The Flynn Effect

Foster Langsdorf
February 9, 2017

Submitted as coursework for PH241, Stanford University, Winter 2017


Fig. 1: Scatterplot of Flynn Effect in Norway (after Sundet et al. [4]).

The intelligence quotient (IQ) test scores have risen for people living in developed and undeveloped countries over the past century according to several studies. James Flynn an American scientist, is credited with discovering this phenomenon after comparing IQ tests from the 1980s to earlier documented IQ test scores. The rise in IQ can be attributed to improved nutrition, advancements in technology and other welfare improvements.

Evidence of the Flynn Effect

In Norway when men are enlisted in the army they are tested on their physical abilities, intelligence and current medical condition. The average IQ scores for Norwegian conscripts from 1954 to 2002 are documented from these tests in Fig. 1. Although, the graph does not show consistent improvement from 1954 to 2002, it is evident that from 1954 to 1975 there was a 10 point improvement that then declined about 1 point after 1975 and hovered at a score of 109 for 3 years. After this stagnant period, the scores slowly rose to 112 from 1978 to 1994 and then declined to 110 and flat lined from there.

There is also proof of improvements in IQ scores of children living in underdeveloped countries. Data of IQ scores was collected for children in Kenya between the years of 1984 to 1998. Over 118 children participants with a mean age of 7.43 years from a rural community, a part of the Embu tribe compared then to a sample 14 years later of over 537 children showed an increase of about 11.22 IQ points in the 14 year span. [1] Please refer to Table 1 documenting the children's scores.

The test subjects results showed great improvement in three cognitive tests of Raven's Progressive Matrices, Digit Span Test and a verbal aptitude test, while controlling for language and cultural influences. [2] These tests were meant to judge the child's ability to reason, short-term memory and assess their fluid intelligence.

Test 1984 Study
(N = 118)
1998 Study
(N = 537)
1998 Restricted-Age Sample
(N = 294)
Raven's Progressive Matrices 12.82 (3.21) 17.31 (2.56)*** 17.14 (2.35)***
Verbal Meaning 24.47 (6.31) 27.04 (4.85)*** 26.96 (4.73)***
Digit Span 4.64 (6.31) 5.03 (1.82)* 4.98 (1.85)*
Table 1: Mean scores on the three cognitive tests. Standard deviations are in parentheses. Asterisks indicate significant differences from the 1984 cohort: * p < 0.05, one-tailed; *** p < 0.0001, two-tailed. (After Daley et al. [1]) -

Causes for the Flynn Effect

Data scientists and researchers observed several factors contributing to the rise of IQ for the groups they studied. They observed what the girls in the Kenya village were eating and noted that the calorie intake of the group of children in 1984 had shown that 55.5% of the children were not getting enough calories compared to the smaller percentage of children in 1998 who did not get enough calories which was 35.8%. [1] This influence is important to note because children who do not take in a sufficient number of calories will not have the energy to go to school due to illness or lack of energy to be to do their work and pay attention. Another factor of the Flynn Effect can be attributed to advancements in technology and its instrumental use in education, this influence is seen in developed countries where education utilizes information technology. For example, a study found that computer learning games played by fourth graders improved their math scores. [3]

© Foster Langsdorf. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.


[1] T. C. Daley et al., "IQ on the Rise - The Flynn Effect in Rural Kenyan Children," Psychol. Sci. 14, 215 (2003).

[2] J. C. Raven, Advanced Progressive Matrices, Set 1 (Oxford Psychologists Press, 1990).

[3] R. B. Kozma, ed., Technology, Innovation, and Educational Change: A Global Perspective (ISTE Publications, 2003).

[4] J. M. Sundet, D. G. Barlaug, and T. M. Torjussen, "The End of the Flynn Effect? A Study of Secular Trends in Mean Intelligence Test Scores of Norwegian Conscripts During Half a Century," Intelligence 32, 349 (2004).