Human Development: Tools for Exploring the World

Describe newborn assessment, reflexes, states, and temperament.
Describe physical changes, growth of the nervous system, locomotion, and fine-motor skills during infancy.
Describe the development of senses, perception, self-understanding, and theory of mind.

Reflexes: Unlearned responses crucial for survival and nervous system health (e.g., rooting, sucking, eye blinks, stepping).
Assessment:
- Apgar Score: Evaluates physical condition (breathing, heartbeat, muscle tone, reflexes, skin color); $7+$ is good, $4-6$ needs attention, $3$ or less is life-threatening.
- Neonatal Behavioral Assessment Scale (NBAS): Assesses $28$ behavioral items, $18$ reflex items, focusing on autonomic, motor, state, and social systems.
States: Alert Inactivity, Waking Activity, Crying (Basic, Mad, Pain), Sleeping (newborns: $16-18$ hrs/day, $50%$ REM sleep).
Co-sleeping: Common outside North America for bonding; risks increase with parental smoking/drinking or soft surfaces.
Sudden Infant Death Syndrome (SIDS): Unexplained death during sleep; risk factors include prematurity, parental smoking, overheating, stomach sleeping. Recommendations: infants on backs or sides.
Temperament: Consistent behavioral styles (Rothbart's 3 dimensions: Surgency/Extroversion, Negative Affect, Effortful Control). Influenced by cultural factors and parental characteristics; relatively stable but nurtureable.

Growth: Rapid in infancy, doubling birth weight by $3$ months and tripling by $1$ year; influenced by heredity.
Nutrition: High caloric needs for rapid growth. Breastfeeding is optimal; bottle-feeding presents challenges, especially in developing countries.
Malnutrition: Affects $1$ in $4$ children under $5$ globally, causing irreversible brain damage and low activity. Food insecurity affects $11%$ of U.S. households.
Emerging Nervous System: Composed of neurons (cell body, dendrites, axon, terminal buttons) and the Cerebral Cortex (outer layer, two hemispheres).
Brain Structures: Neural plate forms at $3$ weeks; nearly all neurons present by $28$ weeks. Myelination begins at $4$ months; peak synapse formation at $12$ months, followed by synaptic pruning.
Brain Specialization: Occurs early; different systems mature at varied rates.
- Experience-expectant Growth: Wiring from commonplace human experiences.
- Experience-dependent Growth: Changes from individual experiences across settings.

Locomotion: Infants sit independently by $7$ months. Toddling and walking without assistance appear around $14$ months. Motor development is influenced by the Dynamic Systems Theory, involving reorganizing distinct skills.
Coordinating Skills: Mastery of walking involves differentiation (individual movement components) and integration (combining skills). Unsupported walking commonly appears between $12-15$ months. Cultural practices can influence development.
Fine Motor Skills: Involve hand-eye coordination.
- Reaching objects: $4$ months.
- Two-hand coordination: $5$ months.
- Zippers vs. buttons: Children age $2-3$ years can use zippers but struggle with buttons. Handedness becomes pronounced during toddler years.

Smell, Taste, and Touch: Newborns have developed senses; differentiate odors, prefer sucrose, and respond to pain.
Hearing Capabilities: Infants show startle responses; best sensitivity in the human speech range. By $4$ months, they distinguish melodies and recognize their names.
Seeing Ability: Newborns follow objects. Visual acuity improves from $20/200-400$ at $1$ month to adult levels by $1$ year. Color perception matures by $3-4$ months.
Depth Perception: Visual cliff experiments show $6$ -week-olds express interest via heart rate changes, while older, crawling infants demonstrate fear.
Object and Face Perception: By $4$ months, infants identify objects using multiple cues. They show an innate preference for moving faces and refine face recognition by $7-8$ months.
Integrating Sensory Information: Infants associate visual with tactile stimuli through intersensory redundancy, which enhances perceptual capabilities.

This section focuses on key questions regarding the age at which children recognize their existence, articulate self-concept, and the emergence of theory of mind.