3.2.3—Development models

A stage theory proposes qualitatively distinct forms of thinking or behaviour that emerge in an ordered sequence; a continuous model proposes gradual, quantitative change as processes strengthen with maturation and experience. Both organize development, but they predict different patterns of transition.

Piaget's account is a stage theory: changes in cognitive structure are used to explain why children solve classes of problems differently across stages. An information-processing model is continuous: gains in attention, processing speed, strategy use and working memory can accumulate and vary by task. Evaluate each by its mechanisms, predictions, cultural range and evidence for abrupt versus gradual change.

If children improve steadily across several memory tasks, the pattern supports continuous change more than a single abrupt transition. If a coordinated new way of reasoning appears across tasks near the same period, that is more consistent with a stage claim—but practice, task language and schooling must still be ruled out.

A stage is not a rigid age label and continuous change is not simply ‘getting older’. Distinguish competence from task performance, look for within-person transitions, and do not assume one model must explain every domain of development.