DEV2004 - Chapter 3 Infancy and Toddlerhood

Overall Physical Growth

• Average weight of a U.S. newborn is about 7.5 pounds and length is approximately 20 inches.
• Infants may lose roughly 5% of their body weight in the first few days, which is normal and followed by rapid weight gain.
• By 4 months, an infant typically doubles its birth weight, and by one year, it has tripled; by age 2, weight quadruples (20-40 pounds).
• Average lengths are about 29.5 inches at one year and 34.4 inches at two years.

Body Proportions

• At birth, the head accounts for 25% of body length; significantly larger proportionally than in adults where it's about 20%.

Brain Development

• Infants are born with approximately 85 billion neurons, starting a phase of rapid dendrite growth, creating thousands of connections (synaptogenesis).
• Synaptic blooming occurs during infancy, followed by synaptic pruning to enhance brain efficiency, resulting in a 40% loss of connections.
• Myelination, occurring more dramatically in early years, speeds up neural impulse transmission and improves motor coordination and thought control.
• Infant brain weight increases from about 250 grams at birth to 750 grams by one year, reaching 55% of adult size within 90 days.

Cortex Development

• The cortex is involved in voluntary activity and thinking, divided into two hemispheres with four lobes each.
• Primary motor areas mature before sensory areas; the prefrontal cortex, responsible for emotion regulation and judgment, develops last.

Lateralization and Neuroplasticity

• Lateralization leads to the localization of brain functions, with the left hemisphere often dominating language and the right for visuospatial tasks.
• Neuroplasticity allows the brain to reorganize itself, creating new connections in response to experience, highly pronounced in infants.

Sleep Patterns

• Newborns typically sleep around 16.5 hours a day, decreasing to about 10 hours by age 2.
• Infants spend about 50% of sleep in REM phase, gradually decreasing as they grow.

Sudden Unexpected Infant Deaths (SUID)

• In the U.S., approximately 3,500 SUID occur each year, including Sudden Infant Death Syndrome (SIDS), which is the leading cause of death for infants aged 1-12 months.
• 1,400 deaths in 2017 were attributed to SIDS; potential causes include brainstem abnormalities affecting breathing regulation.

Bed Sharing Risks

• Bed sharing increases the risk of SIDS, especially in infants younger than 3 months; risks escalate with parental smoking or substance abuse.
• Co-sleeping practices differ globally, with some cultures placing infants on hard surfaces to reduce suffocation risk.

Infant Reflexes

• Newborns exhibit reflexes like sucking, rooting, grasping, and stepping, essential for survival and feeding.
• Reflexes diminish over the first few months as voluntary movements develop, with continued assessment of reflex persistence revealing neurological health.

Motor Development

• Motor skills progress through a cephalocaudal and proximodistal sequence, beginning with head control, leading to sitting, crawling, and walking.
• Developmental milestones indicate average ages for skills like head control (6 weeks) and sitting unassisted (7 months).

Sensory Capacities

• Newborn vision is poorly developed; they can focus at 8-10 inches and improve to 20/200 acuity by 3 months.
• Hearing is keen at birth, evident early in prenatal development, with newborns preferring face-like stimuli.

Visual and Hearing Development

• Binocular vision develops by three months, and depth perception improves with crawling experience, affecting visual attention.
• Sensory systems evolve rapidly: newborns have immature but organized responses to visual stimulation, and hearing ability is fully functional shortly after birth.### Newborn Preferences and Abilities
• Newborns demonstrate a preference for their mother's voice over other female voices, influenced by in-utero exposure to maternal sounds.
• Research showed infants exposed to stories read by their mothers during pregnancy preferentially suck at familiar stories compared to novel ones.
• Infants can distinguish between similar sounds by one month old and prefer exaggerated infant-directed speech.
• Around six to nine months, infants show a preference for their native language, rapidly losing the ability to distinguish sounds from non-native languages.

Sensory Responsiveness

• Newborns are highly sensitive to touch, temperature, and pain, responding with crying and increased heart rate.
• Circumcision without anesthesia leads to immediate and measurable pain responses in infants, highlighting the need for pain management in such procedures.

Taste and Smell Preferences

• Newborns can differentiate between various tastes, showing a preference for sweet flavors and the scent of their mothers.
• Infants as young as six days old are more likely to turn toward their mother's breast pad over strangers'.

