1. The Measurement of Motor Performance
Chapter 2
The Measurement of
Motor Performance

2. Measuring Motor Skill Performance
Performance outcome measures
Category of motor skill performance that indicates the outcome or result of performing a motor skill (i.e., how far did they throw the ball?)
Does not tell us about the behavior of the limbs or body that led to the outcome
Does not provide information about the activity of various muscles involved

3. Measuring Motor Skill Performance, cont’d
Performance outcome measures
Category of motor skill performance that indicates the performance of specific aspects of the motor control system during the performance (i.e., EEG readings)
Additional categories do exist, however, these two represent the motor skill performance measures found in the text

4. Reaction Time
Common measure indicating how long it takes a person to prepare and initiate a movement
The stimulus or go signal is the indication to act

5. Reaction Time, cont’d Types of RT situations
Simple RT: one signal and one response
Choice RT: more than one signal, each signal has a specific response
Discrimination RT: more than one signal, only one response

6. RT Interval Components
EMG enables one to fractionate RT
Fractionate RT has two components
Pre-motor: quiet interval of time between the onset of stimulus and beginning of activity
Motor time: period from the increase in muscle activity until the actual limb movement

7. Pre-Motor and Motor RT
Pre-motor RT
Motor RT
Signal
Movement
EMG

8. Use of RT in Research
RT has a long history as a measuring tool for human performance
It is used as a basis for inferring what a performer does
Identifies the environmental context information a person may use while preparing for action
Assess the capabilities of a person to anticipate a required action and determine when to initiate it

9. Relationship of RT to Movement Time and Response Time
Warning
Signal Go
Signal
Initiation of response
Termination of the response
Foreperiod
Reaction Time
Movement time
Response Time

10. Error Measures
Error measures allow us to evaluate performance for skills for which accuracy is the action goal

11. Assessing Error for One-Dimension Action Goals
We can calculate three error measures to assess the general accuracy characteristics of performance over repeated performances
Absolute error: absolute difference between the actual performance on each trial and the goal. Provides a general index of accuracy

12. Assessing Error for One-Dimension Action Goals, cont’d
(three error measures, cont’d)
Constant error: index of the person’s tendency to be directionally biased when performing the skill
Variable error: measures performance consistency by calculating the standard deviation of the CE scores

13. Assessing Error for Two-Dimension Action Goals
When the outcome of performing a skill requires accuracy in the vertical and horizontal directions
Radial error measures general accuracy for the two-dimension situation
Performance bias and consistency are difficult to assess than the one-dimension

14. Assessing Errors for Continuous Skills
Continuous skills require accuracy
Common error score for continuous skills is the Root-mean-Squared error (RMSE)
An example of performing this continuous skill is pursuit tracking

15. Kinematic Measures
Kinematics: description of motion without regard to force or mass
Includes the following:
Displacement (spatial position of a limb or joint over a period of time)
Velocity (rate of change in an object position with respect to time)
Acceleration (change in velocity during movement)
Linear and angular motion (motion in a straight line or motion along the axis of rotation)

16. Kinetics vs. Kinematics
Kinetics refers to the study of the role of force as a cause of motion
Kinematics refers to descriptors of motion without concern for the cause of that motion
Human movements involve both external and internal sources of force

17. Kinetics vs. Kinematics, cont’d
All three of Newton’s laws of motion refer to force
The effect of a force on rotation is known as joint torque (rotary force)

18. EMG Measures
Movement involving electrical activity in the muscles
Electrodes detect muscle activity
Recordings can indicate when a muscle begins and ends activation

19. Measuring Coordination
Measures complex skills
The use of computer-based technology has furthered research involving complex skills

20. The Measurement of Motor Performance
Chapter 2
The Measurement of Motor Performance