Motor behavior exam 2

DOF

degree of freedom

DOF (motor program theory)

Independent elements in the human body that afford numerous action and possibilities

• Control of independent elements is necessary to produce coordinated movements

Joints

can be moved in numerous directions

DOF problem

How to coordinate the available DOF to produce a particular movement

Coordination

• Process of organizing a system’s DOF into a movement pattern to achieve a specific goal

• Simple tasks require coordination

Writing your name on paper: coordination

• Must manipulate pen

• Most produce a movement that corresponds w/ the dimensions + locations of the word on the page

Writing your name on paper: control

• Must know how hard to push

• Where to start + push

• How to write fast

Control

• Manipulations of variables within a movement to meet the demands in an given situation

• Simple tasks require control

Skilled movement

coordinate available DOF + control resulting movement = DOF problem

Early DOF problem theories

• For every movement, a motor program exists

• When an action is required, the appropriate program was retrieved from memory and executed

Problem with early DOF problem theories

• storage requirement

• production of a new movement

2 theories for DOF problem

• GMP

• Dynamic Systems Theory

GMP

Generalized Motor Program

Generalized motor program theory

represents a class of actions or patterns of movements that can be modified to yield various outcomes

• Every movements doesn’t require a separate motor program for its execution

• More general in nature

• Some elements are fixed (invariant features) and some elements are more flexible from trial to trial

fixed

invariant features

IF

invariant features

invariant features

• ie time, penmanship

• Like fingerprints

Motor programs can be identified by

one of three IF

3 IFs

• Sequence of actions/components

• Relative timing

• Relative force

Sequence of actions/components

actions must be executed sequentially

• Writing your name: 1rst letter must come 1rst

• If the order of letters is disrupted the result is the creation of a new name/word

• ie field the ball then throw it (can’t throw it then field)

Relative timing

 internal rhythm of skill

• ie freestyle swimming

Relative force

when overall force used to execute a movement changes, the relative force of individual muscles remains proportionate

• ie performing a knee extension with different amounts of weight (weight ↑=force ↑)

Schema theory

abstract representation of a rule or set of rules governing discrete movements (starts + stops)

• In GMP, a shortstop can throw to different bases from various positions on the field by assigning an appropriate parameter value (throwing speed) but how does the shortstop know exactly how fast the ball should be thrown in each situation?

• The rule or relationship that directs decision making when a learner is faced  with a movement plan

• Developed as a result of experience within a set of action

• The more movements a performer has executed, the more developed the schema

On each attempt, extract 4 pieces of info which are briefly stored in memory after the movement attempts

• Initial condition: limb, body position, + environmental condition is that present when the movement begins

• response specification

• sensory consequences

• response outcomes

response specification

parameter values used in the execution of a movement (ie speed, force, direction, selection)

sensory consequences

response produced sensory info of sensory feedback of the movement

• Feedback (how did it feel)

response outcomes

success of the response obtained in relation to the originally intended goal or outcome

• Will always likely be different across attempts

• If you throw a ball 3x, you’ll get 3 difference responses

Relationship of all 4 pieces of info

=schema

Executing GMP

• Learner decides what movements to execute in a given situation

• Subconsciously retrieves the appropriate GMP from memory based on existing schema

• Adds GMP to existing parameter desired outcome

• The moment is organized the motor program and is then sent to the rest of the body to carry it out

Many dynamic theories argue that GMP doesn’t account for

the control of complex movements

• “A command couldn't possibly account for all the variations in a skilled movement”

Dynamic systems theory

many systems work together to influence human movement

• New movement patterns emerge or self organize as a function of the interacting, ever changing individual, learner, and environment (ie treadmill: walk → run)

• Movement is a function of the system spontaneously self organizing + compressing the available DOF into a single functional unit that’s designed to carry out a specific task

• Organizing of systems constraints behavior so the body system doesn’t develop at the same rate

  • Like an assembly line, some parts are made faster than other

Systems in dynamics systems theory

nerves, hormones, muscles, skeleton, levers, motivation, fear, gravity, floor, surface

• No one system is in charge

• Near infinite # of possible combinations + resulting movement

  • What combination of systems do we need to walk? To skip?