Intermodal Perception

• Infants possess the ability to integrate information from multiple sensory modalities, such as matching pacifier textures to visual models.
• By four months, infants can coordinate auditory and visual stimuli, revealing early cognitive development links through sensory experiences.

Habituation and Learning

• Habituation procedures assess infants' perceptual and memory skills by measuring changes in their sucking rates in response to familiar versus novel stimuli.
• The ability to habituate quickly is associated with successful language acquisition and cognitive development. High-risk infants may exhibit slower habituation, linking it to potential developmental delays.

Breastfeeding Benefits

• Breast milk is ideal for infants, rich in nutrients and antibodies, with changing composition to meet newborn needs.
• Formula-fed infants may experience higher rates of gastrointestinal issues and infections, emphasizing the importance of breastfeeding.
• Breastfeeding is associated with lower risks of various health issues for mothers and infants, including several cancers and conditions like diabetes and obesity.

Introducing Solid Foods

• Solid foods should be introduced based on developmental readiness, typically between 4 to 6 months.
• Initial foods should be iron-fortified cereals, with new foods introduced one at a time to monitor for allergies.

Global Malnutrition

• Children in developing countries face severe malnutrition, including infantile marasmus, linked to inadequate caloric and protein intake.
• Despite worldwide declines in wasting, millions of children still suffer from malnutrition, primarily in Asia and Africa.

Piaget's Sensorimotor Stage

• Piaget describes cognitive development through schemas, which are shaped by assimilation and accommodation as children interact with their environment.
• The sensorimotor stage consists of six substages, from reflex-based learning to beginnings of representational thought and problem-solving by 18-24 months.

Development of Object Permanence

• Object permanence, understanding that objects continue to exist when out of sight, typically develops by eight months, enabling infants to actively seek hidden objects.
• Stranger anxiety occurs alongside this milestone, where infants exhibit fear of unfamiliar people due to inability to assimilate strangers into their existing schemas.

Critique of Piaget

• Modern research suggests that Piaget underestimated younger children's cognitive abilities, particularly relating to object permanence and understanding basic object properties.
• Studies indicate infants show signs of object permanence earlier than Piaget proposed, challenging the timeline of his developmental stages.### Infant Object Knowledge
• Infants as young as 3 months can demonstrate knowledge about object properties, even with no prior experience.
• A study showed that 3-month-olds looked longer at impossible events, such as a truck passing through a solid, hollow box.
• Baillargeon (1987) concluded that infants understand basic physical properties, contrasting with Piaget’s view of their cognitive limitations.

Infant Memory

• Infant memory is fleeting and fragile due to brain immaturity, causing phenomena like infantile amnesia.
• Several hypotheses explain infantile amnesia, including lack of brain development for autobiographical memory and limited linguistic skills in encoding memories.
• Research by Rovee-Collier showed that 3-month-olds could remember experiences with a mobile, especially if they had previous exposure to it.
• Context dependency is critical; infants recall memories better when retrieval conditions match the original learning environment.
• Infants over 6 months retain information longer and require less prompting to recall past experiences compared to younger infants.

Language Development

• Language is a complex communication system essential for expressing intelligence through talking, reading, and writing.
• Phonemes are the smallest units of sound in a language, while morphemes are meaningful units that include prefixes and suffixes.
• Semantics involves rules that dictate how meanings are derived from morphemes, while syntax governs how sentences are structured.
• Pragmatics refers to the social rules of communication, including turn-taking and context interpretation, which is vital for effective interaction.
• Words' meanings can change based on context, emphasizing the importance of nonverbal communication cues.

Language Acquisition

• Language development follows a consistent order across cultures, starting even before birth as babies recognize their mother's voice.
• Newborns communicate through cries, gestures, and facial expressions rather than spoken language.
• Babies begin cooing shortly after birth, producing vowel-consonant combinations, and typically mimic sounds from their native language.
• By 4-6 months, infants engage in more complex vocal interactions, learning conversational pacing and turn-taking with others.

This quiz covers the crucial development stages during infancy and toddlerhood, focusing on physical, cognitive, and socioemotional changes. Researchers emphasize the dramatic transformations that occur in the first two years of life, highlighting their long-term significance. Test your understanding of this foundational period of human development.