The Flynn effect, country by country
Raw IQ scores rose by about 3 points a decade across the 20th century. Since the 1990s they have stalled or fallen among young men in Norway, Denmark and Finland, while the studies we have from China and Kenya still showed gains. The French "decline" turned out to be a measurement problem. Here are the 13 national studies behind the headlines, side by side.
By the LifeScore Editorial Team · Updated · How we built this
IQ points per decade
Kenya
1984 to 1998
+7.9Netherlands
1952 to 1982
+6.7United States
1932 to 1978
+3.0China
1986 to 2012
+2.4United Kingdom
1942 to 2008
+2.2United States
2008 to 2024
+1.2Finland
1997 to 2009
−1.7Denmark
1998 to 2004
−2.7Worldwide
pooled estimate
+2.8
Every study in the table
Sorted by country. “How we checked” tells you whether we saw the figure in the paper's own summary or only in reports of it; quote the second kind only after reading the paper.
Austria and Germany
1977 to 2014 · Paper's own summary
96 samples, 13,172 people. Three-dimensional cubes test (spatial)
Rise, then fall. Spatial scores rose at first and then fell, after controlling for age, sample type and sex.[15]
China
+2.4 / decade
1986 to 2012 · Paper's own summary
12-year-olds tested in 1985-86 and 2011-12. WISC-R
Rise. Full-scale IQ rose 6.19 points; performance IQ 6.55 and verbal IQ 1.91.[8]
Per decade: 6.19 points ÷ 26 years × 10
Denmark
−2.7 / decade
1998 to 2004 · Paper's own summary
Young men at the draft board. Four tests given at the draft board
Fall. Scores on all four tests fell between 1998 and 2003/04 by about 1.5 IQ points, close to the net gain from 1988 to 1998.[9]
Per decade: −1.5 points ÷ 5.5 years × 10 (the abstract says a "5/6 year period")
Denmark
2006 to 2019 · Paper's own summary
All 400,288 men at the draft board, typically aged 19. Børge Priens Prøve
No clear change. No systematic change over the period. The authors cannot rule out a decline, because who is tested changed.[10]
Finland
−1.7 / decade
1997 to 2009 · Reported by others
Military conscripts. Conscription ability test
Fall. Scores rose from 1988 to 1997 and then fell to 2009. Reported as a fall of about 2 points, after a rise of about 4.[13]
Per decade: about −2 points ÷ 12 years × 10 (figure from reviews)
France
1999 to 2009 · Paper's own summary
79 adults who took two Wechsler editions. WAIS-III and WAIS-IV (French)
Disputed. Reported as a decline. A re-analysis found the drop came from items whose difficulty had drifted with cultural change, and concluded there is no evidence of a negative Flynn effect in France.[13, 14]
Kenya
+7.9 / decade
1984 to 1998 · Reported by others
Rural children aged 6 to 8 in Embu (118 in 1984, 537 in 1998). Raven's matrices and two other tests
Rise. Strong evidence of a Flynn effect over 14 years, largest on Raven's matrices. Reported at about 11 points across the three tests.[6, 7]
Per decade: about 11 points ÷ 14 years × 10 (figure from Science News)
Netherlands
+6.7 / decade
1952 to 1982 · Reported by others
Dutch military conscripts, aged about 18. Raven's-type matrices
Rise. Men tested in 1982 scored about 20 points higher than men tested in 1952. One of the largest gains Flynn reported across 14 nations, where gains ran from 5 to 25 points a generation.[4]
Per decade: 20 points ÷ 30 years × 10
Norway
1962 to 1991 (born) · Paper's own summary
About 730,000 men born 1962 to 1991, tested at conscription. Conscription ability test
Rise, then fall. Scores rose for men born up to about 1975 and fell for later cohorts. The fall appears between brothers in the same family, so its cause is environmental.[11, 12]
United Kingdom
+2.2 / decade
1942 to 2008 · Paper's own summary
Children aged 5 to 15. Raven's Progressive Matrices
Rise, then fall. About 14 points gained from around 1942, or 0.216 points a year. Since 1979 gains shrink with age, and between 12-13 and 14-15 small gains turn into small losses.[5]
Per decade: 0.216 points a year × 10, as reported
United States
+3.0 / decade
1932 to 1978 · Paper's own summary
Standardisation samples of the Stanford-Binet and Wechsler tests. Stanford-Binet and Wechsler scales
