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…

Two studies examined modifiability in intellectual functioning in older adults. The fluid-crystallized theory provided a theory base for the research. (Fluid intelligence follows a normative decline through adulthood, while crystallized intelligence remains stable or even increases.) In the first study thirty subjects (average age 69.2)…

This paper reviews studies in which scores on Piagetian tests of logical thought were correlated with IQ, mental age (MA) and chronological age (CA), and examines the possible effects of the size of the age range and mean age of subjects on these correlations. The data included 44 groups of subjects obtained from 36 studies in which Piagetian and…

Adolescents, ages 11-12 and 13-14, were tested for maturity of judgment about stability-change situations and about time perspective. (CP)