Question
Is the average IQ falling?
Short answer
In some places, slightly. Norwegian conscript data show test scores declining for men born after about 1975, a reversal of the 20th-century rise known as the Flynn effect. Worldwide, a 2015 meta-analysis found gains slowing rather than reversing. Published IQ averages stay at 100 because tests are renormed.
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What the Norwegian study found
Norway tests nearly all young men at conscription with the same test, which gives researchers a long, consistent record. Bratsberg and Rogeberg analyzed those scores and reported that, after rising for earlier generations, average scores declined for cohorts born after about 1975 (Bratsberg & Rogeberg, 2018). Because the study compared brothers within the same families, its authors concluded that the decline is driven by environmental factors rather than by changes in who was having children.
The wider picture
Across the world the long-run trend was up. A 2015 meta-analysis of 271 samples covering about 4 million people estimated gains of about 2.8 points per decade between 1909 and 2013, with the gains slowing in recent decades (Pietschnig & Voracek, 2015). A slowdown is not the same as a decline, and results differ between countries and tests.
Try one · Pattern Recognition
Which tile comes next?
Tap the option you think is right, or show the answer.
Show the answer
The missing tile shows a very large hatched arrow pointing right (option 3).
How to solve it
- Compare neighboring tiles and name what changes each time.
- From tile to tile, the arrow turns a quarter turn clockwise.
- The fill cycles hatched, outline and solid, then starts again.
- Everything else stays the same from tile to tile.
- The last tile shows a very large solid arrow pointing up. Apply each change once more.
- So the missing tile shows a very large hatched arrow pointing right.
That was 1 puzzle. The full test has 25.
Why the published average does not move
IQ scores are scaled so the reference group averages 100 (Wikipedia: Intelligence quotient). Whatever happens to raw performance, each new edition of a test resets the middle to 100. Rising or falling averages show up only when researchers compare raw scores on the same test across time. See why IQ tests are renormed and the glossary entry on the negative Flynn effect.
How to read headlines about it
Be wary of stories that turn a small cohort trend in one country into a claim that humanity is getting less intelligent. The measured change is a few points over decades, in specific populations, on specific tests. For the long rise that came first, read are people getting smarter and the guide to the Flynn effect.
Sources
- Bratsberg, B., & Rogeberg, O. (2018). Proceedings of the National Academy of Sciences, 115(26), 6674-6678. doi.org/10.1073/pnas.1718793115
- Pietschnig, J., & Voracek, M. (2015). One century of global IQ gains. Perspectives on Psychological Science, 10(3), 282-306. doi.org/10.1177/1745691615577701
- Intelligence quotient. Wikipedia. en.wikipedia.org/wiki/Intelligence_quotient