6. Brain & Physical Development (11 cards)

Cephalocaudal development

Physical growth proceeds from head to foot. Head is proportionally largest in infancy; motor control develops from head downward.

Proximodistal development

Growth proceeds from center of body outward. Control of trunk before limbs; fine motor control of hands and fingers develops last.

Synaptic overproduction and pruning

Brain initially produces more synapses than needed (overproduction); unused connections are eliminated (pruning) based on experience. Reflects use-it-or-lose-it principle.

Myelination

Process of coating axons with myelin (fatty sheath) that increases speed and efficiency of neural transmission. Continues through adolescence; supports increasingly complex behavior.

Brain plasticity

Capacity of the brain to be shaped by experience. Highest in early infancy. Underlies the importance of early experience for perceptual, cognitive, and social development.

Dynamic systems theory (motor development)

Motor milestones emerge from the interaction of body, brain, gravity, and environment — not from a fixed maturational program. Thelen's research shows infants learn to walk through practice and feedback.

What are motor reflexes in newborns?

Automatic, involuntary responses present at birth (rooting, sucking, Moro/startle, Babinski, grasping). Disappear as voluntary cortical control develops; absence or persistence can indicate neurological problems.

Werker — Becoming a Native Listener

Infants are born universal phoneme perceivers sensitive to contrasts from all human languages. By 10–12 months perception narrows to native language distinctions (perceptual narrowing/attunement). Relevant to critical periods and early auditory experience.

Perceptual narrowing

The process by which infants become more attuned to the phonemes of their native language and less sensitive to non-native contrasts. Occurs between 6–12 months (Werker).

Campos et al. — Early experience and emotional development

Visual cliff paradigm: once infants begin crawling (self-produced locomotion) they show fear at the deep side and use social referencing. Argument: experience — not maturation alone — drives emotional development.

Visual cliff (Gibson & Walk / Campos)

Apparatus with a glass surface covering a simulated drop. Pre-locomotor infants show little fear; crawling infants show fear and use social referencing. Used to study depth perception and the role of experience in emotional development.