Constraints

movement arises from interaction between the individual, environment, + task

• If any of these 3 factors change, the resulting movement changes

  • Not always negative (enabling + limiting)

  • The factors are constantly changing

    • Softly assembled (flexible, adaptable)

Individual

a person's unique physical + mental characteristics

• structural

• functional

structural

body structure (ie height, body type, weight)

functional

behavioral function (ie trait anxiety, motivation, confidence)

Environmental

factors that exist outside of the human body

• physical (ie force + direction of wind during javelin throw)

• sociocultural (ie football is big in the US but not England so we have an affordance towards the sport)

Task

the goal of movement or activity including the rules associated with that movement or activity and the equipment used (ie softball pitching: start back vs step back rule)

Human system is

constantly searching for stability (attractors)

Attractor states

Perturbation

Perturbation

disturbance of motion, course, arrangement or state (ie adjusting the speed of treadmill)

• If the magnitude of the change is high enough, the state of stability will be altered + the system will reorganize into a new form (walking→running)

• Well learned movement=deep level attractor state

  • High school → college sports

Parameters

features a motor program that are flexible + define how to execute the program

• Ability to produce alterations of a motor response without changing the skill

Parameters allows

• a center fielder to throw to 3rd base from different parts of outfield

• us to walk up/down steps of varying lengths

4 possible parameters

• overall duration

• overall force

• movement direction

• muscle selection

overall duration

speed at which skill is performed can change but the skill stays the same

• ie runners can ↑ their pace but their form will remain the same

overall force

force of amplitude (size) of movement can be modified

• ie soccer players can make short + long passes; open heavy + light doors

movement direction

variations in movement direction can be made to accomplish a movement goal

• ie dart players can throw to various locations on the board

muscle selection

use of different limbs or muscles to perform movements

• ie handwriting example; dribbling a basketball

Control parameter

• Influences the characteristics of the behavior

• Acts as an agent for reorganization; expressed as tempo, force, speed, temperature, frequency

• When the behavior loses stability, the control parameter is altered + a new behavior emerges

Rate limiters

• Factor or system that has the most control over development at a given point in time

• Individual constraint or system that constrains or delays the emergence of a skill (ie a strength deficiency from an injury)

• Development of a skill is only as advanced as the least developed system

Development of a skill is only as advanced as

the least developed system

• “A team is only as good as its weakest athletes”

• ie an infant with an advanced cognitive/neurological system who has the neurological capacity to walk but has very weak leg muscles (lack of muscles is limiter)

Rate limiters for older adults

 bone + joint health, vision, hearing, obesity, cognitive deficit

Rate limiters for walking in infants/toddlers

strength, head to body ratio, cognitive development

encourage learner to adapt movement behaviors to meet

task requirements

• Rule modification

• Scaling equipment

• Altering playing area dimensions

• Manipulation situation factors during performance

Why do we categorize learning?

• To allow practitioners to define needs of learners throughout the process

• Needs different at various stages (ie toddlers vs NHL player)

2 models of stages of learning

• Fitts + Posner’s 3 stage model

• Gentile’s 2 stage model

Fitts + Posner’s 3 stage model

Stages are defined by behavioral tendencies of the learner at certain points in the learning tendency

Fitts + Posner’s 3 stage model stages

• cognitive stage

• associative stage

• autonomous stage

Gentile’s 2 stage model

• Identifies stages from learner’s perspective 

• Emphasize learner’s goal

• Influence of task + environmental characteristics on goal

Cognitive stage of Fitts + Posner

development of basic involvement patterns

Learner in Cognitive stage of Fitts + Posner

1rst introduced to the skill

• Develops an understanding of movement’s requirements

• Attempts different techniques + strategies for learning (trial-and-error approach)

• Performance is inconsistent + filled with errors

• Can't detect or correct errors

Role of practitioner in Cognitive stage of Fitts + Posner

• Help learners detect + correct errors

• Manipulate task + environmental constraints to assist w/ development of movement patterns

Associative stage of Fitts + Posner

refinement of movement patterns

Learner in Associative stage

refines skill 1 particular movement

• Performance is more consistent; fewer errors

• Better at detecting errors + developing strategies to eliminate them

• Coordination is there; control is still a work in progress

Role of practitioner in Associative stage

• Correct errors

• Shifts from providing instructions to designing constructive practice experiences

• Provide feedback to help learners correct their own errors

Autonomous stage of Fitts + Posner

• Requires countless hours of practice

• Not all learners will make it to this stage

• Learner reaches highest level of proficiency

• Can perform multiple tasks simultaneously

• Consent + confident

• Can detect + correct errors

Role of practitioner in Autonomous stage

• Responsible for practice design

• Error detection

• Motivator: performer may become discouraged because improvement occurs less rapidly

