Term
| The key to combining the 2 images is? |
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Definition
is the presence of similar features in each DICHOPTIC STIMULUS ( half-images), independant stimulus presented to each eye alone
see pg. 122 fig. 5-1 |
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Term
Which two monocular images differ greatly in size and distrups fusion? |
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Definition
anisometropia and aniseikonia |
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Term
What type of pt. will note diplopia |
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Definition
intermittent convergence
divergence imbalances
strabismis of recent or sudden onset |
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Term
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Definition
| similiar image/contours falling on widelyu separated non- corresponding retinal pt. outside fusional area |
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Term
| Can misalignments of the visual axes which are dissimilar images form on corresponding pts? |
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Definition
Yes, the result is that two different objects are perceived as occupying the same location in visual space BINOCULAR CONFUSION |
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Term
Can dissimilar images fused together into a unified precept? |
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Definition
No, the visual system must use other mechanism to handle the to different monocular images |
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Term
| How does the visual system handl conflicting info |
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Definition
BINOCULAR SUPPRESSION--by ignoring or turning off either all or part of the image to one eyes, so that only one of the two different images reaches conscious perception |
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Term
|
Definition
is a failure to allow some monocular portion of the binocular field to contribute to the combined binocular precept |
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Term
Suppression undergoes CERTAIN type of suppressed region: which are? |
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Definition
1. reduced sensitivity to visual stimuli
2. elevated light detection
3. prolongation of rxn times |
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Term
| When does suppression begin ? |
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Definition
|
|
Term
| Does suppression only occur under bino condition? |
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Definition
|
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Term
|
Definition
| suppression of a portion of an image when 2 dissilimilar images are presented to the eyes |
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Term
Normal binocular suppression is called ? |
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Definition
physiological suppresion--prevents diplopia of most of the visual scene
prevents diplopia outside of panum's fusional area
ex: fixating a near target while observing a distant target & vice versa |
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Term
| What abnormal suppresssion called? |
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Definition
pathological suppression
usally adaptation to prolonged diplopia or bino confusion
visual system shuts off one eye in order to obtain Single vision
lacks bino summation and stereopsis |
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Term
Which eye will be dominant in case of strabismus pt? nondominant
what is alt. strab? |
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Definition
Fixating eye
deviating eye-- will be suppressed
switch eye dominance so that the formerly deviating eye is now the fixating eye and vice versa
unaware of switch, but can be consciously controlled |
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Term
| What type of image is more likely to suppress? |
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Definition
weaker, less salient image, dimmer, lower contrast, blurred, stationary or in the retinal periphery |
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Term
| Suppression can be triggered by dissimilar binocular inputs known as? |
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Definition
|
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Term
| what is binocular rivalry? |
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Definition
intermittent/alternating suppression of brightness, color and or contour fo one, then the othereye
- usually occurs with vastly dissimilar images in each eye |
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Term
| When is binocular rivalry the strongest? |
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Definition
Dissimilar contours are orthogonally oriented gratings ( gratings rotated 90 degrees angle relavtive to each other) imaged in each eye
-orthogonally oriented gratings are both of medium to high contrast or with both gratings at very low contrast which results in bino summation = plaid pattern |
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Term
| What type dissimilar targets are small in area, each eye's entire image of the target may be alternately suppressed ? |
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Definition
|
|
Term
| what type of dominance are large targets, patchwork perception, contours continuously change over time |
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Definition
|
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Term
| Where does alternation occur |
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Definition
| locally at each location independently which are called SPATIAL ZONES OF BINOCULAR RIVARLY |
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Term
What type of degrees of inhibition is same for most types of stimuli |
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Definition
| luminance , motion, contrast |
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Term
| Is chromatic stimuli are supressed to a greater extent than achromatic stiumuli |
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Definition
|
|
Term
| Is degree of inhibition remains the same throughout period of suppression ? |
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Definition
|
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Term
| A stimulus viewed greater proportion of time than stimulus |
|
Definition
|
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Term
| What are the similarities b/w Rivarly and pathological suppression ? |
|
Definition
1. removal of some parts of the VF from preception
2. similar types of dominant visual stimuli
3. degree of threshold elevation can vary in strength as fxn of stimulus characteristics |
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Term
| What are the differences b/w rivarly and path. suppression |
|
Definition
1. rate of change of visiblilty of targets in each eye
Rivarly--precept continually changes from moment to moment as a result of alt. suppression btw. the 2 eyes
- change is not under voluntary control
- region suppressed maintains an influence on the visual system although it not consciously perceived
Suppressed-- can still modulate length of suppression period
-- can occur even with 2 identical stimuli presented to each
eye
Suppression of rivarly is stronger than pathological suppression |
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Term
| Are chromatic channesls suppressed more than achromatic channels in rivarly or path. suppresion ? |
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Definition
Rivarly
not in path due to strab |
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|
Term
The time of onset of path. suppression ? physiological suppression? |
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Definition
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|
Term
Is Troxler effect due to suppression ? |
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Definition
| NO, it is due to absence of miniature eye mvmts. causing image stabilization |
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Term
| What is Da Vinci stereopsis? |
|
Definition
rivarly in natural viewing conditions
beneficial
occurs when a near object occludes a farther object
provides a cue to relative depths of the two objects
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Term
| What is dichoptic masking? |
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Definition
form of visual masking in which differing stimuli are presented to each eye
targets: target to be detected to one eye
mask that reduces visibility of target to other eye |
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Term
| Is Dichoptic masking and BIno rivalry behave similarly or differently ? |
|
Definition
DIFFERENTLY BUT can actually be combined
they are not the same phenomenon |
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Term
Saccadic suppression is bino rivalry or monocular suppression? |
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Definition
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Term
| The most determinant of fusing, suppressiong, undering rivalry is? |
|
Definition
| Similarity of targets in each eye |
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|
Term
| What is zone of suppression? |
|
Definition
the presentation of contour in one eye's image and field without contours in the other eye
suppression extends over a small area beyond the contour producing a halo
results from inhibitory effect of surround region of center-surround receptive field |
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Term
| Is suppression the strongest at contour location than placed in the retinal periphery? |
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Definition
| YES, the size of zone decreases with increasing spatial frequency of the targets |
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Term
|
Definition
similar shape and orientation, but different colors, luminance, or contrasts
fusion if shape and orientation can occur
fusion of luminance DOES NOT --> light and dark regions perceived as slivery,glossy shimmering
specialized form of rivarly |
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Term
| IF pt. has binocular fusion will they see luster? |
|
Definition
| YES , not seen by a pt with path. suppression |
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|
Term
Color mixing will occur?? |
|
Definition
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|
Term
|
Definition
|
|
Term
| Does rivalry prevent simultaneous perception of stereopsis ? |
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Definition
| NO, rivlalry and fusion with stereopsis are distinct processes |
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