Research findings in the area of brain growth periodization establish that the human brain does not grow on a constant continuum. Eighty-five to ninety percent of youngsters of average and above ability experience periods of great brain growth between ages 3-10 months, 2-4 years, 6-8 years, 10-12 years, and 14-16+ years. Mental growth data have…

Research is described concerning a factor analytic view of adolescent thought in Piagetian context. Included are a description of Piagetian tasks used for determining stage of mental development, studies concerning Piagetian task factor analysis, and the current factorial structure of adolescent thought. (DS)