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Life-Span Development Twelfth Edition. Chapter 4: Physical Development in Infancy. Patterns of Growth: Cephalocaudal Pattern: sequence in which the earliest growth always occurs from the top downward Also applies to gains in motor development

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chapter 4 physical development in infancy

Life-Span Development

Twelfth Edition

Chapter 4:

Physical Development in Infancy

©2009 The McGraw-Hill Companies, Inc. All rights reserved.

slide2

Patterns of Growth:

    • Cephalocaudal Pattern: sequence in which the earliest growth always occurs from the top downward
      • Also applies to gains in motor development
    • Proximodistal Pattern: sequence in which growth starts in the center of the body and moves toward the extremities

©2009 The McGraw-Hill Companies, Inc. All rights reserved.

slide3

Height and Weight:

    • Average North American newborn is 20 inches long and 7 ½ pounds
      • 95% of full-term newborns are 18-22 inches long and weigh between 5 ½ and 10 lbs.
      • Newborns lose 5-7% of their body weight in the first few days of life
        • They typically gain 5-6 ounces per week during the first month
          • Weight usually triples by their 1st birthday
      • Newborns gain approximately 1 inch per month during the first year
    • Growth slows considerably during the 2nd year

©2009 The McGraw-Hill Companies, Inc. All rights reserved.

slide5

The Brain:

    • Brain continues developing past infancy
    • Shaken Baby Syndrome: brain swelling and hemorrhaging from child abuse trauma
    • Brain imaging technologies cannot typically be used with babies
      • EEGs show regular spurts in the brain’s electrical activity
      • Spurts may coincide with important changes in cognitive development
    • At birth, the brain is 25% of its adult weight; at 2 years of age, it is 75% of its adult weight
      • The brain does not mature uniformly

©2009 The McGraw-Hill Companies, Inc. All rights reserved.

slide6

Forebrain: portion of the brain farthest from the spinal cord; includes cerebral cortex

  • Cerebral Cortex: folded surface covering the forebrain
    • Cerebral cortex is divided into 2 hemispheres, each with 4 lobes
      • Frontal lobe: voluntary movement, thinking, personality, and intentionality
      • Occipital lobe: vision functions
      • Temporal lobe: hearing, language processing, and memory
      • Parietal lobe: spatial location, attention, and motor control

©2009 The McGraw-Hill Companies, Inc. All rights reserved.

slide7

Lateralization: specialization of function in one hemisphere of the cerebral cortex or the other

    • Some functions are lateralized, some are not
      • Complex functions involve communication between both hemispheres

©2009 The McGraw-Hill Companies, Inc. All rights reserved.

slide8

Neurons: brain nerve cells that communicate through electrical and chemical signals

    • Axons carry signals away from the cell body
    • Dendrites carry signals toward the cell body
    • Myelin sheath is a layer of fat cells that insulate axons
      • Helps electrical signals travel faster
    • Terminal buttons release chemicals (neurotransmitters) into synapses
      • Synapses: tiny gaps between neurons

©2009 The McGraw-Hill Companies, Inc. All rights reserved.

slide10

Changes in Neurons:

    • Myelination: the process of encasing axons with fat cells
      • Begins prenatally and continues into adolescence
    • Connectivity among neurons increases
      • New dendrites grow
      • Connections among dendrites increase
      • Synaptic connections increase
    • More synaptic connections are created than will ever be used
      • Leads to a “pruning” of unused connections

©2009 The McGraw-Hill Companies, Inc. All rights reserved.

slide12

Changes in regions of the brain:

    • “Blooming and pruning” of synapses varies by brain region
    • Pace of myelination varies as well

©2009 The McGraw-Hill Companies, Inc. All rights reserved.

slide13

Depressed brain activity has been found in children who grow up in a deprived environment

    • Enriched environments promote faster brain development than deprived ones
  • After birth: sights, sounds, smells, touches, language, and eye contact help shape the brain’s neural connections
    • Repeated experience wires (and rewires) the brain
  • Brain is both flexible and resilient

©2009 The McGraw-Hill Companies, Inc. All rights reserved.

slide14

Typical newborns sleep 16-17 hours per day

  • Infants vary in their preferred times for sleeping
    • Most have moved closer to adult-like sleep patterns by 4 months of age
  • Factors involved in night waking:
    • Daytime crying and fussing
    • Distress when separated from mother
    • Breast feeding
    • Co-sleeping

