Differentiation of Two Working Memory Tasks Normed on a Large U.S. Sample of Children 2-7 Years Old.

The Wechsler Preschool and Primary Scale of Intelligence, 4th ed. includes two measures of working memory normed on children 2;6-7;7. The present analyses of the typically developing children (N = 1,591, 812 female, 779 male, with an ethnic distribution approximating the United States) provide new, theoretically important information about these working memory tasks, Picture Memory and Zoo Locations. These new analyses establish developmental trends, individual-difference properties, and cognitive task properties. They show comparable developmental trends for the two tasks, but Picture Memory picks up more individual-difference variation and is more sensitive to knowledge. This analysis of normed tasks starting very young makes possible new methods for research on the early stages of childhood working memory development, about which little is currently known.