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Developmental psychologists haven't yet determined exactly in what proportion heredity and environment are involved in the development of human behavior. Maturation is the genetically controlled process of growth that results in orderly changes in behavior; it triggers changes in the capacity to function, rather than just quantitative changes (for example, the physical development of the sexual organs must take place before sexual reproduction becomes possible).
Learning, the relatively permanent change in behavior that results from experience, is a factor that is presumed by some psychologists to have the most influence on development. For some traits, such as height, it would appear that the genetic influence is stronger than environmental influences. For other traits, such as shyness, it would appear that learning has the greater influence. Most scientists agree that maturation and experience interact to focus and shape development. In some cases, maturation appears to be largely responsible for the development of particular behaviors (such as early motor development). In other cases, maturation provides only the readiness to learn, and the environment plays a more crucial role in behavioral development. Readiness to learn refers to the fact that babies cannot learn until their muscles and neural structures are developed enough. Infants cannot walk at two months of age because their muscles and nervous systems are not yet ready. At what age do you toilet train children? The correct answer is "When they are ready." You cannot teach children something until they are mature enough, physically and mentally. Maturation determines the readiness to learn. For toilet training, the muscles and the brain must be mature enough for children to learn to control their sphincter muscles. For many children, this is around two years old. But what happens when the environmental experiences do not occur once maturation produces readiness to learn? There is evidence that for some animals critical periods exist, during which particular behaviors should ideally be learned. If learning does not occur at that time, the individual has great difficulty learning and may never be able to master the behavior. Critical periods have been noted in the social development of animals such as birds, sheep, and dogs. For example, if a dog has not been house-trained by six months of age, chances are it will never make a good pet (Scott, 1968). To date, no conclusive evidence for critical periods exists for humans. However, critical periods have been suggested for human behaviors such as attachment and language acquisition. |
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