Motor Development

Seite 1

The Structure of Motor Abilities

Fine visual motor coordination

Gross limb-eye coordination

Balance

Rarick , Dobbins & Broadhead, (1976). Three factors identified in 6-9 year olds.

Seite 2

Reflexes

Involuntary, automatic movements in response to specific stimuli.

Some present only in infancy others in whole lifespan.

Some debate about the ‘stepping’ reflex.

Locomotor 'reflexes'

Stepping, swimming.

Resemble later voluntary movements.

Spontaneous movements

Rhythmical stereotypies

When awake and alert, newborns move head, trunk, arms and legs.

Movements are spontaneous, have no goal.

e.g. supine kicking, arm movements.

May appear disorganized but are actually coordinated.

Seite 3

Stepping, kicking & walking

‘Stepping’ reflex and supine kicks are identical in positioning & timing of joint movements (Thelen and colleagues, 1981; 1983).

•Phases of spontaneous infant kicks are similar to adult walking step (Thelen et al. 1981).

Links between stepping & walking

Practice as an explanation of change – stepping and onset of walking.

Studies shown that when walking reflex practiced it increased and resulted in earlier onset of voluntary walking (Zelazo and colleagues, 1972; 1983).

Supported walking may help motivate upright position, strengthen muscles and assist balance control.

Seite 4

Biomechanical constraints

Changes in:

Height

Weight

Head circumference

"Developmental milestones are behaviors or physical skills seen in infants and children as they grow and develop. Rolling over, crawling, walking, and talking are all considered milestones. The milestones are different for each age range. "

Routes of Walking

"There are no rules about learning to crawl”.

Descriptive, longitudinal studies show no predetermined, fixed order of mastering motor skills although preferred patterns can be detected, (Largo et al., 1993).

How do we determine skill 'onset'?

Data: retrospective reports, cross sectional data, longitudinal data months apart.

Accurate estimates require frequent sampling.

Can we identify a specific day for the onset of walking?

Only 16% of the sample showed onset on a single day - with skill absent previously and present subsequently on a daily basis (Adolph et al, 2008).

Seite 6

Historical & cultural differences

Gesell (1946) white, American, middle-class norms – WEIRD populations (white, educated, industrialized, rich, democratic).

Black African infants – earlier gross motor milestones (Geber & Dean, 1957).

Cultural differences: theories of motor development, expected age for milestones & child rearing routines (e.g. Hopkins & Westra, 1990).

Enhanced Experiences

Formal routines practiced in Africa, India, and the Caribbean that are used to facilitate infants’ motor development: (A-C) massage and cosmetic molding of infants’ head and face; (D-F) suspension and shaking by ankles, arms, and head; (G) practice of sitting position; and (H-I) practice of upright stepping movements. (Hopkins & Westra, 1988).

Restricted practice

Swaddling, sandbags & cradle boards.

But doesn’t always lead to delayed motor development.

Seite 7

Training studies

Studies shown that when walking reflex practiced it increased and resulted in earlier onset of voluntary walking (Zelazo and colleagues, 1972; 1983).

Practice stepping on a motorized treadmill accelerates onset age for walking by several weeks in children with Down’s Syndrome (Ulrich et al, 2001).

Seite 8

Precursor forms of mobility

Precursor forms are not obligatory prerequisites for walking.

14% middle class American infants skipped crawling (Trettien, 1900)

17% British infants skipped crawling (Robson, 1984).

29% children of Jamaican mothers using traditional infant massage and exercise routines skipped crawling

Seite 9

Developmental Sequences

the appearance of new skills

refinements in the movement process

refinements in the movement product

acquisition of skill combinations

improved adaptation to the environment

Seite 10

Early walking

feet placed wide

flat-footed, out-toeing

short stride

limited leg & hip extension

little trunk rotation

hands & arms high, do not swing

Seite 11

Proficient walking

Narrow base

heel-toe planting

increased stride length

double knee-lock pattern

pelvis rotates

oppositional arm swing, with arms extended at sides

Seite 12

Learning to move

Infants need to be adaptable - able to respond to novel and variable situations

This involves on-line problem solving, ‘learning to learn’ within a problem space: crawling, cruising, walking

Seite 13

Adaptation paradigms

Descending slopes, spanning gaps, crossing bridges

Novel tasks presented, features varied

Can infants respond adaptively? Attempting safe increments, avoiding risky ones?

