Motor Development Flashcards
1- Intermodal Perception
Intermodal Perception
* The coordinated perception of a singular object or event through 2 or
more sensory systems
- Often vision and at least one other sensory modality
* Intermodal perception is present very early on
Combining Vision and Touch
* Study: Can newborns integrate vision and touch?
- Infants sucked on a pacifier that they couldn’t see
- Preferential-looking procedure: Picture of the pacifier they had sucked on vs. picture of a pacifier of a different shape and texture
* Results: Newborns looked longer at the pacifier that they had sucked on
- i.e., looked at familiar pacifier
* Shows that ability to combine visual information with
touch is present from birth
Combining Vision and Auditory Info
* Classic study: Can infants combine vision with sound?
* Preferential looking procedure: 4-month olds simultaneously watched
two videos side-by-side
- Video of someone playing peekaboo vs. video of someone playing drums
* At the same time, heard audio of person saying “peekaboo”
- i.e., audio is synchronized with only one video
* Results: looked more at the person playing peekaboo vs. person
playing drums
* Shows that infants can integrate visual and auditory information
- Important for language development because children need to
understand that speech sounds are linked with a moving mouth
2- Motor Milestones
Reflexes
* Innate, involuntary actions that occur in response to a particular
stimulation
* Reflexes are adaptive
* Function of some is unclear
- E.g. tonic neck reflex: when an infant’s head is turned to the side, their
arm on that side extends and the arm and knee on the other side flex
* Most reflexes disappear by 2 months of age
- Some don’t like coughing, sneezing, blinking, withdrawing from pain
* Absent reflexes or reflexes that persist for too long can mean the
infant has neurological problems
Motor Milestones in Infancy
* Major motor developmental tasks of a period
* Happen in sequence, rarely out of order
* Huge individual variation in the ages these milestones are achieved
0-1 month: Prone, lifts head
2-4 months: Prone, chest up, uses arm for support
2-4.5 months: Rolls over
3-6 months: Supports some weight with legs
4.5-8 months: Sits without support
5-10 months: Stands with support
6-10 months: Pulls self to stand
7-12.5 months: Walks using furniture for support
9.5-14 months: Stands alone easily
11-14: Walks alone easily
What about crawling?
* 7 – 8 months of age: babies begin crawling
* Crawling is not considered a motor milestone
* Many healthy babies never crawl and skip right to walking
* Why do some babies skip crawling?
- Upper body or core weakness
- Hypersensitive to the texture of the floor
- Tonic neck reflex still present
- Insufficient opportunity
3- Culture differences in motor development
- Average ages of milestones are based
on WEIRD samples, but most infants in
the world are not - Only 15% of the world’s population is
WEIRD - Cultural practices lead to individual
differences in when motor milestones
are achieved
Example 1: Culture and Sitting
* Huge cross-cultural differences in how long 5-month-olds can sit
independently (see graph)
* Why?
-Related to where infants’ are placed to sit
* Earlier independent sitting in countries where infants spent more time
in places with less postural support (e.g., ground)
* Later independent sitting in countries where infants spent more time in
places with lots of postural support (e.g., child furniture or being held)
* How much time an infant spends in places with less postural supports impacts when they’ll be able to sit independently
Example 2: Culture and Encouragement of
Motor Skills
* Motor milestones are affected by how many opportunities infants
have to practice and how much motor development is actively
encouraged
* E.g., in some countries, some infants are actively discouraged from
crawling because of safety or hygiene concerns so crawl later or never
crawl
- e.g., urban China
* E.g., motor exercises in sub-Saharan Africa
- Infants are more advanced in motor skill development than kids in North
America
Motor exercises (see image)
Example 3: Culture, Diapers and Walking
* Diapers affect infant walking
* Infants show more mature walking
when naked vs. when wearing a diaper
- All infants were used to wearing a
diaper
* Diapers may contribute to crosscultural differences in walking
Implications of Cultural Differences
* Cultural practices in one domain can have unintended consequences in another domain
* Context plays an important role in motor development
- Differences in the course of motor development reflect the contexts in
which infants are developing
4- Mechanisms Behind
Motor Development
- Early theories: motor development governed by cortical maturation
- Current theories: motor development governed by complex interplay between numerous factors:
- Neural development
- Increases in physical strength
- Physical abilities, like posture control and balance
- Perceptual skills
- Change in body proportions and weight
- Motivation
- All these factors contribute to individual differences in motor
development
The Role of Weight Changes
* Infants are born with stepping reflex that disappears at 2
months but then start stepping again between 7-12
months of age when learning to walk
* Why does stepping reflex disappear?
