Behavioral Theories of Motor Control

1. Behavioral Theories of Motor Control Chapter 3

2. Overview • Now that we’ve looked at response preparation, what happens during the response programming stage?

3. Early Motor Program Theories • Proposed that for each movement to be made, a separate motor program existed and was stored in memory • Two problems: • Storage: Hard drive (brain) could run out of space • Novel responses: How do you respond to an action never done before?

4. Command Center • Decision> appropriate plan retrieved from memory> instructions to rest of body for action

5. Open Loop Systems • Open loop • Action plans generated by command center then carried out by the limbs and muscles without modification Action Command Center Mechanical Example:Sending Email

6. Closed Loop Systems • Closed loop • Command center generates action plan that initiates the movement • Feedback is used to modify on-going action Action Command Center Feedback Mechanical Example: Thermostat

7. Slow Vs. Rapid Movements • Motor control uses both open and closed loop systems • Movements are planned in advance, initiated & executed with little modification (remember the fake in PRP?) • If a rapid movement, feedback will be used for the next attempt • For slower movements, open loop begins the movement and closed loop will continue to completion

8. Problem: • How does a person do a novel motor skill? • Motor Program • Abstract representation of a movement plan • Stored in memory • Issues instructions that are carried out by the limbs and muscles

9. Generalized Motor Program (GMP) • Represents a class of actions or pattern of movement that can be modified to yield various response outcomes • Invariant features • Relatively fixed underlying features that define a GMP • Parameters • Flexible features that define how to execute a GMP

10. Fixed vs. Flexible Features • Write your name with the following: • Your dominant hand • Your non-dominant hand • Pen in your mouth • Pressing very hard • Pressing very soft • Write quickly, then slowly • Which aspects were fixed? Flexible?

11. Invariant Features • Relatively fixed underlying features • Sequence of actions or components • Relative timing • Internal rhythm of the skill : the amount of time to write each letter of your name will stay the same whether writing fast or slow • Relative force • Internal force relationship: The amount of force given to write each letter stays proportionally the same whether pressing hard or soft

12. Parameters • Adaptable features of program • Easily modified from one performance to another to produce variations of a motor response • Overall duration: Fast or slow • Overall force: Hard or soft • Muscle selection: Writing with hand or foot?

13. Review Question • When swimmers use hand paddles or when baseball hitters swing heavier bats, does this manipulate invariant features or parameter features? • When might such an action hinder the development of correct technique? • What signs would you look for to avoid this problem?

14. Schema • Rule or relationship that directs decision-making when a learner is faced with a movement problem • Developed by abstracting 4 sources of information for each performance attempt • Initial conditions present at start of movement • Response specifications: parameters used in the execution of the movement • Sensory consequences: what did the action feel like? • Response outcome: how successful was the response?

15. Schema Development • For each movement attempt the four sources of information are stored in memory briefly • Feedback from the attempt verifies • How successful was the performance? • Do I need to change the movement? • With each additional attempt, the strength of the schema increases when you compare one attempt to the next

16. Motor Response Schema • Recall schema • Responsible for organizing the motor program • What do I need to do?>What conditions exist?>What parameters & invariant features are required?>Execute the response • Recognition schema • Responsible for the evaluation of a movement attempt : Was the movement correct? • Error signal updates the recall schema

17. Dynamic System Theory • Movement pattern is thought to emerge or self-organize as a function of the ever-changing constraints placed upon it

18. Constraints • Defined as the boundaries that limit the movement capabilities of an individual • Three types • Organismic: structural or functional • Body type, wt, ht • Psychological, cognitive, emotional • Environmental:wind, light, flat surface, grassy • Task

19. Task Constraints • The goal of task: a certain movement • Rules that may limit the movement • One must serve the tennis ball within an area on the baseline • Implements or machines • Using a walker, using weight machines, using a ball

20. Attractor States • Systems prefer states of stability • When a change in constraints is imposed on a system, its stability is endangered • Deep basins = stable systems = difficult to change • Shallow basins = less stable = more susceptible to change

21. Phase Shifts • Changes in behavior are the result of a series of shifts • Control parameters • Variables that move the system into new attractor states: gaining leg strength to perform a skill better • Rate limiters • Constraints that function to hinder or hold back the ability of a system to change :Adult learner, fear

22. So what happens when a skill performance needs to change? • Practice strategies need to create instability in a deep attractor basin • As the skill moves through the phase shift, it will become a combination of the old and new ways • At some point it will be neither the old or new and performance effectiveness is reduced • Eventually through practice, a new attractor state is formed, and eventually a new deep basin

23. Key Point • Movement patterns prefer state of stability • New movements self-organize and emerge with phase shifts where attractors stabilize and destabilize as a function of the control parameters

24. Practical Application • Explain how orthotics function from a dynamic system perspective

25. Exit Slip • How do the recall and recognition schema work together? • How are phase shifts indicative of behavioral change?