Msp 2 Final

Front 1

what is vection

Back 1

the illusion of motion of one's ENTIRE SELF as a result of motion in one's peripheral visual field

ex: sitting in a stationary car and cars around move foward. it seems like you are moving backwards

Front 2

what is a point spread function

Back 2

1. image that an optical system forms of a point source
2. most fundamental obj.
3. forms basis for any complex object

Front 3

what is the relationship between vection and illusory motion

Back 3

although it can be caused by visual stimulation, vection is NOT considered to be a category of "illusory" (visual) motion

Front 4

what is the perfect optical system for a point spread function

Back 4

AIRY DISC

Fraunhofer diffraction pattern for a circular pupil

Front 5

what are characteristics of eye/head motion perception

Back 5

1. subject tracks stimulus with head/eye movement
2. retinal image of moving object remains stationary on fovea
3. info about obj motion involves muscular, EOM, and vestibular system.

Front 6

what is the relationship between airy disc and pupil size

Back 6

theta=1.22(lambda)/(pupil diameter)

increase in AIRY DISC=decrease in pupil diameter

Front 7

what are the characteristics of retinal motion perception

Back 7

1. requires motion of the objects image across the retina
2. info about obj motion mainly within "visual" pathways

Front 8

what is the cut off frequency of a normal pupil (2.5mm) modulation transfer function

Back 8

~60 cycles/deg (aka: cpd)

spot diameter corresponding to 60cpd is approx. 30 seconds of arc.

Front 9

what is the Troxler Effect

Back 9

1. the perceptual disappearance of a STABILIZED RETINAL IMAGE
2. retinal image is stabilized when it moves exactly with the retina, REGARDLESS of any voluntary or involuntary movements of eye

Front 10

what if the spot diameter is smaller than 30 secs of arc

Back 10

TREATED AS A POINT!!

1. produces approx. the same spatial distribution of light on the retina (retinal light distribution)
2. light will be less for a smaller spot

Front 11

what is the relational between the human visual system and light stimulation

Back 11

the human visual system is sensitive to CHANGES in light stimulation

Front 12

what is line spread function

Back 12

convolution of point spread functions along a straight line

Front 13

under normal conditions...why can't we see retinal blood vessels

Back 13

1. shadow of retinal blood vessels are stabilized retinal images.
2. they move WITH THE RETINA as the eye moves so their position on the retina DOES NOT change

TROXLER EFFECT

Front 14

detection threshold in relation to perceived size

Back 14

1. spot larger than 30 sec of arc all have different retinal light distributions
2. perceived size of a point can depend upon the observers detection threshold

Front 15

what is the Purkinje Tree?

Back 15

PURKINJE TREE:
by causing a rapid oscillation of the shadows of the retinal blood vessel across the retinal, you can perceive the pattern of the retinal blood vessel.

Front 16

point spread function vs. pupil size

Back 16

1. increase in pupil size = increase in aberrations
2. increase in pupil size=decrease in airy disc

Front 17

how is minimum amplitude of perceivable motion effected with retinal eccentricity?

Back 17

INCREASES TOWARD PERIPHERY

foveal: ~20 arc sec or less
20 deg: ~3 arc min
40 deg: ~5 arc min

*detect faster movements at the fovea

Front 18

why do we treat spots smaller than 30 sec of arc as a POINT STIMULUS

Back 18

any spot smaller than 30 sec of arc will have the same light distribution on the retina

Front 19

how is the minimum VELOCITY of perceivable motion effect with a nearby stationary reference stimulus?

Back 19

1. ~10X better in the presence of a nearby stationary reference stimulus
2. ~1-2 arc min/sec WITH reference
3. ~10-20 arc min/sec WITHOUT reference

*decreases with increasing luminance

Front 20

what is the considered a complete description of the eye's optical system? why?

Back 20

1. optical MTF
2. the optical performance of the eye and the OMTF depends on pupil diameter
3. high spatial freq cutoff of the eye's OMTF is highest for a pupil diameter ~2.5mm

Front 21

what are the FIVE ways by which an object might appear to move

Back 21

1. real motion
2. autokinetic effect
3. induced motion (motion contrast)
4. aftereffects
5. stroboscopic motion

Front 22

pupil size for narrowest point spread functions and best acuity?

Back 22

2.0-5.0mm

Front 23

what is the autokinetic effect

Back 23

illusory motion in which a small, stationary object viewed against an otherwise COMPLETELY featureless visual field, will appear to move about randomly within a small area

ex. small, station point of light viewed in the dark will seem to move

Front 24

what happens when the pupil is smaller than 2mm?

larger than 5mm?

