motor control unit 2

Performance Outcome Measures

Measures the result or outcome of a motor skill, such as distance thrown, speed, or reaction time.

Performance Production Measures

Measures how the nervous system, muscles, and limbs produce a performance outcome, such as EEG, EMG, force, or limb kinematics.

Reaction Time (RT)

Time between the presentation of the go signal and the initiation of movement.

Movement Time (MT)

Time between the initiation and termination of movement.

Response Time

Total time from the go signal to movement completion; RT plus MT.

Foreperiod

Time between the warning signal and the go signal.

Simple Reaction Time

One stimulus and one required response.

Choice Reaction Time

Multiple stimuli, each requiring a different specified response.

Discrimination Reaction Time

Multiple stimuli but only one requires a response; the others require no response.

RT and MT Relationship

Reaction time does not necessarily predict movement time, and movement time does not necessarily predict reaction time.

Fractionated Reaction Time (FRT)

Uses EMG to divide reaction time into premotor time and motor time.

Premotor Time (PRMOT)

Time between stimulus presentation and the first change in EMG activity.

Motor Time (MOT)

Time between the first change in EMG activity and the initiation of movement.

Purpose of FRT

Helps identify whether reaction-time changes are due to cognitive processes or mechanical features of the limbs.

Absolute Error (AE)

Magnitude of error without regard to direction.

Constant Error (CE)

Signed deviation from the target that indicates directional error or bias.

Variable Error (VE)

Variability of performance across attempts, calculated from the dispersion of constant error scores.

Radial Error

Error measure for two-dimensional actions based on distance from the target.

Measures error between a produced performance curve and a criterion curve over time, such as in tracking tasks.

Root-Mean-Squared Error (RMSE)

Kinematics

Description of motion without regard to force or mass.

Displacement

Change in spatial location during movement.

Velocity

Rate of change in position with respect to time.

Acceleration

Rate of change in velocity during movement.

Kinetics

Study of forces as causes of motion.

Kinetic Measuring Tools

Force plates and strain gauges.

Electromyography (EMG)

Measures electrical activity in muscles.

Electroencephalography (EEG)

Measures electrical activity in the brain.

Positron Emission Tomography (PET)

Measures concentrations of positron-emitting radioisotopes in body tissues.

Functional Magnetic Resonance Imaging (fMRI)

Visualizes brain function through changes in fluid flow, including blood flow.

Lesion Studies

Removal of brain tissue to examine its effect on function, performed on laboratory animals.

Action Preparation

Events in the nervous system from the intention to act until initiation of the action.

Reaction Time as Preparation Index

Reaction time is used as an index of the preparation required to produce an action.

Cognitive Level of Action Preparation

Includes deciding to act, developing a general plan, and adding movement details.

Neuromotor Level of Action Preparation

Involves CNS structures responsible for planning and executing an action.

Decision to Act

Action preparation begins with an intention or decision driven by internal goals or environmental demands.

Developing a General Plan

An action plan is developed using previous experience and evaluation of the situation.

Adding Details to an Action Plan

Selecting movement parameters, body parts, and relevant environmental characteristics.

Movement Parameters

Details such as force, velocity, and displacement selected for an action.

Hick's Law

Reaction time increases logarithmically as the number of response choices increases; RT = K log(N + 1).

K in Hick's Law

Represents simple reaction time in the lecture's formula.

N in Hick's Law

Represents the number of response choices.

Response Predictability

As the predictability of the correct response increases, reaction time decreases.

Precue Correctness

Probability that advance information about the correct response is accurate.

50/50 Precue Probability

No preference toward either response when the two alternatives are equally likely.

Unequal Precue Probability

The performer develops a bias toward the response with a higher probability.

Stimulus-Response Compatibility

Reaction time is faster when the relationship between stimulus and response is compatible.

Stroop Effect

Conflicting stimulus information interferes with the required response.

Foreperiod Length Regularity

A consistent foreperiod across simple RT trials generally decreases reaction time.

Movement Complexity

Reaction time increases as the number of component parts in a movement increases.

Movement Accuracy

Greater accuracy demands increase movement preparation time.