©2009 The McGraw-Hill Companies, Inc. All rights reserved.

slide15

Cultural variations influence infant sleeping patterns

  • Babies average much more REM sleep than do older children or adults
    • REM sleep may provide infants with added self-stimulation
    • REM sleep may also promote brain development
    • We do not know whether infants dream or not

©2009 The McGraw-Hill Companies, Inc. All rights reserved.

slide17

The practice of shared sleeping, in which a newborn shares a bed with mother, varies among cultures

  • Potential benefits:
    • Promotes breast feeding and a quicker response to crying
    • Allows mother to detect potentially dangerous breathing pauses in baby
  • American Academy of Pediatrics discourages shared sleeping
    • Increases risk of injury (rolling over baby) and SIDS

©2009 The McGraw-Hill Companies, Inc. All rights reserved.

slide18

SIDS (Sudden Infant Death Syndrome): infants stop breathing and die without apparent cause

    • Highest cause of infant death in U.S. annually
    • Highest risk is 2-4 months of age
    • Risk decreases when infant sleeps on its back and when a pacifier is used

©2009 The McGraw-Hill Companies, Inc. All rights reserved.

slide19

Other risk factors associated with SIDS:

    • Siblings who died from SIDS
    • Sleep apnea or low birth weight
    • Infants passively exposed to cigarette smoke
    • Being from lower SES or being African American or Eskimo
    • Infants placed in soft bedding
    • Infants with abnormal brain stem functioning involving serotonin

©2009 The McGraw-Hill Companies, Inc. All rights reserved.

slide20

Experts recommend that infants consume 50 calories per day for each pound they weigh

  • U.S. parents typically do not feed infants enough fruits and vegetables
    • By 15 months, French fries are the most common vegetable eaten
  • Increasing rates of overweight and obese infants
    • Other factors:
      • Mother’s weight gain during pregnancy and pre-pregnancy weight
      • Breast feeding vs. bottle feeding

©2009 The McGraw-Hill Companies, Inc. All rights reserved.

slide21

American Academy of Pediatrics strongly endorses breast feeding throughout the first year

  • Benefits for baby can include:
    • Fewer gastrointestinal and lower respiratory tract infections
    • Potentially decreased risk of asthma
    • Less likely to become overweight or obese
    • Less incidence of diabetes
    • Less likely to experience SIDS

©2009 The McGraw-Hill Companies, Inc. All rights reserved.

slide22

Benefits for mother can include:

    • Lower incidence of breast and ovarian cancer
    • Lower incidence of Type 2 diabetes
  • Breast feeding does not:
    • Help mother return to pre-pregnancy weight
    • Guard against osteoporosis
    • Decrease likelihood of experiencing post-partum depression

©2009 The McGraw-Hill Companies, Inc. All rights reserved.

slide23

Women less likely to breast feed:

    • Mothers who work full-time outside of the home
    • Mothers under age 25
    • Mothers without a high school education
    • African-American mothers
    • Mothers in low-income circumstances

©2009 The McGraw-Hill Companies, Inc. All rights reserved.

slide24

Mother should not breast feed if:

    • She has AIDS or other infectious diseases that can be transmitted through milk
    • She has active tuberculosis
    • She is taking a drug that may not be safe for the infant
  • No psychological differences have been found between breast-fed and bottle-fed infants
  • Most breast- vs. bottle-feeding studies are correlational and do not imply causation

©2009 The McGraw-Hill Companies, Inc. All rights reserved.

slide25

Dynamic Systems View:

    • Infants assemble motor skills for perceiving and acting
      • Motor skills represent solutions to goals
    • Development is an active process in which nature and nurture work together
      • Development of nervous system
      • Body’s physical properties and possibilities for movement
      • Goal the child is motivated to reach
      • Environmental support for the skill

©2009 The McGraw-Hill Companies, Inc. All rights reserved.

slide26

Reflexes: built-in reactions to stimuli; generally carry survival mechanisms

    • Rooting Reflex: when the infant’s cheek is stroked, the infant will turn its head to the side that was touched
    • Moro Reflex: automatic arching of back and wrapping of arms to center of body when startled
    • Grasping Reflex: infant’s hands close around anything that touches the palms
  • Some reflexes continue throughout life; others disappear several months after birth