* Hypothesis: Infants gain weight faster than they build leg
muscles and thus have insufficient strength to lift heavier
legs
* Evidence:
- Young infants who still showed stepping reflex stopped stepping when weights were attached to their ankles
- Infants who no longer show stepping reflex resumed stepping when placed in a tank of water : buoyancy of water supported weight
* Proves that disappearance of stepping reflex is due to weight change rather than cortical maturation
The Role of Motivation
* Infants are highly, intrinsically motivated to explore and learn:
- Persistence despite failing
- Continue to practice new skills even though they possess skills that are
more efficient that could accomplish the same goal
–e.g., practice walking even though they know how to crawl
- Look delighted when practicing new skills
* Individual differences in motivation predict when motor milestones
are achieved
* Study: Compared low and high motivation infants on when they achieved motor milestones
- Low motivation infants: movements occur infrequently, prefer activities that require little energy, require lots of stimulation to change position
- High motivation infants: move often, prefer high energy activity,
change position often, do not need clear stimulation to move
Results:
* Highly motivated infants achieved all motor milestones earlier than
less motivated infants
5- Summary so far
Summary of Motor Development So Far…
* Infants are born with reflexes, many of which disappear by 2 months
* Motor milestones are achieved in a predictable sequence
* Lots of individual differences due to numerous complex factors
- E.g., culture, weight gain, motivation, etc.
6- But why does motor development matter?
- Enables active learning and expands an infant’s world
- Allows children to learn by trial and error rather than just passively
observing - Increases opportunities for learning
- Facilitates development of skills in other domains
- Especially vision and social behaviour
7- Motor Development
and Vision
Crawlers and Walkers See the World
Differently
Motor Development and Perceiving 3D Objects
* Reaching enables object exploration which has consequences for
visual development
* 7 months: able to sit independently and to reach
- Allows kids to become more familiar with the properties of different
objects, including 3D
* Does independent sitting and reaching facilitate understanding of 3D
objects?
* Study: Habituation paradigm with 4-7.5 month olds
- Assessed sitting and reaching ability
* Habituation: Presented with rotating object with only 2 sides visible
- Does the infant perceive this shape as a complete 3D object?
* Test: Presented with rotating complete shape beside a rotating hollow
shape
* If infant saw shape as a complete 3D object, should look longer at
incomplete display because novel
* Results:
- Infants that were more advanced in sitting and reaching were more
likely to look at the incomplete display
- Age not related to where the infant looked
* Suggests that motor skills development in sitting and reaching influence development of 3D object perception
Motor Development and Depth Perception
* Motor development impacts depth perception
* Study: Infants placed in front of walkways with either shallow or
steep slopes and encouraged to crawl across
* Can babies tell the difference between slopes (i.e., detect different
depths)?
* Results:
* Perception of slope depended on crawling experience
- Beginner crawlers (about 8 months) confidently went down shallow slope BUT
also attempted slopes that were too steep
- Experienced crawlers avoided steep slopes
* When these same babies started walking, they made the same mistake as with
crawling
- Initially went down slopes that were too steep
- Failed to transfer what they had learned about slopes through crawling to
walking
* Suggests that infants have to learn through experience how to integrate
perceptual information with each new motor skill developed
But sometimes kids make mistakes…
* Scale errors: attempt to perform an action on a miniature object
that is impossible due to the huge difference in size between the
child and the object
* Present until around 2 years of age
* Due to failure to integrate visual information with action planning
8- Motor Development
and Social Behaviour
Motor Development and Understanding Intentions
* Adults proactively shift their gaze to the goal of an action when
observing somebody performing that action
- Indicates that they understand the person’s intention
* Can infants do the same thing?
* Study:
* Eye-tracking in adults, 12 month olds and 6 month olds
* Showed a video of a person placing objects into a bucket
Results: Adults and 12 month olds showed proactive gaze towards bucket
* 6-month olds did not
- Have not yet developed the ability to pick up, carry, and drop objects
* Shows that infants ability to predict others’ actions relies on them being
able to perform these same actions
9- Summary of motor development
Summary of Motor Development
* Infants are born with reflexes, many of which disappear by 2 months
* Motor milestones are achieved in a predictable sequence
* Lots of individual differences due to numerous complex factors
- E.g., culture, weight gain, motivation, etc.
* Motor development allows infants to play a more active role in their
learning and dramatically expands their understanding of the world
* Motor development is tightly linked with visual and social development
