The Flynn effect has always been tinged with mystery. First popularized by the political scientist James Flynn, the effect refers to the widespread increase in IQ scores over time. Some measures of intelligence — such as performance on Raven’s Progressive Matrices in Des Moines and Scotland — have been increasing for at least 100 years. What’s most peculiar is how scores have increased:
1) Scores have increased the most on the problem-solving portion of intelligence tests.
2) Verbal intelligence has remained relatively flat, while non-verbal scores continue to rise.
3) Performance gains have occurred across all age groups.
4) The rise in scores exists primarily on those tests with content that does not appear to be easily learned.