Stages of Development

Imagine a playground full of children on a warm summer day. A toddler tentatively makes her way across the sand to retrieve a shovel then, with a smile of triumph, retreats to her mother's side. Nearby a pair of two-year-olds dig in the sand side by side, practically touching yet seemingly unaware of one another. A band of boisterous five-year-olds rush past them, chasing an imagined pirate on a tumultuous sea. A quick survey of these intersecting scenes shows that these groups of children are clearly going about the business of learning and play in very different ways, at increasing levels of sophistication. Over the years, developmental psychologists have confronted the question of how best to characterize these changes in both cognitive and social functioning. Is it a simple matter of children adding to their repertoire of skills and knowledge as they get older (quantitative change), or do higher levels of functioning actually represent a reorganization of the previous level of functioning, much in the way that a caterpillar goes through discrete stages of life on the way to becoming a butterfly (qualitative change)? "Stage models" of development are based on a combination of these two types of conceptualizations. Psychologists have developed such models for understanding and explaining both cognitive and psychosocial development.