Speed, Accuracy, and Coordination

Question 1

What is spatial accuracy?

Answer 1

the type of accuracy required of aiming movements in which spatial position of the movement’s end point is important to the performance

Question 2

What is timing accuracy?

Answer 2

the type of accuracy required of rapid movements in which accuracy of the movement time is important to the performance

Question 3

Fitts’ law is that movement time increases as:

Answer 3

• movement amplitude increases

- aiming accuracy increase

Question 4

Movement time is consistent whenever…

Answer 4

the ratio of the movement amplitude (A) to target width (W) remains constant.

Question 5

Fitts’ found that the movement time increased as…

Answer 5

the ratio of A (movement amplitude) to W (target width) increased by either making A larger, making W smaller, or both

Question 6

In linear speed accuracy trade off, more force is required when:

Answer 6

• movement time is decreased (fast movement)

- amplitude is increased (movement distance)

Question 7

more force =

Answer 7

increased variability

Question 8

What happens when a movement requires very high levels of muscular contractions (greater than about 70% of the subject’s capabilities)?

Answer 8

• Increasing speed by reducing MT can decrease spatial and timing error.
• greater muscular force requirement increases accuracy, adding inertial load to the movement can decrease error, up to a point.
• An inverted-U relationship exists between spatial accuracy and force requirements, with least accuracy at moderate levels of force.

Question 9

How does decreasing the movement time in temporal goals effect accuracy?

Answer 9

has the effect of decreasing the timing error, making the movement more accurate in time

Question 10

Describe a violation of speed-accuracy trade offs.

Answer 10

• When people were asked to perform a rapid striking task at different times, speeding up the movement resulted in a decrease in timing errors.
• THEREFORE timing accuracy is different than the speed-accuracy trade-off

Question 11

Describe why some skills require spatial accuracy.

Answer 11

• the ability to execute a skill
• ie. hit a target
• generally requires slower movement
• ie. threading a needle

Question 12

Describe why some skills require timing accuracy.

Answer 12

• knowing when to initiate a skill movement
• generally requires shorter time
• ie. judging when 2 seconds has passed