The various aspects of child development encompass physical growth, emotional and psychological changes, and social adjustments. A great many determinants influence patterns of development and change. On the average, a newborn baby weighs 3.4 kg (7.5 lb) and is 53 cm (21 in) long, with the head disproportionately larger than the lower part of the body. As the child grows, increments in height are greatest from birth to three years; thereafter they are relatively constant until adolescence. The growth spurt at adolescence is far less than during infancy. Weight increments are also large during the first three years but are equally large during adolescence. Research shows that growth rates are influenced by the health of the child. Rates of development decelerate during illness; after an illness is cured, however, growth rates accelerate until children attain their appropriate height and weight.Dramatic changes occur in motor skills from birth through the first two years. At birth infants are capable of extensive uncoordinated movements. One feature of the early motor behavior of infants is the large number of reflex-like actions. These actions appear for a short time after birth and then disappear. For example, when the palm of the hand is stroked lightly the fingers involuntarily close, forming a fist; this is called the palmar reflex. From these early movements, distinct sequential patterns of motor development occur. Walking, which occurs on the average between 13 and 15 months, emerges from a sequence of 14 earlier stages. Research shows that the rate of acquisition of motor skills is innately determined and that the acquisition of these skills is not influenced by practice. Severe restrictions on motor activities, however, will alter both the pattern and rate of development. After basic motor skills are acquired, children learn to integrate their movements with perceptual skills, especially spatial perception. This process is cri...
