Motor Development. What IS “motor development”? Crawling

Motor DevelopmentMotor Development

What IS “motor development”?What IS “motor development”?

Crawling Crawling


Newborn- not much activity (except Newborn- not much activity (except when crying)when crying)

Reflexes begin to fade- voluntary Reflexes begin to fade- voluntary comes oncomes on

– (2-4 months)- big increase in activity(2-4 months)- big increase in activity Early movementsEarly movements

– TentativeTentative– Jerky- not smooth; clumsyJerky- not smooth; clumsy– UncoordinatedUncoordinated– Why?Why?


Motor control progresses with neural Motor control progresses with neural developmentdevelopment

– Myelination of the neurons in the cerebellum Myelination of the neurons in the cerebellum occurs with this increase in activityoccurs with this increase in activity

Cephalocaudal/proximal-distalCephalocaudal/proximal-distal– Downward and outwardDownward and outward

Control of Head, trunk, arms, legsControl of Head, trunk, arms, legs Head & trunk before arms and legsHead & trunk before arms and legs

– Arms & legs before hands and feetArms & legs before hands and feet– Hands and feet before fingers and toesHands and feet before fingers and toes

In spite of the fact that there is almost no In spite of the fact that there is almost no difference in physical development, boys are difference in physical development, boys are more advanced over girls in abilities that more advanced over girls in abilities that emphasize force and power. Why?emphasize force and power. Why?

Age NormsAge Norms

Age NormsAge NormsTaskTask 50%50% 90%90%Lifts headLifts head 2.22.2 3.2 months3.2 monthsSits with supportSits with support 5.55.5 7.87.8Independently sitsIndependently sits 6.5 6.5 9.09.0CrawlsCrawls 7.07.0 9.0 9.0 Stands aloneStands alone 11.511.5 13.913.9WalkingWalking 12.112.1 14.314.3

StairsStairs 17.017.0 22.022.0JumpingJumping 23.523.5 30.030.0Running (early)Running (early) 2.5 yrs2.5 yrs 3.0 years3.0 years

These have been changed to 9.0 and 10.5 due to SIDSintervention which decreasesexperience with movementon stomach

Why/how do we develop motor skills? Why do we walk? Nature or nurture?

Theories of Motor Theories of Motor DevelopmentDevelopment

Maturational (nature)Maturational (nature)– Motor development is a genetically Motor development is a genetically

programmed sequenceprogrammed sequence muscles & nerves maturemuscles & nerves mature

– Downward & outwardDownward & outward Sufficient for developmentSufficient for development

– Maturation is all that’s needed for motor skills to Maturation is all that’s needed for motor skills to developdevelop

Twin Studies (Gessell & Thompson, 1929)- Twin Studies (Gessell & Thompson, 1929)- Maturation is what is importantMaturation is what is important– One twin gets practice (walking, stairs)One twin gets practice (walking, stairs)– Co-twin restricted activity/no practiceCo-twin restricted activity/no practice– No difference in age of acquisition (first steps)No difference in age of acquisition (first steps)


Experiential (nurture)Experiential (nurture)– Motor development requires opportunities to learnMotor development requires opportunities to learn

maturation required, but not enoughmaturation required, but not enough– need chance to learn from experienceneed chance to learn from experience

practice facilitates development or improves motor skillspractice facilitates development or improves motor skills institutionalized infants (Dennis, 1960)institutionalized infants (Dennis, 1960)

– Infants in orphanage (Iran)Infants in orphanage (Iran)– Not placed in sitting positionNot placed in sitting position– Fed with propped bottleFed with propped bottle– No interactionNo interaction– Spent 1st two years in cribSpent 1st two years in crib– 18-24 m, none could walk18-24 m, none could walk– ½ were able to sit alone½ were able to sit alone– 3-4 years, only 15% walking3-4 years, only 15% walking– However, these are all “failure to thrive” infants. Many other However, these are all “failure to thrive” infants. Many other

variables that could be playing a role.variables that could be playing a role.– Take home message: practice doesn’t speed up Take home message: practice doesn’t speed up

maturation, but experience is necessary for motor maturation, but experience is necessary for motor skills to developskills to develop


