© 2007 McGraw-Hill Higher Education. All rights reserved. Voluntary Movements of Infancy Chapter 10

© 2007 McGraw-Hill Higher Education. All rights reserved. Objectives List and categorize the voluntary movements of infancy Describe the development of head control during infancy Describe the development of general body control during infancy

© 2007 McGraw-Hill Higher Education. All rights reserved. Objectives Describe the development of prone locomotion during infancy Describe the development of upright locomotion during infancy Describe the development of reaching, grasping, and releasing during infancy

© 2007 McGraw-Hill Higher Education. All rights reserved. Voluntary movement is the ultimate expression in the striated muscle of the integrated effects of a host of cortical and subcortical facilitory and inhibitory influences

© 2007 McGraw-Hill Higher Education. All rights reserved. The rate of acquisition for all voluntary movements during infancy may vary

© 2007 McGraw-Hill Higher Education. All rights reserved. Categorizing the Movements Voluntary movement groups Stability Head control, upright posture Locomotion Creeping, crawling, walking Manipulation Reaching, grasping, releasing

© 2007 McGraw-Hill Higher Education. All rights reserved. Categorizing the Movements Cephalocaudal pattern of development Head control Upper body control Lower body control

© 2007 McGraw-Hill Higher Education. All rights reserved. Stability ~ Head Control Voluntary movements begin at the head Milestone: infant raises head while prone Accomplished by 3 months of age Infant will then push the chest up with arms Raise head in supine position Accomplished by 5 months of age

© 2007 McGraw-Hill Higher Education. All rights reserved. Stability ~ Head Control Minimal voluntary control of the head Elevates head when prone with effort Positions head from left to right or right to left when prone Elevates head when supine

© 2007 McGraw-Hill Higher Education. All rights reserved. Stability ~ Body Control Chest elevation Segmented rolling back to front (visa versa) Crawling Ability to maintain upright posture frees the hands and arms for reaching and grasping

© 2007 McGraw-Hill Higher Education. All rights reserved. Voluntary Control of the Body 3 months: tries to roll from supine to prone position; maintains sitting position when assisted 5 months: sits when holding external supporting object

© 2007 McGraw-Hill Higher Education. All rights reserved. Voluntary Control of the Body 6 months: rolls from supine to prone position; maintains standing position when assisted 7 months: achieves sitting position from prone to supine position

© 2007 McGraw-Hill Higher Education. All rights reserved. Voluntary Control of the Body 8 months: sits alone; rolls from prone to supine position 9-10 months: pulls self to standing position, briefly maintains stand while holding external supporting object 12 months: stand unassisted

© 2007 McGraw-Hill Higher Education. All rights reserved. Study on Infants Ability to Self- sit Phillipe Rochat (1992)(Emery University) Studied the impact of an infants ability to self-sit on the development of early eye-hand coordination Half were able to sit on own Half were not able to sit on own Infants presented with display in seated, reclined, prone and supine positions

© 2007 McGraw-Hill Higher Education. All rights reserved. Rochats Key Findings Half of the infants were unable to sit on their own Sitters were more accurate in their reach than non-sitters All infants were more successful in the accuracy of their reach when supine versus sitting Non-sitters used two hands to reach more often than sitters Sitters reached more with one hand in all positions Non-sitters used one hand only when seated Overall, infants ability to sit appears to influence the use of hands in reaching activities

© 2007 McGraw-Hill Higher Education. All rights reserved. Locomotion ~ Prone Rate of acquisition for attaining prone locomotor movements varies more than any other voluntary movement

© 2007 McGraw-Hill Higher Education. All rights reserved. Locomotion ~ Prone Locomotion evolves from children gaining the ability to position their bodies for movement from one location in space to another 7 months: elevates trunk slightly; forward arm extension and flexion creates occasional forward Movement; leg flexion occasionally creates backward crawling

© 2007 McGraw-Hill Higher Education. All rights reserved. Locomotion ~ Prone Crawling (7-8 months) Precedes creeping Inefficient, highly variable arm and leg movements intended to propel the body forward Body is dragged Creeping (9-12 months) Contralateral or homolateral pattern More efficient form of prone locomotion Body is elevated

© 2007 McGraw-Hill Higher Education. All rights reserved. Locomotion ~ Upright Walking ~ the culmination of the acquisition of voluntary movement There is little evidence demonstrating that early walking will accelerate or refine future skill performance

