The neglected role of individual differences in theoretical models of cognitive development

Based on an analysis of the majority of current theories of cognitive development, which are predominantly universal, general and global in nature, the goal of the present study is to underline the significance of inter- and intraindividual differences in the development of two domains: memory performance and academic achievement. The empirical base consists of two long-term longitudinal studies with children between 4 and 12 yrs. The results showed, besides the expected increase in the level of cognitive competencies, that these increases were by no means universal. Rather, large inter- and intraindividual differences were found for various types of memory tasks as well as for different domains of scholastic achievement. Furthermore, both academic performance and memory performance proved to be fairly stable as early as in elementary school period. Stability was the higher the more the acquisition of new knowledge depended on prior knowledge rather than on general intellectual abilities. In sum, the results of the two longitudinal studies show that it is theoretically necessary and empirically fruitful to complement the dominating universal perspective in current theories of cognitive development by a differential perspective.