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. Understanding Motor Skills Three Anatomical Planes: Flexion — Extension — Abduction — A movement of a segment of the body causing a decrease in the angle of the joint A movement in the opposite direction of flexion which causes an increase in the angle at the joint A movement of a body segment in the lateral (frontal) plane away from the midline of the body Terms to Describe Body Movements Frontal, Sagittal, Transverse

3. Understanding Motor Skills Terms to Describe Body Movements Adduction — A movement of a body segment toward the midline as when moving the arm from the outward horizontal position downward to the vertical position. Rotation — Circumduction — A movement of a segment around its own longitudinal axis A circular or cone-like movement of a body segment

4. Understanding Motor Skills 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

5. Understanding Motor Skills 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 Types of Responses

6. Understanding Motor Skills 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

7. Understanding Motor Skills 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 Sensory Feedback

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

9. Understanding Motor Skills Speed of Movements Total Response Time Reaction 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 = +

10. Understanding Motor Skills Reaction Time - under ideal conditions, simple reaction time is between 150 - 200 msec Influences on reaction time : stimulus modality stimulus detectability preparedness or expectancy of a signal age spatial frequency stimulus location

11. Understanding Motor Skills Choice reaction time this is an issue when one of several possible stimuli are presented, each of which requires a different response. Some influences on choice reaction time : Reaction Time compatibility between stimuli and responses practice warning type of movement more than one stimulus Reaction Time

12. Understanding Motor Skills Movement Time Direction of Movement 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

13. Understanding Motor Skills Fitt’s Law holds for : movements of the head movements of the feet movements of the fingers and more MT = a + b log 2 (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 Movement Time

14. Understanding Motor Skills 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)

15. Understanding Motor Skills Exercise “I saw her friend Jane today” (1) Write the sentence 10 times with your preferred hand (2) Write the sentence holding the pen in your RIGHT HAND in your LEFT HAND in your MOUTH What can you learn from this experiment?