LECTURE 5

Question 1

Open Loop Control

Answer 1

Input - Executive - Effector
Movement executive sends a command to the effectors, no use of sensory information to guide movement. Movements shorter than 150-200ms.

Question 2

Closed Loop Control

Answer 2

Input - Executive - Effector - Sensory Feedback
Sensory information from the effectors is fed back to the executive to inform the control centre about the movement. Movements longer than 200ms.

Question 3

Reflex theories of motor control

Answer 3

Reflexes form the basis of all movements (Sherrington).
Complex movements are enacted by response chaining. Response chaining/reflex chaining.

Question 4

Limitations of Reflex Theories

Answer 4

• Don’t allow for proactive action
• Poor account for open loop control
• Some movements don’t require afferent input

Question 5

Hierarchical theories of motor control

Answer 5

Human motor systems organised like a hierarchy. Assumes all aspects of voluntary movement planning and execution are the sole responsibility of higher cortical centres.
Perceive - decide - control

Question 6

Motor Programmes

Answer 6

Representations of movement stored in memory

Question 7

Generalised Motor Programs

Answer 7

Invariant parameters - relative sequencing of sub-movements, relative timing, relative forces
Variant parameters - specific motor units, absolute timing, absolute forces

Question 8

Schemas

Answer 8

Memory representations of movement parameters. If the movement goes wrong you immediately try to find a way that next time you can succeed in the movement.

Question 9

Motor response schema

Answer 9

Relationship between motor response and outcome

Question 10

Recognition Schema

Answer 10

Relationship between sensory experience and outcome

Question 11

Size principle

Answer 11

Depending on the amount of force required for movement, we recruit motor units dependent on the minimum amount required for movement.

Question 12

Limitations of hierarchical theories

Answer 12

• Cannot explain how direct perception works
• Cannot explain self-organising systems

Question 14

Assumptions of Dynamical/Ecological theories of motor control

Answer 14

• Human movement control is complex and dynamic
• Human perceptual motor system is capable of self-organising via interacting constraints
• Perception of affordances is direct via energy flows from environment

Question 15

Perceptual motor landscape

Answer 15

A manifold of all the possible movement possibilities available to an individual

Question 16

Self-organisation

Answer 16

Natural tendency for the human perceptual motor system to settle into attractors

Question 17

Attractors

Answer 17

Stable and functional patterns of organisation exhibited by the human perceptual motor system

Question 18

Order parameters

Answer 18

Collective behaviour of the systems many components

Question 19

Control parameters

Answer 19

A parameter of internal or external origin that when manipulated controls the system in a nonspecific fashion

Question 20

Stability/Instability

Answer 20

A qualitative state describing the tendency of a system to remain in a particular pattern of organisation or not

Question 21

Hysteresis

Answer 21

The tendency to remain in the current basin of attraction as the control parameter is increased

Question 22

Optic Flow

Answer 22

Patterns of apparent motion of objects caused by relative motion of the observer and a scene. It is a phenomenon of direct perception.