Behavioral Transitions
Gait Transitions
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Measure leg length:
o Supine on the training table
o ASIS to middle of medial malleolus __________
Walk-Run Transitions
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Walk on the treadmill for 1:00 at 3.5 mph
Increase treadmill speed to 4.2 mph and remain at that speed for 20 seconds
Continue to increase treadmill speed 0.1 mph every 20 seconds until the
participant runs, but shield the display from the participant
Participants should make the transition when they feel comfortable running
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Record the speed where the transition from walking-to-running occurred and leg
length on the master score sheet
Repeat the above steps with the next participant
Have everyone in your group complete the walk-run transition trial before doing the runwalk trials.
Walk-Run Transition Velocity__________
Run-Walk Transition
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Begin running on the treadmill at 0.5 mph faster than the walk-run transition
speed and remain at that speed for :20 seconds
Decrease the speed 0.1 mph every :20 seconds until the participant walks, but
shield the display from the participant
Participants should make the transition when they feel comfortable walking
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Record the speed where the transition from running-to-walking occurred and leg
length on the master score sheet
Repeat the above steps with the next participant
Run-Walk Transition Velocity__________
Affordance: Aperture Distance
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Measure shoulder width at the widest point
Measure 125% of shoulder width from the wall to the shoulder of one of the
testers
Have the participant start at the doorway and walk fast through the opening
between the wall and the tester
Continue to reduce the distance between the wall to shoulder of one of the testers
by 5% each trial until the person being tested rotates their shoulders
Record the percentage where shoulder rotation occurred on the master score sheet
Shoulder Rotation % __________
Affordance: Obstacle Height
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Measure lower leg length:
o Seated on the training table
o Measure mid-patella to middle of the medial malleolus__________
Hold a meter stick at a height that is 90% of lower length
Have the participant walk fast toward the obstacle and as they approach it they
must declare if they would “go over” or “go around”—they do not need to go
over or go around, but should honestly declare what they would do
Continue to increase the percentage height by 2% until participants declare that
they would “go around”.
Record the percentage height where participants declared they would “go around”
on the master score sheet.
“Go Around” %__________
Analysis
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Use SPSS to calculate the correlations between leg length:
o walk-run transition velocity
o run-walk transition velocity
(consult the first lab on “General vs. Specific Motor Abilities” for directions
on calculating and interpreting correlations)
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Calculate the mean and standard deviation for:
o Aperture percentage
o Obstacle Height percentage
Questions
1. Are there significant relationships between leg length and either or both of the
transition velocities? Explain your answer in statistical terms.
2. According to Mohler et al. (2007), what would happen to walk-run and run-walk
transition velocities if optical flow rate was increased? Explain why this would
happen.
3. Are the class results on aperture percentage consistent with the findings of
experiment #1 in Warren et al. (1987)? Explain your answer.
4. Look at the figure below and read the caption underneath to determine if our class
results are consistent with the findings of Patla (1997). Explain your answer.
From Patla (1997) showing the relationship between obstacle height and lower leg
length and the ratio where participants will “go over” or “go around”.
5.
Aperture percentage and obstacle height percentage are tests of a concept called
affordances. The idea of affordances originated with ecological psychologist,
James J. Gibson, who believed that humans directly perceive body-scaled
opportunities for movement in the environment. Direct perception implies that
our judgments about what movement to make require minimal information
processing because humans have co-evolved with their environment and,
therefore their perceptual systems are attuned what type of action a particular
environmental situation will allow. “Body-scaled” means we perceive are
opportunities for movement in terms of the relationship between our body’s own
dimensions and some environmental dimension. That is why you determined the
ratio between aperture distance and shoulder width and lower leg length and
barrier height because research has shown that behavioral changes (e.g., frontfacing-to-shoulder rotation or “go over”- to- “go-around”, etc.) occur when the
relationship between human and environmental dimensions reaches some critical
ratio (e.g., 100% of lower leg length, 130% of shoulder width, etc.).
Describe two other situations where you think the relationship between a body
and environmental dimensions represents an affordance.
6. Historical changes in sports techniques provide good examples of what can occur
when individuals perceive the same environmental situation differently and
recognize a new affordance. For example, from early 1890s to late 1940s shot
putters stood sideways to throwing sector. In the late 1940s Parry O’Brien
decided to turn his back to throwing sector and which increased the distance he
could accelerate the shot and led to two consecutive Olympic gold medals. In the
early 1970s Brian Oldfield used the discus spin to increase the acceleration
distance even more and broke the world record with a 75 foot throw. Nowadays
almost all elite shot putters use the discus technique. In the history of the shot
put, the size of the throwing circle did not change, but shot putters discovered that
it afforded different and more effective movements.
Provide two examples of historical changes in sports techniques and explain
why you think they represent the recognition of an affordance.
7. What do our lab results and the research findings indicate about the role
perception plays in determining motor behavior?
Bonus
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In their introduction Mohler et al. (2007) review several explanations for the
walk-run transition, which one would predict that transition velocity would
vary with leg length. Explain your answer.