Behavioral Theories of Motor
Control
Chapter 3
Coordination and Control
• Degrees of freedom (problem) (Bernstein,1967)
– Number of independent elements (nerves, muscles, and joint
movement possibilities) that must come together into an
organized movement pattern
• Coordination (Sparrow, 1992; Turvey, 1990)
– Process of constraining the system’s available degrees of
freedom into a movement pattern
• Control
– Manipulation of those variables within the movement to meet
the demands of a given situation
…..need both coordination and control in the acquisition and
performance of motor skills (Vereijken, Whiting & Beek, 1992)
Command Center (theories regarding brain’s
contribution to skilled movement)
Motor Program
– Abstract representation of a movement plan
– Stored in memory
– Issues instructions that are carried out by the limbs and
muscles
– When a specific action is required, it is retrieved from
memory and executed
Early Motor Program Theories
• Proposed that for each movement to be made, a
separate motor program existed and was stored in
memory
• 2 problems:
– Storage (would need limitless space in memory)
– Novel responses (when you need to do something
NEW)
Generalized Motor Program (GMP)
(Schmidt,1985)
– Represents a class of actions or pattern of movement that can
be modified to yield various response outcomes
• Invariant features
– Relatively fixed underlying features that define a GMP
• Parameters
– Flexible features that define how to execute a GMP, easily
modified from one performance to another
Invariant Features
• Relatively fixed underlying features (eg.fingerprints)
– Sequence of actions or components (e.g. order of actions to
perform a tennis serve)
– Relative timing
• Internal rhythm of the skill (e.g.-arm movement in
freestyle)
– Relative force
• Internal force relationship (changes proportionately as
force increases or decreases)
Parameters
• Adaptable features of program
• Easily modified from one performance to another to produce
variations of a motor response (e.g. ability to throw to 1st base
from various parts of the softball field)
– Overall duration
– Overall force
– Muscle selection
For example, a soccer player can make a long or short pass, as
the situation requires - same basic pattern but different
outcome.
Schema (Schmidt, 1975,1985)
•
Rule or relationship that directs decision-making when a learner
is faced with a movement problem - is the result of accumulated
experiences
•
Developed by abstracting 4 sources of information each
performance attempt
Initial conditions (limb/body/environmental conditions)
Response specifications (parameters e.g. speed/force
required for the throw/ kick/ pass etc…)
Sensory consequences (sensory feedback - how it felt)
Response outcome (relative success of the action)
Motor Response Schema
• Recall schema
– Responsible for organizing the motor program
– Based on relationship with past experience of the action
• Recognition schema
– Responsible for the evaluation of a movement attempt
Both schemas can be ‘fine tuned’ with sensory feedback and
external feedback (from the teacher/ instructor)
Open Vs. Closed Loop
Systems
• Open loop
– Action plans generated by command center then carried out by
the limbs and muscles without modification (feedback can only
be used to vary a subsequent attempt at the movement action)
• Closed loop
– Command center generates action plan that initiates the
movement
– Feedback be used to modify on-going action
– Action can be changed whilst it is occurring
– Not possible in actions that involve speed
Evidence Supporting Motor Program Control
• As complexity of the movement increases, RT increases (Henry &
Rogers,1960)
• Deafferentation studies involving surgical severing of sensory
nerves (e.g. Polit & Bizzi, 1978)
• Effects of unexpectedly blocking a limb during movement (Wadman,
Dernier van der Gon, Geuze & Mol, 1979)
For example, baseball batter infers a specific type of pitch due to the
type of wind-up demonstrated by the pitcher BUT the pitcher adjusts
the way the ball leaves the hand, just prior to release - too late for
the batter to adjust the motor program and therefore misses the
ball!!
Dynamic System Theory
• Argues that other theories ignore the fact that
movement occurs in response to dynamic interaction
of the mover and the environment
• Alternatively, movement pattern is thought to emerge
or self-organize as a function of the ever-changing
constraints placed upon it
Constraints (Caldwell & Clark,1990)
• The boundaries that limit the movement capabilities of an
individual
• Three types (or combination of each)
– Organismic: can be structural e.g. height or functional e.g.
cognitive ability
– Environmental: eg. gravity, temperature, wind speed
– Task: eg goals of the task, rules of the task, implements or
machines required
Attractor States
• Systems prefer states of stability
• When a change in constraints is imposed on a system,
its stability is endangered
• Deep basins = well learned = stable systems = difficult to
change (Ennis, 1992)
• Shallow basins = patterns not set = less stable = more
susceptible to change
Phase Shifts
• Changes in behavior are the result of a series of shifts
• Control parameters
– Variables that move the system into new attractor
states (e.g. direction, force, speed, perceptual
information)
• Rate limiters
– E.g. cricket bat too heavy for the child)
– Constraints that function to hinder or hold back the
ability of a system to change
Dynamic System Theory Synopsis
The complexity of human behaviour leads to the Dynamic System
Theory (DST) approach to understanding motor control
Teachers/ instructors need to:
• Know individual learners’ capabilities;
• Understand the complexity of the task to be taught;
• ‘Break down’ the task into developmentally appropriate stages;
• Minimise or allow for constraints evident when teaching skills;
• Understand the effect of ‘prior learning’ and ‘unlearning’;
• Ensure the environment is conducive to learning;