Is Our Collective IQ Increasing?

IQ graph

Psychologists revise the IQ test every couple years in order to maintain an average score of 100. Source: Damato, Alessio and Mikhail Ryazanov. Creative Commons.

The Flynn Effect is the observation that intelligence quotient (IQ) test scores have, on average, increased significantly from the 1930s to the present day.

IQ tests are intended to have an average score of 100. However, psychologists revise the test every couple years in order to maintain this numerical average. Almost invariably, new samples of test takers record average scores of well over 100 when administered an older version of the IQ test (1).

Richard Zynn was actually the first to note this effect when he observed the pattern in Japanese people in 1982 (2). However, the trend bears the name of James Flynn, as he documented and publicized the effect on a larger scale.

The U.S. population have shown an increase of about 3 points in the average IQ score every decade. The Flynn Effect seems to be more pronounced in populations that are typically considered to be from “more developed” areas, such as in Scandinavia. Recent studies show that the Flynn effect may soon fail to hold for a few developed nations. If this trend continues, and nations with lower average IQ scores continue to show improvement in scores according to the Flynn effect, then discrepancies between average IQ scores among different nations could eventually disappear (3).

Researchers debate whether increases in IQ test scores really correlate to an increase in intelligence, or if these increases simply reflect an improvement of  test taking abilities. The learned content hypothesis states that “massive IQ gains do not represent the sort of skill gains that might be identified with increase intelligence” (1). If the learned content hypothesis is true, then increases in IQ score would not imply gains in general problem solving ability.

The trend of increasing IQ scores over time is generally attributed to both an increase in intelligence and to an improvement of test-specific skills. The greatest increases in scores over time tend to be associated with a reduction of culturally oriented content in IQ tests. These culturally reduced tests place a greater focus on the importance of problem solving and minimize the need for skills specific to a certain culture or familiarity with certain words or images.

The implications of the Flynn Effect are debated amongst psychologists. Those who argue that intelligence is most strongly correlated with IQ tests that place a large focus on problem-solving ability would likely argue that intelligence increases with each cultural generation, (1,3). However, Flynn has reported that the French, who have displayed large increases in average IQ scores, in the range of 15 to 20 points from 1952 to 1982,have not reported of a dramatic increase in genius or mathematical and scientific discovery during their generation. During the 1980s, the number of patents issued in France actually decreased. In 1987, Flynn argued that IQ tests measure abstract problem solving ability, which is different from the real world problem solving ability that most strongly corresponds to functional intelligence. However, Flynn stated in his 2007 paper that improvements in abstract problem solving and formal education could mean a greater appreciation of science – a field that deals largely with the abstract (3).


  1. J. R. Flynn, Massive IQ gains in 14 nations: what IQ tests really measure. Psychological Bulletin 101, 171-191 (1987).
  2. R. Lynn, IQ in Japan and the US shows a growing disparity. Nature 297, 222-223 (1982).
  3. J. R. Flynn, L. G. Weiss, American IQ gains from 1932 to 2002: The WISC subtests and educational progress. International Journal of Testing 7, 209-224 (2007).
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