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Physical Development in Infancy

Chapter 3 Overview

• Focuses on the physical growth and development that occurs during infancy.

Key Concepts

Important Developmental Milestones

• Chris at Various Ages: 7 weeks, 7 months, 11 months, 22 months

• Mai at Various Ages: Birth, 8 months, 11 months, 22 months

Changes in Body Proportions

• The head size relative to the body decreases during growth.

Patterns of Growth

Cephalocaudal Development

• "Head to Tail" principle.

• Growth starts from the top (head) downwards.

• Important for sensory and motor development.

  • Example: Infants can see objects before controlling their torso.

Proximodistal Development

• "Near to Far" principle.

• Growth starts at the center (trunk) and moves towards the extremities (arms and legs).

  • Example: Control of trunk muscles develops before hand use.

Height and Weight Statistics

• Average North American Newborn:

  • 20 inches long and 7.5 pounds.

  • 95% range: 18-22 inches, weights 5.5-10 lbs.

• Newborn weight decreases by 5-7% in first few days.

• Infants double their weight by 4 months and triple by 12 months.

• Growth slows in the second year, averaging half adult height and one-fifth adult weight.

Newborn Brain Development

General Brain Facts

• At birth: tens of billions of cells, 25% of adult weight.

• Continuous development through infancy until mid-20s.

• Areas mature at different rates; vulnerable to damage, e.g., avoid shaking.

Brain Structure

• Cerebral Cortex: Folded surface of the forebrain.

  • Divided into two hemispheres, containing four lobes:

    • Occipital Lobe: vision functions.

    • Temporal Lobe: hearing and language processing.

    • Parietal Lobe: spatial location, touch.

    • Frontal Lobe: voluntary movement, judgment, personality.

Brain Lateralization

• Functions specialized in left and right hemispheres.

  • Left: language, detail perception, controls right side of the body.

  • Right: spatial abilities, big picture perception, controls left side of the body.

• Complex functions involve communication between hemispheres.

Neurons and Their Changes

Basic Structure of Neurons

• Dendrites: receive signals.

• Axon: transmits signals away from the cell body.

• Myelin Sheath: insulates axons to speed transmission.

• Synapse: gap between neurons for neurotransmitter exchange.

Changes During Infancy

• Myelination: encasing axons in fat cells; starts prenatally and continues into adolescence.

• Increased connectivity among neurons: growth of dendrites and synapse formation.

• Pruning: unused synaptic connections disappear, strengthening those that are used.

Impact of Early Experience

Brain Development

• Environmental experiences (sights, sounds, touches) shape brain development.

• Enriched environments lead to faster brain growth than deprived ones.

• Stimulated children are more likely to reach their full potential.

Brain Plasticity

• Infants recover better from brain injury due to brain's flexibility.

• Brain can reorganize to compensate for injuries.

Case Study: Michael

• Severe seizures required removal of left hemisphere; right hemisphere adapted to take over many functions, demonstrating plasticity.

Sleep in Infancy

• Variation in infant sleep patterns (10-21 hours/day; 16-17 average).

• Infants experience more REM sleep compared to adults; may aid in brain development.

Sudden Infant Death Syndrome (SIDS)

• Sudden unexplained infant death, most common between 2-4 months.

• Guidelines for risk reduction:

  • Placing infants on their backs to sleep.

  • Use of pacifiers during sleep.

Risk Factors for SIDS

• Low birth weight, lack of breastfeeding, exposure to cigarette smoke, bed-sharing, and lack of environmental controls.

Nutrition

• Proper nutrition is crucial for rapid growth during infancy.

• Breastfeeding: Recommended exclusively for first 6 months, continued up to 12 months or longer if desired.

• Benefits:

  • Nutritional completeness and weight management.

  • Lowered risk of childhood obesity, SIDS, and infections.

Caregiver's Role

• Caregivers influence eating patterns; recommendation of 50 calories per pound of weight.

• U.S. infants often lack necessary fruits and vegetables.

Motor Development

Dynamic Systems Theory

• Infants develop motor skills by perceiving environments and acting upon them.

• Skills depend on multiple factors: development of nervous system, body movement capacity, child's goals.

Gross Motor Skills Development

• Movements involving large muscle coordination (crawling, walking).

• Important for infants to learn the safe environment and practice new skills.

Fine Motor Skills Development

• Involves finely tuned movements; starts with very limited control at birth and develops through the first two years.

Sensory and Perceptual Development

Sensation and Perception

• Sensation: Interaction of environmental information with sensory organs.

• Perception: Interpretation of sensed information.

Studying Infant Perception

• Visual Preference Method: Infants show a preference for certain stimuli.

• Habituation: Decreased response to repeated stimuli, and dishabituation is a recovery response after change.

Visual Acuity and Color Development

• Newborn vision is poor (20/600) but improves to near adult levels by one year.

Depth Perception

• Infants show depth perception cues by 6-12 months, tested using the Visual Cliff.

Other Senses

• Hearing: Sensitive to human speech; recognize mother's voice.

• Touch and Pain: Newborns respond to touch. Pain perception is well developed.

• Smell: Infants can differentiate odors and show preferences.

• Taste: Preferences develop after birth; sugary tastes are favored.

Cognitive Development

Jean Piaget's Theories

• Piaget believed cognitive development is influenced by errors.

• Children are active participants, learning through interaction with their environment.

Mental Structures

• Assimilation: Incorporating new information into existing schemas.

• Accommodation: Adjusting existing schemas or creating new ones.

Cognitive Development Stages

• Four stages of development defined by distinct reasoning and thinking abilities.

• Sensorimotor Stage (Birth-2 years): Development of object permanence, understanding that objects exist when unseen.

Learning Capacities

Types of Learning

• Classical Conditioning: Associating stimuli with responses.

• Operant Conditioning: Associating behavior with consequences.

• Observational Learning: Learning through imitation and modeling.

Memory in Infancy

• Implicit Memory: Skills and routine without conscious recollection, emerges early.

• Explicit Memory: Accessible memories of specific facts and experiences, typically after 6 months.

• Infantile Amnesia: Difficulty adults face in remembering early childhood experiences.

Attention and Cognitive Processing

Attention Development

• Attention improves throughout infancy, aiding cognitive processes.

• Joint Attention: Focus on the same object or event, essential for language development.

Language Development

Language Basics

• A communication form using symbols; includes rules and generativity.

Key Milestones in Language Development

• Sequence of sounds from crying to cooing and babbling.

• Gestures emerge around 8-12 months.

• First words typically spoken around 13 months.

Parental Influence

• Active engagement and conversation enhance vocabulary and language skills.