Rise. Each new sample scored higher on the old norms: a total rise of 13.8 IQ points in 46 years.[3]
Per decade: 13.8 points ÷ 46 years × 10
United States
2006 to 2018 · Paper's own summary
394,378 adults tested online (SAPA Project). ICAR items: matrices, series, verbal, 3D rotation
Rise, then fall. Scores declined in most domains across ages and groups; three-dimensional rotation was the exception and rose.[16]
United States
+1.2 / decade
2008 to 2024 · Paper's own summary
186 adults aged 16 to 90 who took both tests. WAIS-IV and WAIS-5
Rise. The same people scored 1.9 points higher on the older WAIS-IV, a much smaller gap than earlier Wechsler comparisons found.[17]
Per decade: 1.9 points ÷ 16 years between the norm samples × 10
| Country | Years | Who and what test | What changed | How we checked | Per decade |
|---|---|---|---|---|---|
| Austria and Germany | 1977 to 2014 | 96 samples, 13,172 people. Three-dimensional cubes test (spatial) | Rise, then fall. Spatial scores rose at first and then fell, after controlling for age, sample type and sex.[15] | Paper's own summary | – |
| China | 1986 to 2012 | 12-year-olds tested in 1985-86 and 2011-12. WISC-R | Rise. Full-scale IQ rose 6.19 points; performance IQ 6.55 and verbal IQ 1.91.[8]Per decade: 6.19 points ÷ 26 years × 10 | Paper's own summary | +2.4 |
| Denmark | 1998 to 2004 | Young men at the draft board. Four tests given at the draft board | Fall. Scores on all four tests fell between 1998 and 2003/04 by about 1.5 IQ points, close to the net gain from 1988 to 1998.[9]Per decade: −1.5 points ÷ 5.5 years × 10 (the abstract says a "5/6 year period") | Paper's own summary | −2.7 |
| Denmark | 2006 to 2019 | All 400,288 men at the draft board, typically aged 19. Børge Priens Prøve | No clear change. No systematic change over the period. The authors cannot rule out a decline, because who is tested changed.[10] | Paper's own summary | – |
| Finland | 1997 to 2009 | Military conscripts. Conscription ability test | Fall. Scores rose from 1988 to 1997 and then fell to 2009. Reported as a fall of about 2 points, after a rise of about 4.[13]Per decade: about −2 points ÷ 12 years × 10 (figure from reviews) | Reported by others | −1.7 |
| France | 1999 to 2009 | 79 adults who took two Wechsler editions. WAIS-III and WAIS-IV (French) | Disputed. Reported as a decline. A re-analysis found the drop came from items whose difficulty had drifted with cultural change, and concluded there is no evidence of a negative Flynn effect in France.[13, 14] | Paper's own summary | – |
| Kenya | 1984 to 1998 | Rural children aged 6 to 8 in Embu (118 in 1984, 537 in 1998). Raven's matrices and two other tests | Rise. Strong evidence of a Flynn effect over 14 years, largest on Raven's matrices. Reported at about 11 points across the three tests.[6, 7]Per decade: about 11 points ÷ 14 years × 10 (figure from Science News) | Reported by others | +7.9 |
| Netherlands | 1952 to 1982 | Dutch military conscripts, aged about 18. Raven's-type matrices | Rise. Men tested in 1982 scored about 20 points higher than men tested in 1952. One of the largest gains Flynn reported across 14 nations, where gains ran from 5 to 25 points a generation.[4]Per decade: 20 points ÷ 30 years × 10 | Reported by others | +6.7 |
| Norway | 1962 to 1991 (born) | About 730,000 men born 1962 to 1991, tested at conscription. Conscription ability test | Rise, then fall. Scores rose for men born up to about 1975 and fell for later cohorts. The fall appears between brothers in the same family, so its cause is environmental.[11, 12] | Paper's own summary | – |
| United Kingdom | 1942 to 2008 | Children aged 5 to 15. Raven's Progressive Matrices | Rise, then fall. About 14 points gained from around 1942, or 0.216 points a year. Since 1979 gains shrink with age, and between 12-13 and 14-15 small gains turn into small losses.[5]Per decade: 0.216 points a year × 10, as reported | Paper's own summary | +2.2 |
