Post-formal operational thought is characterized by both relativism and dialecticism. To examine age differences across adulthood in relativistic and dialectical thought, and to determine whether formal operations are necessary but not sufficient for these forms of thought, 20 young (mean age, 19.6), 20 middle aged (mean age, 46.2), and 20 older…

This report reviews a theoretically inspired empirical investigation of individual differences in knowledge, abilities, and nonability traits as part of an ongoing effort to better understand adult intellectual development and to develop more accurate measures of adult intelligence. Twenty Knowledge Scales were constructed, drawing on…