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Understanding Motor Skills

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. Terms to Describe Body Movements. Three Anatomical Planes:

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Understanding Motor Skills

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  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. Terms to Describe Body Movements • Three Anatomical Planes: • Flexion — • Extension — • Abduction — Frontal, Sagittal, Transverse 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

  3. 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. 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. 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

  6. 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. 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

  8. 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. 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. 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. Reaction Time Reaction Time • 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 : • compatibility between stimuli and • responses • practice • warning • type of movement • more than one stimulus

  12. 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. Movement Time Fitt’s Law • Fitt’s Law holds for : • movements of the head • movements of the feet • movements of the fingers • and more 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

  14. 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. 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?

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