Lecture 4 - Motor Performance /Action Prep Flashcards
What is the Speed-Accuracy Tradeoff?
Accuracy requirements influence movement speed.
Emphasis on accuracy reduces speed.
Emphasis on speed reduces accuracy.
What is Fitts’ Law?
Movement time (MT) is predicted by:
- Movement distance (D) - Target size (W)
- MT = a + b log₂ (2D/W)
- Higher index of difficulty (ID) = longer movement time.
What is the formula for Fitts’ Law?
MT = a + b log₂ (2D/W)
What are examples of Fitts’ Law in practice?
Dart throwing.
Moving a cursor on a screen.
Peg-board manipulation in rehabilitation.
Reaching and grasping containers of different sizes.
How does vision contribute to manual aiming skills?
through 3 phases
Preparation phase: Assess regulatory conditions and specify movement characteristics.
Initial flight phase: CNS operates in an open-loop system.
Termination phase: Vision fine-tunes movement for accuracy.
What is Prehension?
The process of reaching for and grasping objects; include 3 components:
- Transport : moving hand toward object
- Grasp : taking hold of the object
- Object Manipulation : using the object as intended
What is the relationship between transport and grasp phases in prehension?
Initially thought to be independent.
Research shows they are interdependent.
Grip closure begins at 2/3 of movement time.
What is the role of vision in prehension?
plays a role through 3 phases
Preparation phase: Estimates movement requirements.
Transport phase: Central vision tracks object.
Grasp phase: Provides feedback to supplement tactile information.
How does handwriting demonstrate motor equivalence?
Handwriting maintains consistency despite variations in limb involvement.
Suggests spatial features are stored in memory in an abstract form.
Based on the study, What role does vision play in handwriting?
Vision maintains word spacing on a line.
Without vision, errors occur (extra/missing strokes, reversed letters)
What are Bimanual Coordination Skills and the types?
Movements requiring coordination of both hands.
2 types:
Symmetric: Both hands move similarly (e.g., rowing).
Asymmetric: Hands perform different actions (e.g., playing guitar).
Why is asymmetric bimanual coordination more difficult?
CNS prefers symmetric control.
Initial movements show coupling between arms.
With practice, individuals learn to decouple limb movements.
What are the three phases of catching a moving object?
- Initial positioning of arm and hand.
- Shaping of hand and fingers.
- Grasping the object.
What role does vision play in catching?
Vision provides advance motor control information.
2 critical time periods:
Initial flight: Assesses direction and distance.
Just before hand contact: Determines time-to-contact (τ).
Based on the study, How important is vision of the hands when catching?
Without vision: Errors in hand positioning.
With vision: Errors in grasping.
Experienced catchers rely less on vision due to proprioceptive feedback.
How do experts and novices differ in striking a moving object?
Experts track the ball longer.
Bat movement timing is consistent across different ball speeds.
Head position remains stable.
What are Central Pattern Generators (CPGs)?
Neural circuits in the spinal cord responsible for rhythmic movement (e.g., walking, running).
Influence from proprioceptive feedback from muscle spindles and Golgi tendon organs.
What are gait transition patterns?
Spontaneous change from walking to running at a critical speed.
No single factor responsible, but metabolic energy efficiency is a key theory.
What role does vision play in locomotion?
Contacting objects: Vision helps determine step length (e.g., long jump preparation).
Avoiding objects: Vision provides information on how to step over or around obstacles.
What is Action Preparation?
The time required to prepare the motor control system before performing a movement.
Occurs between action intention and movement initiation.
What is Reaction Time (RT)?
The most common index of action preparation time.
Research explores how different factors influence RT.
What is Hick’s Law?
RT increases logarithmically as the number of response choices increases.
How does predictability affect RT?
Higher predictability of the correct response = shorter RT.
Precue: Advance information that reduces RT (e.g., hint before response cue).
What is Stimulus-Response Compatibility?
RT decreases when stimulus and response locations are spatially aligned.
Stroop Effect: Processing word meaning is automatic, making color-naming tasks slower.
Based on the study, how does movement complexity influence RT?
RT increases with movement complexity due to greater motor program preparation.
How does movement accuracy influence RT?
Greater accuracy demands = longer RT.
Supports Fitts’ Law: Increased difficulty increases RT and MT.
What is the Psychological Refractory Period (PRP)?
The delay in response to a second stimulus when a first movement is already initiated.
Important in sports (e.g., faking in basketball).
How does performer alertness influence RT?
Warning signals help maintain alertness.
Foreperiod length: 1-4 seconds is optimal.
Vigilance effects: RT increases with prolonged alertness maintenance.
What is the best focus for reducing RT?
Focus on the signal (e.g., starting gun in sprinting), not the movement itself.
What are postural adjustments in action preparation?
Anticipatory postural adjustments stabilize the body before movement initiation.
Adapted to task demands.
What is Rhythmicity Preparation?
Pre-performance rituals improve relative timing of movement execution (e.g., basketball free throws).
How can practitioners apply action preparation research?
Use warning signals to reduce RT.
Ensure stimuli and movements are spatially compatible.
Encourage athletes to fake movements for an advantage.
Rehabilitation should focus on postural preparation as well as movement execution.
