3. Stereopsis and physiological diplopia

Question 1

What is sensory fusion?

Answer 1

Neurophysiological processes in visual cortex combine the two images from the two eyes into a single percept.

Question 2

What is motor fusion?

Answer 2

Process of aligning the visual axes on the fixation target, so that corresponding points are superimposed.

Question 3

Which cues are needed for depth perception?

Answer 3

1. Ocular signals - vergence and accomodation
2. Monocular cues
3. Stereopsis - Disparity

Question 4

As disparity increases what happens?

Answer 4

The greater the disparity = greater sense of depth. This is as long as it is within panum’s fusional area, if not then diplopia.

Question 5

What is absolute depth?

Answer 5

Distance of object from observer

Question 6

What is relative depth?

Answer 6

Comparison of distance between two objects

Question 7

What are the two types of depth and which one does stereopsis process and how?

Answer 7

1. Absolute depth
2. Relative depth

Stereopsis processes only relative depth.
It can code the difference in disparities between objects.

Question 8

What is stereoacuity?

Answer 8

The smallest depth difference we can see

Question 9

Under what factors is stereoacuity greater?

Answer 9

1. At near stereoacuity is strongest.
2. Stereoacuity is greater for thos with larger interpupillary distances. This is because larger disparity

Question 10

What is considered as good stereopsis?

Answer 10

30-60 sec/arc