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Motor Learning and Control
• Defining learning and control
• Measurement Schemes
• Open vs. Closed loop control
• Stages of Learning
• The role of practice– Amount– Composition – Scheduling
Motor Control
Understanding the execution of the events (physiological or behavorial/psychological description) that lead to skilled human movement
• How do we control how much force we produce ?
• What aspects of a movement are remembered to help recall a movement ?
Motor Control: Questions
# of motor units rate coding
spatial location effector used Psychological level
Physiological level
Motor Learning
involves changes in the execution of the events (physiological or behavioral/ psychological description) that lead to improvements (skilled) human movement
• Can we become more efficient in the way we produce force?
Can we recruit motor units differently with practice?
Can we use different frequency to recruit units?
Do we change the manner in which we remember a movement ?
Do we use different information about movement to remember it change (spatial features of movement followed by motor features (flexion-extension)
Motor Learning: Questions
Motor Development
study of changes in human movement behavior across the lifespan and the influence of these changes on human motor performance (p. 238) –
We will get to this in a later section
Measuring Motor Control
• Latency Measurements– Reaction Time
• assessment of planning operations that contribute to organizing/planning a movement
– Movement Time• assessment of movement implementation
Measuring Motor Control
• Error Measures– Absolute Error
• absolute deviation from a target
– Constant Error• movement bias
– Variable Error• movement variability
Measuring Motor Control
• Movement Quality– Kinematics
– Kinetics
– Electromyography
Position, velocity, acceleration, jerk (see biomechanics)
Force, torque (see biomechanics)
Controlling Movement
• Open-Loop (memory-driven)movements are completely pre-planned and
subsequent feedback during the movement doesn’t change the nature of the plan (e.g., traffic lights)
Using Reaction Time to examine movement planning
Warning “GO” Initiation Termination
foreperiod RT MT
Sternberg’s (1969) planning model
Perception Decision Motor PlanI O
Reaction Time
Perception: SRT
F F F F FF E F F FF F F F FF F F F F
O O O O OO E O O OO O O O OO O O O O
YES NO YES NO
Plot reaction time for simple and complex perceptual cases
Perception in Real World
Decision-making: CRT
Decision-making: CRT
0
50
100
150
200
250
300
One Light Two Lights
RT
Choice impacted by Compatibility
Real World Compatibility Effects
Real World Compatibility Effects
Motor Plan: Movement Complexity
Say /ba/ when the circle changes color
Say /ba/ x 4 when circle changes color
Motor Plan: Movement Complexity
0
50
100
150
200
250
300
ba x 1 ba x 4
RT
RT in this case is time to start to say /ba/
Simplifying Movement Planning
• Using feedback or closed-loop processing
Closed-Loop Control: Evidence
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
150 250 350 450
Light Off
Light On
Keele and Posner (1968)Keele and Posner (1968)
Pro
port
ion o
f Targ
ets
mis
sed
Required Movement Time between Targets
Closed and Open-Loop Control
Perception Decision Motor PlanI O
Open
Closed
Fitts and Posner’s Stages of Learning
• Cognitive– high verbalization
• Associative– fine-tuning
• Autonomous– attention-free
Closed-loop
Open-loop
Distinguishing Performance from Learning
• Performance (or acquisition)
• Learning – retention of what is practiced– generalizibility of what is practiced
Transfer Paradigm
Acquisition Retention (transfer)
Importance of Practice: Anecdotal
• “It appears that the patient will require much more opportunity to practice if motor control is to improve” (Duncan, 1997).
• “Skill acquisition is impossible without practice” (Winstein, 1997).
• Practice is repetition without repetition (Bernstein, 1967).
• Practice problem-solving is more effective for learning than simply repeating the solution (Lee et al., 1994)
Importance of Practice
• Power law of practice: Practice Extent
• Composition and Scheduling of practice
Pre-practice considerations
• Pre-practice Considerations– motivation for learning– making the task seem important (rationale)– goal setting (see Fig 11.1 Schmidt & Lee)
• Verbal information (overused, Wulf & Weigelt, 1997)– perceptual presentations better than verbal
Verbal instructions can sometimes interfere (implicit learning)
DV:AmplitudeFrequency
IV:InstructionNo Instruction
Verbal instructions can sometimes interfere (implicit learning)
Change in RT with practice
Change in RT with practice
Power Law of Practice
• The power law of practice is a very general law in human cognition, and in particular in human learning. The higher the level of expertise and the time spent on the task, the more difficult it is to improve (principle of diminishing returns).
• Previous graphs reveal a typical example of data showing a power law (first graph). An interesting feature of the power law is that , when data are plotted by taking their logarithms, they are well fitted by a straight line. (second graph).
Can we make a practice trial more useful?
• Practice Composition– Practice Variability– Mental Practice– Part vs. Whole Practice
• Practice Scheduling– Practice Distribution– Contextual Interference
Practice Variability vs. Specificity
ACQ RET TRAN
Specificity AAAAAAAA A E
BBBBBBBBB B E
CCCCCCCCC C E
Variable AAABBBCCC ABC E
Practice Specificity or Variability?
Mental Practice
• Skill acquisition (?)
• Skill Maintenance (?)
• Arousal Regulation (√)
• Planning and event management (√)
• Stress Management (√)
Whole vs. Part Practice
• Nature of the Skill– task component interdependence
• Capability of Learner– beginners, low aptitude
• Organization of Parts– Segmentation (progressive part),
simplification, fractionation
Key for whole is Interdependence of Parts
Practice Distribution: Using Time
• How to best use 60 hours of training to maximize performance and learning? (e.g., 2-a-days)
1 hour
2 hour
1 Session 2 Session
12 weeks 6 weeks
6 weeks 3 weeks
Baddeley & Longman (1978)
Practice Schedule
# of hrs to learn keyboard
Number of hrs to type 80/min
1 hr / 1 session 34.9 55
1 hr / 2 session 43 75
2 hr / 1 session 43 67
2 hr / 2 session 49.7 80+
Correct # of Keystrokes as a function of practice distribution
Can this work with verbal material: Melton (1970)
Structuring Variability: Contextual Interference
ACQ RET TRAN
Specificity
AAAAAAAA A E
BBBBBBBBB B E
CCCCCCCCC C E
Variable 1
AAABBBCCC ABC E
Variable 2
ABCBCACAB ABC E
A practical Example : Badminton
Shea & Morgan (1979)
Contextual Interference: Applied Examples
• Baseball (Hall et al., 1994)
• Badminton (Goode & Magill, 1986; Lui, 1991)
• Volleyball (Bortoli et al., 1992)
• Pawlata Roll (Smith et al., 1995)
Motor Learning and Control
• Defining learning and control
• Measurement Schemes
• Open vs. Closed loop control
• Stages of Learning
• The role of practice– Amount– Composition – Scheduling