| United States | 1932 to 1978 | Standardisation samples of the Stanford-Binet and Wechsler tests. Stanford-Binet and Wechsler scales | Rise. Each new sample scored higher on the old norms: a total rise of 13.8 IQ points in 46 years.[3]Per decade: 13.8 points ÷ 46 years × 10 | Paper's own summary | +3.0 |
| United States | 2006 to 2018 | 394,378 adults tested online (SAPA Project). ICAR items: matrices, series, verbal, 3D rotation | Rise, then fall. Scores declined in most domains across ages and groups; three-dimensional rotation was the exception and rose.[16] | Paper's own summary | – |
| United States | 2008 to 2024 | 186 adults aged 16 to 90 who took both tests. WAIS-IV and WAIS-5 | Rise. The same people scored 1.9 points higher on the older WAIS-IV, a much smaller gap than earlier Wechsler comparisons found.[17]Per decade: 1.9 points ÷ 16 years between the norm samples × 10 | Paper's own summary | +1.2 |
The big picture: two meta-analyses
| Estimate | Based on | Per decade |
|---|---|---|
| Worldwide, 1909 to 2013[1] | 271 samples, almost 4 million people, 31 countries. Full-scale IQ. Fluid tests about 4.1, crystallised about 2.1. | +2.8 |
| Wechsler and Stanford-Binet comparisons[2] | Meta-analysis of test-to-test comparisons. As reported in reviews of the paper (2.93). | +2.9 |
A 2016 review set strict quality rules and found nine studies showing a negative Flynn effect, in seven countries.[13] The reversal is real in some places, but it is not worldwide, and the gains in the pooled data are much larger than the losses.
How to read these numbers
- Different tests, different samples. Conscript data cover young men only. Online samples, such as the US SAPA Project, are not representative. A matrix test and a vocabulary test move at different speeds. So the per-decade figures show direction and rough size, not a league table.
- Testing years or birth years. Norway's study is by year of birth; most others by year of testing. A turn in men born after 1975 shows up in tests from the early 1990s.
- Who gets tested changes. When fewer men are conscripted, or the mix of schooling changes, averages move for reasons that have nothing to do with ability. The 2021 Danish study says exactly this about its own flat result.
- Old norms flatter. Because of these trends, a score on an old edition reads high. Our guide to the Flynn effect shows how to adjust an old score, and the history of IQ testing lists when each edition was renormed.
Why scores rose, and why they fell
The Norwegian brothers study is the strongest evidence on cause: the fall appears between brothers in the same family, so it is not explained by who is having children or by immigration. It points to changes in the environment, without saying which.[11] Flynn argued that better nutrition cannot explain the British gains, because height and IQ trends moved separately.[5] Schooling, family size and the demands of modern work and media are the usual suspects. None has been shown to be the single cause.
For what this means for a single score, see why the average IQ is always 100 and what affects IQ.
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<p><a href="https://lifescoretest.com/research/flynn-effect-by-country">Flynn effect by country</a> by LifeScore</p>How we built this
- What it covers
- 13 studies of change in IQ test scores within one country (10 entries), plus two meta-analyses. Picked for size, a clear method and how often they are cited, including studies that found no change and one whose finding was overturned.
- Per-decade figures
- Our arithmetic: the change the study reports, divided by its span of years, times ten, rounded to one decimal. The working is next to each number. We did not compute a rate for studies that report only a direction.
- How each figure was checked
- Against the paper's abstract or summary where we could read it. For Kenya, the Netherlands and Finland the size comes from reports and reviews of the paper; the table marks these as "Reported by others".
- What is not here
- Country "national IQ" averages, which measure something different and are disputed. Studies we could not confirm, including Swedish and Argentine conscript and norm data, until we can read them.
