Role of sensory information on movement

Exteroceptors

State of the environment

They are eyes and ears

Proprioceptors

State of our own body

Eye as an effector

Extraocular muscles rotate the eyeball

Responsible for saccades, smooth pursuit, and vergence

How many pairs of eye muscles

3

What are the horizontal muscles

Lateral and medial rectus

What are the vertical rotation muscles

Superior and inferiors rectus

What are the torsion eye muscles

Superior and inferior oblique

Eye as a sensor

Light enters cornea and through pupil to the back of eye on retina and then converted to electrical signals by photoreceptors

Rods

Peripheral and night vision (not at fovea)

Cones

Central and color (at fovea)

Where do electrical signals go after retina

Sent via optic nerve to lateral and contralateral hemisphere, eventually making their way to primary visual cortex

How many visual pathways

2

What is visual pathway #1

Focal, cognitive, ventral, and vision for perception

What is visual pathway #2

Ambient, motor, dorsal, vision for action

Focal vision

• used to identify objects, uses memory

• Linked to consciousness

• VENTRAL (under to temporal)

• Main function: What is it?

Focal vision pathway

Retina, primary visual cortex, inferotemporal cortex

Ambient vision

• can be used without consciousness

• DORSAL (top to parietal)

• Main function: Where is it?

Ambient vision pathway

Retina, primary vis

Optic ataxia

• can recognize object be cant point to it

Visual agnosia

• unable to identify object but can point to it accurately

Illusions

• ventral pathway is fooled but dorsal is not

• Muller-lyre illusion and ebbinhaus-titchener illusions

Open loop control system

Input → information processing → output

Closed loop control system

Input → reference mechanism (error) → information processing → output BUT feedback is over lapping the whole thing from end back to input

Keele and Posner

Discrete aiming task

• move stylus to target 15 cm away with different MT goal times

• On random trials lights extinguished at movement onset

Keele and posner hypothesis

If movements are made quicker than the minimum time required to use visual feedback to correct the movement, errors should be the same for vision and no visions conditions

What time did Keele and posner see not enough time to process error

150 ms

Time to process visual information form Keele and posner

Between 150 and 250 Ms

Estimate on time to process visual information

100-160 Ms to correct a movement that’s underway with visual information

Task dependent!

Visual kinesthesis

Moving room experiment

Lee and whoever else

Vision vs balance

Vision overrides propriocpetion and give rise to overt responses like the moving room

Visual dominance

Held and Hein

Kitten experiment

• One kitten has visual experience of movements

• Other kitten has passive visual experience

Results of Held and Hein

• active kitten shows adaptive placing reactions

• Passive kitten shows no adaptive placing reactions

Correlating movements with changes in visual world is important for visuomotor coordination development

Visual search

Process of directing visual attention to locate relevant environmental cues

Use saccades!

Fixation

Focusing ones visual attention on a specific object

Video simulation technique - visual search investigation

Temporal: watch a video and determine what will happen when paused at different points

Event occlusion: mask out certain aspects to determine importance for accuracy

Eye movement recoridng

• where eyes look

• Central vision

  • Doesn’t measure peripheral and we need peripheral

• May underestimate visual attending

Feature integration theory

• group stimuli according to unique features = maps

• Maps are basis for further search process for identifying specific cues

• More distinctive features = quicker identification

Movement filter

Allows visual attention to be directed at moving items