1. Understanding Motor Skills
Introduction
Focus:
Response mechanism of the human body as the output of information processing
“input—mediation—output”
Knowledge bases from:
Biomechanics
Kinesiology
Psychology
Neuroscience

2. Control & Acquisition of Motor Responses
Skill - the ability to use the correct muscles with the exact force necessary to perform the desired response with proper sequence and timing (Jensen, Schultz, and Bangerter, 1983)
Three Aspects:
spatial-temporal precision
“doing the right thing at the right time”
adaptability to changing
environmental conditions
consistency of action from occasion to occasion

3. Types of Responses Discrete Movements — Repetitive Movements —
Sequential Movements—
involving a single reaching movement
to a stationary target; may or may not be visually guided
involving a repetition of a single
movement to a stationary target(s)
involving discrete movements to a
number of stationary targets regularly
or irregularly spaced

4. Continuous movements —
Types of Responses
Continuous movements —
Static positioning —
involving movements that require
muscular control adjustments of some
degree during the movement
consisting of maintaining a specific
position of a body member for a period
of time

5. Sensory Feedback
motor responses can be influenced by both internal and external feedback
Close-loop servocontrol model
feedback — ( high impact )
feedforward —
sensory information that is available
during or after the motor response
sensory info that is available prior
to the action that regulates and
triggers coordinated responses

6. Sources of feedback Sensory Feedback Kinesthesis (proprioception)
Receptors:
Muscle spindle for muscle length and rate of change
Golgi tendon organ for muscle force
Vision
Sound

7. = + Speed of Movements Total Response Time Reaction time Movement time
—>the time from onset
of a signal calling for
a response until the
beginning of the
response +
Movement time
—>the time from the
beginning of the response
until its completion

8. Reaction Time
- under ideal conditions, simple reaction time is between msec
Influences on reaction time :
stimulus modality
stimulus detectability
preparedness or expectancy of a signal
age
spatial frequency
stimulus location

9. Movement Time Direction of Movement Distance and Accuracy Required
this affects the time to make the movement
controlled arm movements that are primarily based on a pivoting of the elbow take less time than those that require a greater degree of upper-arm and shoulder action
Distance and Accuracy Required
Fitt’s Law

10. Fitt’s Law Fitt’s Law holds for : Movement Time MT = a + b log2 (2D/W)
where :
MT = movement time
a,b = empirically derived constants,
movement type dependent
D = distance of mvmt from start to target center
W = width of target
Fitt’s Law holds for :
movements of the head
movements of the feet
movements of the fingers
and more

11. Accuracy of Movements
Often accuracy of a response is of greater importance than the response time, within limits
—Location
close-in, straight-ahead, below- shoulder positions reduce error (Fig. 9-11)
—Distance
overshooting short distance and undershooting long distance
(Fig. 9-12)
—Speed of Movement
Schmidt’s Law: W = a+b(D/MT)