The Seattle Longitudinal Study: a thirty-five-year inquiry of adult intellectual development.

The Seattle Longitudinal Study (SLS) over the past 35 years has investigated individual differences and differential patterns of change for selected psychometric abilities from young adulthood old age. It has determined the magnitude and relative importance of age changes and cohort differences in different abilities. A number of contextual, health, and personality variables have been identified that offer explanations for differential change and provide a basis for possible interventions. Cognitive similarity within parent-offspring and sibling pairs has been studied and cognitive interventions were designed that have successfully remedicated carefully determined declines and have improved the cognitive functions of older persons who have remained stable. Most recently, we have begun to study age changes and differences in cognitive ability structure at the latent construct level, have conducted analyses of the relative effect of speed and accuracy in age-related decline and training gain, and have investigated the relevance of cognitive training to real life tasks.