Developmental psychology
Developmental psychology is the study of changes in
behaviour during a lifetime. Many developmental psychologists study only a
part of the lifespan. Most are chiefly interested in childhood and
adolescence, the period of a person's life between birth and the early 20's.
There are four main theories of child development that psychologists use in
research on the behaviour of children: (1) maturational theory, (2)
psychoanalytical theory, (3) learning theory, and (4) cognitive theory.
Maturational theory states that the chief principle of developmental
change is maturation, which means physiological "ripening," especially of the
nervous system. Arnold L. Gesell, the leading American supporter of this
theory, found that the growing child's behaviour seems to follow a set
developmental pattern. He described in detail the ways in which behaviour
changes with age. Gesell believed that differences among people result more
from heredity than from environment.
Psychoanalytical theory is based on Sigmund Freud's theory of
psychoanalysis. According to Freud, children are driven by impulses of sex and
aggression. Children develop through a complicated interaction between their
needs, based on sexual impulses, and the demands of their environment.
Environmental demands are represented first by loving and restricting parents,
and later by the children's own version of their parents' demands.
Anna Freud, Erik Erikson, and others have modified Freud's theory and applied
it to child behaviour. In the psychoanalytical view of development, children
change through conflict, chiefly between their own impulses and the demands of
reality. A successful solution of this conflict brings normal development, and
an unsuccessful solution may lead to mental illness.
Learning theory says a child's development depends mainly on experience
with reward and punishment. The child must learn certain responses--such as
speech, manners, and attitudes--to adults. Children learn these responses
through their association with reinforcement (any condition that makes
learning occur). If a mother smiles at her child each time the child is polite
to adults, her smile reinforces the learning of manners. The task of the adult
is to arrange the environment so that it provides suitable and effective
reinforcements for desired behaviour.
Learning theorists base their ideas on two basic learning experiments--studies
of classical conditioning by Ivan P. Pavlov and studies of instrumental
conditioning by E. L. Thorndike and B. F. Skinner. Maturation and heredity
have relatively little importance in the learning theory of development.
Cognitive theory regards the child as an active solver of problems.
Cognitive theorists emphasize the role of a child's natural motivation as the
key factor in development. This motivation can include the desire of children
to satisfy their curiosity, master challenging tasks, or reduce the
inconsistencies and ambiguities they find in the world about them. According
to cognitive theory, children form their own theories about the world and the
relationships among its different aspects. The theories are primitive at
first, but become more realistic after they have been tested against the
child's experience.
Comprehensive cognitive theories of development have been proposed by a number
of authorities, including the Swiss psychologist Jean Piaget. Piaget described
in detail how growing children change their ideas about number, cause, time,
space, and morality. First, the children represent the world in terms of their
own activities. Then they move to a limited set of generalizations based on
their knowledge of specific cases. Finally, the children gain the ability to
make valid and abstract generalizations about reality.
Maturity and old age.
In general, the study of psychology in maturity and old age
has been based on observation. There have been no clear theoretical principles
to guide the search for consistent patterns of development.
Scientists have established that sensory acuity (keenness), speed of response,
productivity in art and science, and the ability to process new information
decline with age, particularly after the late 50's. Less well documented are
declines in memory and in the ability to solve familiar kinds of problems.
Psychologists know little about the most remarkable fact of old age--that some
people go through a degrading decline with the passage of years, and others
remain capable and active until the end of their lives.
