Chapter 5: Physical
Development in Infants and
Toddlers
MODULES
5.1 Healthy Growth
5.2 The Developing Nervous System
5.3 Motor Development
5.4 Sensory and Perceptual Processes
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Module 5.1 Healthy Growth
LEARNING OBJECTIVES
Outline the important features of physical
growth in infants and toddlers and how they
vary from child to child.
Describe how heredity, hormones, and nutrition
contribute to physical growth.
Summarize how malnutrition, disease, and
accidents affect infants’ and toddlers’ physical
growth.
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Features of Human
Growth
Follows the cephalocaudal principle.
Muscles become longer and thicker.
During the first year, a layer of fat is
added.
Cartilage is replaced by bone.
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Variations on the Average Profile
Secular Growth
Trends: generational
changes in physical
development.
Average and normal
are not the same.
Average Height and Weight
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Mechanisms of Physical
Growth
Heredity influences adult height.
The pituitary gland secretes growth hormone.
Nutrition is particularly important during
infancy when growth is rapid.
At 2 years, growth slows and kids become
“picky” eaters.
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Challenges to Healthy
Growth
Malnutrition is especially damaging in infancy.
Malnutrition needs to be treated with adequate diet
and parent education.
Many diseases that kill young children are
preventable with vaccines, improved health care,
and changing habits.
After the first year of life children are more likely to
die from accidents than from any other single cause.
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Module 5.2 The Developing
Nervous System
LEARNING OBJECTIVES
Be able to draw a nerve cell and
identify its major parts.
Discuss how the brain is organized.
Identify when the brain is formed during
prenatal development and when
different regions of the brain begin to
function.
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Organization of the Mature Brain
Neuron: basic unit of
nervous system, specializes
in transmitting information.
Synapse: a gap or space
between neurons.
Cerebral hemispheres: right
and left halves of the cortex.
Frontal cortex: area of the
cortex that controls
personality and the ability to
carry out plans.
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The Developing Brain
Brain originates in neural plate.
Brain regions specialize early (e.g., left
hemisphere for verbal functioning; frontal
cortex for emotion).
“Flexible” or neuroplasticity of brain
organization shown by children who recover
from brain damage.
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Module 5.3 Motor Development
LEARNING OBJECTIVES
State how reflexes help infants interact with
the world.
Detail the component skills involved in
learning to walk, and at what age infants
typically master them.
Describe how infants learn to coordinate the
use of their hands and why most children
begin to prefer to use one hand.
Discuss how maturation and experience
influence children’s acquisition of motor skills.
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The Infant’s Reflexes
Newborns’ reflexes prepare them to interact
with the world.
Some reflexes are important to survival (e.g.,
rooting and sucking).
Some protect the newborn (e.g., blink and
withdrawal).
Some are foundations for later motor
behaviour (e.g., stepping reflex).
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Locomotion
Dynamic Systems
Theory: motor
development involves
many distinct skills.
Differentiation and
integration of
component skills
(posture and balance,
stepping, perceptual
skill) is necessary.
Source: Based on Shirley, 1931, and Bayley, 1969
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Fine Motor Skills
Maturation, Experience,
and Motor Skill
Reaching and
grasping becomes
more coordinated
throughout infancy.
Toddlers prefer to
use one hand and
this preference
becomes stronger
during the preschool
years.
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Maturation is
important: Studies of
Hopi infants.
Experience matters,
too: African infants
and training studies.
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Module 5.4 Sensory and
Perceptual Processes
LEARNING OBJECTIVES
Describe the sensory abilities of the newborn.
State how well infants hear and how they use
sounds to understand the world.
State how accurate infants’ vision is and
whether they perceive colour and depth.
Summarize how infants integrate information
from different senses.
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Smell, Taste,
and Touch
Even newborns can
smell, taste, and feel.
These skills are useful
in recognizing their
mothers and in feeding.
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Hearing
Infants hear well,
though not quite as
accurately as adults.
-Auditory threshold:
the quietest sound that
a person can hear.
Infants’ can distinguish
different sounds and
use sounds to judge the
distance and location of
objects.
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Seeing
Acuity is 20/400 at birth but
improves rapidly.
Infants perceive colours by 3
or 4 months.
Infants master perceptual
constancies early.
Many cues are used to infer
depth.
Edges & motion are used to
perceive objects.
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Wavelength of Light
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Perception of Objects
Infants’ Scanning of Faces
Use of Motion to Perceive Objects
Face-like Stimuli
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Integrating Sensory
Information
By 1 month, can integrate sight and touch.
By 4 months, can integrate sight and sound.
4- and 7-month-olds can match facial
appearance (boy or man) with sound of
voice.
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Infant Watching
Videos
Time Spent
Looking at Videos
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Conclusions
Nutrition is important for physical growth in children.
The brain and nervous system develop throughout
childhood through synaptic pruning and myelination.
Infants are born with many reflexes while their locomotor
skills progress through a series of milestones and reflect
maturation and experience.
Soon after birth, infants coordinate information from
different senses (vision, hearing, smell, touch). They
recognize by sight an object they have touched before and
integrate what they hear with what they see.
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