Abstract
This study examined five aspects of change (or
stability) in cognitive abilities in middle adulthood across a
12-year period. Data come from the Interdisciplinary Study
on Adult Development. The sample consisted of N = 346
adults (43.8 years on average, 48.6% female). In total, 11
cognitive tests were administered to assess fluid and crystallized
intelligence, memory, and processing speed. In a
first series of analyses, strong measurement invariance was
established. Subsequently, structural stability, differential
stability, stability of divergence, absolute stability, and the
generality of changes were examined. Factor covariances
were shown to be equal across time, implying structural
stability. Stability coefficients were around .90 for fluid and
crystallized intelligence, and speed, indicating high, yet not
perfect differential stability. The coefficient for memory
was .58. Only in processing speed the variance increased
across time, indicating heterogeneity in interindividual
development. Significant mean-level changes emerged,
with an increase in crystallized intelligence and decline in
the other three abilities. A number of correlations among
changes in cognitive abilities were significant, implying
that cognitive changes
Zimprich, D