Atu: Motor development PDF

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PY2TA (lecture 4)
Motor development...

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PY2TA (lecture 4) Motor development Learning Objectives: ⚫ Describe early motor development in humans ⚫ Explain the importance of (loco)motor experience for development in other domains ⚫ Demonstrate an understanding of the maturational and dynamic systems approaches to motor development ⚫ Critically evaluate the maturational account of motor development, using a range of evidence

Ubiquitous movement ⚫ Interaction with objects and how objects interact with each other. ⚫ Movement facilitate a lot of social behaviour ⚫ Leversen, Haga & Sigmundsson H (2012) – o Had participants from different age group do a variety of task that varied in terms of different type of movements and measured how fast they performed these task. The faster they performed these task then the better their motor performance was. o Results; motor performance is shown to peak at 19-25 year olds and then slowly deteriorate over the years after this peak.

o Motor skill development: ⚫ From birth we need to develop our neck for movement ⚫ Control our movement such a crawling or walking ⚫ Develop gross motor skills; broad movement of the limbs rather than fine motor skills.

⚫ Physical growth trends: o Cephalocaudal: head to foot

▪ Controlling neck to hold head up high ▪ Control of shoulder muscle ▪ Control of torso muscle o Proximodistal: spine to hands and fingers ▪ Development of the spine ▪ Development of extremities and fingers and toes. ⚫ Motor difficulties: o Are (or can be) experienced by children with:

▪ Developmental coordination disorder (DCD) ▪ Attention deficit hyperactivity disorder (ADHD) ▪ Williams syndrome ▪ Premature birth ▪ Down syndrome ▪ Dyslexia ▪ Autism and more. o A lot of comorbidity between disorders. Sometimes it is due to the comorbidity between the disorders that results to the evident motor difficulties seen in children. ⚫ Examples of gross-motor behaviour: o Climbing, rolling, jumping, standing, walking. ⚫ Example of fine motor behaviour: o Treading, drawing, using Lego, grasping, handwriting. Motor development ⚫ Why study motor development? o Directly measurable, observable development o Visible: crawling, standing, running, dancing o Well-described developmental change and developmental norms o Used to study more general developmental processes o Connections with other domains (perceptions, cognition) o motor behaviour is quite straightforward to measure. ⚫ History of motor development research o The “Golden Age” (1880s to 1940s) ▪ Motor development was one of the first domains to be studied in human development. ▪ Influences from biology (maturational) – detailed descriptions / motor ‘catalogues’ ▪ Gesell (influenced by Darwin) and McGraw: importance of maturation (biological ‘unfolding’) form central nervous system. ▪ Developmental norms and standardised testing – e.g., Bayley Scales of Infant Development o The Dormant Years (approx. 1950-1970s) ▪ Catalogues made. Maturation: case closed? ▪ dominance of experimental & cognitive psychology at expense of motor domains/developmental norms. o Rebirth (1980s onwards). ▪ Advances in theory e.g. dynamic systems and links between motor and other domains ▪ technology e.g. brain activity ▪ brain knowledge e.g. plasticity.

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This advances in knowledge allowed to test the assumptions of the maturational and learning accounts of motor development.

Motor milestones & Early Motor development ⚫ Neonates (Newborns): o Have immature nervous system with poorly controlled limb movements but they have motor control such as use of crying for attention and coordinate sucking, swallowing, breathing when feeding o Reflexes in first six months – basis for later development, e.g., ▪ Until ~2 months: stepping (precursor to walking) ▪ Until ~ 3-4 months: Palmar grasp (precursor to voluntary grasp) ▪ Until ~4 months: sucking reflex (then becomes voluntary behaviours) o Other examples of reflexes; ▪ Babinksi- spread toes out when side of foot is stroked. This reflex actually disappears as children grow, and if this reflex does not disappear (if this reflex is seen in adults) then it indicates neurological damage. ▪ Moro- spread arms out after being tickled in stomach o Research have shown there is a normal distribution of behaviours at certain ages (Bayley, 1969, Frankenburg et al., 1992, Adolphs & Robinson, 2015). But there is also a variation in order.

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Consistent with the fact that rhere is an innate mechanism that we develop certain behaviours at certain ages but based on experiences this can affect the behaviours that is learned at different ages.

⚫ From reflexes to motor skill learning:

o Reflexes disappear o We learn new motor skills o We perform existing motor skills with more control ▪ The maturational account would be that this control that we gain is due to our genetics ▪ The learning would account that our experiences is that plays a role in the development of more control in our motor skills.

