Motor Development Notes

Children undergo significant changes in locomotive ability in a little over a year.
Important Milestones:
- 4 months: Sit up.
- 6-7 months: Sit without support.
- 7-8 months: Stand up with help.
- 11-14 months: Stand alone.
Not all children hit these milestones at the same time, but they generally go through them in the same order.
Possible explanations for the order:
- Genetic “blueprint” (maturational theory).
- Ties to neurological development (maturational theory).
Motor development is a dynamic process, not simply maturation.

Balance is not mastered just once.
Different muscles are required for sitting, crawling, standing, walking, and moving while holding an object.
Infants must adjust and recalibrate their balance each time they master a new position.

Development involves many distinct skills that are organized and reorganized over time to meet the demand of a certain task.
Example: Walking reflects balance, moving limbs, perceiving the environment, and being motivated to move.

Children do not voluntarily step until 10 months.
Muscles in their legs are not strong enough to hold their weight.
Must be able to stand upright before stepping.
Thelen & Ulrich (1991) study:
- Babies placed on a treadmill (supported) showed mature stepping motions at 6–7 months.

Research shows that experience influences the timing of motor development (both good and bad).

Study of children in orphanages in East Europe:
- Stayed in cribs for prolonged periods with minimal toys.
- Results: Significant deficits in standing & balance.
- Suggests that early deprivation can lead to deficits.

Some cultural practices lead to “delays” (based on US standards) in motor development.
- Extended baby carrying or babywearing leads to later walking.
Infants in urban China spend more time on (safe) soft beds:
- Not enough resistance to attempt to pushup.
- Lack arm strength, leading to later crawling.
Cultural differences can also “accelerate” motor development.
- Routines practice in Africa, India, & Caribbean for motor development.
- Enhanced experience leads to early mastery of specific skills (postural control, sitting).

The coordination of small muscles — usually involving the synchronization of hands and fingers — with the eyes.
Dexterity and hand-eye coordination are important.
A major motor accomplishment during infancy is the use of the hands.
Newborns have very little control over their hands.
1-year-olds have advanced hand coordination.

By 4 months, infants can successfully reach for objects.
Early reaching appears clumsy:
- Moves a short distance.
- Slows.
- Moves again in a different direction.
- Repeats until it reaches the object.

At 4 months, infants can voluntarily grasp, but they tend to hold only with their fingers (Ulnar Grasp).
By 7-8 months, they include their thumbs.
They also begin to position their hands in a more efficient way.
At 9 months, develop more sophisticated “Pincer” grasp.

As infants develop, they start to use both hands in conjunction with each other.
At 4 months, infants can use each hand, but each seems to have a ‘mind of their own.’
At 5-6 months, children will begin to coordinate their hand movements, where each performs a different task—but they serve a common goal.
- E.g., Hold a dog's face with one hand and pet with the other.
Continues to develop past child’s first birthday.

Young infants do not seem to prefer one hand over another — early reaches do not indicate handedness.
Around the 1st birthday, most infants are emergent right-handers (90%).
- Will use left hand for stabilization and right hand to manipulate (petting dog).
Becomes more consistent in preschool — typically well established by kindergarten.

Genetics play a role, as identical twins tend to have the same handedness.
Culture can influence, with historical biases against left-handedness.
- Traditionally, schools taught all children to write with their right hand.