PSYC 1040:
Developmental Psychology
Week 4: October 5, 2011
Physical, Sensory, and Perceptual Development in Infancy
Chapter 4
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Class Schedule
9 – 10 am - Test #1
10 – 10:20 am - Break
10:20 – 11:50 am Chapter 4 – Development in Infancy
Chapter 4
Physical Changes
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Greatest degree of physical change occurs in the first 2 years
of life
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Babies grow 25 – 30 cm and triple body weight in first year

By age 2 (girls) & 2.5 (boys) children reach half of their full
adult height.
Chapter 4
Brain and the Nervous System

Develops rapidly during the first 2 years
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Midbrain and medulla are most fully developed at birth
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Vital functions such as heartbeat & respiration
Attention, sleeping, waking, elimination and movement of
head & neck
Cortex is least developed

Perception, body movement, thinking & language
Chapter 4
Brain and the Nervous System
Infant Brain Development – The Critical Intervention Point
http://www.youtube.com/watch?v=_0EYXx9iI64
 Idea of helping to form a brain – brain is a developing organ

Birth - 25% wired
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1 year - 75% wired
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3 years - 90% wired
Chapter 4 – Brain & the Nervous System
Changes in the brain result in predictable changes in reflexes,
sensory capacities and patterns of waking and sleeping.
Adaptive Reflexes – Help survival
 Sucking
 Withdrawal from pain
 Opening and closing pupil in response to brightness
Chapter 4 – Brain & the Nervous System
Primitive Reflexes – controlled by less sophisticated parts of
brain
 Startle (Moro) reflex – arch back and throw arms
outwards
 Babinski reflex – splay and curl toes when bottoms of
feet are touched
Typically disappear by 6 – 8 months
Chapter 4 – Brain & the Nervous System
Stimulation of reflexes may facilitate later motor
development.
Weak or absent adaptive reflexes may indicate
developmental problems
Persistent primitive reflexes may also indicate neurological
problems
Chapter 4 – Brain & the Nervous System
States of Consciousness (states of sleep & wakefulness)
 Patterns of sleep and wakefulness stabilize with age
 Newborns (neonates) sleep 80% of the time
 By 8 weeks most babies sleep through the night
 By 6 months, babies average 14 hours sleep per day
Chapter 4 – Brain & the Nervous System
Basic states of infant sleep:
Deep sleep
Active sleep
Quiet awake
Active awake
Crying & fussing

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Basic cry signals hunger – rhythmic
Anger cry – louder / more intense
Pain cry – very abrupt onset
Chapter 4 – Brain & the Nervous System
Developing Body Systems and Motor Skills

Acquisition of motor skills depends on brain development

Physical development develops from head downward and from
centre of the body outward

Motor skills interact with other aspects of physical development

Muscles, bones and weight all work together

Infants need opportunities to practice motor skills
Chapter 4 – Brain & the Nervous System
Developing Body Systems
Bones:

Changes in number & density responsible for improved coordination
Muscles:

All muscle fibres present at birth, however small in size and contain both
water and fat

By age 1 changes in muscle composition lead to increases in strength
Lungs & Heart:

Lungs grow rapidly and become more efficient

Heart muscle increases in strength
Chapter 4 – Brain & the Nervous System
Developing Motor Skills
Changes to body systems responsible for increased motor skills
Locomotor (Gross Motor) Skills:

Rolling over, crawling, sitting, standing, walking

Enable infant to get around their environment
Nonlocomotor Skills:

Controlling head movements, claps, jumps

Uses senses and motor skills to interact with objects and people
Manipulative (Fine Motor) Skills:

Holds, reaches for and grabs objects, hand preference, stacking, uses spoon to feed

Involves use of hands
Chapter 4 – Brain & the Nervous System
Motor Skill Development:
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Infant Milestone Study at U of M

Babies born in spring reach crawling & walking milestones
earlier
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Experience influences development
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Gender differences

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Girls are ahead of boys in some aspects of physical maturity
Studies shown that boys are typically more physically active
and display more physical aggression
Chapter 4 – Brain & the Nervous System
Motor Skill Development & Baby X?
“Differences between boys and girls in physical aggression
are already evident near the end of the second year, a
finding that has been replicated in studies of many
cultures.” pg. 100
Early Childhood
For Wednesday, October 12th
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Read Chapters 7 & 8 on Early Childhood
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You will have your first of three in-class writing assignments
on October 19th.
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Make sure you have read: Policy Question – What are the
Effects of Childhood Poverty in Canada? Pg. 244 – 246.
This in-class test is open book and open notes.
Remember you will keep your best 2 or 3 grades for these
writing assignments.
Vote - Thursday October 6th
www.youtube.com/MercerReport#p/search/0/OYgwUQTSC3I