Chapter 6- Space Perception And Binocular Vision Flashcards
Euclidean
Geometry of the real world
Why 2 eyes
So we can lose one but still see; see more of the world
Visual field is limited
190 degrees from left to right with 110 covered by both
140 degrees vertically with 60 above eyebrows and 80 down cheeks
Retinal images vary in __ dimensions (__ and __), but the world is in ___ dimensions
Two (x and y), three
Number of visual cues in the image provide information about the third dimension, which is ___
Depth
Eye cues are also available in the state of the ___ muscles
Oculomotor; physically moving eyes, muscle signals
____ cues involve combining the info from our two eyes together
Neural; only in higher level brain area
monocular cues
1 eye; depth cue that is available even when the world is viewed by just 1 eye
binocular cues
2 eyes; info from both eyes; setereopsis, convergence, seeing more info
relative size
object of a known size; comparison
relative height
further away, the higher up they appear on retina; objects at different distances from viewer on the ground plane will form images at different heights in the retinal image
texture gradient
building with windows, see fine detail vs things smooshed together
occlusion
something in front of something else; cue to depth order
arial perspective
due to the atmosphere, you lose contrast with distance (scattering); more light is scattered when we look through more atmosphere
linear perspective
as parallel lines get further away, they start to look closer; parallel in 3D, look like they converge in 2D, converge at vanishing point
visual cues (pictoral cues) include
relative size, relative height, texture gradient, occlusion, aerial perspective, motion parallax, shadows
eye cues (muscle cues) include
accommodation, vergence
neural cues (cortical) inclue
binocularity disparity
occlusion and shadows offer ___ info only
ordinal; just know that one thing is in front of the other
accomodation
the eyes lens must change shape to maintain sharply focused image as object distance varies; change shape to influence optic power
light rays from distant objects are nearly parallel and don’t need as much ___ to bring them to focus
refraction
lights rays from close objects ____ and need more refraction for focusing
diverge
ciliary muscles ___, fibers slack, lens rounds to ___ strength for close vision
contract, greater
ciliary muscles ___ fibers taut, lens at ___ strength for distant vision
relaxed, minimum
less refraction for stuff ____, more refraction for stuff ___
far way, up close
vergence
the extraocular muscles turn the eyes in toward each other to maintain binocular fixation, to an extent that depends on fixation distance; vergence angle is how much eye is turned (strabismum)
divergence
fixating a distant object, vergence angle is small, eyes turn outward
convergence
while fixating a near object, vergence angle is large, eyes turn inward
binocular disparity
the differences between the two retinal images of the same scene
disparity
basis for stereopsis, vivid perception of the three-dimensionality of the world that is not available with monocular vision
eyes are set apart, so they get ____ images
slightly different
when looking at something, eyes straight ahead, spot fall on ___ of ___
both, foveas
if we aren’t directly looking at something, it falls ___
on different spots
the farther away the thing we are looking at is
the more inside it is on the fovea
the closer something is that we are looking at
outside fovea
crossed
right eye to left visual field, left eye to right visual field ; near disparity; in front of plane of fixation
uncrossed
eye and visual field are the same; far disparity; behind plane of fixation
zero disparity
equidistant from point of fixation, horopter line
stereopsis
ability to use binocular disparity as cue to depth
corresponding retinal points
geometric concept stating that points on the retina of each eye where the monocular retinal images of a single object are formed at the same distance from the fovea in each eye
horopter
the location of objects whose images lie on the corresponding points; surface of zero disparity
random dot stereorgrams show that ___ alone is sufficient to support and impression of depth
disparity
how are random dot stereogram’s constructed
one image is deliveredto each eye, two images contain identical arrays of dots, except that a subset of dots in one image is shifted in position relative to their position in the other image
an object is possible if ____ between two eyes made
correct match
objects on the ___ are seen as single imaged when viewed with both eyes
horopter
panum’s fusional area
the region of space, in front of and behind the horopter, within which binocular single vision is possible; wider range around the horopter
objects closer or farther away from the horopter fall on ___ points in the two eyes and are seen as two objects
noncorresponding
diplopia
double vision. if visible in both eyes, stimuli falling outside of panum’s fusional area will appear diplopic
binocular rivalry
the competition between the two eyes for control of visual perception, which is evident when completely different stimuli are presented to the two eyes
the competition of binocular rivalry is ____ an d___
equal and balanced
interocular suppression
image from one eye perceived, image from the other eye is not perceived; people with strabismus
input from two eyes must __ onto the same cell
converge
binocular neurons respond best when the retinal images are on __ points in the two retinas: neural basis for the ___
corresponding; horopter
___ neurons are tuned ot particular binocular disparity
binocular
texture gradient
relative distance of the object, squash faster along vertical rather than horizontal
motion parallax
images closer to the observer move faster across the visual field than images farther away; based on head movement, objects closer shift position more
cast shadows
1 object onto another, relative distance between object and light source
attached shadows
within same object, local depth parts of object put shadows on other parts of the object
shadows assume
convex objects, light is from above
combining info from different cues can derive robust, reliable depth estimates when given the ___ between cues
correlation
___ vary in availability and reliability
individual cues
assumed that human depth estimates are based on ___ average of cue values, with weights varying according to viewing conditions
weighted
hollow face illusion
concave mask perceived as convex when monocular cues dominate because of assumptions about objects and shadows
strabismus
misalignment in the eyes; brain suppresses 1 image of the 2 on each fovea to avoid diplopia
amblypia
weak vision in one eye
strabismus and amblypia are main reason to not have __ __ __
stereoscopic depth perception, environmental causes
