Life-Span Perspective on Development

Development is the pattern of progressive, orderly and predictable change that begins at conception and continues throughout life. It is not the same as growth or maturation, though it includes both. Growth refers narrowly to an increase in the size of the body or of a body part — something that can be measured, such as height or weight. Development is broader: it applies only to changes that have a clear direction and that hold a definite relationship to what came before and what will come after — a temporary change caused by, say, a brief illness, is not part of development. Development includes growth as one of its components, but also covers changes in proportion (a child's body proportions are different from an adult's), changes in features (such as losing baby teeth), and the appearance of entirely new features and abilities. Maturation refers specifically to those changes that follow a fixed, orderly sequence and are largely dictated by an individual's genetic blueprint — they seem to 'unfold from within' on a species-typical timetable (for example, most infants can sit without support by around 7 months and walk by about one year, regardless of any special training, provided the underlying physical structures are ready). Evolution is different again — it refers to very slow, species-wide changes carried across generations through natural selection, operating over enormous stretches of time (the emergence of modern humans from earlier ape ancestors is estimated to have taken about 14 million years, with Homo sapiens appearing only around 50,000 years ago).

Development itself results from the interplay of three broad kinds of processes, which are always interwoven rather than separate. Biological processes cover genetically inherited change — for instance in height, weight, and the development of the brain, heart and lungs. Cognitive processes cover the mental activities involved in knowing and experiencing the world — thought, perception, attention, problem-solving, and so on. Socio-emotional processes cover change in how a person interacts with others, and in their emotions and personality — a child's hug for a parent, a sibling's affectionate gesture, or an adolescent's sadness at losing a match are all socio-emotional in nature. Although a textbook has to describe these three kinds of processes in separate chapters, in a real, developing person they are constantly interacting and influencing one another. …