motor learning test 2

Motor Program

A prestructured set of movement commands that defines and shapes a movement, organized centrally by the nervous system before execution.

Basic Open-Loop System Parts

An executive that plans the actions and an effector that carries out the pre-programmed instructions.

Open-Loop Control Efficiency

In stable and predictable environments (i.e., closed skills).

Absent Feature in Open-Loop Execution

Feedback, which prevents any error correction during the process.

Open-Loop System Dominance

For very fast or brief movements (e.g., a punch or kick) where no mid-course sensory adjustments are required.

Observation About Skilled Movements

They appear as fluid actions executed as a single unit, suggesting preplanned organization with minimal feedback reliance.

Reaction Time (RT) Studies and Motor Program Theory

They show that movement programming affects the time it takes to initiate a movement.

Movement Complexity and Reaction Time (RT)

RT slows (i.e., the RT interval increases) when more elements are added, multiple limbs are coordinated, or movement duration increases.

Startle RT

The reaction time to a stimulus (like a loud 130 dB noise) that triggers a preplanned movement up to 100 ms faster than a voluntary reaction time.

Startle RT Evidence for Motor Programs

It suggests the executive prepares the motor program in advance, and the startle accelerates its release.

Deafferentation

The surgical removal of sensory nerve inputs in the spinal cord, eliminating feedback from limbs while preserving motor pathways.

Deafferentation Studies Evidence

Movements can occur without sensory input from limbs, supporting the idea that motor programs centrally control actions in an open-loop manner.

Central Pattern Generators (CPGs)

Specialized neural networks that generate rhythmic, patterned outputs for innate activities like walking, chewing, and breathing.

Point of No Return in Action Inhibition

The moment the motor program commits to execution; for simple movements, this "go signal" is sent approximately 130-150 ms before the intended action.

Quick Elbow Extension Block EMG Studies

The predefined muscle activation timing (triple-burst pattern) occurs for about 100-120 ms even though no motion happens, indicating preplanned execution independent of feedback.

Key Functions of Motor Programs

They organize the many degrees of freedom into a coordinated unit, and they modulate reflex pathways.

Reflex-Reversal Phenomenon

When reflex responses vary depending on when the stimulus is applied in the movement phase (e.g., leg extension vs. flexion in a cat depending on swing/stance phase).

Novelty Problem in Simple Motor Program Theory

The challenge of explaining how unique movements or newly learned actions are produced.

Storage Problem in Simple Motor Program Theory

The challenge of needing a separate program for every possible movement variant.

Generalized Motor Program (GMP) Theory Developer

Schmidt (1975).

GMP Theory Addressing Storage and Novelty Problems

It proposes that a single stored pattern (GMP) can be flexibly adjusted during execution via parameters.

GMP theory

It proposes that a single stored pattern (GMP) can be flexibly adjusted during execution via parameters.

Invariant Features

The core, unchanging characteristics of a motor program that define its fundamental structure and remain stable across executions (e.g., relative timing).

Surface Features

The observable characteristics of a movement that change with each execution, reflecting the specific way the GMP is expressed (e.g., speed, size).

Parameterization

The process of tailoring a motor program to the situation by adding specific details (parameters) before execution.

Parameters in GMP theory

Adjustable characteristics, such as movement speed, movement amplitude, or the limb used, that are applied to adapt the GMP.

Relative Timing

The proportional timing of different segments within a movement that stays constant regardless of the overall duration or speed.

Armstrong's study

Participants maintained the same timing ratios (peaks) of a lever movement even when performing the action too quickly.

Invariant feature difference between walking and running

Relative timing (each class of movement has a unique, yet invariant, relative timing pattern).

Movement time and movement amplitude

Two parameters that adjust the surface features of movement.

Effector choice

What parameter allows the same GMP to be used for writing with the dominant hand, the non-dominant hand, or the foot?

Fitts' Law

The principle that the time to complete a movement (MT) depends on the distance moved (A) and the precision required (W).

Index of Difficulty (ID)

The term $Log_2(2A/W)$ in Fitts' equation, which quantifies how challenging a movement task is.

Causes for ID increase

A larger movement amplitude (A) OR a smaller target width (W).

