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?