Adolph (2008)

Evidence for learning to learn

Flexibility:

Coping with novel variations in the environment

Working out new ways of moving within sessions

2. Specificity

Failure to transfer outside the boundaries of a problem space

Seite 14

Methods of assessment

Individual movement biographies

Shirley (1931) described progress and changes in 25 infants from birth to 2 years.

Harvey: “At 72 weeks he inserted a hesitation step into his walking record; he stamped with his right foot, tossing his head and body to the left side, hesitated, stepped on his left foot, stamped with his right and so on. Quite clearly this was not his method of walking to get somewhere but merely his way of jazzing up the dull old test….His test, more than that of any other child, reflects his mood of the moment and his general personality traits.”

Clinical Observation & assessment scales

Bayley Scales of Infant and Toddler Development, Third Edition (Bayley-III)

Griffiths Scales of Child Development, Third Edition

Standardised Tests

Henderson, S.E., Sugden, D.A. & Barnett, A.L. (2007). Movement Assessment Battery for Children-2. 2nd Ed. (Movement ABC-2) Test & Checklist. Examiner’s manual. London: Pearson.

Seite 15

Footfall analysis

Large sample of infants

9-17m, 5-6yrs, adult

Inexpensive ‘footfall’ method

Ink applied to tabs on shoes

Left trail of footprints on paper

Adolph, Vereijken & Shrout (2003) What changes in infant walking and why. Child Development, 74 (2), 475-497

Infant walking – description

Stride length

distance between heel strikes on same foot

2. Step length

distance between heel strikes on consecutive feet

3. Step width

lateral distance between feet

Seite 16

2D Motion Analysis

GAITRite mat

Stride length, Step length, Step width

Description of natural activity

Adolph et al (2012)

12-18 month olds

Huge amount of variable practice

�Walking: 2368 steps, 701 m, 17 falls per hour

�Correlated with measures of periodic gait: step length, step width

Seite 17

Adolph (2008)

This paper considers what is involved in learning new locomotor skills in infancy, with examples of the type ‘problem-solving’ that occurs within each new ‘posture’

Stationary and dynamic positions of the body that characterise a form of stance or locomotion (e.g., sitting, crawling, standing, cruising, walking). All postures except lying flat on the ground require balance control

First, learning is always nested in the context of larger developmental changes. Changes in bodies,

skills, and environments are especially dramatic during infancy, but we never cease developing.

A second, related point is that we are always learning to learn to move. Development is an exaggerated version of the temporary changes that result from the flux of everyday activity. Environments and bodies are always variable.

Infants descending slopes, spanning gaps, and crossing bridges

Observed infants over dozens of trials while varying increment size from trial to trial.

Compared infants’ attempt rates on safe and risky increments to their success rates at those same increments.

Data from these paradigms indicate that flexible and adaptive solutions require learning. When infants first acquired a new posture, they appeared oblivious to the limits of their abilities relative to environmental features. For example, In their first weeks of crawling and walking, infants plunged straight down impossibly steep slopes (Adolph, 1997). Over weeks of locomotor experience, exploratory behaviours became more discerning and responses became more adaptive: Infants attempted safe slopes and refused to crawl or walk down risky ones.

The locomotor experience was a better predictor of adaptive responding than age.

Seite 18

Adolph et al (2012)

This study describes the characteristics of natural infant locomotion (crawling & walking) observed during spontaneous free play.

After walking onset, natural locomotion improved dramatically: Infants took more steps, travelled farther distances, and fell less.

Traditional studies of infant locomotion during periodic gait could not have revealed these findings.

The consensus in the literature on expertise is that large amounts of regular practice, accumulated over years of training, promote expert performance (Ericsson & Ward,2007). The same principle could apply to acquire expertise in walking.

Why walk? This corpus of natural locomotion indicates that infants accumulate massive amounts of time-distributed, variable practice. Over days of walking, they take more steps, travel farther distances, and fall less. And they may be motivated to walk in the first place because walking takes them farther faster than crawling without increasing the risk of falling.

