Physical Development in Infancy & Early Childhood Chapter 3

Reflexes

 Babies born with host of unlearned reflexes  Triggered by specific stimuli & are adaptive  Sucking (feeding)  Blink (protect eyes)  Moro (aids clinging behavior)  Some are precursors to voluntary behavior  Palmar (grasping)  Stepping (walking)

Infant Health

 Apgar score indicates overall health  Vital signs (heart rate)  Neonatal Behavioral Assessment Scale  Reflexes, hearing, vision,alertness, irritability and consolability

Newborn States

 4 hour cycle between  Alert inactivity  Waking activity  Crying (2-3 hours/day)  Basic v. mad v. pain  Sleeping (16-18 hours/day)  Cycles of 3 hours of sleep, 1 hour of wakefulness  50% REM first 4 months (20% for adults)

Temperament

(not all babies are alike)

 Consistent style of behavior & emotional responding (seen upon birth)  Emotionality  Activity  Sociability  Highly heritable (~60%) & stable  NOT fate as environment also plays a role (Kagan)

Physical Growth

 Rapid growth  40% energy spent growing  Double weight by 3 months, triple by 12 months  Size closely related to biological parents

Physical Growth

 Diet  Babies eat lots! (50 calories/lb)  Adults consume 15-20 calories/lb  Breast feeding best (1st year)  Antibodies protect against illness  Less digestive problems  Transition to solid food easier  No contamination • Slow introduction of solid foods

Early Brain Development

 After conception:  3 weeks: the neural plate forms  4 weeks: folds into a tube (brain & spinal cord)  10 weeks: neurons are produced until week 28 (4,000/second)  Neurons migrate to various locations in layers  Deepest layers form first, then the next layer, etc.

 7 months post conception and all layers in place  4 months post conception: myelin beings to form

Early Brain Development

 After birth brain grows rapidly  Axons, dendrites grow longer  Make many new connections with other neurons  Specialization begins  Frontal lobe: personality, judgement  Left hemisphere: language  Depends to some extent on experience

Early Brain Development

 Brain plasticity: flexible structure & function?

 Nature nurture issue  Brain has some plasticity  Neurons can reorganize and change function  Plasticity may also express itself through unique neuronal connection density due to experience • Adult exposed to music/athletics at an early age  Brain also has unalterable organizational plan  Visual cortex always at back of brain  Areas for hearing near temporal lobe

Locomotion

 Dynamic Systems Theory  Motor development involves learning & coordinating many skills together (practice)  Posture & balance develops in a few months • Visual cues and inner-ear mechanism used to adjust posture  Stepping occurs automatically at 7 months  Walking develops around 15 months • Use perceptual cues to walk/crawl

Fine Motor Skills

 Reaching & grasping  Birth grasping with fingers (not thumb)  4 months reaching & grasping  5-6 months coordinating both hands  7 months grasping with finders & thumb  Increasing dexterity with age

Handedness

 90% of people are right handed  Most infants show no preference until ~1 year  Heredity key  Culture/values

Perception

 Smell & taste  Babies born with good sense of smell  React to pleasant/unpleasant odors in obvious ways  Recognize familiar odors (e.g., mother)  Babies also have good sense of taste

Perception

 Touch & pain  Babies are sensitive to touch and pain  Respond reflexively to touch  React strongly to painful stimuli (cry)  Hearing (good at birth and develops)  Best hear pitches in range of human speech  Can differentiate different speech sounds  4.5 months can recognize their name  Use sound to locate objects in space

Perception

 Sight  Visual acuity not as good as adults  Rapidly develops (12 months = adults)  Color vision develops within a few months  Newborns perceive few colors  Cones in visual cortex begin functioning soon • 4 months old = adults

Perception

 Depth  Can perceive depth by 5 months of age  Use various cues to depth  Retinal disparity  Motion  Sound  Sensory integration  Infants understand connections among sensations

Self-Awareness

 Develops around 18 months  2 years old all kids have self-concept  Touch their nose with red mark  Look at photos of themselves more  Declare their possessions as part of their self concept • “Mine!”

Theory of Mind

 Phase 1: aware of desires causing behavior  Age 2  Phase 2: can distinguish mental from physical world  Age 3  Phase 3: understand beliefs cause behavior in self & others  Age 4