Maturation and the environmental conditions are the two prime factors which influence growth and development in large scale. Maturation, an innately governed sequence of physical changes, does not depend upon particular environmental events.
Many behavioral changes that occur in the early months of life are clearly related to maturation of the nervous system, muscles, and glands. These changes represent a continuation of the growth processes that guided the development of the foetus within the uterus.
The environmental conditions to which the infant is exposed are, of course, another major influence on development. Each culture differs in its methods of child-rearing, and each family with in a culture has its own schedules and ways of doing things. An infant is exposed to many different conditions- some are shared with other infants in his culture, some are common only to his family group, and some are uniquely his own.
To what extent does a certain skill (such as walking or speaking) develop through maturation and to what extent does its appearance depend on experience or environmental conditions?
It is difficult to separate the effects of “nature” and “nurture”. Maturation can be accelerated or impeded by the quality of the environment; and environmental conditions or special training can stimulate behaviour only when the organism possesses the appropriate neural and muscular equipment.