Movement Repetition

Repeating the same movement across trials generally decreases reaction time on later trials.

Alertness

Being alert and attentive reduces movement initiation time.

Attentional Focus During Preparation

Reaction time decreases when the performer focuses on the signal rather than the movement.

Four CNS Areas in Action Planning

Limbic system, association cortex, projection system, and spinal system.

Limbic System

Responsible for the intention to act according to environmental demands.

Limbic System Structures

Fornix, amygdala, hippocampus, and cingulate gyrus.

Association Cortex

Analyzes intentions generated by the limbic system and transforms them into general action plans.

Association Cortex Functions

Recognition, selection, and integration of relevant sensory input.

Projection System

Determines how an action should be carried out by adding movement dynamics to fit environmental constraints.

Projection System Structures

Includes sensory and motor cortical areas, basal ganglia, and cerebellum.

Spinal System

Regulates timing of muscle activation patterns and fine-tunes action execution.

Feedback Loops in Action Planning

Allow the CNS to modify movement by comparing the produced action with the intended goal.

Attention

Engagement in perceptual, cognitive, and motor activities before, during, and after motor-skill performance.

Conscious Attention

Attention activities that a person can consciously identify and verbally describe.

Perceptual Attention

Attention directed toward sensory information, such as what a person sees.

Cognitive Attention

Attention directed toward thinking and mental processing.

Motor Attention

Attention directed toward movement activity.

Non-Conscious Attention

Attention activities that are difficult to describe verbally but are evident during skill performance.

Automaticity

Performance showing evidence of non-conscious attentional activity.

Limited Attention Capacity

A limited amount of attention is available for performing activities simultaneously.

Central Resource Theory

Proposes one central supply of attentional resources shared among attention

Fixed Attention Capacity

The amount of available attention remains constant.

Flexible Attention Capacity

The amount of available attention varies across situations.

Kahneman's Flexible Central Resource Theory

Proposes that available attention capacity varies with arousal level.

Arousal Level

A person's excitability involving emotional, mental, and physiological states.

Maximum Attention Capacity

Occurs at the optimal arousal level for the situation.

Arousal-Performance Relationship

Performance is highest near an optimal arousal level and lower at very low or very high arousal.

Task Demands for Attention

Attention requirements are task-specific and change with skill learning.

Enduring Dispositions

Involuntary allocation of attention.

Momentary Intentions

Intentional allocation of attention.

Attention Allocation Policy

Distribution of available attention among tasks demanding attention.

Multiple Resources Theory

Proposes attention resources from multiple sources rather than one shared supply.

Wickens

Researcher associated with Multiple Resources Theory (1980, 1992).

Three Sources of Multiple Resources

Input/output modalities, stages of information processing, and codes of information processing.

Input/Output Modalities

Resource categories involving modalities such as vision and speech.

Stages of Information Processing

Perception, memory encoding, and response output.

Codes of Processing Information

Verbal and spatial codes.

Dual-Task Procedure

Assesses attention demands by having a person perform two tasks simultaneously.

Primary Task

Main task that the participant is instructed to perform normally.

Secondary Task

Additional task used to assess the attention demands of the primary task.

Geurts and Mulder (1994)

Studied standing balance and attention demands in unilateral leg amputees with a new prosthesis and non-amputees.

Geurts and Mulder Primary Task

Maintaining standing balance for 30 seconds.

Geurts and Mulder Secondary Task

Verbally determining whether addition problem sums were correct or incorrect.

Geurts and Mulder Results

Amputees showed increased body sway and arithmetic errors; non-amputees showed no body sway change.

Prezuhy and Etnier (2001)

Studied attention demands during different phases of horseshoe pitching.

Prezuhy and Etnier Primary Task

Pitching a horseshoe from 37 feet.

Prezuhy and Etnier Secondary Task

Responding to a tone by pressing a button in the non-throwing hand

Prezuhy and Etnier Measurement Points

Beginning of movement, maximum backswing, and just before release.

Prezuhy and Etnier Results

Secondary-task reaction time was highest just before release.

Strayer and Johnson (2001)

Studied effects of cell-phone conversations during simulated driving.