THREE BASIC ISSUES OF DEVELOPMENT
For almost as long as psychologists have been interested in development, they have wrestled with the extent to which changes in individuals over time reflect the influence of genetically programmed maturation (nature) or of learning and experience (nurture). Maturation refers to biologically based changes that follow an orderly sequence, each step setting the stage for the next step according to an age related calendar. Infants crawl before they walk and they utter single syllables before they can talk in complete sentences. Unless reared in a very deprived environment,, or physically impaired, virtually all human infants follow these same developmental patterns in the same sequence and at roughly the same age, give or take some months. Most psychologists believe that development, like personality or intelligence, reflects the action and mutual influence of genes and the environment. In other words, nature provides a fertile field for development, but this field requires cultivation.
2 – Critical Periods in Development
Critical periods in human development are periods of sensitivity to specific types of learning and sensory stimulation which shape the capacity for future development. Critical periods in psychological development have been demonstrated in many animal species. The first few hours after hatching are a critical period for goslings (baby geese). They are biologically wired to follow whatever moving object they see, usually their mother. The concept of critical periods in humans is more controversial. Can a child who does not experience nurturant care taking in the first five years of life ever develop the capacity to love? What about a child who was raised by wolves? Human development is more flexible than in other animals, but the brain is still particularly sensitive to certain kinds of environmental feedback at certain times. During some periods, the nervous system is most sensitive to forming new synapses between neurons, given the right environmental stimulus. Equally important is the pruning of neurons: infants are born with an abundance of neural connections, and those that are not used or activated by the environment are gradually lost. Children also have sensitive periods, which are times that are more important to subsequent development than others. In some domains, such as language, these sensitive periods may actually be critical; appropriate environmental input at certain points may be required or further development is permanently impaired. In most domains, however, sensitive periods are simply sensitive – particularly important but not decisive.
3 – Stages or Continuous Change?
The third basic issue in development concerns the nature of developmental change. According to one view, development occurs in stages, relatively discrete steps through which everyone progresses in the same sequence. Behaviour in one stage is not just quantitatively different from the next, involving a little less or more of something, but qualitatively different; a stage theorist would suggest, for example, that the ability to engage in abstract thinking is a novel development in adolescence, not just a gradual refinement of the way younger children think. An alternative perspective sees development as a continuous process, characterised less by major transformations than by steady and gradual change. From this point of view, what may look like a massive change, such as becoming literate between the ages of five and eight, may actually reflect a slow and steady process of learning or increased reinforcement for independent behaviour. So basically, this view suggests that behaviour might appear to appear in a new stage, it has been practiced leading up to that point. Most psychologists now believe that development involves both stages and continuous processes, this is because psychologists don’t like to fight.