Overview • What is motor development • Theories & Examples • Action and Perception • An exercise • What is the link?
What is motor development? A stagelike progressions that transform babies from being unable even to lift their heads to being able to grab things off the supermarket shelves, chase the dog, and become active participants in family social life (Thelen, 1995)
Studying motor development as key to understand infants’ social cognition
Thelen: The developmental questions are not what abilities or core knowledge infants and children really "have" or what parts of their behaviour are genetic or culturally constructed but how the parts cooperate to produce stability or engender change
Movements as action Properties of movements as actions: • is visible and perceivable • Prospectivity: action is forward-looking • Fundamentally dynamic and time dependent • is embodied and situated in the environment • Presents invariants
Motor development is visible and perceivable by others and Self • Movement is a pervasive feature of infants development • New motor skills are the most dramatic and observable changes in an infant's first year
Infants make experience of the world ONLY because they are able to explore it by moving! • The content of children’s thoughts, perceptions, emotions, intentions can be understood from overt motor behaviours • Necessary to discover own body-boundaries and movements in space and time (sense of agency)
Theories of Motor Development • Gesell & Thompson, 1938: emerging motor skills reflect regularities in brain maturation, a genetically driven process common to all infants • Bernstein, 1967:movements are always a product of not only the central nervous system but also of the biomechanical and energetic properties of the body, the environmental support, and the specific demands of the particular task
Two models for motor development • Dynamic Systems Theory: focuses on the formal structure of movements with the aim of building a unified theory of development (Thelen, Corbetta) • Ecological approach: emphasizes the functional links between perception and motor actions in an effort to understand the psychological underpinnings of motor development (Gibson)
Dynamic System Theory • Challenges the idea that developmental changes are driven by some factor or set of factors, located in the environment, the brain, or the genes. All these factors are equally important • motor development may result from the spontaneous self-organization of the various components in the body (e.g., Thelen & Smith, 1994)
Possibilities for action depend on the size, shape, mass, compliance, strength, flexibility, and coordination of the various body parts. • biomechanical constraints on action • Multi-causality of action, including the physical, energetic, and physiological components • The same functional outcome can require very different motor actions depending on the body’s status
An example: Walking • Starts early as stepping reflex Requires: • Acquisition of locomotion involves an initial decrement in performance. • Acquisition of sufficient arm strength to push up and keep balance with legs • Practicing of new balancing act, sometimes rocking back and forth rhythmically
Stepping reflex https://www.youtube.com/watch?v=CkGjOwPXsvo
Pre- walking: newborn stepping reflex • Newborn infants, when held upright with their feet on a support surface, perform alternating, step-like movements. • Very well-coordinated patterns at an age when infants are motorically immature • Within a few months, these movements "disappear” Infants do not step again until late in the first year, when they intentionally step prior to walking.
Walking is a transition • Developmental transition from expert, controlled quadruped to novice, falling-down crawler requires infants to give up developmental stability for variability and poor performance.
When finally acquire sufficient strength and control to maintain balance in an upright standing position, they experience an initial decrement in performance when they take their first walking steps a few weeks later
Walkers must deliberately induce disequilibrium to shift the body weight onto one foot and to produce the propulsive forces necessary to move the body forward (Breniere & Do, 1991)
Observe and describe • Is the infants’ walk smooth or uneven, and why? • What happen to the body balance? Does it change? • Is the walking quality influenced by external factors?
Action and Perception “We must perceive in order to move, but we must also move in order to perceive” Gibson, 1979
Motor development is a perception-action system • Meaningful actions are always goal directed • Infants achieve their goals by detecting and adapting to changes in surrounding environments
Motor development is a perception-action system • Meaningful actions are always goal directed • Infants achieve their goals by detecting and adapting to changes in their surrounding environments • Flexibility and Specificity in learning to detect affordances for action
Affordances • J.G. Gibson, 1979 “The Ecological Approach to Visual Perception” “The affordances of the environment are what it offers to the animal, what it provides or furnishes, either for good or ill. (…) It implies the complementarity of the animal and the environment.” • Unique for that animal /organism and environment
Relational nature: characterizes the suitability of the environment to the observer, and so, depends on their current intentions and their capabilities
The same aspect of the environment can provide different affordances to different people, and even to the same individual at another point in time.
A key aspect: flexibility Example: Infants’ learning to traverse slopes (Adolph, 1997) • New walkers do not immediately perceive the slope as something to walk on • 2 groups of children: control and frequent exposure (lab) • Experience helps new learning: how to cope with the slope in both groups • Experience in normal daily circumstances provided something transferable to the unusual slopes encountered in the laboratory
Flexibility Flexibility as a strategy for exploratory search and knowledge of when to use any skills already possessed Behaviours TASKS FUNCTIONAL UNITS STRATEGIES SUBSKIILLS
As small differences are encountered new sub-skills are learned • alertness in watching for information about surface properties, • slower steps on slopes • using arms protectively
Perception • specifies the current status of the body and the environment in which it is embedded, giving infants access to the current constraints on action (Gibson, 1979). • allows actions to be planned prospectively and links action to the environment
Fundamental for action? YES • Through perceptual information infants can • guide their movements prospectively and adaptively (von Hofsten, 2003, 2004) • Explore and discover the world! • Possibilities for action depend on the fit between actors’ bodies and the perceived surrounding environmental properties (E. J. Gibson, 1982; J. J. Gibson, 1979)
Moving is perceiving • The coupling between action an perception is high-wired and morphologically pre-structured in the human brain since birth (von Hofsten, 2007) • Motor actions complete the perception-action loop by generating information for perceptual systems • Linking the appropriate sensory apparatus to the available information
Prospectivity • To move requires perceiving the environment, and predicting the possible outcomes, constrains, trajectories, obstacles (Gibson 1994; 1997) • Capacity to perceive what will happen ahead of time and to have prospective control, the ability to guide actions in the future • Action is intimately connected to its environment, and is non static, but rather perspective Adolph & Berger, 2006; Smitsman & Corbetta, 2010
Motor development and experience • Experience of different positions, environments, constrains shapes action capabilities, brain plasticity and growth (Corbetta, Thelen, & Johnson, 2000). • Action experience influences perception of own and others’ movements (Sommerville et al., 2005; Thelen & al., 2001) • early perception of self-movements leads to later, more coordinated movements • Indirect experience (action observation and imitation) fundamental in developing capacity of perceiving and discerning intentions in dynamic human actions (Baldwin & Baird, 2001)
Environmental constrains for action To bring their hands to their mouths at 7 weeks after conception, fetuses must raise their arms at the shoulder because their arm very short (Moore & Persaud, 1993). To produce the same hand-to mouth action several weeks later, fetuses must deeply bend their arms at the shoulder and elbow because their arms are much longer.
Exploratory movements • are prompted by the perception or interest towards someone/something • provide the perceptual basis for guiding actions (moving is perceiving NEW things!) • The case of grasping and reaching
Grasping and reaching • Moving one part of the body to look or reach for creates disequilibrium by displacing the location of the entire body’s centre of gravity. • Prospective control over the components of looking and prehension is need • and develop asynchronously