competence studies – about one to two standard deviations below Western norm values, sometimes so low they seem hardly credible. However, comparisons across different scales (e.g., reading vs. math), tests (e.g., curriculum-based TIMSS vs. comprehension-oriented PISA), test paradigms (student achievement vs. intelligence tests), cohorts (e.g., 2000 vs. 2018), populations (children vs. adults), and data sources (e.g., World Bank vs. Hanushek or Rindermann) reveal similar patterns. Predictions based on correlated or assumed causal variables (e.g., amount of education) also yield roughly similar results, though with slightly lower standard deviations (Rindermann, 2025a). It can be argued, however, that all these statistical data may be artifacts that systematically underestimate the true cognitive abilities observable in everyday activities. To investigate this, the conditions for positively influencing developmental factors – especially school education – were examined in case studies, and thinking in cognitively informative everyday situations was described and interpreted (Africa, Cuba, Ecuador, Amazonia, Brazil, Haiti). Compared to large-scale quantitative studies testing thousands of individuals, only a few qualitative analyses of behavior can be conducted. Nonetheless, these examples illustrate phenomena typical of specific levels of cognitive ability and corroborate both the measurement results (if not selective samples) and the regression-predicted cognitive values. In addition, as in the test results, the qualitative descriptions also reveal a range of both high and low abilities as well as high and low levels in different dimensions. Finally, distance from prevailing institutions and modes of thought offers the advantage of unbiased judgment.