– Dynamic Systems (Esther Thelan)Dynamic Systems (Esther Thelan) Incorporates both maturation and Incorporates both maturation and

learning as equally importantlearning as equally important Maturation, experience, perceptual Maturation, experience, perceptual

skills (systems) interactskills (systems) interact Changes involving growth and skill Changes involving growth and skill

acquisition in one area or system will acquisition in one area or system will impact performanceimpact performance

Motor skills are constructs (Thelan)- Motor skills are constructs (Thelan)- Emerges as infant actively reorganizes Emerges as infant actively reorganizes existing motor skills into new and more existing motor skills into new and more complex actionscomplex actions– Early constructs- tentative, uncoordinatedEarly constructs- tentative, uncoordinated– Toddler- spends lots of time on behindToddler- spends lots of time on behind

Dynamic Systems cont.Dynamic Systems cont.

Multiple factors influence developmentMultiple factors influence development– BiologicalBiological

Development of sensory systemDevelopment of sensory system CNS, Skeletal & muscular systems develop CNS, Skeletal & muscular systems develop

creating muscle tone and strengthcreating muscle tone and strength

– SocialSocial Mother-infant dyadMother-infant dyad Stimulating environment? Reinforcing? Stimulating environment? Reinforcing?

EncouragingEncouraging Facilitating development of skills with experienceFacilitating development of skills with experience

– ExperientialExperiential Floor time increases development of trunk controlFloor time increases development of trunk control


Infants are goal directedInfants are goal directed– Why work so hard? Why do we Why work so hard? Why do we

walk?walk?– Eager to acquire new skills that will Eager to acquire new skills that will

helphelp Get interesting new objectsGet interesting new objects Facilitate social/comfort contactFacilitate social/comfort contact

– Humans are curiousHumans are curious


Example: Crawling-Example: Crawling- any delay in any of any delay in any of these steps delays crawling.these steps delays crawling.

– Infants develop 3 skills independentlyInfants develop 3 skills independently Lift & turn headLift & turn head Hand preference in reachingHand preference in reaching Kicking legsKicking legs

– This turns into:This turns into: Raise head & turn it towards sight/soundRaise head & turn it towards sight/sound Reach with preferred hand for objectReach with preferred hand for object Kick with leg opposite of outstretched handKick with leg opposite of outstretched hand

– Infant reorganizes these into crawlingInfant reorganizes these into crawling Visual orientationVisual orientation Reach orients body in right directionReach orients body in right direction Kicking propels body forwardKicking propels body forward

At the beginningAt the beginning

The Completed ProductThe Completed Product

Developmental MilestonesDevelopmental MilestonesDirectionsDirections: Below is a list of gross and fine motor : Below is a list of gross and fine motor

milestones that develop during the first two years. Place milestones that develop during the first two years. Place them in the order in which they typically occur (that is, them in the order in which they typically occur (that is, average age achieved).average age achieved).

Milestones:Milestones:1. rolls from side to back1. rolls from side to back2. plays pat-a-cake2. plays pat-a-cake3. grasps a cube3. grasps a cube4. when held upright, holds head erect and steady4. when held upright, holds head erect and steady5. jumps in place5. jumps in place6. pulls to a stand6. pulls to a stand7. walks alone7. walks alone8. rolls from back to side8. rolls from back to side9. scribbles vigorously9. scribbles vigorously10. stands alone10. stands alone11. walks on tiptoe11. walks on tiptoe12. walks up stairs with help12. walks up stairs with help13. sits alone13. sits alone

1. 42. 13. 34. 85. 136. 67. 28. 109. 710. 911. 1212. 513. 11

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Motor Development. What IS “motor development”? Crawling