Extensive continuing analysis of adult intellect and intellectual operation using the Primary Mental Abilities evaluation (see: primary abilities) and employing a sequential pattern (a blend of cross-sectional and longitudinal data-collection techniques). The investigation started in 1956, with assessments completed at regular intervals of seven years, and continues to the present.
SEATTLE LONGITUDINAL STUDY: “The Seattle Longitudinal Study is being conducted by U.S. psychologist K. Warner Schaie (1928- ).”