The developmental stages comprise the various stages of human development from birth to childhood and adulthood as theorized by developmental psychologists.
The stages of human development refer mainly to cognitive development, which includes developing mental skills such as information processing, intelligence, reasoning, language usage, and memory. Development begins at birth and continues through childhood and adulthood. Children begin to learn from birth as they become aware of their surroundings and gain some understanding of their world. Although the factors that contribute to cognitive development have been debated and various theories proposed, the consensus in biological and behavioral sciences is that cognitive development is influenced by gene activity in conjunction with life events and experiences within an individual's environment.
Developmental psychologists study the way humans develop from an embryo to adulthood, focusing mainly on the factors that contribute to intelligence, personality, morality, and lifestyle. The effects that certain stimuli have on human development is of particular importance and interest. For instance, it may be useful to know if genetics pre-programs an individual to be introverted rather than this trait resulting from specific life events. Psychologists might also investigate whether the concentrated study of music from an early age makes someone a gifted musician rather than genetic pre-programming from the moment of conception.
Erikson's second stage of development, autonomy versus shame, occurs between ages one and three years. Here, children learn to be independent and autonomous on the condition that they are adequately encouraged to explore their world and given the freedom to do so. Children with overly restrictive or anxious parents who wield too great an influence over their children's behavior may stifle creativity and independent exploration of the environment, and their children may become self-doubting.
Between the ages of three and six, children pass through the initiative-versus-guilt stage, in which they seek to explore their world further by initiating new experiences. Unexpected consequences involved in these initiations may lead to feelings of guilt. The final stage of childhood development, for Erikson, industry versus inferiority, lasts from age six to 12. Here, children seek to become industrious in all areas of life, from school to interpersonal relationships. Mastery of skills, with adequate support at home and in school, brings about a sense of overall competence whereas failure or self-doubt may bring about a sense of inferiority.
Jean Piaget (1896–1980) proposed four stages of cognitive development that are still recognized and accepted. He theorized that people pass from one stage to another not just as a matter of course but only when they are confronted with the correct type of stimulation to initiate a change. Piaget believed that in the absence of the correct kinds of stimulation, children are not likely to reach their full potential.
At the center of Piaget's theory is the principle that cognitive development occurs in four distinct, universal stages, each characterized by increasingly sophisticated and abstract levels of thought. These stages always occur in the same order, and each builds on what has been learned in the previous stage. In Piaget's construct, children from birth to two years are in the sensorimotor stage of cognitive development. During this stage, knowledge is gained primarily through sensory impressions and motor activity. These two modes of learning are experienced both separately and in combination, and they allow children to learn gradually how to control their own bodies and objects in the external world. However, they have little or no ability to conceptualize objects existing beyond their immediate environment. The ultimate task at this stage is to achieve a sense of object permanence, the sense that objects go on existing even when they cannot be seen.
Piaget's next stage, preoperational, spans ages two to seven and involves the manipulation of images and symbols. At this stage, children begin to use language and other representational systems as a way of manipulating symbols and begin to conceive of, and even discuss, absent objects and people. Egocentric thought is the chief marker of this stage, indicating that children can conceive of objectss that are not present but cannot conceptualize that others perceive what the children cannot. The classic example of this kind of thinking is the young child who simply covers his eyes to hide, thinking that since he can no longer see, no one else can either.
Piaget's next stage, concrete operational, covers ages seven to 12. Here, children can perform logical operations, but only in relation to concrete external objects rather than abstract ideas. They can add, subtract, count, and measure, and they learn about the concepts of length, mass, area, weight, time, and volume. At this stage, children can sort items into categories, reverse the direction of their thinking, and think about two concepts, such as length and width, simultaneously. They also begin to better understand spatial relationships and matters of time and may begin to lose their egocentric focus, becoming able to understand a situation from the viewpoint of another person.
During the formal operational stage, from age 12 to adulthood, individuals begin to think logically and systematically and to understand abstractions and the concepts of causality and choice. Adolescents are capable of formulating and testing hypotheses, understanding causality, and dealing with abstract concepts such as probability, ratio, proportion, and analogies. They become able to reason scientifically and speculate about philosophical issues. Abstract concepts and moral values become as important as concrete objects. They are beginning to see that different outcomes can proceed from different actions and that they are free to choose between various actions depending on a desired outcome. Piaget and those who accept his framework believe that only about 25% of individuals reach this stage of cognitive development. Still others suggest that it is a culture-based phenomena and that in less technological societies, almost no one reaches this stage, mainly because such thinking is not valued or may even be considered unnecessary.
See also Cognitive development ; Psychosexual stages .
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