Chapter 3 - Sensory Contributions To Skilled Performance
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22 Dec 2011
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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)
Kinesthesis
•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