© 2007 McGraw-Hill Higher Education. All rights reserved. Locomotion ~ Upright 7 months: walks with considerable support or assistance 10 months: walks laterally around furniture using handhold for support 7 months

© 2007 McGraw-Hill Higher Education. All rights reserved. Locomotion ~ Upright 11 months: walks when led with slight handhold to maintain balance 12 months: walks unassisted

© 2007 McGraw-Hill Higher Education. All rights reserved. Locomotion ~ Upright Experience is an important indicator in mature walking patterns Children with smaller bones or linear frames walk somewhat earlier than larger-boned or larger-framed children A child's muscle mass at 6 months of age may predict onset of independent walking

© 2007 McGraw-Hill Higher Education. All rights reserved. Locomotion ~ Upright Training children on a treadmill Increases number of steps taken Aids children with non-stable walking patterns Ground reaction forces may be used to help children with gait abnormalities and neurological disease

© 2007 McGraw-Hill Higher Education. All rights reserved. Manipulation ~ Reaching, Grasping, Releasing Use of the hands enables children to gather information about their environment in a new way Recall that early manipulation is reflexive Palmar grasp reflex

© 2007 McGraw-Hill Higher Education. All rights reserved. Manipulation ~ Reaching, Grasping, Releasing Phase IPhase II Simultaneous reaching and grasping Differentiated reaching and grasping One-handed reachingTwo-handed reaching Visual initiation of the reachVisual initiation and guidance of the reach Visual control of the graspTactile control of the grasp

© 2007 McGraw-Hill Higher Education. All rights reserved. Manipulation ~ Reaching, Grasping, Releasing BirthPhase I reaching 1 monthPhase I reaching disappears 4 monthsPhase I reaching reappears 4-5 monthsUnable to receive multiple toys 5-6 monthsThumb used to oppose fingers in grasping 6 monthsReceives two toys while storing one toy in opposite hand 6-8 monthsReceives two toys while storing one toy in opposite hand

© 2007 McGraw-Hill Higher Education. All rights reserved. Manipulation ~ Reaching, Grasping, Releasing 9 monthsAdjusts arm and hand tension to objects weight after grasping 9-10 monthsThumb can oppose one finger in grasping 9-11 monthsReceives three toys; stores first two toys on lap or chair 12 monthsAdjusts arm and hand tension upon repeatedly receiving the same object monthsReceives three or more toys and crosses midline to hand toys to other person 18 monthsReleases objects with relative ease; anticipates arm and hand tension for repeated presentation of same object; expects unknown long objects to weigh more than short objects

© 2007 McGraw-Hill Higher Education. All rights reserved. Manipulation ~ Reaching, Grasping, Releasing Development of prehension continues to evolve until the end of the first decade of life

© 2007 McGraw-Hill Higher Education. All rights reserved. Anticipation and Object Control in Reaching and Grasping By 18 months, infants exhibit anticipation Given the same object, repeatedly, infants display awareness that an object weighs the same Anticipation is not always accurate Expects unknown long object to weigh more that short object Anticipation and strength of grip develop over several years (2yr to 9yr)

© 2007 McGraw-Hill Higher Education. All rights reserved. Anticipation and Object Control in Reaching and Grasping 9 months Adjust weight of object after grasping it Limited anticipatory abilities 1 year Develops skill in adjusting arm and hand tension when handed an object No carry-over to new objects 18 months Child exhibits anticipation Aware that the same object weighs the same Develops a rule that similar objects weigh more or less than the familiar object (uses length) Not always accurate 2 yearsGreater speed with grasping an object coupled with less force 3 yearsGreater speed with grasping an object couplded with greater force 4 yearsChildren control rate of speed in grasping Burst of speed to grasp

© 2007 McGraw-Hill Higher Education. All rights reserved. Bimanual Control Complementary use of two hands to achieve a goal (receiving toys) is evident at 6-8 months 4-5 monthsVarying abilities Child cannot handle more than one toy 6-8 monthsHighly developed reaching and grasping Easily grasps first toy and sometimes a second one Cannot handle three toys 9-11 monthsCan hold on to three toys May place one of the objects on the lap or table monthsHands toys to parent or other adult for safekeeping while more toys are grasped Older children use a storage method to handle more toys

© 2007 McGraw-Hill Higher Education. All rights reserved. Bimanual Control Walking is correlated with childs ability to grasp with one hand Using a one or two hand grasp may be related to walking experience Less walking experience: one hand Greater walking experience: two hands

© 2007 McGraw-Hill Higher Education. All rights reserved.