Psychology 235 Dr. Blakemore Physical Development Psychology 235 Dr. Blakemore

General Principles Growth is rapid in infancy then slows down and is gradual in childhood and speeds up again at puberty Developmental follows the cephalocaudal and proximodistal principles. cephalocaudal = head downwards. Proximodistal = center outwards

Gender Differences Girls develop faster than boys Newborn girls are ahead of boys (bone growth is 6 weeks ahead) Puberty is about 2 years sooner in girls

Gender Differences, cont’d Girls complete development sooner Are sexually mature sooner

Skeletal Development All bones start out as soft cartilage. Ossification begins in prenatal development and continues through adolescence. Most infant bones are not ossified to a great extent. Different bones in the body ossify at different times.

Fontanelles The skull has six soft spots called fontanelles which ossify gradually. They do not totally disappear until the child is 2 years old. You can’t damage a child by touching the fontanelles

Muscular Development The newborn has all the muscle fibers he/she will ever have. In adulthood the muscles weigh 40 times what they did at birth.

Neural Development At birth, the infant has all the neurons he/she will ever have. An important process that takes place after birth is myelination.

Growth At birth the average infant weighs 7.5 pounds, and is 20 inches long. By age 5 years the average boy weighs 43 pounds and is 44 inches tall. Size at birth is unrelated to eventual size. Double the height of a 2-year-old girl (or a 2.5 for a boy) to get a reasonably good estimate of her adult height.

Motor Skills There are large age changes in children’s abilities to perform motor skills. Physical development underlies these changes, and so the changes are often called maturational. Learning is involved, however, because the skills clearly improve with practice. Children follow their own developmental timetables, and they differ.

Nutrition Physical development depends on nutrition. Most children in the world do not get adequate nutrition. If brain and body do not develop in early life due to malnutrition, it cannot be made up later At least 20% of U.S. children live in poverty – considerably higher than most other Western, democratic, industrialized nations.

Poverty Rates In Various US States In US overall about 15%, but about 22% for children. Why the difference? Some US States, child poverty Mississippi 32% New Mexico 31% DC 30% Kentucky 27% Michigan 25% Indiana 23% California 23% Illinois 22% Minnesota 15% New Hampshire 12% Some US counties have incredibly high rates, as high as 50 or 60%. Mostly in South Dakota, Louisiana, Texas, Alabama and Mississippi.

Child Poverty in various Industrialized Democracies Canada 13% Australia 11% United Kingdom (England, Wales, Scotland) 12% Sweden 7% Germany 7% The Netherlands 8% France 7% Japan 15%

Former Iron Curtain and Eastern European Countries Romania 27% Russia 24% Poland 15% Czech Republic 6%

Final Comparison Mexico – 28% Why is US more similar to Russia and Mexico than to Sweden, Germany, and France, and considerably higher than Canada, Australia, and the UK? Before and after transfer poverty.

Other Areas of Development Later we will consider other kinds of child development that are affected by growing up in poverty