Chapter 3 - Sensory Contributions To Skilled Performance

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Sept 29 Chapter 3 – Sensory Contributions to Skilled Performance
Sources Of Sensory Info
Exteroception: from outside the body (vision and audition)
Proprioception: from inside the body (vestibular apparatus, muscle spindles,
GTO, cutaneous receptors)
Optical Illusion
Identical sensations can yield different perceptions
Vestibular Apparatus
Structure of the inner ear
3 semi-circular canals – angular acceleration
Otholith organs: utricle (horizontal) and saccule (vertical)
Role: maintain static and dynamic equilibrium
Vestibule-occular reflex – stabilize image on retina during head movement
(ex. Read)
Muscle spindle tell how much a muscle is being stretched
GTO send info on strength or force of contraction
Muscle Spindles
Intrafusal muscle fibers
Lie parallel to skeletal muscle fibers (extrafusal muscle fibers)
Activated when muscle is stretched
Muscle contraction reduces activation of spindle
Cutaneous Receptors tactile Sensation
sense organs located in most skin areas: touch, pressure, stretch, vibration,
temperature, pain
free and encapsulated nerve endings
proprioceptros may monitor several different kinds of stimuli (stretch, rate of
change, joint position)
movement perception is teh result of integration of various inputs from
sensory modalities in the CNS
A Closed –Loop Control System
use of feedback and error detection/correction to maintain movement goal
4 elements
Driven from periphery
Slow controlled, deliberate movements
Continuous, long duration skills
Flexibility in movement control
Limitations for closed loop control
stages of processing require time and attention
detected error = new stimulus input (3 corrections per second)
rapid movement – preplanned
no processing (OK stable environments)
open-loop control
stable environments
locking yourself out
Fast Movements And Time To Process Info
Slater-Hammel (1960) – inhibit anticipatory response
stop sweep hand at 800 ms (lift finger)
random stops before target location (no finger lift)
time to process visual FB > 170 ms
M1 Response
mono-synaptic stretch reflex
onset at 30-50 s
compensation -...
automatic, (parallel processing)
M2 Response
Onset at 50-80 ms
Compensation more forceful, longer duration
Involves inter-neurons (other spinal segments, and/or supra-spinal structures)
More flexibility/ role of instruction (ex. Resist or let go)
Triggered Reaction
Polysynaptic reflex – onset at 80-120 ms
Unique type of reflex – unconscious
Response – pre-structured
Recruits muscles close and far from stimulated site
More or less automatic (learning?)
Cutaneous receptors that facilitate the crossed extensor reflex and the
“wineglass effect”
Can control higher brain centers
M3 Response
Voluntary reaction time (RT)
Latency 120-180 ms