©2009 The McGraw-Hill Companies, Inc. All rights reserved.

slide27

Gross Motor Skills: skills that involve large-muscle activities

    • Walking, grabbing for objects
  • Gross motor skills require postural control
    • Posture is a dynamic process linked with sensory information in the skin, joints, and muscles
  • Infants can produce stepping movements needed for walking from a very early age
    • They lack the ability to stabilize balance on one leg at a time
    • Infants learn what kinds of places and surfaces are safe for locomotion

©2009 The McGraw-Hill Companies, Inc. All rights reserved.

slide29

Development in the 2nd Year:

    • Toddlers become more skilled and mobile
    • Motor activity is vital to the child’s development of competence and independence
    • By 18-24 months, toddlers can:
      • Walk quickly or run stiffly
      • Balance on their feet in a squat position
      • Walk backward
      • Stand and kick a ball without falling
      • Jump in place

©2009 The McGraw-Hill Companies, Inc. All rights reserved.

slide30

Cultural Variations: mothers in developing countries tend to stimulate their infants’ motor skills more than mothers in more modern countries

    • Infants can reach motor milestones slightly earlier if provided with physical guidance or given opportunities for exercise
    • Even when activity is restricted, many infants still reach milestones at a normal age

©2009 The McGraw-Hill Companies, Inc. All rights reserved.

slide31

Fine Motor Skills: involve finely tuned movements

    • Reaching and grasping is a significant milestone for infants
    • Palmer grasp: grasping with the whole hand
    • Pincer grip: grasping with the thumb and forefinger
  • Perceptual-motor coupling is necessary for infants to coordinate grasping
  • Experienced infants look at objects longer, reach for them more, and are more likely to mouth the objects

©2009 The McGraw-Hill Companies, Inc. All rights reserved.

slide32

Sensation: occurs when information interacts with sensory receptors (eyes, ears, tongue, nostrils, and skin)

  • Perception: the interpretation of what is sensed
  • Ecological View: we directly perceive information that exists in the world around us
    • The perceptual system selects from the rich information provided by the environment
    • Perception enables interaction with, and adaptation to, one’s environment

©2009 The McGraw-Hill Companies, Inc. All rights reserved.

slide33

Visual Preference Method: infants look at different things for different lengths of time

    • They look at preferred objects longer
  • Habituation: decreased responsiveness to a stimulus after repeated presentations
  • Dishabituation: recovery of a habituated response after a change in stimulation

©2009 The McGraw-Hill Companies, Inc. All rights reserved.

slide34

Newborn’s vision is about 20/600 (an object 20 feet away appears as if it were 600 feet away)

  • By the age of 6 months, vision is 20/100 or better
    • Vision approximates that of an adult by the infant’s first birthday
  • Infants show an interest in human faces soon after birth
    • The way they gather information about the visual world changes rapidly with age

©2009 The McGraw-Hill Companies, Inc. All rights reserved.

slide35

Eleanor Gibson and Richard Walk studied development of depth perception using a “visual cliff”

    • Infants 6-12 months old can distinguish depth
    • Infants 2-4 months old show heart rate difference when placed on deep side of cliff
    • Infants develop binocular depth cues by about 3-4 months of age

©2009 The McGraw-Hill Companies, Inc. All rights reserved.

slide37

Fetuses can hear and learn sounds during the last two months of pregnancy and can recognize their mother’s voice at birth

  • Newborns:
    • Cannot hear soft sounds as well as adults
    • Are less sensitive to pitch
    • Are fairly good at determining the location of a sound

©2009 The McGraw-Hill Companies, Inc. All rights reserved.

slide38

Touch and Pain: newborns respond to touch and can feel pain

  • Smell: newborns can differentiate odors
      • Preference for mother’s smell by 6 days
  • Taste: sensitivity to taste may be present before birth

©2009 The McGraw-Hill Companies, Inc. All rights reserved.

slide39

Intermodal Perception: the ability to integrate information from two or more sensory modalities

    • Babies are born with some innate abilities to perceive relations among senses
    • Their abilities improve considerably through experience
  • Perceptual–Motor Coupling: action guides perception, and perception guides action

©2009 The McGraw-Hill Companies, Inc. All rights reserved.