Week 2 - Motor Development Flashcards
Two types of movement
- Reflex
- Voluntary Movement
Reflex
- Fixed, automatic, triggered in response to a specific sensory stimulus
- Patellar reflex
Voluntary Movement
- Purposeful, goal-directed
- Initiated entirely within the central nervous system
- Performance improves with practice
Examples of Reflexes
- Rooting reflex
Newborn’s mouth moves toward brush on cheek - Grasp reflex
Newborns grab on to anything in their hand - Stepping reflex
Baby will walk when lowered on surface - Moro reflex
Arms move to side when baby is unsupported
Two Theories of Motor Development
- Maturational theory
- Dynamic systems theory
Maturational Theory
- Motor development depends entirely on the development of the cortex
- As the cortex develops, it begins to override these early reflexes
Support for Maturational Theory
- Practice has little effect on the age at which children begin walking
- Reduced motor experience does not appear to affect
onset of walking - Extreme deprivation may result in motor delays, but they can be reversed
Challenges to the Maturational Theory
- Some research does suggest that experience affects
motor development- Restrictive parenting may delay the onset of walking
- Back to Sleep Campaign
Back to Sleep Campaign
___
Newborn Walking Reflex Change
- Goes away at 8 weeks
- See upright walking again (with help!) at around 5 months of age
Experiment to see why newborn walking stops
- Observed their stepping (walking) reflex at 2, 4, and
6 weeks of age - Counted the number of steps they took in one minute
- Observed their arousal level (Rated on a 6-point scale
from 1 (asleep) to 6 (crying hard)) - Got detailed measures of their bodies
Result of newborn walking experiment
- Number of steps decreased from 2 to 6 weeks
- Arousal predicted the number of steps at each age (did not change at different ages)
- Infants gained weight most rapidly between 2 and 4 weeks
- Infants who showed the greatest weight gain showed the greatest stepping decrease at 4-weeks
Followup experiment of newborn walking to see if weight gain really was the reason
- Used data collected in Study 1 to figure out what the average weight gain between 4 and 6 weeks was 163 grams
- Mind 4 tiny weight bands that could be strapped around infants’ thighs and calfs
- Infants stepped twice: Once with and once without the weights
(also did other experiment with water, stepped in and out of water; water made baby weigh less)
Results of followup of newborn walking experiment
- weight gain explains why newborn walking stops
- inconsistent with maturational theory
Dynamic Systems Theory
Development of complex behavior must be understood in terms of the interactions between all of the components involved in executing that action
According to the Dynamic Systems Theory, what parts of processes are involved in movement?
- Physical properties of the body
- Perception
- Navigating an environment
- What is the context for and the goal of the movement
Voluntary Movement in Newborns
Can move head only if supported
Voluntary Movement in 2-3 week olds
Lift chin off floor
Voluntary Movement in 5-10 week olds
Lift head and chin off floor
Voluntary Movement in 3 month olds
- Can hold steady while propping themselves up on arms or while being held by a grown up
- Rolling over!
Voluntary Movement in 6-7 month olds
Sitting without support
Variability in Motor Milestones
- sequence of the stages is not universal
- some infants skip stages
- often infants partake in different stages at the same time (continuously discovering new ways to do things faster but don’t necessarily give up on old ones immediately)
Posture-specific learning
- What babies learn at one locomotor stage may not transfer to another - The development of locomotor skills reflects changes in balance, strength, and coordination - Perceptual information will also change
Visual Cliff Experiment
- glass table with checkered part and glass only part (with checkers on the floor –> illusion of cliff
- 7-8 mo
Visual Cliff Experiment Results
- Babies have to have locomotor experience
to learn not to go over the cliff - more experienced crawlers are more likely to avoid the cliff than less experienced ones
Mind the Gap Experiment
- Tested infants at gaps of different sizes
- Toy on far side of gap and infants were encouraged to reach or crawl across it
- 9 mo, experienced sitters, less experienced crawlers
Mind the Gap Experiment Results
- Infants successfully avoided risky gaps when sitting
- They did not avoid them when crawling
Living on the Edge Experiment
- Tested infants on an apparatus that allows steps to be made different heights
- 1 yo who were either experienced crawlers or novice walkers
Living on the Edge Experiment Results
- Crawlers avoided more risky steps (cliffs) than did walkers
- Days of walking experience predicted walkers avoidance of risky steps, crawling experience did not
Why would you want to learn to walk? Experiment
- Observed crawlers and walkers in a playroom with toys
Learning how to walk results based on walking age
As walking age increases:
• Take more steps
• Covered more distance
• Fell less
Learning how to walk general results (walking vs. crawling)
- Walkers spent more time in motion, covered more distance, and took more steps
- Accounting for activity differences, walkers do not fall more
How do infants learn to walk?
Practice
How Do Caregivers Help Children with Motor Action?
- General motivation and security
- Motor experience
- Providers of information
Social Referencing
- looking at the emotions of adults to determine their own action
- Infants approach and avoid novel tasks, objects, and people based on caregiver’s expressions of emotion
Cues that Guide Motor Behavior
- Perceptual
- Social
Do Infants Rely on Social or Perceptual Information when Making Motor Decisions? Experiment
- 18-month-olds; Experienced walkers
Phase 1
• Determined infant’s ability to walk down a slope
• For each infant, determined safe, risky, and borderline slopes
Phase 2
• Moms provided encouragement or discouragement while babies walked down slopes
Do Infants Rely on Social or Perceptual Information when Making Motor Decisions? Results
Infants nearly always:
• Walked down safe slopes
• Never walked down risky slopes
• Borderline slopes: more likely to attempt if mom encouraged, less likely if mom discouraged
Walking and Social Interactions
- Observed infants in a play space with toys once a month
- When infants were crawling: watched others communicate more than when walking
- When infants began walking: made more bids for interaction than when crawling
Walking and Language
- Followed infants from 10 to 13 months of age
- Parents were emailed every two weeks
- Asked to report on:
• Locomotion milestones
• Receptive language
• Expressive language - Found language improved as milestones improved
