ch 6- speed accuracy trade off

Question 1

When does speed accuracy trade off occur?

Answer 1

when the goal is to move a limb/body part as fast as possible to reach a target with minimal error

Question 2

3 different paradigms

Answer 2

1. logarithmic (fitt’s paradigm)
2. linear
3. temporal

Question 3

Experimental paradigm

Answer 3

-person moves a stylus back and forth to two targets as fast and accurately as possible
-experimenter manipulates target width and amplitude (distance between targets)
-emphasis on accuracy
-experimenter changes the index of difficulty (ID)

Question 4

Index of difficulty formula

Answer 4

ID=Log2(2A/W)
A= amplitude
W= target width

Question 5

When speed and accuracy are graphed logarithmically it produces a

Answer 5

straight line

Question 6

logarithmic straight line (Movement time line)

Answer 6

MT= a+b[log2(2A/W)]
therefore MT= a+b(ID)
a and b are constants

Question 7

MT= avg movement time/tap (from number of taps in a given time period)
what is 50 taps in 20 sec?

Answer 7

0.4 s/tap

Question 8

Fitt’s law shows a(n) — relationship between difficulty of movement and speed

Answer 8

inverse

Question 9

movement time must be traded off to maintain

Answer 9

accuracy under different values of ID (index of difficulty)

Question 10

ID=0
accuracy required=?

Answer 10

none

Question 11

When is ID=0
(give an example)

Answer 11

when two targets overlap in width

Question 12

Different effectors have different

Answer 12

slopes
(because each effector has its own sensitivity to changes in ID)

Question 13

slope — for larger effectors

Answer 13

increases
(larger and heavier limbs are more sensitive to changes in ID)

Question 14

slope increase for larger muscles, what does this tell us?

Answer 14

-large/heavy limbs= more sensitive to changes in ID
-Fingers can be controlled more precisely
-older adults usually have higher slopes

Question 15

Fitt’s law holds true for..

Answer 15

different age groups, lower/upper limb movements, underwater movements and imagined movements

Question 16

Linear speed accuracy trade-off:
WHEN is this relationship observed?

Answer 16

during rapid single-aiming movements

Question 17

Linear speed accuracy trade-off:
describe action and what the task required

Answer 17

the person reaches with a stylus from a starting position to a target that is 10-60cm away. MT (movement time) is constrained by experimenter. Target width is maintained. Task requires timing and distance accuracy

Question 18

Errors are measured as

Answer 18

standard deviation (SD) of movement amplitude
= also called the variation in movement end point (We)
=variability/error

Question 19

What is the linear-speed accuracy trade-off relationship equation?

Answer 19

We= a+b(A/MT)
a and b= constants
A= movement amplitude
MT= movement time

Question 20

Linear speed-accuracy trade-off:
What happens to variability (We) as movement amplitude (A) increases

Answer 20

We (error) increases as amplitude increases

Question 21

velocity=?
relation to A and MT

Answer 21

velocity= A/MT

Question 22

What happens to We as velocity increases?

Answer 22

We increases
(error increases/accuracy decreases as velocity increases)

Question 23

Logarithmic trade-off occurs for movements that are controlled by…

Answer 23

feedback-based corrections

Question 24

Linear trade-offs occur for tasks that are…

Answer 24

entirely preprogrammed (NO FEEDBACK USED)

Question 25

Feedback hypothesis

Answer 25

logarithmic trade off= feedback based
linear trade-offs= no feedback

Question 26

What is an example of a linear trade off task?

Answer 26

rapid reaching task (no feedback used)

Question 27

Movement time goal hypothesis

Answer 27

to increase accuracy, move slower

Question 28

Temporal Speed-accuracy trade off:
give an example of a task and what is required

Answer 28

-tasks that require anticipation and timing
-example= hitting a baseball
–> you need to anticipate the flight of the ball, internal motor planning, and limb movement (effector anticipation) to decide when to swing

Question 29

Temporal speed-accuracy trade off:
typical paradigm?

Answer 29

must move a slider to intercept/hit a target moving along a track

Question 30

Temporal speed accuracy trade-off:
what is accuracy measured in terms of?

Answer 30

errors of time
(early of late arrival of the slider to the target)

Question 31

Temporal speed accuracy trade-off:
the more “violently” the person performs the movement, the more — the timing

Answer 31

accurate
-violent movement= smaller MT or larger movement velocity
-timing is more accure

Question 32

What principle is this violent movement, more accurate timing relationship opposite to?

Answer 32

temporal speed accuracy trade-off is opposite to the speed-accuracy principle for spatial accuracy movements

Question 33

Does the temporal speed accuracy trade-off have anything to do with spatial accuracy?

Answer 33

NO

Question 34

It is easier to estimate — time intervals

Answer 34

shorter

Question 35

Variation of temporal speed accuracy trade-off

Answer 35

person performs discrete movement timing tasks
goal= to produce a specific MT

Question 36

Smaller MTs produce — movement-timing consistency
(give an example)

Answer 36

improved
-example= have someone time you trying to count to 2 seconds and then to 20 seconds. it is easier to estimate shorter time intervals

Question 37

Temporal speed accuracy trade-off
Application: baseball swing example about MT and errors

Answer 37

Temporal speed accuracy trade-off suggests that the person should swing the bat harder (smaller MT, larger movement distance) to decrease errors in timing
–> could be why batters practice with a weight on the end
–> when you take the weight off you will swing much harder