Two thirds of the age-based changes in fluid and crystallized intelligence, perceptual speed, and memory in adulthood are shared

a Faculty of Psychology and Educational Sciences, University of Geneva, Boulevard du Pont d'Arve 40, 1211 Geneva, Switzerland b Distance Learning University, Switzerland c Department of Experimental Psychology, University of Oxford, 9 South Parks Road, Oxford, OX1 3UD, U.K. d University of Western Australia, Perth, Australia e Department of Statistics and St. Hughs' College, University of Oxford, 1 South Parks Road, Oxford, OX1 3TG, U.K. f Center for Lifespan Development, Max Planck Institute for Human Development, Lentzeallee 94, 14195 Berlin, Germany