Through most of the twentieth century, average IQ scores rose by roughly three points every decade in many countries. The finding is named after the researcher who documented it, James Flynn, and it raises a strange question: were our grandparents less intelligent than we are?
Why the rise happened
Nobody believes human biology changed in a few decades. The leading explanations are environmental:
- More years of schooling, with more abstract thinking.
- Better nutrition and health in childhood.
- Smaller families and more attention per child.
- A world full of symbols, maps, screens and puzzles, which trains the kind of reasoning tests measure.
Why test makers renorm
Because the average drifts, tests have to be re-standardised every so often. A person who scored 100 on a thirty-year-old test would score lower on a fresh one. That is why the scale is always defined as "average = 100 today".
The pause, and even a reversal
In several countries, including some in northern Europe, scores have stalled or slipped in recent cohorts. Researchers disagree on the cause: changes in education, in how we use our time, in test motivation, or simply that the easy gains from schooling and nutrition have already been made.
What it means for you
The Flynn effect shows that intelligence test scores respond to environment. That is good news: how you learn, rest and challenge your mind matters. It is also a reminder that a single number is not a permanent label.
See how scores are distributed in our average IQ guide, then check your own with the Real IQ Test.