Motor Control Theory Chapter 5 – slide set 3 Um, what about humans? We’re far from equilibrium all the time We metabolize food, produce energy, eliminate.
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Slide 1
Slide 2
Motor Control Theory Chapter 5 slide set 3
Slide 3
Um, what about humans? Were 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
Slide 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
Slide 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
systems parts V A potential energy (V) function Current state of
the system Potential energy minimal value maximum entropy
Slide 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)
Slide 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
Slide 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
Slide 9
Application & a change in thinking Motor development
Infants have a step reflex Why? Whats the function of the reflex?
Traditional ways of thinking differed quite markedly from
ecological approaches
Slide 10
Application & a change in thinking Arnold Gesell:
Development as rule-based progressions: The morphogenesis of human
behavioris 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
Slide 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?
Slide 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?
Slide 13
Application & a change in thinking See anything that
changes? New born 3 months
Slide 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 movinga pair of big, fat legs! (Esther Thelen, quoted on
IU web page).