Eye movements and perception of motion

Question 1

Why do we move our eyes?

Answer 1

• In order to place the image of the thing that interests us on the fovea in order to get the highest resolution.
• To compensate for head movement
• Keep images of moving objects stationary on the retina.

Question 2

What are antagonistic muscles?

Answer 2

Pairs of muscles that work alternatively.

Question 3

What are the 3 muscles in the eye?

Answer 3

Medial rectus + lateral rectus
Superior rectus + Inferior rectus
Superior Oblique.

Question 4

What is vergence (or conjugate) eye movements?

Answer 4

Points the fovea at a near or further away target, prevents double vision.
The eyes rotate in opposite directions.

Question 5

What are saccadic movements?

Answer 5

Moves the fovea to an object of interest, very fast and accurate, effectively blind during a saccade and both eyes move together.

Question 6

What are pursuit movements?

Answer 6

Their purpose is the keep our fovea on a moving target, it is involuntary and cannot be initiated in the absence of a moving target.

Question 7

What are Vestibular Ocular Reflex movements, (VOR) ?

Answer 7

They keep the image of the world stationary on the retina when we move our head.

Question 8

What did Riggs et al do?

Answer 8

Shone an image from projector, mounted a contact lens in front of the eye in order to carry a small mirror. The image was projected onto the little mirror which then reflected the image on the screen in front. Added more mirrors to reflect the light more in order to project the image back onto the fovea.

Question 9

What did Riggs et al find?

Answer 9

That when they move the image on the projector or the screen the image at the back of the eye was always stabilised, demonstrating VOR movements. Also that once the eye had stabilised the image it began to fade.

Question 10

Why do things not fade when fixated on in the real world?

Answer 10

Because the eye is never perfectly stable in the world, due to the controlling of 3 muscles there will always be some tremor even when we believe our eyes are still.

Question 11

What is apparent movement (Phi movement)?

Answer 11

Must be just right to see, not too fast and not too slow.

Question 12

What is real physical movement?

Answer 12

Movement of things such as car, person, real life movement.

Question 13

What is induced movement?

Answer 13

Experience when two things are near each other and it feels like one os moving when it is in fact the other.

Question 14

What is motion aftereffects?

Answer 14

When motion is experienced after the absence of real motion in the opposite direction to the stimulus.

Question 15

What is the structure for motion?

Answer 15

Objects you can only see when they are moving.

Question 16

What is motion induced blindness?

Answer 16

Loosing or suppressing the stationary elements of something as the brain is focused on the motion.

Question 17

What is motion capture?

Answer 17

Small elements that move with the larger elements.

Question 18

What is kinetic depth?

Answer 18

When a rigid object moves sideways all points on the object move at the same speed, when a 3D objects rotates in space points at the equator move across the retina faster than points at the poles.

Question 19

What is biological motion?

Answer 19

The idea that when a few markers are stationary they are unrecognisable but when they move in the right order it can be perceived as a biological motion of a creature moving for example.