Overview Motor Development Developmental Psychology Week 3 Dr Kirsty Miller Why look at motor development? Name an area of developmental psychology that utilises motor control. 2. What do children use motor control for in the real world? 1. • • • • • • Normal motor develoment à à à à à Why motor control? Foetal movements Newborn movements Reflexes Milestones Obesity Culture Before birth 8000% increase in height 42 500% increase in weight To move the external world To move yourself To prevent movements: maintain equilibrium Communication Sensation Generate perceptual info Foetal Movements Foetal Movements Movements begin as soon as rudimentary muscles have formed along with primitive neural circuitry (Humphrey, 1944) 9 weeks‐ startle, hiccups, writhing movements. 10 weeks‐ arm and leg movements, isolated limbs, digits, whole body activation. Purposeful limb movements à Handedness??? à 14 weeks, 2/3 hand movements directed to objects in uterus. Quickening (16‐20 weeks) occurs at time of reduction of foetal movements. à 15/16 weeks 60% à 38 weeks 10% Foetal Movements‐ Why? Newborn movements Developmental functions Why should newborns be less able than foetuses? à Normal development of muscles, bones, joints and skin. à Alcohol suppresses foetal movements for several hours‐ FAS. Why do foetuses move? à Response to stimulation à Because they can à Reflexive hard wired programs? (Gessel) What can newborns do? • Blink eyes, track objects. à Environmental factors. Amniotic fluid à Late gestation foetus‐ limited gross motor repertoire due to confinement à Newborn‐ limited gross motor repertoire due to gravity and inertial forces of own movements Reflex • Open and close hands, wiggle their fingers and toes. • Suck on hands, fingers and toes. Simion, Regolin & Bulf ,2008 Duration Sole of foot stroked Fan out toes, 9 months- 1 twist foot in year Grasping Palms touched Grasps tightly Weakens 3m Disappear 1yr Moro Startle, throw 3-4 months Sudden move or loud out limbs then pull in noise Stepping Held upright, feet touching ground Rooting 3-4 months Turns to Cheek source, open stroked or side of mouth mouth, suck. • Arch back • Flail arms and kick legs. Response Babinski • Turn head. • Protrude tongue, open and close mouth, purse lips Stimulation Moves feet as if to walk 3-4 months Simion, Regolin & Bulf ,2008 Cephalocaudal Proximodistal Independent movement Gessel – 23 ordered stages Stability Locomotion Manipulation à Reaching à Grasping à Releasing 2 months – able to lift head up on his own 3 months – can roll over 4 months – can sit propped up without falling over 6 months – is able to sit up without support 7 months – begins to stand while holding on to things for support 9 months – can begin to walk, still using support Crawling Trettian & Hall, 1900. 150 infants à 42% hands and knees crawling à 10% belly crawl à 5.5% bear crawl à 2.5% hands and feet onto belly à 30% sitting and hitching à 7% log rolling à Stage 1. à Stage 5. à Stage 19. à Stage 23. passive kneeling. ‘swimming’ crawl H & K walking 1 week 4 months 10 month 14 month All stages necessary and invariant. Reflect underlying maturity of infants neuromotor system maturation • 10 months – is able to momentarily stand on her own without support • 11 months – can stand alone with more confidence • 12 months – begin walking alone without support • 14 months – can walk backward without support • 17 months – can walk up steps with little or no support • 18 months – able to manipulate objects with feet while walking, such as kicking a ball Back to sleep and crawling delay SIDS campaign resulted in babies put to sleep on back. Back sleepers dislike ‘tummy time’ Davis et al (1998) – tummy time related to earlier onset of sitting, crawling and pulling to stand. Dewey et al (1998) – back sleepers later for above & scored lower on gross motor skills measures. Tummy time & Crawling 2‐3 weeks‐ chin off floor 5 to 10 weeks‐ head and chest 3 months‐ mermaid 5 months‐ shift weight But is crawling normal? Western Maturation drives motor devel. Crawling necessary stage. à Sit à Crawl Jamaica & Mali Training & exercise provides impetus for motor devel. Crawling dangerous, primitive & unnecessary. à Walk Babies overfed to meet flawed ideal US National Centre for Health Statistics à High protein milk à Atypically heavy infants Revised 2000 by CDC – more breastfed babies World Health Organisation‐ new charts 8500 breastfed infants from 6 diverse countries. Thelen et al, 1982, 1984, 1991 Stepping doesn’t disappear but is masked à Thinner vs fatter legs à 4 week stepping and weights Newborn stepping‐ disappears 8 weeks and reappears 8 months. McGraw 1940‐ cortical maturation suppresses. Myelinisation of corticospinal tract causes reappearance under cortical control at 8 months. Maturation Argument National Association for Sport and Physical Education (NASPE) Obesity in infants related to developmental delays in crawling and walking. à Non stepping 7 month and treadmill Newborn movements constrained & facilitated by devel changes in non neural biomechanical factors Zelazo et al 1972 12 min upright stepping a day from 1‐8 weeks‐ No typical decline. Sanefuji, Ohgami & Hashiya, 2008 Learning to walk changes infants social interactions Clearfield, 2011 The transition to independent walking marked increased interaction time with mothers, as well as more sophisticated interactions, including directing mothers’ attention to particular objects Assessment…
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