First, third, fifth and eleventh graders were videotaped as they completed the Block Design Subtest of the WISC-R. Neither the order of placement of blocks within each design nor the degree to which children persisted in placing a given block correctly before moving to the next one evidenced developmental differences. (Author/RD)

Change in cognitive functioning is an important aspect of human aging and a key outcome in many medical conditions. However, cognitive change can rarely be measured directly, since prior cognitive data do not exist for most people. We examined the criterion validity and one-year stability of the difference between National Adult Reading Test…