Cognitive Variability: A Key to Understanding Cognitive Development

Among the most remarkable characteristics of human beings is how much our thinking changes with age. When we compare the thinking of an infant, a toddler, an elementary school student, and an adolescent, the magnitude of the change is immediately apparent. Ac counting for how these changes oc cur is perhaps the central goal of re searchers who study cognitive development. Alongside this agreement about the importance of the goal of deter mining how change occurs, how ever, is agreement that we tradition ally have not done very well in meeting it. In most models of cogni tive development, children are de picted as thinking or acting in a cer tain way for a prolonged period of time, then undergoing a brief, rather mysterious, transition, and then thinking or acting in a different way for another prolonged period. For example, on the classic conserva tion-of-liquid quantity problem, children are depicted as believing for several years that pouring water into a taller, thinner beaker changes the amount of water; then undergo ing a short period of cognitive con flict, in which they are not sure about the effects of pouring the wa ter; and then realizing that pouring does not affect the amount of liquid. How children get from the earlier to the later understanding is described only superficially. Critiques of the inadequacy of such accounts have been leveled most often at stage models such as Piaget's. The problem, however, is far more pervasive. Regardless of whether the particular approach de scribes development in terms of stages, rules, strategies, or theories; regardless of whether the focus is on reasoning about the physical or the social world; regardless of the age group of central interest, most theo ries place static states at center stage and change processes either in the wings or offstage altogether. Thus, 3-year-olds are said to have nonrep resentational theories of mind and 5-year-olds representational ones; 5-year-olds to have absolute views about justice and 10-year-olds rela tivistic ones; 10-year-olds to be in capable and 15-year-olds capable of true scientific reasoning. The em phasis in almost all cognitive developmental theories has been on identifying sequences of one-to-one correspondences between ages and ways of thinking or acting, rather than on specifying how the changes occur.