ABSTRACT
The question of stability in development generally, and in mental development specifically, is traditional in developmental study. Stability in development describes consistency in the relative ranks of individuals in a group with respect to status or performance over time. On this construal, stability in mental development means that those individuals who perform well at one time can be expected to perform well again at a later time, and those individuals who perform poorly at first can be expected to perform poorly again later. By contrast, instability implies fluctuation in the relative performance of individuals over time.