Seite 19

Ecological perspective

Two branches:

Dynamic Systems perspective

Concerned with motor control and coordination (Peter Kugler, Scott Kelso, Michael Turvey, 1980’s)

� 2. Perception-Action perspective

Concerned with perception (J.J. Gibson, 1960-70’s)

�

Seite 20

Dynamic systems perspective

Considers development of multiple systems within body (not just nervous system) e.g. sensory, perceptual, muscle, postural, cardiovascular etc.

Promotes idea that movements are (self-) organised, based on laws from physics, biology & thermodynamics to explain complex systems

Kelso et al (1980), Kugler et al (1980)

Components of a motor synergy self-organise

We have ‘preferred’ coordination modes

E.g. different gaits depending on speed of movement

Development is discontinuous, even in the face of continuous change

Considers development of multiple systems within body (not just nervous system) e.g. sensory, perceptual, muscle, postural, cardiovascular etc.

Promotes idea that movements are (self-) organised, based on laws from physics, biology & thermodynamics

Stresses interrelationship between individual capabilities, the environment and the task

Seite 21

Ecological perspective & stepping

Distribution of leg fat & muscle mass as explanation of change – reflex stepping and onset of walking

Stepping can be increased or decreased with certain manipulations

Submerging in water to chest or holding over treadmill increased reflex stepping (Thelen, 1983; 1986)

Adding weights to ankles reduced reflex stepping (Thelen, 1983)

Seite 22

Infant walking - description

Large sample of infants

9-17m, 5-6yrs, adult

Inexpensive ‘footfall’ method

Ink applied to tabs on shoes

Left trail of footprints on paper

What changes & why?

Age

Growing body dimensions (weight, height, leg length, head size, ‘chubbiness’)

Walking experience (time since onset of independent walking)

Adolph, Vereijken & Shrout (2003) What changes in infant walking and why. Child Development, 74 (2), 475-497

Seite 23

Perception-Action Perspective

J.J. Gibson 1960s, 1970s

Interrelationship between perceptual and motor system

Development of each must be studied together to be ecologically valid (applicable to real world)

Cannot study individual while ignoring surrounding environment

Using vision for action

Perception & action are inseparable

Perception is ‘direct’

Perception is essential for movement, but movement also informs perception

Seite 24

Visual cliff experiments

Gibson & Walk (1960; 1966), Svejda & Schmidt (1979)

Depth perception

Infants encouraged to cross the "cliff " to reach their mother

Younger children appear not to ‘see’ cliff and cross it happily

Once children have ‘seen’ the cliff, refuse to cross and can become distressed (Gibson & Walk, 1960)

After several weeks of crawling experience, they will begin to refuse to crawl over the drop-off.

Infants refuse because they are afraid of heights, but it is more of a child's sense of depth perception.

Campos et al. (1992) 6-8-month-olds, crawling for a week. Over time they became reluctant.

Conclusion. NOT innate – the experience of mobility may develop depth perception abilities.

‘Travel broadens the mind’

Seite 25

Perception-Action Perspective II

Based on work of Eleanor Gibson and James Gibson

Ability to directly perceive structured information in the environment enabling us to functionally act within it – ‘direct’ perception

Need to match movement abilities with opportunities in world around us.

Objects are perceived in terms of what they permit or afford an individual to do - ‘Affordances’

Relates to size and shape of object and individual and their movement capabilities

Can you walk up stairs with alternate footsteps? Need to consider height of stair in relation to own body - ‘body scaling’ plus your balance capabilities

Seite 26

Links between motor development and other domains of development

Learning to move - moving to learn : ‘Travel broadens the mind’

The role of locomotor development in: social & emotional development, referential gesturing, wariness of heights, distance perception, spatial search ….etc. (Campos et al. (2000). Infancy, 1 (2), 149-219).

