Child Development Chapter 5

Describe changes in body size for the first 2 years of life

children's bodies change enormously - faster than at any other time after birth

By the end of 1st year height is...

50% greater than at birth (about 32 inches)

By the end of the 2nd year height is...

75% greater than at birth (about 36 inches)

By 15 months birth weight...

doubles (about 15 lbs)

By 1st year birth weight...

triples (about 30 lbs)

Infants and toddlers grow in .....

little spurts

"Baby fat" peaks at...

9 months

What does baby fat help infants do?

maintain constant body temperature

How does the rate of muscle tissue grow during infancy?

very slowly, won't peak until adolescence

Babies are....

not muscular, their strength and physical condition is limited

Parts of the body grow at...

different rates

How many growth patterns are there?

2, cephalocaudal trend and proximodistal trend

What are the characteristics of the cephalocaudal trend?

the head develops more rapidly than the lower part of the body

By age two in the cephalocaudal trend...

the lower half of the body catches up to the top

What are the characteristics of growth of the proximodistal trend?

growth proceeds from the center of the body outward

What are some gender differences in growth?

- girls are shorter in infancy and have a higher fat to muscle ratio
- sex differences persist throughout early and middle childhood and are magnified in adolescence

What are growth norms?

heigh and weight averages for children of the same age

Children of the same age differ in....

rate of physical growth

What is skeletal age?

best estimate of child's maturity - measure of bone development

How is skeletal age measured?

x-ray long bones of the body to see the extent to which soft, pliable cartilage has hardened into bone, gradual process completed in adolescence

What is the size of the brain like at birth?

Nearer to its adult size than any other physical structure

The brain develops at what kind of pace?

an astounding pace through infancy and toddlerhood

What two vantage points is brain growth best understood through?

1) microscopic level of individual brain cells
2) larger level of cerebral cortex

What is the significance of the cerebral cortex?

1) most complex brain structure
2) responsible for highly developed intelligence

What is a neuron?

nerve cells that store and transmit information

What are synapses?

tiny gaps between neurons → fibers from different neurons come close but don't touch

What are neurotransmitters?

chemicals released by neurons that send messages across synapses

What brain development is happening during the prenatal period?

neurons produced in embryo's primitive neural tube
migrate to form the major parts of the brain, they are produced over-abundantly, and once neurons are in place, they differentiate in order to establish their unique functions

During the first two years, neural fibers and synapses...

increase at an astonishing pace

What is programmed cell death?

as synapses form, many surrounding neurons die → makes room for other synapses to be formed

As neurons form connections...

stimulation becomes vital to their survival

Stimulated neurons...

continue to produce synapses which supports complex abilities

What is synaptic pruning?

returns neurons that aren't stimulated to uncommitted state

What does synaptic pruning allow for?

re-arranging and strengthening of remaining synapses → fine tunes neural circuitry and is essential for effective information-processing

What are glial cells?

make up 1/2 of the brain's volume → multiply rapidly form 4th month of pregnancy through 2nd year of life
- responsible for myelination

What is mylenation?

coating of neural fibers with myelin

What is myelin?

an insulating fatty sheath

What is the significance of myelination?

to improve the efficiency of message transfer

what do gains in neural fibers and myelination account for?

overall increase in size of the brain

How much does the brain increase from birth?

30% of adult weight at birth → 70% by age 2

Brain development is jointly influenced by...

genetically programmed events and the child's experiences

Which measures of brain functioning measure changes in electrical activity in the cerebral cortex?

EEG and ERP

What are EEGs?

used to examine brain wave patterns for stability and organization → signs of mature functioning of cerebral cortex

What are ERPs?

used to detect general locations of brain-wave activity

What do neuroimaging techniques do?

provide more precise information about which brain regions are specialized for certain capacities and about abnormalities in brain function

What do PET scans and fMRIs measure?

map activity changes throughout the brain

What do NIRs do?

measures function of cerebral cortex

What is significant about the cerebral cortex?

largest brain structure, contains largest number of neurons and synapses, sensitive to environmental influences for longer period than any other part of the brain

What are frontal lobes?

cortical regions with the most extended period of development

What is the prefrontal cortex?

lies in front of areas controlling body movement, responsible for complex thought

When does the prefrontal cortex grow?

undergoes rapid myelination and formation during preschool and school years, followed by another period of accelerated growth in adolescence, when it reaches adult level of synaptic connections

The cerebral cortex has 2...

hemispheres

What is laterlization?

specialization of the hemispheres

What is the left hemisphere responsible for?

verbal activities and positive emotion

What is the right hemisphere responsible for?

spatial abilities and negative emotion

What is the most obvious reflection of cerebral lateralization in humans?

handedness

What is handedness?

hand preference

What is brain plasticity?

the brain's ability to change, high plasticity = high capacity for learning.