Relationship between MT and ID

MT has a linear relationship with ID, meaning MT increases predictably as ID increases.

Speed-Accuracy Trade-off

The tendency for people to sacrifice speed (increase MT) to maintain acceptable levels of accuracy.

Why slower movements improve accuracy

They allow more time for error detection and correction using visual feedback (a blending of open-loop and closed-loop control).

Fitts' Law applicability

Holds true for reciprocal tapping tasks and single movements.

Schmidt's Law

How movement time (MT) and distance affect accuracy in very fast movements where feedback corrections are minimal.

Effective Target Width ($W_e$)

The standard deviation of movement endpoints, used to quantify the amount of aiming error in rapid movements.

Schmidt's Law on aiming errors ($W_e$)

Aiming errors increase linearly with average movement velocity ($A/MT$).

Type of movement for Schmidt's Law

Applies specifically to rapid, open-loop movements (≤ 200 ms).

Why errors increase with speed or distance

Increased force is required, which generates more variability (neuromuscular 'noise') in muscle contractions, causing the movement to deviate.

Exception to the speed-accuracy trade-off

In near-maximal efforts (e.g., force above 70% of maximum), force variability levels off, and reducing movement time can actually enhance spatial accuracy.

Visual illusions affecting aiming accuracy

The Ebbinghaus-Titchener illusion and the Müller-Lyer illusion.

Visual Illusions

Practice with a perceptually larger target (due to surrounding circles) led to greater retention of performance improvement the next day.

Accuracy in Temporal Tasks

Measured by how consistently participants achieve the goal Movement Time (MT), assessed as timing variability.

Reducing MT Effects

Reducing MT decreases timing variability and improves temporal accuracy (e.g., halving MT roughly halves timing errors).

Swing MT Reduction

Delays the swing's start, providing extra time (e.g., 20 ms) to view the ball's flight and anticipate its trajectory.

Gunslinger Effect

The phenomenon where self-initiated movements are slower than movements initiated reactively to an opponent's move.

Exteroception

Sensory information that originates outside the body (primarily through vision and audition).

Proprioception

Sensory information arising from within the body (about limb position, muscle tension, and orientation relative to gravity).

Inherent Feedback

Cues derived from exteroception and proprioception that are directly available to inform us about the quality and outcome of our movements.

Vestibular Apparatus Components

Saccule, Utricle, and Semicircular canals.

Joint Receptors Function

To provide information about extreme joint positions, acting as limit detectors of joint movement.

Muscle Spindles

Detect muscle stretch (changes in muscle length).

Golgi Tendon Organs (GTOs)

Detect tension or force; they regulate force production by inhibiting muscle contraction if tension becomes too high.

Cutaneous Receptors Function

To respond to pressure, temperature, and touch, contributing to our haptic sense.

Closed-Loop Control System Parts

Executive, Effector, Comparator, and Error Signal.

Comparator Role

To compare the expected state (feedforward) to the actual state (movement-produced feedback) to define the error.

Feedforward Information

The anticipated sensory consequences of the movement that should be received if the movement is performed correctly.

Closed-Loop Control Limitation

It requires several hundred milliseconds to process errors, limiting corrections to about three per second.

Fast Reflexive Proprioceptive Loops

M1 (Monosynaptic) and M2 (Multisynaptic).

M1 Loop Latency

Approximately 30-50 ms.

M2 Loop Latency

Approximately 50-80 ms.

M3 Process

Voluntary Reaction Time, which involves full information processing and deliberate, goal-directed corrections with a latency of hundreds of milliseconds.

Visual Processing Streams

The dorsal stream and the ventral stream.

Ventral Stream Function

The 'What' pathway, specialized for conscious object identification.

Dorsal Stream Function

The 'Where' pathway, specialized for non-conscious movement control.

Tau ($\tau$)

A variable that specifies the time remaining before an object reaches the plane of the eye, used by the dorsal stream for interceptive timing.

Quiet-Eye Effect

The tendency for highly skilled performers to fixate their gaze for an extended period just moments before the movement begins, potentially stabilizing visual information or shifting attention to motor programming.