Part 1 of Gentile’s 2 stage model

Getting the idea of the movement

Getting the idea of the movement

• Development of ability to discriminate between regulatory and non-regulatory condition

• Development of basic movement patterns

Part 1 learner’s goal

• Understand movement requirements + environment in which the task should be performed

• Organize a corresponding movement

• Attend to relevant info; ignore irrelevant info

Part 1 role of practitioners

• Facilitate development of basic movement pattern

• Communicate task’s goal to the learner

• Help identify regulatory + non-regulatory condition

Part 2 of Gentile’s 2 stage model

Refine the skill (depending on the environment in which the skill is performed)

fixation=

closed skill

diversification=

open skills

Fixation (closed skill)

• Fixed, stable environment

• Requires learner to replicate movement consistently + accurately

• Practice should reflect fixed conditions

• Non-regulatory cues should be implemented (ie crowd noise)

• Inter-trial variability implemented when appropriate

Diversification (open skill)

• Unpredictable environment (ie soccer player)

• Performer must adapt responses by diversifying movement patterns to reflect changing environment

• Variations in environment should be introduced

• Stimulate unpredictable environment

What indicators look for to know that learning has occurred?

• Movement patterns

• Attention

• Knowledge + memory

• Error detection + correction

• Self-confidence

Movement patterns (indicator): 4 improvements in movement patterns

• ↑ coordination + control

• More fluid muscle activity

• More effective energy expenditure

• ↑ consistency = regulatory permanent change in learning

↑ coordination + control

• freezing and freeing of DOF

• Novice will limit (freeze) the DOF to a more manageable quantity in order to accomplish a task’s goal

Freezing of DOF

stiff, rigid, inefficiently timed movements

• New learners

• As learner progresses, constrained DOF are “released”

Freeing of DOF

• Highly skilled performance

• Use multiple + sequential joint action (ie upper + lower body)

• Movement is faster

• ROM is more fluid at certain joints

More fluid muscle activity

• As proficiency ↑, the # of activated muscle needed to produce movements will reduce to only those that are fundamental for correct performance

• Timing + sequence in which the muscles are activated are altered

More effective energy expenditure

beginners are “mechanically inefficient” which results in ↑ energy expenditure during performance (ie novice vs Olympian swimmer)

↑ consistency = regulatory permanent change in learning

Must be careful not to confuse consistency of action with consistency of performance

Knowledge + memory (indicator)

• Accomplish performers have more knowledge about a skill

• 2 types of knowledge

2 types of knowledge with example of softball catcher during a game

• Declarative

• Procedural

Declarative

rules (ie catcher sits behind home plate)

Procedural

what to do in a given situation (ie the catcher will throw to 2nd to get lead runner out)

Error detection + correction (indicator

• With practice, learners are better able to detect + correct errors

  • Autonomous stages of learning

  • Fixation/diverscation stage

• ↑ confidence = ↑ motivation

  • Practitioner should make sure learner experiences some degree of success during practice especially when relearning something (ie relearning to walk)

Progress can be measured in 3 ways

• performance curve

• retention tests

• transfer tests

performance curve

obtained by plotting the results from repeated measurements of a specific performance across time

• Must select a variable that’s indicative of the skill (ie wouldn’t use a 3 pt shooting performance to measure free-throw shooting ability)

• 4 types of performance curves

4 types of performance curves

• Negatively accelerating

• Positively accelerating

• Linear

• S-shaped combination

Positively accelerating

little initial improvement but larger gains occurring later

Negatively accelerating

reflects the power law of practice

• When learning a new skill, performer will demonstrate large initial improvement in performance which slows later in practice

Linear

direct relationship between performance + time

• Not common because many factors

S-shaped combination

of negatively + positively accelerating

• Big spike then taper off (ie injury or time off)

Limitation of performance curves

• Represents temporary effects

  • Not a learning curve but a performance curve

• Constructed from measurements that are often obtained by calculating the means of several trials which can hide things

Retention tests

•  used to infer a relatively permanent change in performance has occurred

  • Best thing to make sure learning has occurred

  • ie riding a bike despite not doing to for months

Retention tests are given after a period where the learner

engaged in any practice