Chapter 2

Chapter 2

The Measurement of

Motor Performance

Concept: The measurement of motor performance iscritical to understanding motor learning

Why Study the Measurement ofMotor Performance?

Performance measurement essential for:

____________________________

Measuring Motor SkillPerformance

Two General Categories of PerformanceMeasurements

1.Performance ____________ measures

•Category of motor skill performance thatindicates________________________________________________________________________(e.g. How far did a person throw the ball?)

•Does not tell us about the behavior of thelimbs or body that led to the outcome

•Does not provide information about theactivity of various muscles involved

Measuring Motor SkillPerformance, cont’d

2.Performance _______________measures

•Measures of motor skill performancethat indicate____________________________________________________________________________________________________________________________________

 e.g. EMG, EEG recordings

See Table 2.1 for examples ofmeasures in both categories

Reaction Time

Common measure indicating_______________________________________________________________________________________

A _____________ or go signal isthe indication to act

Events and Time Intervals ofRT and Movement Time

_____

______________________

____________________

_________

______________

__________________

__________

Time

Reaction Time, cont’d

Types of RT situations [See Figure 2.2]

•______________: One signal - Oneresponse

•______________: More than onesignal - Each signal has a specificresponse

•______________: More than onesignal - only one response

RT Interval Components

EMG enables us to fractionate RT toobtain more specific information aboutmovement preparation

Fractionated RT has two components

•_________________________: Quietinterval of time between the onset of stimulusand beginning of activity

•_________________________: Interval oftime from the initial increase in muscleactivity until the actual limb movement

* See diagram on next slide *

Fractionated RT

_______________

________________

________________________

_______________

__________________

EMG Recording

What do you think occurs in each RT component?What do you think occurs in each RT component?

Error Measures

Error measures allow us to evaluateperformance for skills that have spatial ortemporal accuracy action goals

What are some examples of skills for whichspatial or temporal accuracy determinesperformance success?

Assessing Error for Skills withOne-Dimension Accuracy Goals

Three error measures

1. ___________________________:Absolute value of difference betweenthe actual performance on each trial andthe criterion for each trial

•AE = |(performance – criterion)| / no. oftrials

•Provides a general index ofperformance accuracy

Assessing Error for One-DimensionAccuracy Goals, cont’d

2. ___________________:Algebraic valueof difference between the actualperformance on each trial and thecriterion for each trial

•CE = (performance – criterion) / no. oftrials

•Provides an index of a tendency for theperformance error to be directionally biased

3. __________________: The standarddeviation of the CE scores; an index ofperformance consistency (i.e.variability)

Assessing Error for One-DimensionAccuracy Goals, cont’d

See “A Closer Look” on p. 32 foran example of calculating AE, CE,and VE to determine the accuracycharacteristics of stride lengths forwalking

Assessing Error for Two-Dimension Accuracy Goals

When the outcome of performing a skillrequires accuracy in the____________________________ directions

•e.g. Golf putt

_____________________= General accuracymeasure for two-dimensions

•See Figure 2.4

_____________________ and___________are difficult to quantitativelyassess, although can do qualitative assessmenteasily

•See Fig. 2.5

Assessing Errors forContinuous Skills

Many continuous skills require________________________________________________________________

•e.g. Driving a car on a highway

________________________________Common accuracy measure forcontinuous skills

•See Fig. 2.6 for example of calculatingRMSE for a pursuit tracking task

Kinematic Measures

_________________: description of motionwithout regard to force or mass

Includes the following measures [see Fig. 2.7]:

•_______________=Spatial position of a limb orjoint over a period of time

•_______________ = Rate of change in an objectposition with respect to time (i.e. speed)

 = Displacement / Time

•_______________= Change in velocity duringmovement

 = Velocity / Time

Kinetics

__________: Force as a cause of motion

Human movements involve bothexternal and internal sources of force

Importance of force as a movementmeasure: All three Newton’s laws ofmotion refer to force

Force measurement:

•_______________

EMG Measures

__________________________________

Electrodes detect electrical activity

Electromyography (EMG) =____________________________________________________________________

•Common use is to determine when a musclebegins and ends activation [see Figure 2.10]

•Also – Recall our earlier discussion aboutuse of EMG for fractionated RT as an index ofmovement preparation

Brain Activity Measures

Researchers have adopted brain activitymeasures commonly used in hospitalsand clinics for diagnostic purposes

Three measures commonly reported inmotor learning and control research

•__________

Brain Activity Measures, cont’d

Electroencephalography (EEG):Measures electrical activity in brain

•_________________________________________________________________________

Positron Emission Topography (PET):Neuroimaging (i.e., brain scanning)technique that measures blood flow in thebrain

•_________________________________________________________________________

Brain Activity Measures, cont’d

Functional Magnetic Resonance Imaging(fMRI): Neuroimaging (i.e., brainscanning)_________________________________________________________________________________________________________

To see examples of PET, fMRI, and other brainscanning techniques, go to http://www.pbs.org/and type “brain scanning” in the Search box

Measuring Coordination

Assessment of the relationship ofmovement of limb-segments andjoints

Quantitative measurement of angle-angle diagrams

•______________________________

•______________________________[see Figure 2.11]