L7B: Sensory Contribution II

Question 1

What is is the main limitation of conscious closed-loop control?

Answer 1

Time (to process feedback) is the main limitation of conscious closed-loop control

System needs time to make quick voluntary changes because error detection & correction are long

Question 2

How long does Visual processing take?

Answer 2

Visual processing and adjusting is going to at least be as slow as the fastest simple RT (~100ms -150 ms)

Question 3

Assuming that stages of information processing take ~100-150 ms, why do we see corrective muscle activity (in response to the perturbation) before?

Answer 3

Proprioceptive closedloop control Start the corrective process before voluntary processes kick in.

Question 4

What are the 2 Types of Closed-Loop Control Systems?

Answer 4

Conscious Closed-Loop Control

Reflexive (proprioceptive) Closed-Loop Control

Question 5

What is Conscious Closed-Loop Control?

Answer 5

• Consciously controlled adjustments based on sensory information
• Require selective attention
• Involves information processing stages
• Controlled, voluntary, not so rapid (delays>150ms)

Question 6

What is Reflexive (proprioceptive)
Closed-Loop Control?

Answer 6

• Little or no conscious control.
• Does not require selective attention
• Reflexive modulations during performance of a motor skill “low-level” (occur in spinal cord and brainstem)
• Stereotyped, involuntary, rapid fashion

Question 7

Answer 7

Question 8

Motor system can respond to stimuli that are too small to be detected consciously

Task
* Keep position of handle constant with RH
* Lift finger of LH when sense change in pressure

Answer 8

Results
* RH responds to v. small changes (.03 dynes)
* LH responds only to larger changes.
Detects when > .56 dynes!

19X larger for conscious detection

Question 9

Answer 9

Stimulus Identification

Question 10

Answer 10

Approximate: 205 - 125 = 80 ms

Subtract the Goalie RT with the control RT at SOA = 150

Question 11

Answer 11

SOA = 50 ms