- Last checked
- 14 October 2026
- Corrections
- Found an error or a newer figure? Tell us and we will fix it and date the change in the public change log.
Sources
- 1.Pietschnig, J., & Voracek, M. (2015). One century of global IQ gains: A formal meta-analysis of the Flynn effect (1909-2013). Perspectives on Psychological Science, 10(3), 282-306. doi.org/10.1177/1745691615577701
- 2.Trahan, L. H., Stuebing, K. K., Fletcher, J. M., & Hiscock, M. (2014). The Flynn effect: A meta-analysis. Psychological Bulletin, 140(5), 1332-1360. doi.org/10.1037/a0037173
- 3.Flynn, J. R. (1984). The mean IQ of Americans: Massive gains 1932 to 1978. Psychological Bulletin, 95(1), 29-51. doi.org/10.1037/0033-2909.95.1.29 · semanticscholar.org
- 4.Flynn, J. R. (1987). Massive IQ gains in 14 nations: What IQ tests really measure. Psychological Bulletin, 101(2), 171-191. iapsych.com
- 5.Flynn, J. R. (2009). Requiem for nutrition as the cause of IQ gains: Raven's gains in Britain 1938-2008. Economics & Human Biology, 7(1), 18-27. ideas.repec.org
- 6.Daley, T. C., Whaley, S. E., Sigman, M. D., Espinosa, M. P., & Neumann, C. (2003). IQ on the rise: The Flynn effect in rural Kenyan children. Psychological Science, 14(3), 215-219. doi.org/10.1111/1467-9280.02434
- 7.Bower, B. (2003). Harvesting intelligence: IQ gains may reach rural Kenya's kids. Science News. sciencenews.org
- 8.Liu, J., & Lynn, R. (2013). An increase of intelligence in China 1986-2012. Intelligence, 41(5), 479-481. pmc.ncbi.nlm.nih.gov
- 9.Teasdale, T. W., & Owen, D. R. (2008). Secular declines in cognitive test scores: A reversal of the Flynn effect. Intelligence, 36(2), 121-126. gwern.net
- 10.Hegelund, E. R., Okholm, G. T., & Teasdale, T. W. (2021). The secular trend of intelligence test scores in the present century: The Danish experience. Intelligence, 85. ideas.repec.org
- 11.Bratsberg, B., & Rogeberg, O. (2018). Flynn effect and its reversal are both environmentally caused. PNAS, 115(26), 6674-6678. doi.org/10.1073/pnas.1718793115
- 12.Science Norway (2018). Our IQ is steadily declining. sciencenorway.no. sciencenorway.no
- 13.Dutton, E., van der Linden, D., & Lynn, R. (2016). The negative Flynn Effect: A systematic literature review. Intelligence, 59, 163-169. doi.org/10.1016/j.intell.2016.10.002 · repub.eur.nl
- 14.Gonthier, C., Grégoire, J., & Besançon, M. (2021). No negative Flynn effect in France: Why variations of intelligence should not be assessed using tests based on cultural knowledge. Intelligence, 84, 101512. doi.org/10.1016/j.intell.2020.101512 · research.dial.uclouvain.be
- 15.Pietschnig, J., & Gittler, G. (2015). A reversal of the Flynn effect for spatial perception in German-speaking countries: Evidence from a cross-temporal IRT-based meta-analysis (1977-2014). Intelligence, 53, 145-153. doi.org/10.1016/j.intell.2015.10.004 · ucrisportal.univie.ac.at
- 16.Dworak, E. M., Revelle, W., & Condon, D. M. (2023). Looking for Flynn effects in a recent online U.S. adult sample: Examining shifts within the SAPA Project. Intelligence, 98, 101734. doi.org/10.1016/j.intell.2023.101734
- 17.Winter, E. L., Trudel, S. M., & Kaufman, A. S. (2024). Wait, where's the Flynn effect on the WAIS-5? Journal of Intelligence, 12(11), 118. pmc.ncbi.nlm.nih.gov
How we choose sources is in our editorial policy. Every source we cite is on the sources page. Spotted an error? Tell us.
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