The first 2 years Biosocial development PDF

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Summary

Development over the life span...

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Growth in Infancy

Body size • Birthweight doubles by month four and triples by 1 year • Average weight at birth: 7.5 pounds • Average length: 20 inches

Birth catch-up • Small babies experience extra gain to catch up to the norm Growth in Infancy Norms •

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Defined standards of typical performance by which a child's development in a variety of domains can be measured These numbers are norms or average measurements; individuals vary

Percentile

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Number that indicates rank compared to other similar people of the same age Percentiles range from zero to 100

Weight of Boys and Girls: Birth to 24 Months

Same Boy, Much Changed Growth in Infancy

Brain Growth Two-year-olds are totally dependent on adults, but they have already reached half their adult height and three-fourths of their adult brain size. Growth in Infancy

Head-sparing • Biological mechanism • Protects the brain when malnutrition disrupts body growth

• Brain is the last part of the body to be damaged by malnutrition Brain Growth Brain Development The Developing Cortex Brain Development: Dendrites Sprouting Hello? Is Anybody There? The infant brain actually contains billions of neurons, each with one axon and many dendrites. Every electrochemical message to or from the brain causes thousands of neurons to fire each synapse to neighboring neurons. This electron micrograph shows neurons greatly magnified, with their tangled but highly organized and well-coordinated sets of dendrites and axons.

How Two Neurons Communicate Brain Development Exuberance and pruning

• Specifics of brain structure and growth depend on genes and maturation, but even more on experience. • Expansion and pruning of dendrites occur for every aspect of early experience. • Unused dendrites whither to allow space between neurons in the brain, allowing more synapses and thus more complex thinking. Experience Shapes the Brain Examples from twin studies Until about 10 months, experienceexpectant circumstances not influenced by SES After 10 months, genetics vary more than context in high-SES families

Examples from bird brains

Birds inherit genes that produce the brain cells they need to learning new songs or find hidden seeds For the dendrites and neurons to connect, birds depend on specific experiences with song-learning or seedfinding

Harming the Infant Brain Infants need stimulation • Playing, allowing varied sensations, and encouraging movement necessary for brain connections

Stress and the brain • Overabundance of stress hormones damages later brain functioning (bad environment)

Infants need protection • Shaken baby syndrome is a lifethreatening injury that occurs when an infant is forcefully shaken back and forth.

This motion ruptures blood vessels in the brain and breaks neural connections

Face Recognition Fusiform face area of brain •

Makes newborn infant adept at face recognition

Experiences •

Refine face perception and trigger immediate recognition

Own-race effect •

Apparent before first birthday and persists throughout life

Sleep Sleep specifics vary because of biology and the social environment. • Newborns sleep about 15-17 hours a day, in one- to three-hour segments. • Newborns' sleep is primarily active sleep.

• Newborns have a high proportion of REM (rapid eye movement) sleep. Sleep

Sleep problems •

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First born infants typically receive more attention and this may contribute to sleep problems. One-fourth of parents of children under age three reported sleep problems. Parent reactions to infant sleep shape the baby’s sleep patterns, which in turn affect the parents.

Co-Sleeping Asian and African mothers worry more about separation; European and North American mothers worry more about sex. Pros – Easier response time – Less parental exhaustion

– More convenient for breast-feeding

Cons – Higher SID – Ghosts in the nursery phenomenon

Awake at Night Why the disparity between Asian and non-Asian rates of co-sleeping? It may be that Western parents use a variety of gadgets and objects— monitors, night lights, pacifiers, cuddle cloths, sound machines—to accomplish the same things Asian parents do by having their infant next to them.

Perceiving and Moving

Sensory development • Typically precedes intellectual and motor development

Sensation • Response of a sensory system (eyes, ears, skin, tongue, nose) when it detects a stimulus

Perception • Mental processing of sensory information when the brain interprets a sensation Perceiving and Moving

Perception follows sensation • Infants' brains are especially attuned to their own repeated social experiences and perception occurs • Infant brain and auditory capacity to hear sounds in the usual speech range • The parts of the cortex dedicated to the senses develop rapidly

Moving and Perceiving: Hearing and Seeing

Hearing • Develops during the last trimester of pregnancy • Most advanced of the newborn's senses • Speech perception by 4 months after birth Smelling, Tasting, and Touching

Seeing • Least mature sense at birth • Newborns focus between 4 and 30 inches away • Experience and maturation of visual cortex improve shape

recognition, visual scanning, and details • Binocular vision at 3 months Moving and Perceiving: Smelling and Tasting Smell and taste • Function at birth • Rapidly adapt to the social world • Related to family and cultural preferences • May have evolutionary function

Moving and Perceiving: Touch and Pain Touch •

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Sense of touch is acute in infants. Although all newborns respond to being securely held, soon they prefer specific, touches.

