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Preparatory Hand Motion in Pre-performance Routines. By Justin DiSanti. Pre-performance Routines. Slow-motion Dart Throw. Pre-performance Routines. “Cognitive behavioral pre-performance routines in sport” (Cohn, 1990) Prior to practiced, repeated action Muscle memory Gross body movement - PowerPoint PPT Presentation
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Preparatory Hand Motion in Pre-performance Routines
By Justin DiSanti
Pre-performance Routines
Slow-motion Dart Throw
Pre-performance Routines“Cognitive behavioral pre-performance routines in sport” (Cohn,
1990) Prior to practiced, repeated action Muscle memory Gross body movement Superstition Conscious, practice
Preparatory Hand Motion Unconscious motion of the hand in preparation of a fixed action Action involving precision and aim Focus on unconscious, unpracticed
Hypothesis Optimal patterns of preparatory hand motion begin to develop
unconsciously as a person becomes more proficient at a repeated task
Hypotheses
Hypothesis: Variance of hand preparation motion (HPM) is directly related to the width of the target zone
Alternative hypothesis: Variance of HPM is inversely related to the width of the target zone
H0: There is no relation between variance of HPM and the width of target zone
Variance in HPM VS. Width of Target Zone
20 cm 40 cm 60 cm02468
10121416
Chart Title
Variance in HPM
Width of Target Zone (cm)
Vari
ance
of H
PM
(cm
)
Hypotheses (cont.)
Hypothesis: Number of movements in hand preparation motion (HPM) is related inversely to the width of the target zone
Alternative hypothesis: Number of movements in HPM is directly related to the width of the target zone
H0: There is no relation between number of movements in HPM and the width of the target zone
Number of Movements in HPM VS. Width of Target Zone
20 cm 40 cm 60 cm02468
10121416
Number of Movements in HPM
Number of movements in HPM
Width of Target Zone (cm)
Num
ber
of M
ovem
ents
in
HPM
Hypotheses (cont.)
Hypothesis: Probability of success in a fixed action is predicted by optimal variance in hand preparation motion
Alternative hypotheses: Probability of success in a fixed action is directly/inversely proportional to variance in hand preparation motion
H0: There is no relation between probability of success in a fixed action and variance in hand preparation motion
Probability of Success VS. Variance of HPM
5 10 150
0.2
0.4
0.6
0.8
1
1.2
20 cm40 cm60 cm
Prob
abili
ty o
f Tas
k Su
cces
s
Variance of HPM (cm)
Experiment 1
Motion Sensor
Table Surface
Books
Stopper
X Target 2Target
1
Subject View
Starting Point
16 ptsCue Card
PASCO low-friction track
Experiment 1Setup
Overhead View
X
Starting Point
Target 1
Target 2
Experiment 1Method
Participant stands parallel to track with hand on the middle of the cart
The “X” on the cart should be lined up with the starting zone Participant begins with their eyes closed The experimenter adjusts the target zone and corresponding
point value Participant opens eyes, evaluates point value and target
distance, then launches the cart The goal of the experiment is to launch the cart and have it
reverse within the target zone When center of the cart (marked by “X) reverses correctly
within the target distance, the participant is rewarded points (20 trials) 16
pts.X
Results (Pilot)
ResultsRun 3Blue line, missed target zone of 20 cm-Variance of HPM smaller, more preparatory motions, longer time until launch
Run 4Orange line, correctly reversed target zone of 40 cm-Variance of HPM larger than 4, less preparatory motions
Predictions & ImplicationsIntentional or not, participants become more
consistent with preparatory motion as the experiment progressesLess frequent, longer range of motion for larger
targetsMore frequent, shorter range of motion for shorter
targetsIs there an optimal formula for preparatory hand
motion?Is motion wasted/unnecessary? How do individual differences affect this motion? Can preparatory hand motion be trained to maximize
performance?