Seite 27

Motor Development & Language Development

Yingling (1981) - sitting

Biomechanical changes with unsupported sitting

Greater lung capacity, changes in respiration and speech articulators

5.5 m olds followed up longitudinally to unsupported sitting

Found vocalisations changed: greater control over utterance production, more consistent, shorter vowels, greater vowel combinations, more combinations of C&V

Campos et al (1997) - Crawling

Onset associated with dramatic change in type and source of social signals infants receive as they explore the environment

Opportunity for infants to gain experience in attending to and interacting with distally located objects and people

3 groups infants 8.5 months

Pre-locomotor

Pre-locomotor with some ‘walker’ experience

Crawling for 6 weeks

Experimenter looked at and drew attention to toys in different locations at right and left

Pre-locomotor group looked equally to both sides

Those with locomotor experience looked more than other group to correct side and on significantly more trials

Crawling shapes the language and gestures caregivers use to encourage and discourage actions – this enhances attention to distal events – this helps with communication skills

Karasik et al (2011) - Walking

11m olds - crawling

1y1m olds – crawling, half of them walking

Observed at home with caregiver – recorded hands contacting objects

Grasping

Carrying

Showing/offering toy to adult – when stationary or moving (crawling, cruising, walking)

Found walkers carried objects more frequently and more likely to share objects by moving (44% vs 3%)

The onset of walking related to qualitative changes in way infant engaged with and shared objects and made object-related social bids

More joint attention. Walking broadens range of communicative referents. Rich opportunities for language learning.

Seite 28

Walle & Campos (2014)

Is walking onset related to infant language development?

Study 1: longitudinal design (N=44)

Assessed locomotor & language development with questionnaires

Every 2 weeks: 10m - 13.5 m

Acquisition of walking associated with significant increase in both receptive and productive language, independent of age.

Walle & Campos (2014) Study 2

How do features of the infant’s social environment relate to infant language development

Age-held-constant: 12.5m (38 crawling; 37 walking

[Replicated the differences in infant language development between locomotor groups]

Also naturalistic observation of parent–infant interactions (20 crawling dyads; 24 walking dyads)

10-minute free –play session

Parent seated in chair, no other instructions

Infant free to explore

Coding:

Parent vocalizations

Infant & parent location in each area of room

Amount of parent & infant movement (changed locations)

Reliability checked – good for all measures

Exploration of potential mechanisms to account for difference in language development between groups

Infant movement predicted receptive vocabulary size for both groups

Walking infants with greater parent language input had larger vocabularies (not for crawlers)

Walking infants whose parents moved less had larger vocabularies

Walking infants spending more time at medium distance from parent had larger productive vocabularies (not for crawlers)

Language development predicted by multiple factors in social environment, but only for walking infants.

Seite 29

He, Walle & Campos (2015)

A cross-national investigation of the relationship between infant walking and language development

Attempt to replicate previous findings and investigate whether relation exists cross-nationally

Chinese infants exposed to Mandarin (also walk 6 weeks later than American infants)

Walking infants in both American & Chinese samples had greater receptive and productive vocabularies

�Differences between crawling and walking infants were similar in each sample

Seite 30

Developmental Disorders

There is common co-occurance

Motor and language difficulties

Motor and attention difficulties

Motor and learning difficulties

Developmental Coordination Disorder (DCD), Specific Language Impairment (SLI), Attention-Deficit, Hyperactivity Disorder (ADHD), Dyslexia, Autism Spectrum Disorder (ASD)

They may have a shared genetic basis (Hill, 1998)

Seite 31

Diamond (2000) - neurophysiology

Motor and cognitive development both have protracted developmental timetables

When one is perturbed, the other is often adversely affected

The cerebellum matures late, like the prefrontal cortex – and may help to explain the relationship between motor and cognitive development

Evidence

Co-occurance of motor and cognitive deficits in developmental disorders

Abnormalities in cerebellum and prefrontal cortex in same disorders

�Imaging shows close interrelation of dorsolateral prefrontal cortex and neocerebellum – correlated activation

Brain damaged patients show close association of these two areas

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Embodied Cognition

Recognises that all of our development occurs in the context of a growing physical body that can move and interact with the environment in a range of ways

Views cognition and language as grounded in daily sensorimotor child-environment interaction

Importance of perception-action links

Systems approach - Multiple and various factors make a contribution to the emergence and development of behaviour