2 Theories of Motor development: ⚫ For any theory to be robust in attempting to explain motor development, it must be able to explain the emergence of new skills that are not the same as those reflexive movements that are present at birth. 1. Maturational accounts of motor development ⚫ The biological-maturation perspective views change as an internal process that is dictated by an individual’s body clock. Advocates believe that, since development is the result of inheritance, no amount of stimulation can alter its course. ⚫ Arnold Gesell (1954) observed and documented patterns in the way children develop, showing that all children go through similar and predictable sequences at their own pace and these re controlled by genetic factors. o Patterns must be brain maturation o There is a fixed sequence of emergence of separate skills o Increasing cortical control of muscular movements drives development o Innate and genetically determined; hierarchical behaviour o Minor role given to experience, some effect from enviroment/experience but small compared to biology. ⚫ McGraw (1943) believed that maturation of the CNS was the catalyst for the emergence of new physical skills, and Gesell’s work was built upon this belief. ⚫ Broadly speaking the maturational account say that our motor development begins in our central nervous system and then slowly becomes evolved. And our genes have certain milestones and some of them involves development of cortical control of the muscular movements. ⚫ Jimmy & Johnny (Mcgraw, 1935 – see thelen, 2000) o McGraw was influenced by Gesell but also recognised intertwined nature of experience and biology. She is often cited as a maturationist, but not always. o Trained one twin in culturally generic skills (walking / sitting) and culturally specific skills (swimming / roller skating). o Other twin: no training o Results: some improvements in trained twin’s skills, but small effects long-term in terms of their motor skills. so in the long term they become convergent in terms of their motor skills. this shows that there is to some extent influence of genetics in our motor skill development. ⚫ Limitations:

o Cross-cultural differences; (Adolph, Karasik, Tamis-le-monda, 2010) ▪ Variations in cultural child-rearing practices are associated with different motor outcomes ▪ E.g., West Indians of Jamaica and Kipsigies of Kenya  Practice motor skills, Keep babies upright in holes dug in the ground, with blankets tend not to crawl and this type of practice lead children to walk but by not needing to crawl, in contrast to Western trends – evidence against innateness and with the dynamic system theory. o Bernstein’s degrees-of-freedom problem; Bernstein (1967 translation from 1930s): ▪ how does the brain organise all the nerves, muscles, cells into movements? ▪ Some movements do not arise from a neural signal, but from forces in the environment ▪ Environment constrains the degrees of freedom: need to stay upright, move forward…walking is most efficient (Thelen, 1995) ▪ Therefore: Not just due to increasing cortical control as the maturationists suggested

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There is not need to refer to an innate mechanism for movements, it depends on what the appropriate movement is depending on the enviroment.

o Individual differences & related skills; ▪ Skills related to one another and are not separate E.g., head control + chest control = sit with support ▪ Individual differences in order of acquisition as well as in the types of movement produced along the way (Adolph & Joh, 2007, Adolph, Tarasik & Tamis-LeMonda, 2010) – emergence sequence is not fixed.

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Crawling usually precedes walking in the western world but not always (so no hierarchical) So children have different way of using their motor skills that can lead to the development of walking. So it is not based on their genetics but based on the type of ways that they used their motor skills in their enviroment that will lead to the development of walking. This type of evidence support the dynamic system theory; there are more dynamic ways to develop our motor abilities.

2. Ecological (Gibsonian) Psychology – James and Gibson 1960s-1980s ⚫ A child perceives the world in an organised way to for interaction with it. o So the action changes based on the perception of the enviroment. o Alternatively our perception can also alter our action ⚫ Focus on matching capabilities with environment: “Affordances” for action. ⚫ Perception and action are closely linked suggesting that both are important in order for infant to develop motor development. ⚫ Movement, perception and action Visual cliff (e. j. Gibson & walk, 1960); o Visual cliff where the safety glass is invisible to infants and the caregiver beckons. ▪ From a young age children wont have depth perception yet so will walk over towards the glass side. o Experienced and inexperienced crawlers of the same age (7.5-8.5m) o Results; Experienced: 65% avoidance of visual cliff. Inexperienced: 35% avoidance of visual cliff, suggesting less depth perception in infants who have not crawled as infants who have crawled. o Crawling (motor) experience predicts perception of affordances (ways of doing things) for action ▪ Gibson affordances; the enviroment provides many opportunities for various actions, were infants need to seek out their own affordances in the context of the enviroment, usually by trial and error – a method of discovery. ⚫ Multimodal movement – moving room paradigm (Lee & Aranson, 1974) o stable floor but moving walls = infant loses balance.

