Motor Control Theory 1

11Augmented FeedbackChapter 15 slide set 2

2Feedback schedulingReducing guidanceimproving learningRelative frequencyless is moreSummary100% feedback but only 10% of the timeSelf-selected frequency (tend to choose less frequent)Choose to get feedback when accurate, and works best when the choice is after performance (Chiviakowsky & Wulf, 2005)Bandwidth feedback1

2

3

3Feedback scheduling0% (no) bandwidth (100%KR)10% bandwidth (?% KR)425ms

475ms

525ms

575msTarget (500ms)425ms

..

..

575msCorrect4505501

4Feedback schedulingReducing guidanceimproving learningBandwidth feedbackProvides guidance (correction) only when necessary (big errors)Also tells people NOT to correct when they are reasonably accurate1

5Feedback schedulingBandwidth feedbackmore than just a relative frequency effectFrom:Lee and Carnahan (1990)1

2

3

6Feedback schedulingBandwidth feedbackeffects on performance?Blockingsimilar to guidance ideasWhen you increase the bandwidth, you decrease relative frequency of feedbackIn doing so you reduce blocking of sensory feedbackMaladaptive short-term corrections1

7Feedback schedulingBandwidth feedbackeffects on performance?Maladaptive short-term correctionsIncreased bandwidths reduce attempts to correct very small errors in performanceNote influence of no-feedback trials1

81Feedback schedulingBandwidth feedbacklearning? Larger bandwidths (up to a point) may improve learningCause:BlockingReduction in MSTC.You want the bandwidth to be sized so that it reduces RF to an appropriate level and reduce the occurrence of MSTC

9More recent findingsRecent research has suggested guidance ideas are not always accurateSometimes frequent feedback seems desirable even for learningThe effect of the feedback on attentional focus seems to be important1

10High frequency is goodWulf & Shea (1999) (ski sim.)Concurrent feedbackThe more often feedback was presented, the better people performedWhy? Performance improvementSmith, Taylor, & Withers (1997) (golf chip)Terminal feedbackBW (10%) better than BW (0%), for transitional feedbackPerformance improvement1

2

11High frequency can be goodRetention data from a soccer kicking studyPay attention to:Feedback frequencyAttentional focusInteraction between the two1

2

12High frequency can be goodAnother way of looking at that data1

The feedback statements...Internal Focus FeedbackPosition your foot below the balls midline to lift the ballPosition your bodyweight and the non-kicking foot behind the ballLock your ankle down and use the instep to strike the ballKeep your knee bent as you swing your leg back and straighten your knee before contactTo strike the ball, the swing of the leg should be as long as possibleExternal Focus FeedbackStrike the ball below its midline to lift it, that is, kick underneath itBe behind the ball, not over it, and lean backStroke the ball toward the target as though passing to another playerUse a long-lever action like the swing of a golf club before contact with the ballTo strike the ball, create a pendulum-like motion with as long a duration as possible

13From the lab thing:14