Personality Development Collaborative

The Seattle Longitudinal Study (SLS) began in 1956 in cooperation with the Group Health Cooperative of Puget Sound (GHC). The purpose of the research project was to study various aspects of psychological development during the adult years. Originally, in 1956, five hundred GHC members were randomly selected. They ranged in age from their early 20s to late 60s. The study has continued in seven-year intervals since 1956: 1963, 1970, 1977, 1984, 1991, 1998, and 2005. At each interval, all persons who had previously participated in the study were asked to participate again. In addition at each seven-year interval until 1998, a new group of people randomly selected from the Group Health membership have been asked to participate. Approximately 6,000 people have now participated at some time in this study. Of the original participants, 26 people remain who have now been in the study for 50 years.

Current participants range in age from 22 to 101 years. In addition to the main study, data has been collected from many adult children, as well as sisters and brothers of the main study participants, in 1989/90, 1996/97, and 2003/04, in order to determine the extent of family similarity in mental abilities and other psychological characteristics. Many of these relatives were studied again in 1996/97 and in 2003/04. In 2002, grandchildren of the main study also began to participate. Some of our study participants aged 64 years and older also received cognitive training designed to slow or remediate cognitive age changes. Three training studies were conducted in 1983/84, 1990/91, and in 1997/98.

For more information about the study and a broader history, see here. 

Principal Investigator(s): Dr. K. Warner Schaie, Dr. Sherry Willis