o Balance was affected in the perceived direction in 82% of the traisl o Shows importance of vision to postural control. o Lee & Aranson, 1974; Human infants learning to stand use visual proprioceptive information about body sway in order to maintain stable posture. Moreover, the visual proprioceptive information is more potent than the nonvisual. This is shown by an experiment in which infants were caused to sway and even fall forward or backward in response to appropriate visual stimulation. ⚫ There does not seem to be a need to refer to an innate mechanism on how we perform our motor skills in our enviroment bc other things like (gravity and etc.) how we interact in the enviroment also influence on decision on what motor skills to use (walking, running) a. Dynamic systems theory of motor development (Adolph & Berger, 2006; Thelen, 1989, 1995) ⚫ Dynamic system; movement defined and analysed by using mathematical terms, symbols and values. Where future evolution is predictable from present states. o Movement skills evolve from initial attempts to fully automated and consistent mastery. ⚫ Dynamic system theory: suggests that motor co-ordination takes place by changes in the enviroment and the demands of a specific task. This theory proposes that development cannot be separated from the context in which a person develops. o Based on the idea from physics which was applied to motor development by Thelen 1995. o It is through self-organising properties in the body that movement emerges. Even the most simple of skills demands co-ordination of postural, perceptual and muscle systems. o As new patterns emerge and older ones become redundant, there may be discontinuities (periods of time) when motor performance is disrupted. - patterns that do not wholly come from CNS - Pattern stability is disrupted = elements rearranged. o Flexible movement patterns – not hardwired (multiple causes) o Importance of thinking about movement over time e.g. learning o Emphasis on practice to refine and improve skills o Muscle forces and mechanical interactions between muscle groups are influenced by overall intentions of the action, by body position, speed of limb, and direction and size of specific body segments being used. o Exploration as a driving force for development

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o Adolph & Berger, 2006 – when learning a new skill, previously learnt skills can become less stable. Some repeated movement patterns are stable and preferable to other ‘attractors’. ▪ Attractors can change depending on conditions (walking – running)

⚫ The case of the disappearing reflex- Thelen & Fisher (1982, 1983): o Infants (and their legs!) gain weight at the same time as stepping disappearing o Stepping could be ‘restored’ or ‘inhibited’ depending on the context o Same movement in brain but difference in outcomes based on the enviroment (whether o

upright or lying down) Maturational account: states that reflexes are inhibited with increasing cortical maturity.

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The case of the disappearing reflex seems to be support for the dynamic system theory. Because the enviroment can influence whether the reflex is restored or not.

⚫ Evaluation of Dynamic systems theory:

o Advantages: ▪ Formal language for emergence of new behaviours (Yates, 1987); framework for study (Wolff, 1992) ▪ Can be modelled mathematically; enable generation of predictions (e.g., under what conditions change will occur) ▪ Accounts for the evidence of the role of experience and multiple interacting influences, the more information about the diff influences, the better it is to predict the future of the motor development. o Disadvantages: ▪ Does not explain how we set goals for action. Still need executive functioning ▪ Does not explain why a system goes for a particular ‘attractor state’ and how one moves to another. ▪ Does not explain how infant from crawling to walking just that it has multiple influences that impact this motor development. Maturational vs dynamic systems

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Onset of locomotion (Campos et al., 2000) ⚫ The beginning of locomotion (self-initiation of movement) is thought to be related the development of a range of skills in other domains, e.g., perception of distance, wariness of heights, spatial search strategies, receiving social signals, proximity seeking for attachment ⚫ Locomotion & joint attention; Campos et al. 1997 (see Campos et al. 2000) o 8.5 month–olds, 22 per group who were either: ▪ Prelocomotor (not crawling), locomotor (1-4 months), locomotor (5+ months) or Walker (5+ months) ▪ All of these infants had experience of navigating around their enviroment either by crawling, using a walker or both. o Ps heard ‘look over there’ + pointing to a toy and measured where the infant looked. o Results; ▪ Prelocomotor infants were more likely to look at the experimenter than the target. ▪ As the walking ability experience increase, infants were more likely to look at the target and less likely to look at the experimenter.

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Children who were more mobile they were more inclined to look toward the correct target area suggesting that they were likely to gage in joint attention. Mobile behaviour can thus lead to this social behaviour of joint attention

⚫ Locomotion: cross-cultural; Tao & Dong 1997, doctoral thesis (see Campos et al. 2000)

o Infants in urban China: onset of locomotion approx. 3 months later than Western norms (Bayley, 1969). ▪ this is because of traditional practice: kept swaddled on a bed, think warm clothing, crawling discouraged for cleanliness. o Expt 1: 90 Chinese infants, 8-11 months ▪ Crawlers (5+ weeks) took significantly fewer trials to look to the correct direction than prelocomotors and ≤ 3 week experienced crawlers ▪ Effect of crawling experience still significant after controlling for age o Expt 2: Limited locomotor experience vs. allowed to crawl on floor of flat (equivalent ages) ▪ Floor crawlers turned to correct direction on significantly more trials than infants with limited locomotor experience. o These findings are consistent with that the ability to navigate around the world allow you to gage in social interactions. Summary: ⚫ Theories of motor development have evolved significantly over the last 150 years or so ⚫ The maturational account has been very influential and leaves a lasting legacy of standardised testing and developmental norms but is now generally recognised as outdated and flawed because it doesn’t take account of multiple, interacting influences on motor development ⚫ In turn, locomotor experience is closely connected to development in many other domains...