1. Motor Control Theories
Chapter 5
Motor Control Theories
Concept: Theories about how we control coordinated movement differ in terms of the roles of central and environmental features of a control system
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2. Theory and Professional Practice
What is a theory?
__________________________________________
______________________________________________________________________________________(Hawking, 1996)
Motor learning and control theories focus on:
_________________________________________
Providing explanations about why people perform skills as they do
How does a theory have relevance to professional practice?
[See Figure 5.1]
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Motor Control Theory
Describes and explains how the _________________ produces coordinated movement during _______________________________in a variety of environments
Two important terms:
___________________________
___________________________________
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4. ___________________________
________________________________________________________________________________________________________________________________ (Turvey, 1990)
Two parts to consider:
Movement pattern of a skill in relationship at a specific point of time
Context of the environment of the head, body, and/or limb movements so the actions can be accomplished
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5. _________________________________
_____________________________= Number of independent elements in a system and the ways each element can act
Degrees of freedom problem = ______________________________________________________________________________
e.g. The control of a helicopter’s flight (described in the textbook)
Degree of freedom problem for the control of movement:
How does the nervous system control the many df of muscles, limbs, and joints to enable a person to perform an action as intended?
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6. Two General Types of Control Systems
___________________________________________
[See Figure 5.3]
Incorporated into all theories of motor control
Models of basic descriptions to show different ways the CNS and PNS initiate and control action
________________________________________
Function to generate and forward movement instructions to effectors (i.e., muscles)
________________________________________________________________________________
Content of the instructions differs between systems
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7. Differences Between the Systems
Two differences
Open-Loop
__________________________________
_____________________________________________________________________________________
Does not use feedback to continue and terminate movement
Closed-Loop
________________
________________________________________________________________________________
Relies on feedback to continue and terminate movement
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8. Two Theories of Motor Control
______________________________:Memory-based mechanism that controls coordinated movement
_____________________________________________________________:Describes and explains coordinated movement control by emphasizing the role of information in the environment and mechanical properties of the body and limbs
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9. __________________________________________________________________
Best example comes from “Schema Theory” by Schmidt (1988)
________________________________: Hypothesized memory-based mechanism responsible for adaptive and flexible qualities of human movement
Proposed that each GMP controls _________________________, which are identified by common invariant characteristics
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10. Motor Program-Based Theory, cont’d
GMP Function
_____________________________________________________________________________________________________________________________________
GMP Characteristics
______________________________
Characteristics of the GMP that do not vary across performances of a skill within class of actions
The identifying signature of a GMP
________________________
Specific movement features added to invariant features to enable skill performance in a specific situation
________________________________________________________________________________________
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11. Motor Program-Based Theory, cont’d
Invariant features and parameters
Example of an invariant feature
_______________________________________________________________________________________
Example of a parameter
___________________________________________a skill
An Analogy from Music and Dance
Relative time = Rhythm (beat) of the music, (e.g. The 3 beats to a measure for a waltz)
Overall time = Tempo (The speed at which you waltz)
Regardless of how fast or slow you waltz, the rhythm remains the same (i.e. invariant)
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12. Motor Program-Based Theory: _____________________________________
Experiment by Shapiro et al. (1981)
Used gait characteristics to test prediction of ______________________for a class of actions controlled by a GMP:
Are walking and running one or two classes of action?
__________________________________________
Calculated relative time for each component at 9 speeds (3 – 12 km/hr)
_____________________________________________________________________
Results: Relative time similar within speeds when walking but different from speeds when running (similar within speeds when running)
[See Figure 5.5]
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13. _________________________________(a.k.a., Dynamical Systems)
Describes the control of coordinated movement by emphasizing the role of environmental information and dynamic properties of the body/limbs
Began to influence views about motor control in early 1980’s
Views the process of human motor control as a complex system that behaves like any complex biological or physical system
Concerned with identifying laws (natural and physical) that govern changes in human coordination patterns
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14. Dynamic Pattern Theory Concepts
Motor control system operates on the basis of _____________________:
Behavioral changes are not always continuous, ________________________________________________________________
Behaviors specified by environmental and task characteristics/conditions
________________________________
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15. Dynamic Pattern Theory Concepts: Attractors
___________________ – A stable state of the motor control system that leads to behavior according to preferred coordination patterns (e.g. walking)
Characteristics of an attractor:
_________________________(e.g., relative phase)
Control parameters (e.g., speed) influence order parameters
Minimum trial-to-trial performance variability
_________________ – Retains present state despite perturbation
_____________________________
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Dynamic Pattern Theory Concepts: ______________________________________
Order parameters
Also called collective variables
_______________________________________________________________________
Enable a coordinated pattern of movement that can be reproduced and distinguished from other patterns
_________________is the most prominent of order parameters which represents the ________________________________________________________________________ (see chapter 2)
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17. Order and Control Parameters, cont’d
______________________________
A variable, when increased or decreased, will influence the stability and character of the order parameter
_____________________________________________________________________________________________________________________________
Provides the basis for determining attractor states for patterns of limb movement
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18. Dynamic Pattern Theory Concepts: Self-Organization
____________________________
______________________________________________________________________________________________
This pattern of movement self-organizes within the characteristic of environmental conditions and limb dynamics
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19. Attractors and Self-Organization for Movement Coordination
Gait Transitions
Research (to be discussed more in ch. 7) shows that if a person begins walking on treadmill at slow speed
Treadmill speed increases every few minutes
Person begins to run at a certain speed [not same speed for all people]
Same effect if person begins running on treadmill - Begins to walk at certain speed
Swim Stroke Transitions
Research in France (2004)
14 elite male swimmers
Each trial involved a swim velocity increase [began at preferred velocity]
Arm-stroke analysis showed 2 distinct arm movement coordination modes
Began in one mode but abruptly began 2nd mode at a specific swim velocity
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20. Attractors and Self-Organization for Movement Coordination, cont’d
Discuss how the two research examples on the previous slide demonstrate the dynamic pattern theory concepts of:
Self-organization
Control parameter
Attractors (i.e., stable coordination states)
Non-linear behavior change
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Dynamic Pattern Theory Concepts: Coordinative Structures (__________________________________________)
___________________(i.e. cooperative groups) of muscles and joints that act cooperatively to produce an action
If a perturbation stops one set of muscles from working, another works in its place
e.g. walking with a leg in a cast
Develop through practice, experience, or naturally
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Dynamic Pattern Theory Concepts: ______________________________________
__________________________________________________________________________________
The ______________________________
The detection of critical invariant information in the environment
The movement that becomes associated with what is specified by the environmental information
An example
When walking, the time to contact an object in your pathway (specified by the perception of the changing size of the object) determines when you initiate stepping over the object
i.e. Your stepping action is “coupled” with your visual perception of the object
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23. Present State of the Control Theory Issue
Currently, both the motor program-based theory and dynamic pattern theory predominate
Research investigating each has shown that a theory of motor control cannot focus exclusively on movement information specified by the CNS
Task and environmental characteristics must be also be taken into account
Speculation exists that a hybrid of the two theories as a compromise theory could emerge to explain the control of coordinated movement
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