ND - Depth Perception - Week 4 Flashcards
List four possible visual outcomes from having two eyes. Explain each.
Fusion - stable representation from two eyes
Suppression - one eye’s image dominates perception
Diplopia - double vision
Rivalry - swapping between the two percepts
What is the first point in the visual pathway where neurons receive binocular input.
V1 is the first point
Can we see depth without edges? Explain.
Yes, random-dot-stereograms demonstrate that depth can be seen without border/edge cues
Consider random-dot-stereograms. Where is disparity encoded?
V1 cells
Where does disparity tuning occur in the brain (what stream)?
Dorsal stream
Where does dynamic-disparity occur in the brain? What kind of information does it provide (2)?
Some cells in the MST are linked direction/disparity selective cells
Provides information about parallax, depth cues for self-motion
List 9 monocular cues to depth.
Relative size
Occlusion
Cast shadows
Shading
Dynamic shadows
Aerial perspective
Linear perspective
Height within the image
Explain the relationship of retinal image size to object size in terms of monocular cues for depth.
The size of the retinal image of an object is proportional to the object’s size, but inversely proportional to the distance to the object.
Describe size interpretation and what it depends on. Give an examples using apparent circle sizes.
Depends on a range of cues relating to the visual context
Consider two same-sized circles, where one is surrounded by smaller circles and the other by larger circles
The one surrounded by smaller circles will appear larger compared to the one surrounded by larger circles (which appears smaller) even though they are both the same size
Describe linear perspective using train tracks.
The width of the tracks becomes smaller with distance - perspective
Two superimposed lines of equal distance over the tracks at different distances along the tracks will give the impression that the one further up the tracks is larger.
Describe what is meant by size constancy.
Our interpretation of the size of objects is relatively constant, despite large differences in the size of objects on the retina
Describe the monocular cues of texture.
Objects with more detailed, larger or shaper textures are seen as closer
Describe binocular rivalry.
When dissimilar images are presented to corresponding retinal locations in the two eyes, the two stimuli compete for perceptual dominance.
Evidence suggests that early stage binocular rivalry is encoded at what two regions of the visual pathway?
LGN and V1
Describe the parallax motion cue to depth.
Objects move at different speeds on the retina depending on the distance from the observer (assuming a static environment)
