PSYC 243 MT2-PT.2

How much do height and weight change during the first two years?

Height increases approximately 75%, and weight quadruples.

What is the cephalocaudal trend?

Growth proceeds from head to toe (top-down).

Essentially, babies develop control over the upper parts of their bodies before the lower parts.

What is the proximodistal trend?

Growth proceeds from the centre of the body outward toward the extremities.

Essentially, babies develop control over their arms and legs before they develop precise control over their fingers and toes.

How do body proportions change from birth to age 2?

At birth, the head is about 25% of body length and legs 33%;

by age 2, head is 20% and legs 50%.

What is synaptic pruning?

Elimination of less-used neural connections while frequently activated connections are strengthened.

What determines which synapses are pruned?

Neural activity and experience influence which connections are maintained or eliminated.

What is myelination?

Formation of a fatty insulating sheath around axons that increases the speed and efficiency of neural transmission.

Which brain region develops relatively late?

The prefrontal cortex.

What is lateralization?

Specialization of functions between the brain's two hemispheres.

Left Hemisphere	Right Hemisphere
Language and speech (usually)	Spatial awareness
Grammar and word processing	Recognizing faces
Analytical processing	Processing emotional tone of speech

What is the neuroconstructivist view?

Brain development results from ongoing interactions among neural activity, experience, and the environment; specialization emerges through development.

What are reflexes?

Automatic, involuntary responses to particular stimuli.

Why are infant reflexes important?

They support early survival and adaptation, and their presence or absence can help assess neurological functioning.

What happens to many infant reflexes during development?

They disappear or become integrated into voluntary movements as the nervous system matures.

What is dynamic systems theory of motor development?

Motor skills emerge through interactions among the body, nervous system, environment, and the infant's goals and experiences.

According to dynamic systems theory, is motor development simply genetically programmed?

No. Motor development emerges from multiple interacting factors.

Do motor skills automatically transfer from crawling to walking?

No. Skills are often task-specific, so learning one motor skill does not guarantee mastery of another.

What is the purpose of sticky mittens in infant motor research?

They allow infants to experience successful object contact and manipulation before they can grasp independently.

What does sticky-mittens research demonstrate?

Early action experience can influence infants' reaching and object exploration.

What is the visual preference method?

Researchers present different visual stimuli and measure which one an infant looks at longer.

1. Faces over many non-face patterns.

2. Complex patterns over simple patterns.

3. High-contrast patterns (like black and white) over low-contrast patterns.

What is habituation?

A decrease in responding after repeated exposure to the same stimulus.

What is dishabituation?

An increase in responding when a new or changed stimulus is presented.

What does dishabituation suggest?

The infant detects a difference between the familiar and new stimuli.

What is eye tracking?

A method that measures where infants look and how their gaze moves.

What is visual acuity?

The ability to perceive fine visual detail.

How does visual acuity change during infancy?

It is relatively poor at birth and improves substantially with development and visual experience.

What is depth perception?

The ability to perceive distance and three-dimensional spatial relationships.

What is intermodal perception?

The ability to integrate information from two or more sensory modalities, such as sight and sound.

What does research on infant cataracts demonstrate?

Early visual experience is important; deprivation can produce lasting visual difficulties even after cataract removal.

a baby’s brain needs to practise seeing to develop normal vision!

What is perceptual narrowing?

Experience-dependent specialization in perceiving familiar categories, accompanied by reduced discrimination of unfamiliar categories.

How does perceptual narrowing affect face perception?

Infants become better tuned to frequently experienced face categories and may lose some ability to distinguish unfamiliar categories.

What are two examples of perceptual narrowing in face perception?

Reduced discrimination of other-race faces and monkey faces following specialization through experience.

How do synaptic development and pruning change during infancy and childhood?

Synaptogenesis (formation of synapses) increases rapidly in infancy, producing an excess of neural connections.

Synaptic pruning then eliminates less-used connections while strengthening frequently activated ones.

What is the developmental pattern of myelination, and which brain regions develop first versus last?

Myelination begins before birth and continues through childhood and adolescence.

Brain regions supporting basic sensory and motor functions develop earlier, while higher-order association areas develop later.

MEMORY: Brain stem is FIRST, prefrontal cortex LAST.

Which brain regions develop first and last, and why is this important?

The brainstem is functional at birth, supporting essential survival functions.

The cerebral cortex develops over a longer period, with the prefrontal cortex developing last.

This explains why basic functions emerge before advanced planning and self-control.

How does walking develop according to dynamic systems theory?

Walking emerges through interactions among nervous system development, muscle strength, balance, body proportions, motivation, and environmental opportunities.

Infants gradually develop postural control and coordination through practice.

Learning to crawl does NOT automatically transfer to walking.

How does reaching and grasping develop during infancy?

Prereaching (early, poorly coordinated movements)

→ reaching with TWO hands

→ reaching with ONE hand

→ ulnar/palmar grasp (using fingers against the palm)

→ pincer grasp (thumb and index finger).

Infants gradually improve accuracy and adjust their grip to objects.

How does visual acuity develop during infancy?

Visual acuity improves rapidly:

approximately 20/600 at birth

→ 20/300 at 2 weeks

→ 20/40 by 6 months.

MEMORY: Babies start with blurry vision, which becomes much sharper during the first six months.

How does depth perception develop during infancy?

Depth perception (ability to judge distance) develops gradually as babies’ vision and movement skills improve.

Babies learn to use two important depth cues:

• Binocular disparity: Each eye sees a slightly different image, helping the brain judge distance.

• Motion information: Movement helps babies tell which objects are closer or farther away.

Visual cliff experiment: Babies may hesitate to cross an apparent drop-off, demonstrating their ability to perceive depth.

How does face perception develop during infancy?

Newborns show an early preference for face-like patterns.

With experience, infants become increasingly skilled at recognizing familiar faces and distinguishing individual faces.

During the first year, perceptual narrowing makes infants more specialized in recognizing frequently experienced face categories.

What is the head-mounted camera method in infant perception research?

Researchers place small cameras on infants' heads to record what they actually see during everyday activities.

This helps researchers understand infants' visual experiences from their own perspective.

How does brain growth change during the first year of life?

At birth, the brain weighs approximately 300–400 grams (about one-quarter of adult brain weight).

Head circumference increases from about 34 cm at birth to 46 cm by the first birthday, reflecting rapid brain growth.

What are the main benefits of breastfeeding for infants?

provides appropriate nutrition and antibodies that help protect infants against infections.

is associated with reduced risk of some gastrointestinal and respiratory illnesses

When should a mother avoid breastfeeding?

Breastfeeding may be unsafe in certain situations:

1. Maternal infections: Certain infections can be transmitted to the baby.

2. Medications or treatments: Some drugs or medical treatments can harm the baby through breast milk.

3. Infant metabolic disorders: Certain conditions prevent babies from safely processing components of breast milk.

What are the rooting and sucking reflexes?

ROOTING: When an infant's cheek is stroked, they turn toward the touch and open their mouth.

SUCKING: Touching the roof of the mouth triggers sucking. Both help newborns feed.

What are the Moro and grasping reflexes?

MORO: A sudden loss of support or startling stimulus causes an infant to extend their arms and then bring them inward.

GRASPING: Touching the palm causes the infant to close their fingers around an object.

What is the stepping reflex?

When a newborn is held upright with their feet touching a surface, they make alternating stepping movements.

This reflex typically disappears during early infancy before voluntary walking develops.