CHAPTER 6
GROWTH AND MOTOR
DEVELOPMENT DURING
INFANCY
Li-Chiou Chen and Jane E. Clark
Made by Wang Yan
§6.1 INFANT GROWTH
§6.2 INFANT MOTOR BEHAVIOR
§6.3 REFLEXIVE PERIOD
§6.4 REFLEXES:THE BUILDING BLOCKS
§6.5 SPONTANEOUS MOVEMENTS
§6.6 PREADAPTED PERIOD
§6.7 THEORETICAL PERSPECTIVES ON
INFANT MOTOR DEVELOPMENT
§6.8 MOTOR DEVELOPMENT AFTER THE
FIRST YEAR
§6.9 SUMMARY
§6.1 INFANT GROWTH
Changes in Body Weight and Length
 The growth changes during infancy are
amazing.
 In general, boys are heavier and longer
than girls during infancy.
 The growth of infant can be influenced by
many factors, including social, economic,
and cultural variables.
 It is suggested that those who were born
with low birthweight and thereafter rapidly
gained body weight after infancy had
higher rates of cardiovascular disease
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Changes in Body Proportion
 One of the most noticeable physical
features of neonates is their large head
size in comparison to the rest of their
body.
 Head circumference is similar across
countries.
 Head circumference has been commonly
used as an indicator of brain development.
 As the head becomes smaller and the
legs grow longer in relation to the total
body, the center of gravity of the whole
body descends.
Physical Growth and Motor Development
 Physical growth plays an important role in
infants’ motor development.
 Aspects of growth may influence infants’
motor development in different ways.
§6.2 INFANT MOTOR BEHAVIOR
 The newborn infant shows very
limited mobility and is highly
dependent on others to move in
the environment.
 This transformation in the
infant’s motor behavior over the
first year is significantly aided by
reflexes.
 Clark (1994) has identified six
periods in motor development:
 Reflexive
Period
 Preadapted Period
 Fundamental Motor Skill Period
 Context-Specific Motor Skill
Period
 Skillful Period
 Compensation Period
§6.3 REFLEXIVE PERIOD
 Both the spontaneous and stereotypical
movements represent the characteristic
behaviors of the “Reflexive Period”.
 The Reflexive Period starts from about the
3rd month of gestation when reflexive and
spontaneous movements can be observed
in the fetus, and lasts until around 2 weeks
after birth, when the infant starts to show
voluntary movements
 Because reflexes are critical building
blocks for motor development as well as
used to test the integrity of the infant’s
nervous system, the reflexes will be
discussed in detail in the next section.
§6.4 REFLEXES:THE BUILDING
BLOCKS
 Reflexes are stereotypical, involuntary
motor responses to specific external
stimuli.
 Healthy full-term neonates are born with a
collection of reflexes that ensure their
survival.
 Some reflexes, often referred as
infantile reflexes, become weaker
and gradually disappear after the
infant gains the ability to voluntarily
control her movements.
 Some reflexes do not disappear and
last longer or exist through the life
span, like tendon reflex.
Infantile reflexes can be categorized
into two types
 primitive reflexes
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rooting reflex
sucking reflex
Moro reflex
palmar grasp reflex
foot grasp reflex
Babinski reflex
asymmetric tonic neck reflex, ATNR
symmetric tonic neck reflex, STNR
 postural reflexes
 walking reflex
 swimming reflex
 neck righting reflex
 body righting reflex
 labyrinthine righting reflex
 linear acceleration reflexes
 parachuting reflexes
Function of Infantile Reflexes
 one of the important functions of
infantile reflexes is for survival and
protection
 For infants with very limited
mobility, infantile reflexes also
function as opening a dialogue for
the infant to the external world.
Appearance and Disappearance
of Infantile Reflexes
 infantile reflexes appear and
disappear in a certain sequence
and, on average, around the
same age in typically developing
infants.
 Any absence or prolonged existence of
an infantile reflex is usually associated
with pathological conditions in the
central nervous system (CNS).
 neuromaturation theory
 dynamic systems perspective
§6.5 SPONTANEOUS MOVEMENTS
 Neonates most often exhibit spontaneous
movements
 Because of the relatively invariant
movement patterns, infants’ spontaneous
movements are often called as
stereotypies.
 One of the most common and earliest
spontaneous movements of young infants
is leg kicking.
 Arm waving, with or without an object, is
another frequently observed spontaneous
movement in early infancy.
§6.6 PREADAPTED PERIOD
Sensorimotor Control of Posture
Postural control involves continuous and
dynamic interactions between the
neuromuscular system and the sensory
system (Horak & Macpherson, 1996).
 The Preadapted Period of motor
development begins with the onset
of voluntary movements and spans
the first year of life.
 In the Preadapted Period, the infant
develops motor skills that are
precursors for later motor behaviors
and are species-typical
(phylogenetic).
 Although motor development is
influenced by multiple sources of
constraints, biological constraints
play a very important role during the
Preadapted Period and only a little
specific environmental support is
required.
 motor milestones
The acquisition of infants’ basic
motor skills can be generally
categorized into three groups.
 postural control
 locomotion,
 manual control.
 Postural Development in Infants
Postural control refers to the
person’s ability to maintain the
body’s equilibrium and to assume
a desired orientation of the body
to the environment (Horak &
Macpherson, 1996).
• Head and upper trunk control
• Rolling
Rolling the body from one position
to another requires a certain level of
coordination between the two major
segments of the body, the head and
trunk, and the two sets of limbs, arms
and legs.
• Sitting
Sitting is the first acquired upright
posture in humans.
• Standing
Standing on two feet is a significant
milestone in the first year of life as it is
fundamental to many later appearing
motor skills, such as walking and
jumping.
 Locomotion Development in
Infants
Crawling
Walking
§6.7 THEORETICAL
PERSPECTIVES ON INFANT
MOTOR DEVELOPMENT
 The development of infants’
motor skills follows a fairly
consistent sequence.
 Most infants develop motor skills
in the same order and at
approximately the same age.
 Not every infant develops in the same
way or at the same rate.
 The development of infants’ motor
control is an emerging, not pre-wired,
process that is influenced by multiple
factors.
 The emergence of new motor
behaviors is a dynamic, self-organizing
process of the interacting constraints of
the organism, environment, and task.
§6.8 MOTOR DEVELOPMENT
AFTER THE FIRST YEAR
 Once the infant acquires the motor
skills of independent walking and
self-feeding, she enters into a new
period of motor development, called
the Fundamental Pattern Period
(Clark & Metcalfe, 2002) or the
Fundamental Motor Skills Period
(Clark, 1994).
§6.9 SUMMARY
 Infancy is a period of time when dramatic
changes in physical growth and motor
behaviors can both be observed.
 Infancy can be divided into three periods:
Reflexive, Preadapted, and Fundamental
Pattern Period.
 Although individual differences
may exist due to cultural or
environmental factors, the
general developmental direction
and sequence of behaviors
observed during infancy are
relatively consistent and
universal.
Tanks a lot!