Motion Perception Flashcards
What are the three main functions of eye movement?
To keep the image of things that interest us on the fovea (attention-driven).
To keep images of moving objects stationary on the retina.
To compensate for head movements - keeping eyes locked on a screen while the head moves in any direction.
How does eye movement work?
Extra-ocular muscles.
Various pairs of antagonistic muscles move the eyeballs, there are muscles that move the eyes up & down, side to side and rotate the eye.
Which nerves control eye movement?
3 - Oculomotor nerve.
4 - Trochlear nerve.
6 - Abducens nerve.
What are the four types of eye movement?
Saccadic.
Vergence.
Pursuit.
VOR - Vestibular Ocular Reflex.
What are Saccadic movements?
the most common eye movements, they re fast movements in Bothe yes which move the Fovea towards the object.
don’t really have any voluntary control over the speed of saccades.
How many fixations occur in normal vision?
a typical fixation lasts about 250ms which means that we usually have about 3-4 fixations per second. we rarely keeps our eyes focussed on anything for very long unless we have to.
What is the fovea?
the high-resolution portion of the retina which is responsible for the entire of our vision.
What are pursuit movements?
smooth movements in the eye which are made in order to keep fovea focused on a moving target.
involuntary, therefore cannot have these movements without a target moving.
What are vergence (conjugate) movements?
movement of the eyes which keeps the image of an object focussed on the fovea on each of our eyes as we move the object closer ad further away.
what are convergent and divergent movements?
convergent - keeps the eyes focussed on an object moving closer to us.
divergent - keeps the eyes focussed on an object moving further away from us.
what is the vestibular ocular reflex?
a critical type of involuntary reflex which stabilises the visual field and the retina when the head is moving. a result of the reflex loop between the vestibular system and the cranial nerves that are responsible for innovating our eyeballs.
