Human capital plays an important role in the theory of economic growth, but it has been difficult to measure this abstract concept. We survey the psychological literature on cross-cultural IQ tests, and conclude that modern intelligence tests are well-suited for measuring an important form of a...

I show that in a conventional Ramsey model, between one-fourth and one- half of income differences across countries can be explained by a single factor: The steady-state effect of large, persistent differences in national average IQ on worker productivity. These differences in cognitive...

The years following the Second World War were those of the greatest economic growth that Europe had ever seen. If the countries of the Iberian Peninsula, neutral in the conflict and ruled by dictatorial regimes, enjoyed that growth and had participated in the convergence phenomenon, Ireland,...