Kin 312-Scientific Measurement and Motor Control

2 general categories of measuring motor performance

1) performance outcome measures
2) performance production measures

performance outcome measures

measures the result/outcome of a skill
ex: distance thrown, speed, reaction time

performance production measures

inform us about how the nervous system, muscular system, and limbs are acting to produce the performance outcome
ex: EEG, EMG, force, limb kinematics

types of performance outcome measures

-reaction time (RT)
-movement time (MT)
-response time

reaction time (RT)

indicates how long it takes to prepare and initiate movement

movement time (MT)

the interval of time between the initiation of a movement and the completion of the movement

response time

the time interval involving both reaction time and movement time; the time from the onset of a signal to the completion of a response
-aka: RT + MT

types of reaction time

-simple reaction time
-choice reaction time
-discrimination reaction time
-fractionated reaction time

simple reaction time

the reaction time that involves 1 signal/stimulus and 1 response

choice reaction time

the reaction time that involves more than one signal & each signal requires its own specified response

discrimination reaction time

the reaction time that involves more than one signal but only one response--which is to only one of the signals--the other signals require no response

reaction time related to movement and response time

-reaction time does NOT predict movement
-movement time does NOT predict reaction time
-RT and MT are SEPARATE motor abilities
-when comparing individuals, they may have differing rates of both RT and MT

fractionated reaction time (FRT)

-requires the use of EMG to partition into 2 parts:
1) premotor time (PRMOT)
2) motor time (MOT)
-allow researchers to identify if changes in movement RT are due to cognitive processes or mechanical features of the limb(s)

premotor time (PRMOT)

time that elapses between the presentation of a stimulus and the first change in EMG(muscle) activity

motor time (MOT)

begins with 1st change in EMG activity and ends when movement begins

error measures for 1 dimensional actions

absolute error
constant error
variable error

absolute error

a measure of error without regard to direction
ex: distance from target

constant error

signed deviation from the target (biases)
ex: directional biases (given + or - )

variable error

an error score that represents the variability of performance consistency
-standard deviation of a series of constant error scores

error measures for 2 dimensional actions

radial error
root-mean-squared error (RMSE)

radial error

use the pythagorean theory to solve

root-mean-squared error (RMSE)

-error measure for continuous skills
-indicates the amount of error between the performance curve produced and the criterion performance curve for a specific amount of time
-ex: tracking

kinematic measures

-kinematics: the description of motion without regard to force or mass; displacement

-displacement: describes changes in spatial location as a person carries out a movement

-velocity: rate of change in an object position with respect to time

-acceleration: change in velocity during movement

kinetic measures

-kinetics: force as the cause of motion
-measuring tools: force plate, strain gauge

EMG

(electromyography)
-measures electrical activity in muscles

EEG

(electroencephalography)
-measures brain activity

PET

(position emission tomography)
-used for measuring the concentration of positron-emitting radioisotopes within different body tissues

fMRI

(functional magnetic resonance imaging)
-visualizes brain function through change in fluid flow (cerebrospinal fluid, blood)

lesions

remove portion of brain matter to see its effect on function (performed on lab animals or people with lesions already such as stroke victims)