Back 24

diameter smaller than 2mm:
1. wider PSF
2. poor acuity due to diffraction

diameter greater than 5mm:
1. wider PSF
2. poorer acuity due to peripheral optical aberrations

Front 25

what is induced motion

Back 25

1. illusory motion in which a stationary object appears to move due to the motion of surrounding obj or contours
2. always perceived to be in the direction opposite to that of the inducing objects

example: moon appears to be moving in the opposite direction of cloud movment

Front 26

what is minimum visible (detection) acuity

Back 26

INCREMENT THRESHOLD

1. angular subtense of the smallest object that can be detected visually AT VERY HIGH CONTRAST
2. acuity depend on contrast of the test target
3. quoted at 1 second of arc

Front 27

what is motion contrast

Back 27

1. a special case of induced motion
2. only operates across very short distances

Front 28

what is minimum localizable acuity

Back 28

Relative Spatial Localization
Hyperacuity

1. threshold (in visible angle) for a reliably discriminating small differences in the position of one object relative to another
2. threshold 4-10 arc seconds
3. very resistant to optical blur

Front 29

why do we see motion with repeating asymmetric patterns

Back 29

NEURAL IMAGE CONTRAST
1. high contrast points in the optical image are registered BEFORE low contrast point
2. ration of neural responses in the high and low contrast areas of the neural image change over time
3. apparent shift in phase is what activates the local velocity detectors

Front 30

what is vernier acuity

Back 30

1. subject is asked to indicate the spatial location of one target with respect to one or more other targets
2. changing the line length and spacing between the line effects the acuity

Front 31

what is the difference between motion ADAPTATION vs. motion AFTER EFFECT

Back 31

1. adaptation: illusory changes in the perception of motion that occur DURING prolonged viewing of moving objects

2. after-effect: illusory perception of motion of stationary objects OR changes in the perception of motion of moving objects AFTER prolonged viewing of moving objects

Front 32

what is another term for minimum separable acuity? what is it?

Back 32

resolution acuity: spatial resolution

the minimum visual angle between two objects or contours for them to be reliably discriminated as separated and distinct from on another

Front 33

waterfall illusion is an example of...

Back 33

MOTION AFTEREFFECT

Front 34

what are the requirements for minimum separable acuity

Back 34

1. good change in luminance discrimination (low contrast threshold)
2. relative spatial localization (hyperacuity)

Front 35

what is velocity adaptation

Back 35

prolonged viewing of an object moving at a constant velocity may cause a DECREASE in the PERCEIVED speed of motion

Front 36

what are the THREE requirements for recognition acuity

Back 36

1. good change in luminance discrimination (low contrast threshold)
2. relative spatial localization (hyperacuity)
3. prior experience of the object, memory and recognition ability

Front 37

what is direction specific adaptation

Back 37

motion detection and contrast detection threshold INCREASE during prolonged viewing of moving objects but only for objects moving in the SAME/SIMILAR direction

Front 38

what is recognition acuity (VA)

Back 38

the smallest visual angle of critical detail needed to accurately identify an object

Front 39

what is stroboscopic motion

Back 39

apparent motion:
1. resulting from the successive presentation of a stimulus at different locations along a continuous path
2. example lights going around a marquee

Front 40

what does measurement error of acuity depend on

Back 40

1. number of measurements made
2. slope of the psychometric function (steep slope gives a narrow range of error)

Front 41

what is KORTE'S LAW

Back 41

1. describes the relationship among various stimulus parameters necessary to maintain optimum PHI motion when any one parameter is changed

Front 42

what are NINE factors contributing to visual spatial resolution and recognition acuity

Back 42

1. pupil size
2. mean luminance (adaptation level)
3. contrast
4. stimulus orientation
5. retinal position
6. optical blur
7. crowding
8. motion velocity
9. age

Front 43

what is first order motion

Back 43

movement of areas that are defined by their LUMINANCE

Front 44

what is the effect of orientation on acuity

Back 44

1. vertical orientation is best
2. horizontal orientation is just as good
3. oblique orientation result in the WORST ACUITY

Front 45

what is second order motion

Back 45

movement of areas whose contours are defined by TEXTURE

NOT LUMINANCE

Front 46

LARGER LogMAR...

LARGER SNELLEN fraction...

