We read the original studies and say clearly what they do and do not show.
Guide ·
For most of the 20th century, average IQ test scores rose from one generation to the next. Newer data from Norway and the US show a more mixed picture. What the studies actually found.
4 min read
Read the articleGuide · 4 min read
Why the average IQ is 100, what a standard deviation of 15 means, how a score turns into a percentile – and why honest tests report a range.
Guide · 4 min read
Pattern matrices are among the most widely used reasoning tasks in psychology. What they measure, which rules hide inside them, why some are much harder than others – and how to approach them.
Guide · 4 min read
Brain-training apps promise a sharper mind. Large reviews of the research find clear gains on the trained tasks – and little evidence that they spread to reasoning or everyday life.