The science of intelligence: g-factor research, fluid vs crystallized intelligence, Flynn effect, and psychometric methodology explained.
There is no single peak age. See how 10 professions map onto the abilities that peak at 19, 25, or the late 60s, and why experience offsets raw-speed decline.
Why working memory caps expert performance, what the deliberate-practice meta-analyses show, and what to train when more reps stop working. The science.
Decade-by-decade IQ data from Hartshorne, Salthouse, Schaie, and Singh-Manoux shows no single peak age. See which abilities decline, hold, or rise after 45.
National IQ averages vary dramatically, but the data is more contested than most sources admit. Here's what the science shows, and what it means for you.
Cognitive intelligence predicts job performance better than any other trait. Learn the science behind g-factor, fluid vs. crystallized IQ, and career impact in 2026.
Intelligence doesn't protect against cognitive biases. Research shows some get worse with higher IQ. See 13 biases with their measured decision costs.
Research-backed signs of giftedness in children and when IQ testing makes sense. Assessment options, costs, and program placement.
Why IQ follows a normal distribution: mean 100, SD 15, and what that means for your score. Percentages per band, US figures, and the sources behind them.
IQ predicts income only up to ~$70K, then plateaus. The top 1% of earners score lower than those just below. See the data.
Your fluid intelligence peaked years ago. That's actually good news. Learn how to use the Gf-Gc framework for strategic career development at any age.
G-factor predicts income and job performance better than any other measure. Discover what this means for your career and how to use it strategically.
Does grit or IQ matter more for entrepreneurs? Research shows perseverance outperforms raw intelligence in startup outcomes.