Infancy

Summary

This lesson explores the first two years of human development, covering physical, cognitive, language, and psychosocial growth in infancy and toddlerhood. It details rapid physical changes, including weight gain, brain growth, motor skill development, and sensory maturation. Cognitive development is explained through Piaget’s sensorimotor stages, highlighting learning through exploration, trial-and-error, and early problem-solving. Language acquisition progresses from cries and coos to first words and telegraphic speech. Emotional and social growth includes attachment, self-awareness, and temperament, with Erikson’s stages of trust versus mistrust and autonomy emphasized. The lesson provides a comprehensive understanding of how early experiences shape a child’s development and emerging personality.

Takeaways

• 😀 Infants undergo rapid physical growth during the first two years, doubling their birth weight by 4 months and tripling it by 12 months.
• 😀 Newborns' brain grows dramatically, reaching 75% of its adult weight by age 2, with significant development in dendrites and myelination.
• 😀 The head of a newborn accounts for 25% of their body length, but by adulthood, the head is proportionately smaller.
• 😀 Motor skill development progresses from reflexive actions to voluntary movements, including both gross motor (large body movements) and fine motor (hand/finger coordination) skills.
• 😀 Newborn vision is underdeveloped, but by 14 weeks, they can focus both eyes and begin to distinguish objects. Hearing, on the other hand, is well-developed at birth.
• 😀 Breast milk is the ideal diet for newborns, offering optimal nutrition, immunity, and decreased infection risks, but should be avoided by mothers with certain health conditions.
• 😀 Malnutrition concerns include infantile marasmus (starvation) and kwashiorkor (protein deficiency), with the risk of iron deficiency if toddlers drink too much milk.
• 😀 Piaget’s sensorimotor stage outlines cognitive development through six sub-stages, focusing on reflexes, object permanence, and experimentation.
• 😀 Language acquisition begins with vocalizations like cooing and babbling, progressing to single words (holophrastic speech) and expanding into two-word sentences by 18 months.
• 😀 Infants develop emotional responses like fear, jealousy, and attachment, with early attachment styles (secure, insecure-resistant, insecure-avoidant, and disorganized) influencing later relationships.
• 😀 Erikson's psychosocial stages describe trust vs. mistrust in infancy and autonomy vs. shame/doubt in the second year, emphasizing the importance of consistency and independence in early development.

Q & A

What is the typical weight and length of a newborn, and how do these change in the first year?

The average newborn weighs about 7.5 pounds (ranging from 6 to 9 pounds) and is about 20 inches long. By 4 months, the infant usually doubles in weight, and by 12 months, the birth weight is typically tripled. A typical two-year-old is 32 to 36 inches in height.

How does brain development progress during the first two years of life?

At birth, the brain is about 25% of its adult weight. By age 2, it grows to 75% of adult weight. Dendrites grow to form connections between neurons, with unused connections being pruned. Myelination also occurs, insulating neurons to improve signal transmission, though the prefrontal cortex matures later.

What are reflexes in newborns, and how do they relate to motor development?

Reflexes are automatic responses to stimuli, such as the sucking reflex, rooting reflex, and palmar grasp. Over the first weeks, these reflexes gradually transition to voluntary movements, forming the foundation for gross motor (large muscle) and fine motor (precise hand/finger) skills.

Which senses are developed at birth, and how does vision mature in infants?

Hearing is well developed at birth, but vision is the least developed sense. Newborns can only focus on objects 8–16 inches away and have difficulty tracking moving objects. Binocular vision begins around 14 weeks, and the ability to distinguish similar hues develops after a few months.

What are the nutritional benefits and limitations of breastfeeding?

Breast milk is ideal for newborns, providing perfect nutrition, immunity, and reduced infection risk. It should be avoided if the mother has HIV, untreated tuberculosis, is on chemotherapy, or uses illicit drugs. In some cases, donated human milk can be used, such as in neonatal care units.

How does Piaget’s sensorimotor stage explain cognitive development in infants?

Infants explore the world using senses and motor skills. The six sub-stages include reflexive action (0–1 month), primary adaptation (1–4 months), repetition of actions (4–8 months), anticipation and object permanence (8–12 months), experimentation through trial and error (12–18 months), and mental combinations or deferred imitation (18–24 months).

How do infants develop communication skills in the first two years?

Newborns communicate via cries, facial expressions, and body posture. By 2–3 months, intentional vocalizations like cooing occur. Babbling begins around 6 months, with first words emerging around 12 months. Vocabulary expands rapidly at 18 months, with two-word sentences developing into 'telegraphic speech' (3–5 word sentences).

What are the main theories of language development in infants?

Noam Chomsky proposed that language ability is inborn, with a language acquisition device in the brain, while Skinner suggested language is learned through reinforcement, with praise and rewards increasing repetition of words and communication skills.

How do emotions and social interactions develop during infancy?

Infants demonstrate attraction and withdrawal early on. Social smiling begins around 2 months, laughter at 3–5 months, and fear, anger, and sadness follow. Jealousy may emerge at 6 months. Stranger wariness and separation anxiety develop as infants recognize familiar caregivers and form attachments.

What are the different attachment styles, and how do they develop?

Attachment styles include secure (consistent care leads to trust), insecure-resistant (inconsistent care leads to clinginess), insecure-avoidant (child avoids closeness, appears independent), and disorganized (unpredictable caregiver behavior leads to confusion). Culture and caregiving practices influence these styles.

What is temperament, and what are its key dimensions in infants?

Temperament refers to inborn behavioral tendencies that are fairly consistent and influence personality. Key dimensions include activity, rhythmicity, approach/withdrawal, adaptability, intensity, mood, persistence/attention span, distractibility, and sensory threshold. Understanding temperament helps caregivers provide a 'goodness of fit.'

How does Erikson’s psychosocial theory apply to the first two years of life?

In the first year, the challenge is trust vs. mistrust: consistent, loving care builds trust. In the second year, autonomy vs. shame/doubt emerges: children explore independence within safe limits, developing pride and self-confidence when allowed to complete tasks.