Interceptive Control Flashcards
Draw the key events during interceptive tasks graph
….
Tresilian and Plooy 2006
Explain movement time onset
Initially determined MT from non occluded trials (mt = 183ms)
Then introduced occluded period (op) relative to movement onset (mo)
Firstly, began when ppt decided to move finger
Then 200ms prior to movement onset ect… (
= determine temporal error
What are the findings from the temporal error studies
(Average MT = 183ms)
200ms OP relative to MO = greatest temporal error
When is the most critical period
200 ms before movement onset ect
What is the first theory of how and when we use vision in interceptive control
Optical height
What is optical height
Height of the ball / distance left to travel
Explain optical height
- assumes motion of the projectile is under constant acceleration
- newton 1/2 law
What happens if the catcher is in exactly the right place to catch it
Moving up the plane at constant velocity, vertical optical acceleration of ball = 0
Optical height should have constant velocity if perfect parabolic flight path and position to catch it
What happens when the projectile is not moving at constant velocity
Catcher will run at constant velocity to maintain optical height acceleration at 0
(Vertical optical acceleration VOA = 0)
Gaps between ball getting smaller - move forward
What are issues with optical height
In order to run at constant velocity, must know when and where projectile will drop
Why don’t we just run and wait
Trajectory rarely a parabola
What are issues with optical height
In order to run at constant velocity, must know when and where projectile will drop
Why don’t we just run and wait
Trajectory rarely a parabola
What is the second theory of interceptive control
Gaze angle
What is gaze angle and how to work out
Estimation of able made between catcher ball projectile
Does not rely on fixed head position, unlike optical height acceleration
Tab of angle = opp/adjacent
How does gaze angle effect catching
If angle between 0 and 90, chance we could catch it
If not going to, look at rate of angle change to decide direction to move
If gaze angle has negative velocity = angle getting smaller = move forward
According to gaze angle, how do we move to catch a ball
NOT AT CONSTANT VELOCITY
Recorded how fast ppt moved to ball = gaze angle
Found they adjusted speed throughout
Have not moved at point 0, deciding
Once moved can reevaluate
Nobody guesses exact distance then just runs there
How do we decide to adjust speed in gaze angle theory
Second derivative = gaze angle, acceleration
If we are moving forward
If 2nd derivative of tan a is negative = dropping quicker = speed up
If it is positive = slow down
If we are moving backwards:
If 2nd derivative of tan a is positive, speed up
