• Skill is the integration of well-adjusted muscular performance rather than a tying together of mere habits (Pear, 1927)
• Skill is both mental and motor; and they are learned patterns (Bartlett, 1948)
• Skill is a continuum from predominatly habitual (not required to think) to predominantly perceptual (necessary to think about) (Knapp, 1961)
• Skill is the process of mastering redundant degrees of freedom in the moving organ. In other words, it is conversion to a controllable system (Bernstein, 1967)
• Skill consists in the ability to bring about some end result with maximum certainty and minimum outlay of energy, or time and energy (Guthrie, 1972)

Early Period (1898-1950)

• Bryan and Hunter - learning curve (nonlinear)
• Book - breathing places or plateaus
• Thorndike's Law of Effect - (1874)
• Learning is an automatic process without intervention of conscious awareness, unconscious strength training of a habit and connections between stimulus and response.
• Thorndike's Knowledge of Results (KR)
• declarative vs. procedural
• qualitative vs. quantitative
• augmented (Newell, 1977)
• Woodworth (1898) - transfer of training

Middle Period (1950-1960)

• Motivation and insormation views of KR (Bilodeau, 1959)
• Fitts' (1962) - stages of learning
• Fitts' Law (1954)
• Adams' "closed loop" theory of motor control
• Henry and Rodgers' "open loop" theory

Current Period (1960-Present)

• Bernstein - degrees of freedom problem and coordinative structure (1967- present)
• Gibson - ecological psychology (1975-present)
• Turvey & Kugler - dynamic system approach (1980-present)
• Nashner's Design
• Preparatory activity examples
• Postural perturbation experiments

• Information feedback prior to action
• verbal instruction
• demonstration
• Information feedback during the action
• guided practice
• support and motivation while practicing
• Information feedback after the action
• qualitative knowledge of results (KR)
• quantitative knowledge of results (KR)

• Initial stages of skill acquisition (5)

1. goal
2. selective attention (key element)
3. motor plan (imagery, mental skill)
4. information feedback
5. decision process and next response

• Application for teaching (coaching)
• verbal communication
• visual input
• direct movement control

• Maximum outcome and minimum energy expenditure (Sparrow, 1983)
• mechanical efficiency
• energy demands
• efficient agonist
• antagonist activation
• Efficiency concept
• effortlessness of performance
• mechanical and physiological efficiency

• Coordination and control
• experimental psychology; motor skill and motor learning
• neurophysiology; motor control
• Motor program concept
• arguments supporting motor program concept:
• de-afferentation design (Leshley)
• reaction tme design (simple vs. complex)
• feed-forward command in posture
• Nashner's design
• plan program - execution

• Three types:

1. restitution - the brain can contintue activity because other cells can take over the job of the injured cell
2. partial restitution - all cells are dead in one area, but compensatory cells perform the neccessary activity
3. substitution - the same results are achieved

• Storage of motor programs
• Jasper and Penfeild esperiments
• Novelty of motor tasks
• no previous experience
• Bernstein's concept - movement is not completely determined by effector processes, but also by sensory information from internal and external sources
• functional non-univocality of connection between central nervous system and periphery organs

• Source of Indeterminacy
• Anatomical
• multiaxial joints, musclular complexity, large number of biomechanical kinematic chains
• Mechanical
• reactive and inertial forces
• interaction effect of different muscles
• Pyhsiological
• selective relationship between central nervous system and periphery
• Phychological
• arousal, anxiety, motivation apprehension, fear, etc.

• Environment - Knowlage of Results (KR)

1. Influences response initiation which is the memory trace mechanism
2. Influences perceptual trace which detects error and corrects the error

• Central Nervous System - the execution mechanism which is movement production

1. Affected by the perceptual trace
2. Affected by the response initiation
3. Influences the moving organ

• Moving Organ

1. Detects any errors
2. Sends feedback information to the brain to correct errors in movement
3. Slow movements need more feedback than faster movements
4. Highly skilled actions rely more on the motor programs than less skilled actions

• Movement phases - initial adjustment and current control
• Movement is a function of distance versus velocity

• Speed-Accuracy Trade-Off
• Both direction and distance are taken into account
• Movement characteristics

1. duration
2. distance
3. accuracy

• Types of tasks

1. discrete
2. continuous

• Types of errors

1. constant error
2. variable error
3. mean absolute error

• Movement is a function of speed versus accuracy
• Movements are time matched by using a metronome to keep cadence
• Two types of systems

1. eyes closed system
2. eyes open system

• Result:
• faster movements cause more error (less accuracy) in the action
• regardless of speed, the eyes closed system is inaccurate
  

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