Presentation on theme: "Movement Planning. After 90 grueling minutes of regulation and 30 minutes of overtime, the score was tied: USA 0, China 0. The 1999 Woman’s Soccer World."— Presentation transcript:
After 90 grueling minutes of regulation and 30 minutes of overtime, the score was tied: USA 0, China 0. The 1999 Woman’s Soccer World Cup would be decided by penalty kicks. China shot first, they were up by 1. U.S. captain Overbek answered back. Next, China and the U.S. were equally successful, tying it up at 2-2. This brought up Ying. As her kick shot towards the left side of the goal, the U.S. goalkeeper, Briana Scurry, dove with outstretched arms, making an amazing save that sent the record crowd of 90,000 into a frenzy. The U.S. then went ahead 3-2 with the next kick. China’s Zhang beat scurry with the 4th penalty shot while Mia Hamm answered, putting the U.S. ahead once again. The final kicker for China put her shot far left of Scurry, tying the game at 4-4. The hopes of the U.S. team rested on the 5th and final kicker, Brandi Chastain. The packed stadium was silent as they watched her approach the ball. She drilled it off her left foot. The Chinese goalkeeper responded but she was too late. The ball soared past her, and history was made: USA 5, China 4.
Planning a Response StimulusResponse Response IdentificationSelection Programming The ball is perceived Backhand is chosen Backhand is initiated
Movement Preparation What is so important about getting ready to perform a skill? What makes preparation such a critical part of successful performance?
Planning a Response RT is not constant As demands increase, time to prepare increases - delay can be detrimental!
Planning a Response What factors influence how long it takes to prepare an action or how well this is done? If a person is prepared, how long can the person maintain this readiness?
Task-Related Variables Affecting RT Movement Complexity Number of Choices Movement Accuracy Predictability
Person-Related Variables Affecting RT Alertness Practice Arousal
Movement Complexity Simple Simple with 1 movement Simple with 1 movement & 1 reversal Fastest @ 150 ms Slower @ 195 ms (sprint start) Slower @ 208 ms
Response Choices - Hick’s Law Choices Increase Reaction Speed Slows As the number of decisions increases the ability to react slows by about 150 ms
Hick’s Law 400 500 100 600 200 300 RT in ms 123456 Number of Choices
Chastain’s Goal Goalkeeper has 360 ms from time ball leaves kicker’s foot to decide on response & execute movement (RT & MT) before ball crosses goal Assuming has only 2 response choices, RT about 300 ms Leaves only 60 ms to execute response!
Effects of Increasing Number of Alternatives Closed SkillOpen Skill
Closed Skill - Putting Stimulus contrast – As contrast RT Number of environmental features – Break – Speed of surface – Distance – Direction Practice
Open Skill - Tennis Serve Flat serveDirectly at receiver Served to outside corner Effects of increasing number of serves Fast BallDirectly at receiver Served to outside corner Slice serveServed to inside corner Served to outside corner
RT and Tennis Serve ServerDistance = 60 ftReceiver Server Distance = 60 ft Receiver
Tennis Serve A ball served at 90 mph will reach receiver in 660 ms 20 ft 220 ms
Practical Implication? Increase repertoire to increase choices for opponent Reduce uncertainty by systematically organizing and prioritizing choices
Strategies for Improving RT Increasing the size, contrast & intensity of the stimulus Practice under a variety of stimulus conditions If possible simplify the movement Precue participants on what to expect Teach participants to anticipate
Anticipation Predicting from current information into the immediate future – Event anticipation (what) – Spatial anticipation (where) – Temporal anticipation (when) The more predictable the more accurate response
Teaching Athletes to Anticipate Practice in varied situations so better know what, where & when an event will happen Detect precues for particular responses Prepare for most likely events On the flip side… Athletes must vary strategy Avoid signaling movements
Practical Applications Practice to recognize cues & tendencies Prepare learner to respond – Warning signal like “set” command – Toss of ball in serve Vary foreperiod or warning signal – Interval time should range from 1 - 4 seconds for prediction and precision – Randomize foreperiod length to decrease anticipation
The Fake RT slower for second response then for first response Successful fake – Must be realistic – Timing is critical Comes with practice Practice allows reading fakes better
The Fake Stimulus 1 (Fake) Response 1 (Respond to Fake) Stimulus 2 (Actual move) Delay Response 2 (Response to actual move)
Stimulus-Response Compatibility Extent to which stimulus & response naturally related – If low - increased preparation time – If high - decreased preparation time
Accuracy & Movement Fitts Law Speed accuracy trade-off 3 factors influence accuracy Distance Movement Speed Accuracy Requirement
Distance A B Increased distance = increased movement time
Target Size A B Smaller targets = increased movement time or decreased accuracy
Improving Accuracy in Skills Distance move closer to net choke down on racket short handle racquet Target Size larger ball larger racket face increase boundaries Increase time to Respond ball speed
Improving Accuracy in Skills Distance move closer to hole choke down on putter Target size larger ball increase size of hole
Improving Accuracy in Skills Should we teach speed or accuracy first?
Reducing Response Time Reducing Movement Time – Increase speed of movement – Reduce length of movement Self-defense no back arm movement Hockey shot in front of net no backswing – Increase distance between performer and opponent Receiving serve behind baseline