Seeing, Thinking, and Doing in Infancy
How Children Develop
Chapter 5
Infant Development
Perception
Action Learning
Cognition
Motor Development
Reflexes Motor Milestones Current Views of Motor Development
The Expanding
World of the Infant
Infancy: Motor Development
Newborns – neonates – are surprisingly capable.
• Which capacities are innate?
• Which require maturation?
• Which develop through interaction?
• Are there discontinuities?
The Organized Newborn
Newborn Reflexes
• A reflex is
• Often used to judge neurological damage early in life
SURVIVAL REFLEXES: Serve obvious physical needs
breathing sucking eyeblink
rooting swallowing pupillary
The Organized Newborn
Newborn Reflexes
• A reflex is
• Often used to judge neurological damage early in life
PRIMITIVE REFLEXES: Serve no obvious physical needs; may be vestiges of important reflex behaviors at earlier stages of human evolution
moro tonic neck stepping
Palmar Babinski swimming
Reflex Procedure/response Does what?
Rooting Stroke cheek near mouth – baby turns head
Sucking Finger in infant’s mouth – infant sucks
Moro
Palmar grasp
More specifics on reflexes
Adaptive Value of Reflexes
• Many have survival value: Sucking crucial to eating.
• Others protect infants: Eye blink protects from stimulus.
• Others encourage gratifying interaction:
Sucking for feeding, Palmar for physical contact.
• Some no longer needed: Moro reflex helps baby
cling to mother - but in West babies not carried all
day.
Reflexes and motor skills
Disappear by 6 months as voluntary control increases.
Issue: Are reflexes building blocks for voluntary control?
1. Babies adapt reflexes: Palmar changes depending on how palm is stimulated.
2. Some reflexes disappear but
return later: swimming & stepping.
How do reflexes contribute to motor control?
Zelazo (1983): Practice stepping increases spontaneous stepping movements.
Hence, exercising reflex helps develop area of cortex related to movement.
No exercise, reflex disappears.
Thelen (1983): Weight gain not matched by leg strength. Exercise
builds muscles – reflex retained.
The Fish Tank Experiment (Thelen, Fisher, &
Ridley-Johnson, 1984)
The Fish Tank Experiment (Thelen, Fisher, &
Ridley-Johnson, 1984)
0 5 10 15 20 25
Out-of-Water In-Water
Average Steps per Minute
Weighting the Legs
(Thelen, Fisher, & Ridley-Johnson, 1984)
0 5 10 15 20 25
Without Weights Weights Added
Average Steps per Minute
How do reflexes contribute to motor control?
Zelazo (1983): Practice stepping increases spontaneous stepping movements.
Hence, exercising reflex helps develop area of cortex related to movement.
No exercise, reflex disappears.
Thelen (1983): Weight gain not matched by leg strength. Exercise builds muscles – reflex retained.
So, should parents encourage walking reflex?
Motor Development
The organization and sequence of motor development
1. Gross motor development: actions that help infant get around – crawling, standing, walking.
2. Fine motor development: smaller movements – reaching &
grasping.
Milestones of Motor Development
Infancy
Differentiation and integration in Postural Control, Locomotion, and Manual Control leads to:
• Improvements in timing, balance, and coordination Motor advances lead to:
1.
2.
3.
4.
Infancy
Differentiation and integration in Postural Control, Locomotion, and Manual Control leads to:
• Improvements in timing, balance, and coordination Motor advances lead to:
1. opportunities for
2. better understanding
3. more accurate judgments
4. more interaction
• The developmental sequence of motor skills is quite uniform.
But, large individual differences in rate of development:
Motor skill Average age Range (90% infants) Grasps cube 3 months 3 weeks 2-7 months
Crawls
Walks alone
Often, a baby is slow on some motor skills but advanced on others.
• We are concerned only if slow on many skills.
Developmental norms imply maturation:
• a hard-wired sequence directed by motor development genes But:
• Interaction of multiple factors, each of which may be influenced
by genes and experience
Psychologists ignored motor
development for 40 years because of maturationist assumptions:
Early pioneers Arnold Gesell and Myrtle McGraw believed that motor skills were determined
mainly by neurological maturation of the brain.
(Perspective = Nature, Passive Child)
Motor Skills as Dynamic Systems (Thelen, Pick, Smith) Dynamic systems theory (DNS) views motor development as
acquiring ever more complex systems of action Not just development of independent skills:
1. head and chest control combine into sitting with support
2. crawling, standing, and stepping combine for walking.
Dynamic Systems Approach
New forms emerge through processes of self-organization
patterns and order emerge from the interactions
of the multiple components of a complex system
without explicit instructions from
organism or environment
Extraordinarily complex structural patterns can emerge from very simple initial conditions in dynamic systems
During development, living things with particular properties spontaneously organize themselves into patterns
Movie: Baby body sense
Evidence for DS – Microgenetic research (Thelen, 1994)
• Attach mobile to 3-month-olds’ legs.
Infants’ usually kick with one leg or two in alternation.
• Attach mobile so that two legged kick works best
Infants soon learn, and start to use, two legged kick.
Locomotion
At around 8 months of age,
infants become capable of self- locomotion for the first time as they begin to crawl
Infants begin walking
independently at around 13 to 14 months of age, using a
toddling gait
Integration in locomotion
Locomotion
Karen Adolph and her colleagues have found that
infants do not transfer what they learned about
crawling down slopes to walking down them
Back-Lying and Locomotion
The campaign to get parents to put babies to sleep on their backs to reduce the risk of SIDS seems to make infants less likely to roll over on schedule
It may be that the better view of the world from their backs results in less motivation to roll over
It may also be that spending less time on their tummies causes arm strength to develop more slowly
