2. Motor Control Theory Chapter 5 – slide set 3

3. Um, what about humans? We’re far from equilibrium all the time We metabolize food, produce energy, eliminate waste, exchange O 2 and CO 2, pass on strategies for survival, learn language, etc... This encourages self-organization (according to this theoretical view) Learning in this sense involves the de- stabilization of one pattern so that a new pattern of stability may be found

4. Systems far from equilibrium Implications of being far from equilibrium 2 nd Law of non-equilibrium thermodynamics Entropy – any closed system is always attracted to maximum entropy (and when here it is stable) The system goes from a state where there is maximum energy exchange (low entropy), to one where there is none (high entropy) - equilibrium

5. Systems far from equilibrium Modeling progress from low to high entropy high entropy is an attractor for closed systems When systems are open, and far from equilibrium, they can exchange energy (dissipate it), allowing a range of behaviors from the system’s parts V A potential energy (V) function Current state of the system Potential energy minimal value – maximum entropy

6. Pattern formation in systems far from equilibrium conditions When a system is pushed far from equilibrium, in seeking stability, it adopts certain patterns which are “locally stable” The water in the pan, when heated, adopted a different pattern – hexagons, then turbulence Heat was a control parameter An outside variable that can push the complex system into different behaviors There is also an order parameter The macroscopic description of the emergent behavior pattern (e.g. hexagons, turbulence)

7. Pattern formation in systems far from equilibrium conditions The order parameter... The macroscopic description of the emergent behavior pattern (e.g. hexagons, turbulence) Behavior patterns are expressed by order parameters It represents some relationship among the component parts of the system The relationship changes when the control parameter alters so that the order parameter loses stability The pattern always fluctuates due to oscillation of parts When the fluctuation reaches a critical point, order is lost and a new pattern may emerge

8. Pattern formation in systems far from equilibrium conditions Applying order and control parameters to human movement Haken (1988) suggested that order and control parameters would change across types of complex system, but that research within each field should attempt to uncover parameters particular to the field Kelso (e.g. 1997) and others have taken this charge on within the field of human movement

9. Application & a change in thinking… Motor development Infants have a step reflex Why? What’s the function of the reflex? Traditional ways of thinking differed quite markedly from ecological approaches…

10. Application & a change in thinking… Arnold Gesell: Development as rule-based progressions: “The morphogenesis of human behavior…is subject to lawful sequences which normally are never circumvented. The motor control of the eyes precedes that of the fingers; head balance precedes body balance…”[Gesell and Amatruda, 1945 #1563], p. 162. Myrtle McGraw: A neuro-maturational approach Attributed development to the maturation of the cerebral cortex Cortical inhibition theory increased cortical control results from the inhibition of early reflex patterns

11. Application & a change in thinking… An example of emergent patterns from motor development Stepping/Walking 0-2 months Stepping a stable behavior 3-4 months Stepping disappears Why? Where might you look if you believed in constraints and affordances? How might you examine this?

12. Application & a change in thinking… An example of emergent patterns from motor development What causes this loss of stability? How might you regain it? 1 month3 months And how else might you lose it?

13. Application & a change in thinking… See anything that changes? New born 3 months

14. Application & a change in thinking… An example of emergent patterns from motor development What causes this loss of stability? How might you regain it? 1 month3 months And how else might you lose it? “As predicted, our wet and slippery subjects all stepped like crazy. Before then, no one had thought about what the nervous system was moving—a pair of big, fat legs!” (Esther Thelen, quoted on IU web page).