Pain and temperature •

Pain and temperature are often connected to touch.

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Some people assume that even the fetus can feel pain. Others say that the sense of pain does not mature until months or years later.

Motor Skills: Gross Motor Skills

Motor skills • Learned abilities to move some part of the body, in actions ranging from a large leap to a flicker of the eyelid.

Course of development • Cephalocaudal (head-down) and proximodistal (center-out) direction Motor Skills: Gross Motor Skills Gross motor skills

• Physical abilities involving large body movements, such as walking and jumping

Dynamic Systems Underlying Motor Skills Three interacting elements underlying motor skills • Muscle strength • Brain maturation • Practice The entire package of sensations and motor skills furthers three goals. • • •

Social interaction Comfort Learning

Motor Skills: Fine Motor Skills Fine motor skills • Physical abilities involving small body movements, especially of the

hands and fingers, such as drawing and picking up a coin • Shaped by culture and opportunity Surviving in Good Health Statistics • At least 9 billion children were born between 1950 and 2010; more than 2 billion of them died before age 5 • World death rate in the first five years of life has dropped about 2 percent per year since 1990 – Improvement in clean water, nourishing food, immunization, medical treatments

More Babies Are Surviving Well Protected Disease and early death are common in Africa, where this photo was taken,

but neither is likely for 2-year-old Salem. He is protected not only by the nutrition and antibodies in his mother’s milk but also by the large blue net that surrounds them. Treated bed nets, like this one provided by the Carter Center and the Ethiopian Health Ministry, are often large enough for families to eat, read, as well as sleep in together, without fear of malaria-infected mosquitoes. Success and Survival Immunization • Primes the body's immune system to resist a particular disease

• Contributes to reduced mortality and population growth; herd immunity Successes • • • •

Smallpox Polio Measles Rotavirus

Cases of Polio Worldwide, 1985-2011 Cases of Polio Worldwide, 1999-2011 Surviving in Good Health

Immunizations are unsafe • Embryos exposed to rubella • Newborns • People with compromised immune systems

Problems • No effective vaccine found for AIDS, malaria, cholera, typhoid, and shigellosis

• Many rural areas of world not reached Nutrition

Adequate nutrition • For every infant disease (including SIDS), breast-feeding reduces risk and malnutrition increases it, stunting growth of body and brain. • Breastfed babies are less likely to develop allergies, asthma, obesity, and heart disease. • As the infant gets older, the composition of breast milk adjusts to the baby's changing nutritional needs. The Benefits of Breast-Feeding U.S. Trends in Breast-Feeding Rates Stunting in Children Under Five by Region, 2000-2010

Surviving in Good Health

Malnutrition • Protein-calorie malnutrition – Condition in which a person does not consume sufficient food of any kind that can result in several illnesses, severe weight loss, and even death

• Stunting – Failure of children to grow to a normal height for their age due to severe and chronic malnutrition

• Wasting – Tendency for children to be severely underweight for their age as a result of malnutrition

Additional Effects of Chronic Malnutrition Brains may not develop normally. Protection against common diseases may be reduced.

Some diseases result directly from malnutrition – Marasmus – Kwashiorkor

Sudden Infant Death Syndrome Sudden infant death syndrome (SIDS) • Situation in which a seemingly healthy infant, usually between 2 and 6 months old, suddenly stops breathing and dies unexpectedly while asleep. • Beal: Studied SIDS death in South Australia and concluded factors related to increased risk • • •

Sleeping position (Back is best!) Maternal smoking Bedding type

Before and After Stop and Think!

The success in reducing SIDS underscores several themes first described in this chapter. Can you identify these themes?...