motor 4

Reaction Time (RT)

From onset of stimulus to onset of movement.Reaction Time in Children

Reaction Time in Children

Longer than adults; a 6-year-old is ~3x slower than a 17-year-old, with major improvement from ages 6–15

Reaction Time in Older Adults

Peaks around age 20, gradually declines until 60, then declines more rapidly from 60–90

Fitts' Law

Predicts movement time based on distance and target size; MT = a + b log2(2D/W)

Fitts' Law in Children

Spend less time and distance in first submovement; with practice increase first submovement time and movement smoothness

Fitts' Law in Older Adults

Favor accuracy over speed; less time/distance in first submovement; practice decreases MT but not submovement ratio

Attention in Children

Reduced attentional capacity, rely on controlled processing, selective attention driven by enduring dispositions

Selective Attention Development in Children

Infants prefer faces/contrast/colors; ages 2–5 too focused; 6–11 too broad; adolescence becomes adult-like

Dual Task in Babies

Neonates suck with eyes closed; 9 weeks suck in bursts/look during pauses; 3–4 months can suck and look simultaneously

Dual Task in Children

Coupling develops first (same task both hands); decoupling develops later (different tasks)

Attention in Older Adults

Reduced attentional capacity, difficulty dividing attention, inhibiting distractors, switching tasks; visual-spatial attention preserved

Memory in Older Adults

Short-term memory decreases ~1 item after 50; long-term mostly intact; procedural learning needs feedback; issues with encoding/retrieval

Neuroplasticity

Brain’s ability to form new connections and prune old ones; occurs throughout life (synaptic, network, cortical remapping)

Purpose of Dual Task Tests

Assess attention demands and ability to perform two tasks simultaneously; helps identify impairments

Dual Task Test Evaluation

Secondary task affects primary performance; evaluation depends on instructed focus (or both if none given)

Gait and Cognition (Traditional View)

Instability → slow gait → falls; cognition separately declines → MCI → dementia

Gait and Cognition (Alternative View)

Instability and cognition influence each other; both lead to slow gait, MCI, falls, and dementia; variability ↑ = fall risk

Attention

Limited, effortful processing that determines ability to perform tasks and multitask

Controlled Processing

Effortful, conscious, flexible processing limited by attentional capacity

Automatic Processing

Requires little/no attention; used in skilled performance; develops with practice

Processing Transfer

Practice shifts performance from controlled → automatic and closed-loop → open-loop

Factors Influencing Multitasking

Automaticity, task similarity, task complexity, arousal level

Filter/Bottleneck Theory

Suggests tasks processed serially causing a bottleneck (limitation: brain processes more in parallel)

Kahneman’s Theory (One Pool)

Single pool of cognitive resources influenced by available capacity and arousal

Inverted U Principle

Optimal performance at moderate arousal; too high/low reduces attention and alters cue use

Kahneman’s Allocation Rules

Ensure completion, enduring dispositions, novelty, and momentary intentions guide attention

Wickens’ Theory (Multiple Resources)

Multiple resource pools based on modality, processing stage, and code (verbal/spatial)

Focusing Attention (Width/Direction)

Attention can be broad/narrow and internal/external depending on task

Attention Switching

Shifting focus between tasks or stimuli; required for eye movement changes

Action Effect Hypothesis

Better performance when focusing on movement outcome rather than movement itself

Visual Focus Example: Catching a Ball

Narrow and external focus

Visual Focus Example: Walking Through Crowd

Broad and external focus

Visual Focus Example: Driving a Car

Broad and external focus

Visual Focus Example: Shooting Free Throw

Narrow and internal/external depending on strategy

Visual Focus Example: Lifting Weights

Narrow and internal (muscle focus) or external (movement outcome)

Index of Difficulty (ID) & Target Size

Larger target decreases ID

Index of Difficulty (ID) & Distance/Time

Greater distance or time increases ID

Speed-Accuracy Trade-Off (Preparatory Phase)

Decision-making phase; vision used for assessment

Speed-Accuracy Trade-Off (Initial Flight)

First submovement; ballistic, open-loop, minimal vision

Speed-Accuracy Trade-Off (Termination Phase)

Second submovement; error correction, closed-loop, vision-dependent

Reach-to-Grasp (Prehension)

Includes reach, grasp, manipulation; vision involved; follows Fitts’ Law

Handwriting

Example of motor equivalence; vision controls spatial accuracy

Locomotion Control

Controlled by CPGs; arm-leg ratio 1:1 normal, 2:1 slow; vision used for obstacle navigation

Catching and Striking (Vision Role)

Uses tau (rate of retinal change) to estimate time to contact