Survey of Expert Opinion on Intelligence: Causes of International Differences in Cognitive Ability Tests

Heiner Rindermann et al., Frontiers in Psychology, March 23, 2016


Following Snyderman and Rothman (1987, 1988), we surveyed expert opinions on the current state of intelligence research. This report examines expert opinions on causes of international differences in student assessment and psychometric IQ test results. Experts were surveyed about the importance of culture, genes, education (quantity and quality), wealth, health, geography, climate, politics, modernization, sampling error, test knowledge, discrimination, test bias, and migration. The importance of these factors was evaluated for diverse countries, regions, and groups including Finland, East Asia, sub-Saharan Africa, Southern Europe, the Arabian-Muslim world, Latin America, Israel, Jews in the West, Roma (gypsies), and Muslim immigrants. Education was rated by N = 71 experts as the most important cause of international ability differences. Genes were rated as the second most relevant factor but also had the highest variability in ratings. Culture, health, wealth, modernization, and politics were the next most important factors, whereas other factors such as geography, climate, test bias, and sampling error were less important. The paper concludes with a discussion of limitations of the survey (e.g., response rates and validity of expert opinions).



Causes of General Cross-National Differences

Seventy-one experts rated possible causes of cross-national differences in cognitive ability based on psychometric IQs and student assessment studies (e.g., PISA, PIRLS, TIMSS). Genes were rated as the most important cause (17%), followed by educational quality (11.44%), health (10.88%), and educational quantity (10.20%) (Table 1). The sum of both education factors yielded the highest rating (21.64%). Of all factors, genes had by far the largest standard deviation (SD = 23.85; all other factors, SD < 10), indicating disagreement about the importance of genetic influences. Only 5 of 71 experts (7%) who responded to the genetic item thought that genes had no influence. If non-responses to the genetic item are converted to 0% (4 additional experts), 13% of experts doubted any genetic influence. The frequency of zero-percentage-ratings was larger for genes than for culture or education (about 1%), but experts who believed that genes had no influence were a minority: Around 90% of experts believed that genes had at least some influence on cross-national differences in cognitive ability.

Items with lower percentages (< 10%) included wealth, culture, and modernization (7–9%). Methodological bias factors (sampling error, test knowledge, test bias) were rated as less important (3–6%, together 11.78%).

Causes for the Ability Levels of Single Countries and Groups

The Finnish miracle refers to the top student test results in Finland (Simola, 2005). The top results in Finland have been attributed to progressive educational methods. However, traditional factors and declines in them (e.g., discipline and teacher authority) have been associated with recent drops in test results (Sahlgren, 2015). In the current study, experts attributed the top results in Finland to high educational quality (19.11%), followed by genetic-evolutionary factors (14.89%) and educational quantity (12.71%). The two educational factors combined totaled 31.87%. Educational quality was rated higher in Finland than in any other country.

East Asian countries attain high student test results in nearly all student assessment and psychometric IQ studies. Early test results from East Asia were attributed to better and more efficient instruction (Stigler et al., 1999), culture (Confucian achievement orientation; Helmke and Hesse, 2002), and evolutionary-genetic factors (Lynn, 1990;Kanazawa, 2004; Rushton, 2004). In the current study, experts attributed the high results in East Asia to genes (19.89%), education (quantity: 16.87%, quality: 14.72%), and culture (14.49%). Compared to other countries and regions, East Asia had the strongest ratings for educational quantity and test knowledge.

Sub-Saharan Africa has the lowest student test results (in participating countries), a finding confirmed by psychometric IQs and Piagetian tasks (Lemos, 1974; Hallpike, 1978; Rindermann, 2013; Rindermann et al., 2014b). Similar to discussions of low intelligence in the US, the findings for sub-Saharan Africans are highly contentious, especially when factors other than the environment are examined (e.g., Segerstråle, 2000; Nyborg, 2003). Factors that have been implicated in the low results include health, wealth, evolution, political problems (corruption affecting educational means), modernization, and education (e.g., Lynn, 1990; Glewwe and Kremer, 2006). Measurement issues were also mentioned (e.g., Wober, 1969; Wicherts et al., 2010). In the current study, experts attributed the low results in sub-Saharan Africa to genetic-evolutionary factors (18.58%), followed by educational quality (12.27%), health (11.73%), and educational quantity (11.60%). The two educational factors together had the strongest rating (23.87%), and health had a high rating compared to other regions and countries (12%). While genes were rated as the most important single factor, there was considerable diversity of opinion: 10 of 60 experts gave genes a rating of zero (17%), and the standard deviation in ratings for genes was the highest of all factors (SD = 24.88; all other factors: SD < 10). Similar to other countries and regions, sub-Saharan Africa had low ratings for discrimination and methodological problems (sampling error, test bias, test knowledge).


[Editor’s Note: The full article is available at the original article link below.]

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