The brain is most plastic during...

first few years than it will it ever be again

experience greatly influences...

the rate and success of hemispheric specialization

Extreme sensory deprivation early in life results in...

permanent brain damage and loss of function

Those that overwhelm children with expectation beyond their current capacities...

interfere with the brain's potential

What are the two types of brain development?

1. experience-expectant brain growth
2. experience-dependent brain growth

What is experience-expectant brain growth?

refers to the young brain's rapidly developing organization, which depends on ordinary experiences

What is experience-dependent brain growth?

occurs throughout our lives, consists of additional growth as a result of specific learning experiences

When does experience-expectant brain growth occur?

early and naturally as caregivers offer babies and preschoolers age-appropriate play materials and engage them in daily routines

the growth of experience-expectant brain development provides foundation for....

later-occurring experience-dependent development

Rushing early learning...

harms the brain by overwhelming its neural circuits → reducing brain's sensitivity to everyday experiences it needs for a healthy start in life

Physical growth results from...

continuous complex interplay between genetic and environmental factors

Heredity...

contributes considerably to physical growth

What is catch-up growth?

a return to a genetically influenced growth path once conditions improve

Genetic make up also effects...

body weight

Nutrition is especially crucial for development during...

the first two years

What is important about breastfeeding?

- ideally suited to infant's needs
- provides some protection against respiratory and intestinal infections
- helps increase spacing among siblings bc nursing mothers are less likely to get pregnant
- has become more common in industrialized nations

Is there a psychological difference between babies that are breastfed and bottle fed?

No

Breast milk is easily...

digestable

Most chubby babies...

thin out during toddlerhood and early childhood

Why do chubby babies thin out?

because weight gain slows and they become more active

Recent evidence indicates strengthening relationship between...

rapid weight gain in infancy and later obesity

What can parent's do to help reduce the risk of obesity?

- breastfeed for the first 6 months
- avoid giving babies unhealthy foods
- provide toddlers with opportunities for energetic play

Once toddlers learn to walk, climb, and run...

parents can provide plenty of opportunities for energetic play

Malnutrition is most widespread in...

developing countries and war-torn areas where food resources are limited

Malnutrition contributes to...

nearly half of worldwide infant and early childhood deaths and growth stunting

What are the two dietary diseases?

Marasmus and Kwashiorkor

What is marasmus?

wasted condition of the body caused by a diet low in all essential nutrients

When does marasmus normally occur?

in the first year of life when a baby's mother is too malnourished to produce enough breast milk and bottle-feeding is also inadequate

What is Kwashiorkor?

caused by an unbalanced diet very low in protein.

When does kwashiorkor occur?

between 1 and 3 years of age, common in regions where children get just enough calories from starchy foods but little protein

Children who survive these extreme forms of malnutrition...

often grow to be smaller in all body dimensions and suffer from lasting damage to the brain, heart, liver, etc.

What effects do malnutrition have on development?

poor fine-motor coordinator, have difficulty paying attention, often display conduct problems, and show persisting low scores on intelligence tests

What is weight faltering?

term applied to infants and young children whose weight is substantially below age-related growth norms and are withdrawn and apathetic

Intense parental stressors...

contribute to weight faltering

What can weight faltering lead to?

lasting cognitive and emotional difficulties

What is classical conditioning?

learning in which a neutral stimulus is partied with a stimulus that leads to a reflexive response

What does classical conditioning help infants do?

recognize which events usually occur together in the everyday world, so they can anticipate what is going to happen next

What is unconditional stimulus (UCS)?

a stimulus that leads to a reflexive response

What is an unconditioned response (UCR)?

reflexive response that is produced by an unconditioned stimulus

In classical conditioning, a neutral stimulus is presented...

just before or at the same time as the UCS

Conditioned stimulus (CS)?

neural stimulus turns into CS if learning occurs

Conditioned stimulus turns into...

conditioned response, similar to a reflexive response