Infant Development: Brain, Reflexes, Senses

• Lifespan Development covers Module 4, Infancy

Module Learning Outcomes

• Human development during infancy, physical and cognitive development in infants and toddlers, and emotional and social development during infancy is covered.

Physical Growth & Development in Infants

• Physical growth and development in infants and toddlers are described
• Physical growth patterns during infancy are summarized
• Growth of the infant's brain is described
• Gross and fine motor skills are explained
• Newborn perceptual abilities are explained
• The merits of breastfeeding is detailed
• Nutrition for early physical growth also covers nutritional concerns like marasmus and kwashiorkor.
• Sleep concerns for infants is covered
• The vaccination debate and its consequences are explained

Overall Physical Growth

• Normal weight range for newborns is between 5lb 8 oz to 8lb 13oz.
• Normal length range for newborns ~ 19.5 inches is normal
• Babies lose about 5% of body weight in the first few days
• Head comprises 25% of the total length at birth
• Percentiles range from 1-100
• Failure to thrive occurs when a child born in normal ranges falls below 20th percentile

Physical Growth

• At 4 months old, weight typically doubles
• At one year, weight triples
• By age 2, weight quadruples
• Average length at 12 months ~28.5-30.5 inches
• Average length at 24 months ~33.2-35.4 inches (CDC, 2010).

Brain Growth - The First Two Years

• The physical size of the brain increases
• At birth, the brain is 25% of its adult weight
• At 2-years-old, the brain is 75% of its adult weight
• Most neurons are present at birth
• Transient exuberance is a period of prolific dendritic connections
• Myelination protects axons and speeds neural transmissions
• Pruning eliminates unused connections
• Prefrontal cortex is the least-developed portion of brain at birth; substantial growth occurs

Motor Development

• Reflexes are inborn and involve rooting, breathing, and sucking
• Palmar grasp, stepping and Moro reflexes also emerge
• Motor development is cephalocaudal which is head-down
• Motor development is proximodistal which is center-out
• Gross motor skills use large muscle groups
• Fine motor skills use small, coordinated muscle movements like pinching and grasping

Motor & Sensory Development

• Sensation is the interaction with sensory receptors
• Perception is interpreting information sensed
• Sight is the least developed sense at birth with newborns seeing ~8-16 inches in front of them
• Newborns prefer faces, unusual, interesting, and exciting images
• Hearing is the most developed at birth and babies know the sound of mother's voice in the womb
• Physiological reactions indicate a sensation of pain
• Touch is necessary and comforting
• Babies distinguish flavors: sweet, salty, sour, bitter and prefer sweet tastes
• Babies easily identify mother's smell

Nutrition

• Breastfeeding is considered optimal for newborn babies
• Colostrum is "liquid gold" for its nutrient-dense properties during the first days of life
• Breastmilk has iron, fats, and proteins for proper development
• Alternatives if breastfeeding is difficult or impractical include formula
• Solid foods should be introduced simply, one at a time, spaced days apart to identify allergies
• Malnutrition and clean water access are very important
• Kwashiorkor affects babies with sufficient calories but insufficient protein
• Marasmus affects babies who face starvation from lack of calories and protein
• Milk anemia can occur from drinking cow's milk in place of more nutritive foods
• Clean water is crucial for clean formula

Sleep & Health

• Infants from 0-2 years require an average of 12.8 hrs/day of sleep
• Newborns need 14-17 hrs/day of sleep
• SIDS has many risk factors and many unknowns
• Sudden Unexpected Infant Deaths (SUID) has identified causes
• Back-sleeping is recommended for every sleep and is part of "Back to Sleep"
• There should be no soft bedding or blankets to avoid potential hazards
• Co-sleeping benefits skin-to-skin contact
• Co-sleeping may result in an increased risk of child suffocation, especially with parental drug/alcohol use
• Nighttime waking is common
• Many infants sleep 6 hrs during night by 6 months, but not doing so does not indicate a serious problem

Vaccinations

• Immunization debates include personal and religious beliefs with opt-out programs
• Need for community protection to prevent resurgence of diseases
• Herd immunity may occur when 90%+ of a population is vaccinated
• Approx. 1 in 14 children lack vaccinations
• Outbreaks of disease are more frequent as fewer opt to vaccinate

Cognitive Development in Infants & Toddlers

• Cognitive development in infants and toddlers is explained
• Piaget's theories and stages of sensorimotor intelligence are described
• Brain growth during infancy is discussed.
• Learning and memory abilities in infants and toddlers are explained
• Stages of language development during infancy is described
• Theories of language development is provided
• Moral reasoning in infants is covered

Cognitive Development

• Schemas are mental representations used to understand the world
• Assimilation is the adaptation of new information to fit into existing schemas
• Accommodation is the reorganization of knowledge to fit new information
• The Six stages of sensorimotor intelligence include:
• Stage 1 - Reflexes (Birth - 6 weeks)
• Stage 2 - Primary Circular Reactions (6 weeks - 4 mo.)
• Stage 3- Secondary Circular Reactions (4-8 mo.)
• Stage 4 - Coordination of Secondary Circular Reactions (8-12 mo.)
• Stage 5 - Tertiary Circular Reactions (12-18 mo.)
• Stage 6 - Mental Representation (18-24 mo.)
• Object Permanence develops at ~8 months and mastery at ~12-24 months

