Fusion, Rivalry, and Suppression Flashcards Preview

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Flashcards in Fusion, Rivalry, and Suppression Deck (41)
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where does fusion happen in the brain
where do we stop seeing monocularly in the brain

fusion happens in the visual cortex
stop seeing mono in layer 4C of the striate cortex


what are the 2 parts of fusion process

1. sensory: images near corresp points are fused
2. motor: move eyes in or out to fuse images at diff distances


what are the 2 types of diplopia, which is abnormal

physiological: nonfixated objects off the horopter
pathological: seeing 2 of the image you are paying attentino to, NOT NORMAL


what is confusion
where is it most visible in
what does it usually accompnay
another name?

when you perceive 2 diff objects to be in the exact same place in the vf
-most visible in foveal vision
-usually accompanies diplopia
-aka binocular rivalry


what is panum's area

an area on the retina of one eye wehre an image may be placed and still fuse w/ an image at a fixed location in the fellow eye


what is panum's space

the region of 3D space where singleness is perceived


do all points fused in panum's area appear in the same location in visual space

no-each diff pair of retinal points in PA creates a unique stereo depth and direction in visual space so there is no loss of spatial info w/ fusion


where is the horopter in panum's space

in the middle


what is allelotropia

the oculocentric directions of fused images are averaged to form a cyclopean direction
-direction averaging process is influenced by ocular dominance


how is PA related to retinal eccentricity

PA size increases w/ retinal eccentricity


when patients report diplopia, where is it usually from

-it is not easily observed in peripheral vision


how does PA change in the periphery

increases as you move out to the periphery


what kind of motion increase the size of PA

target motion and patient motion


higher spatial freq (sharp edges) are associated w/ ____ PA size



what are the various sizes taht have been reported for foveal panum's area?
using what kind of things?

2' (woo, using fine bars)
6' (ogle, using horopter rods)
15' (mitchell, using small flashing spots)


how is PA shaped for very brief stimuli?
how is it shaped for long duration stimuli?
how is it shaped for static targets?
how is it shaped for foveal?

-round for brief
-PA diamter slightly increased vert and greatly increased horiz (3x) for long duration
-horizontal ellipse for static
-elliptical for foveal


how is panum's area is strabismic patients

most constant strabismus have no fusion or panum area


why do patients w/ microtropia have single peripheral vision

-ocular misalignment is too large in microtropes to allow images to fall w/in normal panum's area in the foveal macular area


how does PA develop in pts w/ constant microtrope strab

very large panum's areas in the periphery


what is binocular summatino

a change of nonspatial quality of vision caused by binocular interaction


what are the possible levels of mathematical binocular summation

1. facilitation: when stimulus is more than twice as bright OU than w/ one eye. 1+1>2
2. complete summation: when stimulus is twice as bright OW
3. partial summation: when stimulus is brighter OU
4. zero summation: when stimulus is as bright OU
5. inhibition: when stimulus is not as bright OU


what is most binocular summation in terms of math

zero summation or partial summation


how do eyes behave for dim scotopic images falling outside panum's area

weak stimuli more detected w/ 2 eyes than 1 bc you get 2 changes of detection


how is binocular summation related in CFF, contrast threshold, and resolution threshold

CFF: goes up
contrast threshold: goes down
resolution threshold: goes down bc of contrast threshold


how are small differences in luminance and large difference in luminance handled by the brain

small: averaged by the brain
large: not averaged and the dimmer eye is suppressed


what is color luster

for small differences of color btwn the 2 eyes image, we average them


what color does the eye end to see more w/ brighter luminance? dimmer luminance?

brighter: eye tends to see things more towards blue
dimmer: eye tends to see images more toward red


what does the eye do for large differences btwn colors of the 2 eyes

we do not average them
we will see rivalry (see one color then it turns into another, then back to the first)
-rate of alternation is dependent on luminance


what is interocular transfer
when does this happen

binocular vision ells get adapted to a pattern when looking at another pattern and maysee an aftereffect which affects the new pattern
-happens w motion (waterfall effect), tilt, and size


when does suppression occur
when does amblyopia occur

suppression=BINOCULAR VISION, momentary thing
amblyop=monocular vision