Flashcards in Horopter and Distance Perception (F) Deck (48):
What is the indication when AFPP is outside the VM circle at all distances?
What is the horopter a reference for? 1. What happens if it is abnormal? 2
1. reference surface for spatial relationships
2. spatial distortions in distance
What does the apparent curvature of OFPP cue?
Where is the stereothereshold the smallest?
near the horopter
What is SILO driven by?
1. process disparity
2. determine distance
3. apply size constancy
What are the different types of direction perceptions?
What is the locus of points in physical space that have their images on corresponding retinal points (horizontal and vertical) called?
If you judge an object to be nearer to you, do you perceive the object to be smaller or larger?
What is the ability to perceive the correct size of an object despite changes in its retinal image size called?
What is the relationship of the visual angle to physical size and physical distance? 1. Is this a perceptual or physical law? 2
1. Law of Visual Angle
What law is an artist drawing more distant objects with a smaller angular subtense to represent greater distance an example of?
Law of visual angle
What is the concept of movement of body causes differential retinal image motion of objects at different distances?
What is considered to be the "true" horopter because of the fewest assumptions?
Where is the line horopter relative to the Vieth-Muller circle for a patient with nasal packing?
line inside the VM circle
What is the pictorial representation that is relative depth is cued by the position of highlights and shadows on objects? 1. Why does this happen? 2
1. light and shadow
2. we interpret shadows as if light were coming from above
If you overestimate the distance of an object (station point), what happens to the distance between objects?
Does the amount of temporal packing increase or decrease at near? 1. Why? 2
2. effect is neural in origin
Do we tend to over or under estimate station points? 1. What is the result? 2
2. depth foreshortened
What are the different methods for measuring the horopter?
1. the apparent frontal parallel plan (AFPP) criterion
2. the Nonius criterion
3. the center of region of binocular single vision criterion
4. the stereoscopic sensitivity (made to be maximum sensitivity) criterion
What is the phenomenon of seeing more texture at near than distance, giving you an idea of what is closer called?
At what distance is the OFPP equal to the AFPP? 1. What is this called? 2
1. about 1m
2. abathic distance
If you underestimate the distance of an object (station point), what happens to the distance between objects?
What would happen if you perceived an object moving nearer to you, however the image size of the object on your retina remained constant?
percept would appear smaller because of size constancy
What is the pictorial representation that is the relative sizes of retinal images provide information about the relative distances of the objects?
When working with prism to increase convergence or divergence how do you perceive size and distance relationships?
opposite of SILO (SOLI)
What are the types of distance perception?
1. relative: distance between objects
2. absolute: distance from body (egocenter)
Does the OFPP appear more concave, convex, or the same with increasing distance?
What is the pictorial representation to distance that has nearer objects occluding more distant ones called?
What is the plane parallel to the face plane that includes the fixation point called?
objective fronto-parallel plane
What are the components of spatial localization?
1. distance perception
2. direction perception
What is the pictorial representation that more distant objects are less distinct than closer due to atmospheric scatter?
What does the Nonius horopter pass through as it deviates from the VM circle? 1. Where does it intersect? 2
1. through axis of the head
What are the assumptions we make about object size when it comes to linear perspective?
1. similar looking objects are assumed to have identical sizes
2. continuous objects are assumed to be unchanging in size
3. familiar objects are assumed to be their expected size
How do the temporal beta angles for a patient with temporal packing compare to normal? 1. Nasal beta angles? 2
What is the method to measure the horopter in which the positions of points in physical space that appear to lie in an apparent fronto-parallel plane is analyzed?
What are the different types of constancies that the brain "assumes" about the world (and what each are irrespective of)?
1. shape constancy (irrespective of P.O.V.)
2. size constancy (irrespective of distance)
3. color constancy (irrespective of illuminant)
4. lightness constancy (irrespective of illuminant)
What is the method to measure the horopter in which the positions of points in physical space are such that the visual directions of the images formed in the two eyes are identical?
What relationship is the basis for linear perspective?
between angular size and distance
What are the motion parallax rules?
1. image velocity is inversely proportional to object distance
2. image velocity is zero for the point toward which the body is moving (this is focus of expansion)
3. images of objects farther than the focus of expansion have with motion
4. images of objets nearer than the focus of expansion have against motion
What law is an observer perceiving the representation having a smaller angular subtense as more distant and larger an example of?
What are the limitations of distance perception?
1. stereoscopic relative distance perception is excellent only for short distances
2. absolute distance perception is not very accurate
3. size and distance perception interact
4. oculomotor cues to distance are not great
What is the idea that the distance of object is from an observer along the ground is inversely related to the angle subtended from the horizon?
What is a 2-dimensional surface showing the lateral position of corresponding points called? 1. What are the targets? 2
1. Line horopter
2. vertical lines
Where is the line horopter relative to the Vieth-Muller circle for a patient with temporal packing?
line outside VM circle
What is the rational behind the AFPP criterion to measure the horopter?
equidistant objects should form a flat surface (Hering)
Where is the line horopter relative to the Vieth-Muller circle for a patient with no retinal density difference?
matches the VM circle
What is the relationship of the perceived size and perceived distance? 1. Is this a perceptual or physical law? 2
1. Emmert's Law