Principles of Speed, Accuracy and Timing - Chap. 6

Question 1

what is the idea behind fitts law

Answer 1

movement time is constant whenever the ratio of the movement amplitude to target width remains constant (long movements to wide targets = short mvoemetns to narrow targets)
-MT increased as ratio of amplitude to width increased

Question 2

what does fitts law predict

Answer 2

how much time you require to move to a target when speed and accuracy matter

Question 3

what is the fitts law equation

Answer 3

MT = a + b [log2(2A/W)]
A = amplitude (distance between 2 targets)
W = target width
log2(2A/W) = index of difficulty

Question 4

how does speed-accuracy trade-off relate to open and closed loop control

Answer 4

faster = open loop commands are more variable

Question 5

what are 3 things that fitts law tells

Answer 5

-movement time increases as distance icnreases
-mt increases as target widht decreases
-mt is different for a given index of difficulty

Question 6

what are 2 cases in which the speed-accuracy trade-off does not hold

Answer 6

-extremely rapid and forceful actions are involded
-accuracy in timing is the actions critical feature

Question 7

how do extremely rapid and forcelful actions not hole to the speed-accuracy trade off

Answer 7

-increasing speed by reducing MT can decrease spatial and timing error
-greater msucualr force requirment actually increases accuracy in this range, adding an inertial load can decrease error (up to a point)
-

Question 8

how is effective target width a violation of fitts law

Answer 8

how scattered are movement endpoints within a given target
-effective target width = actual target width
-BUT if only honing into one area on the target, for example the middle, fitts law wont hold because behaving as if target is narrow rather than bid so effective target does not equal actual target

Question 9

what is schmidts law

Answer 9

describes relationship between movement force and mvoement variability

Question 10

effective target width increases as what increases

Answer 10

velocity

Question 11

moving faster results in what

Answer 11

a linear increase in an endpoint variability

Question 12

what is a question regarding sources of error in rapid movements

Answer 12

where does the noise come from

Question 13

when motor program is sent down spinal cord fast, there is more opportunity for what

Answer 13

noise/mistakes
-dont take time to take in feedback and compare to wanted outcome and modify actions
-gives less time to corrrect any possible mistakes

Question 14

what are 3 exceptions to speed accuracy trade off

Answer 14

-extremely rapid and forceful movements
-visual illusions
-movement timing

Question 15

when it comes to speed, what movements have hte most spatial accuracy and hte least

Answer 15

MOST
-very rapid and very slow
LEAST
-moderate-speed
**goes against the speed-accuracy trade off (faster moements are always less spatially accurate)

Question 16

what is one way to help train someone to perform better

Answer 16

ex golf: practice putting into a hole that is percieved smaller than what it really is and this will transfer postitvely into the actual size hoel allowing to be more accurate

Question 17

skills with purely temporal goals seem to follow somewhat different principles than what

Answer 17

those having purely spatial goals

Question 18

why does a task that takes longer produce more errors than one thats shorter

Answer 18

becuase hte longer durations allow for more noise/variability and they acculumate as the duration of the even to be timed increases

Question 19

in what context is movement time not accurate to the speed accuracy trade off

Answer 19

when tasks are timed
-the longer the duration of the task, the more possibility for errors

Question 20

when performing a rapid movement what is critical

Answer 20

timing

Question 21

when to initiate a rapid movement is based on knowing the what

Answer 21

the duration of the movement

Question 22

what is a coincidence anticipation task

Answer 22

predict the arrival of a moving object at a point in space
-swinging at a baseball

Question 23

what is the process of executing a rapid movement

Answer 23

decision making (stimulus identification)
implementing decision (reponse programming)
executing movements (movement time/actually performing respponse)

Question 24

from a visual processing standpoint why do basbelal players swing near maximmum

Answer 24

shortening MT, delyas the beinning of the swing
-provides additional time for viewing the balls trajectory and for determining time to contact
-more accruately predict where ball will be at impact

Question 25

from a swing-initiation timing accuracy standpoint, why does a baseball player swing near maximum

Answer 25

if swing of bat is sped up, decision about when to intiate hte movement is made later and more temporally accurate
-shortening MT stabilized the initiation time of movement allowing for greater mt accuracy
**decision made closer to ball contact - less time for error

Question 26

from a mvoement time accuracy standpoint, why do baseball players swing enar maximum

Answer 26

player has to estimate their own movement time to be able to hit ball in the middle of the movement
-if actual mt is different then the estimated = timing errors
**reduced MT increases movement timing consistency

Question 27

from a movement spatial accuracy, why does a baseball player swing near maximum

Answer 27

when movments are very fast and forcefyl, reducing the MT tends to increase the accuracy rather than decreasing it
-improving spatial accuracy

Question 28

from a ball impact standpoint, why do baseball players swing near maximum

Answer 28

faster swing gives more impact to ball

Question 29

who will msot likely win, person initiating or respondng to stimulus

Answer 29

person responding

Question 29

what is prehension

Answer 29

the act of taking hold, seizing or grasping

Question 29

prehension and fitts law works for objects in eveyday life as well primarily due to what

Answer 29

increased duration deceleration phase

Question 30

fitts law and walking with typical populaiton compared to parkinsons disease

Answer 30

TYPICLA
-scale walking to door widths
-slower, shorter steps
PARK
-larger reponse - even slower
-sensitive to visual info

Question 31

desrcibe the speed-accuracy trade off reconsidered

Answer 31

accuracy does not continue to diminish with increasing speed, instead, the coordination pattern changes so that stability can be reestablished

Question 32

when increases in speed result in decreased accuracy, the motor system is faced with what 3 alternatives

Answer 32

-reduce the speed and maintain accuracy
-decrease inaccuracy and maintain speed
-main the speed and change the movement pattern in order to reestablish stability