Learning & Memory Abilities in Infants

• Piaget underestimated infant memory ability
• Infants and toddlers form memories, remember them weeks, months later
• Lacking in language to express memory
• Infantile amnesia includes a lack of memory years later and encoding/ retrieval failures

Language Development

• Phonemes are basic units of speech, which make morphemes, the smallest meaningful units of speech
• Stages of language development include:
• Stage 1: Reflexive Communication
• Stage 2: Reflexive communication, interest in others
• Stage 3: Intentional communication
• Stage 4: First words
• Stage 5: Simple sentences (two words)
• Stage 6: Sentences of three or more words
• Stage 7: Complex sentences

Language Development

• Intentional vocalizations include gurgling, cooing, and learning conversational cadences
• Babies understand more than they can produce
• Holophrasic speech uses partial words that convey thoughts
• People close to the child often interpret correctly as part of holophrasic speech
• Underextension happens when a word may only be used for one specific thing such as "Mommy" for only their own mom.
• Overextension is more common for generalizing such as calling all older women "Mommy"
• Vocabularies expand rapidly
• Many new words are nouns and children often name things around them
• Two-word sentences or telegraphic speech lacks complete grammar but conveys meaning
• Child-directed speech captures children's attention and articulates sounds

Theories of Language Development

• Nativism is supported by Noam Chomsky
• Nativism proposes a Language Acquisition Device for innate ability to learn language and understand syntax
• Children learn language through mere exposure
• Critical periods may be the most important
• Behaviorism as promoted by B.F. Skinner says language is taught through reinforcement
• Social Pragmatics claims communication develops from a need to join a social world
• All theories have components of truth and help explain language learning

Moral Reasoning in Infants

• Kohllberg relies on asking questions to determine moral justification
• Infants & toddlers can't communicate and Hamlin & Wynn devised other methods.
• The experiments performed by Hamlin and Wynn discovered:
• Children prefer prosocial behavior
• Children prefer others like themselves
• Children may believe in just world and/or revenge motives

Emotional & Social Development During Infancy

• Emotional and social development during infancy is discussed
• Self-awareness, stranger wariness, and separation anxiety are explained
• Styles of attachment are contrasted
• Temperament and the goodness-of-fit model are described
• Erikson's theory is referenced to show psychosocial development during infancy

Emotional Development

• Social smiling appears at ~2 months, laughter at 3-5 months
• Frustration is normal, sadness can indicate withdrawal
• Stranger wariness appears ~6-15 months
• Separation anxiety shows cognitive development: “where has my caregiver gone?”
• Separation anxiety peaks around 8-10 months and declines later with healthy attachment
• Emotional regulation, the parent helps manage amount of stimuli, is performed through co-regulation

Emotional Development - Self Awareness

• Indicators include "I, me, my, etc."
• Develops around 15-24 months
• Babies understand self as an object
• "Rouge test" or mirror test measures if the baby touch their own nose or the mirror?
• Rochat's stages include:
• Differentiation from birth indicating self vs. non-self awareness
• Situation involves copying others and reaching for objects
• Identification includes self-referential language where babies pass "rogue test"
• Permanence is where One's sense of self persists through time & space
• Meta-self-awareness uses a third-person perspective

Infant Attachment

• Emotional needs are measured against physical needs
• Emotional needs provide comfort compared to sustained existence
• Ainsworth's strange situation test is used to gauge attachment styles and reactions
• Babies can be secure, insecure-avoidant, insecure-resistant/ambivalent, and disorganized
• Secure (~65% of babies): parent serves as secure base of exploration
• Insecure avoidant: similar reactions to parents and strangers
• Insecure-resistant/ambivalent: clingy to parents and rejects caregiver return

Attachment

• Lease secure attachment is disorganized which stems from unpredictable parental behavior or potential abuse
• The child has not learned emotional regulation from this model in disorganized attachment

Psychosocial Development

• Temperament as defined by Chess & Thomas is multidimensional
• Dimensions include activity level, regularity, approach-withdrawal, adaptability, responsiveness, reaction intensity, mood quality, distractibility, persistence and attention span
• From these dimensions, 4 main categories will define
• Easy babies (40%): overall positive disposition
• Slow-to-warm (15%): relatively calm, slow to adapt, withdraw from new situations
• Difficult babies (10%): negative moods, slow to adapt to new situations.
• Undifferentiated (35%): combination/variety of dispositional factors
• A Goodness-of-fit model exists through Children's adjustment with their environment Parenting/communication style

Erikson's Stages

• Infant and toddler stages include trust versus mistrust
• The hope is a Resolution where learning the world is a safe place
• An Unresolved life looks untrustworthy or dangerous for the infant
• Independence versus shame & doubt
• Resolution includes taking initiative and trying to do desirable things.
• The absence of this approach stifles confidence

Development in the Real World

• The Canadian Paediatric Society recommends that children under 2 years be discouraged from watching television
• By 10 months of age, infants imitate what they saw on TV
• Viewing TV with antisocial themes has been connected with aggression
• TV viewing by children under 3 years of age may be harmful to cognitive and language development