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Unformatted text preview: PSY 231 Chapter 4: Physical Development in Infancy and Toddlerhood First two years of life Body Growth 1. Childs body changes faster during this time than at any other time after birth A. Changes in Body Size and Muscle Fat Makeup 1. 5 months: body weight has doubled (about 15 lbs.) 2. End of 1 st year a. Height = 32 inches (more than 50% greater than at birth) b. Weight has tripled (22 lbs.) c. Middle of their 1 st year transformation into round, plump babies or baby fat-Peaks around 9 months-Helps infant keep constant body temp. 3. 2 years a. Height = 36 inches (nearly 75% greater) b. Weight has quadrupled (30 lbs.) c. Toddlers slim down continues into middle childhood 4. Infants and toddlers grow in little spurts rather than steady gains children are described as irritable and very hungry on the day before the spurt 5. Muscle tissue increases very slowly during infancy a. Will not reach peak until adolescence 6. Strength and physical coordination are limited B. Individual and Group Differences 1. Gender differences girls tend to be slightly shorter and lighter than body with a higher ratio of fat to muscles a. These differences tend to persist through early and middle childhood and are greatly magnified in adolescence 2. Growth norms height and weight averages for children at a particular age a. Varies by culture -Asian children have lower body size norms than North American children-African-American children tend to be slightly above the average norm 3. Rate of physical growth progression of body maturation a. Skeletal age a measure of bone development determined by an X-ray of long bones of the body to see the extent to which the soft, pliable cartilage has hardened into bone-This is a gradual process that is completed in adolescence-Cultural/Gender differences: African-Americans tend to be slightly ahead of Caucasian children at all ages Girls considerably ahead of boys A. At birth sexes differ by 4 to 6 weeks a gap that widens over infancy and childhood and accounts for PSY 231 the fact that girls reach their full body size several years before boys B. May be contributed to girls greater resistance to harmful environmental influences C. Changes in Body Proportions 1. Cephalocaudal trend from Latin word meaning head to tail a. Prenatal period the head develops more rapidly than the lower part of the body b. Birth head takes up 1/4 th of the total body length (legs =1/3 rd ) c. Age 2 the head accounts for only 1/5 th (legs =1/2) 2. Proximodistal trend growth proceeds from near to far or from center of the body outward a. Prenatal head, chest, and trunk grow first, then the arms and legs and finally the hands and feet b. Infancy and childhood arms and legs continue to grow somewhat ahead of the hands and feet Brain Development 1. Birth brain is nearer to its adult size than any other physical structure 2. Two vantage points: a. Microscopic level of individual brain cellsa....
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- Spring '08
- Developmental Psychology