Back 46

1. LARGER LogMAR, worse acuity

2. LARGER SNELLEN fraction, the better the acuity

Front 47

what is third order motion

Back 47

1. motion defined ONLY by difference in COLOR!!
2. motion defined as figures with NEITHER LUMINANCE NOR TEXTURE boundaries
3. PARVOCELLULAR PROCESSING

Front 48

what is crowding effect

Back 48

1. normal: VA is poorest when there are neighboring contours within 2-5 arc minutes of the test target
2. strabismic amblyopes: significantly greater effect (requires target isolation)

Front 49

what are the SEVEN characteristics of NORMAL neonate vision

Back 49

1. small eye (~16.5mm)
2. clear ocular media
3. reasonably good image quality
4. hyperopia and astigmatism common
5. small pupils (miosis)
6. poor control of accomodation
7. foveal photoreceptors are wider, shorter, and more widely spaced than in adults

Front 50

what is motion effect and dynamic acuity

Back 50

1. velocities lower than ~3-4 deg/sec can be tolerated with light, VA loss
2. obj motion lower than ~60-80 deg/sec can be tolerated with little loss of acuity as long as eye and head pursuit movements are not restrained

Front 51

what is coherent motion

Back 51

1. motion of elements that all share the same velocity of motion
2. form from motion
3. Gestalt organizing principal (common fate)
4. evaluates mainly MAGNOCELLULAR processing
5. elevated thresholds in glaucoma and ONH disease

Front 52

what is the difference between weber contrast and michelson contrast

Back 52

1. weber: used when studying the visibility of APERIODIC stimuli
2. Michelson: used when studying the visibility of PERIODIC stimuli

Front 53

what is the braddick limit

Back 53

1. maximum displacement threshold
2. typically ~15 arc minutes

Front 54

what is contrast threshold

Back 54

minimum luminance modulation required for the subject to see the grating (rather than just a gray field)

Front 55

what is short range motion

Back 55

1. SECOND order stroboscopic motion
2. within Dmin and Dmax range
3. SOA<100 msec
4. NOT perceived with DICHOPTIC STIMULATION or bright ISI

Front 56

what does contrast sensitivity function combine

Back 56

the sum of the components contributed by the optics (MTF) and the neuroretinal enhancement (RTF)

Front 57

what is long range motion

Back 57

1. FIRST order motion
2. operates with displacement larger than Dmax
3. SOA 100-500 msec
4. works WITH DICHOPTIC stimuli and with bright ISI

Front 58

at what spatial frequency (cpd) has the highest contrast sensitivity

Back 58

6-8 cpd

cutoff is at 60cpd

Front 59

what does short range and long range motion rely on?

Back 59

both are believed to rely heavily on MAGNOCELLULAR PATHWAYS

Front 60

in respects to contrast sensitivity which is more debilitating...optical blur or glare

Back 60

GLARE!!!

1. people usually adapt to the refractive errors

Front 61

what is aperture effect?
example?

Back 61

1. receptive fields of neurons signaling visual motion function as viewing apertures
2. the aperture itself can influence perception of the direction of motion within

example: Barber Pole Illusion

Front 62

what is the reason for low sensitivity in infants?

what is the reason for low resolution in infants?

Back 62

1. low sensitivity: result from photoreceptor morphology
2. low resolution: results from photoreceptor density

Front 63

visual illusions

Back 63

erroneous perception due to incomplete, ambiguous, or contradictory visual information

Front 64

what animal is closest to humans in CSF

Back 64

MACAQUE

Front 65

what are some theories that support object recognition

Back 65

1. feature analysis (bottom up)
2. global processing (top down)
3. computational models (newer bottom up)
4. feature integration theory (BOTH)

Front 66

how is MTF used

Back 66

evaluates the quality of an optical system by comparing contrast in the image to contrast of the object, for various spatial freq.

Front 67

what is analytical introspection

Back 67

STRUCTURALISM:
identify the smallest set of PRIMARY SENSATIONS necessary to uniquely identify any object

ex: a bunch of dots making up a picture

Front 68

how are square wave gratings created

Back 68

1. summing a set of sinusoidal gratings of INCREASING FREQ and DECREASING CONTRAST
2. the contrast of the lowest spatial frequency sinusoidal grating is greater than the square wave grating

Front 69

what are Pandemonium Models?

this is an example of...

Back 69

FEATURE ANALYSIS:
1. feature demons find vertical lines, acute angles, etc.
2. cognitive demons have ideas about the features of their letters
3. decision demon identifies the letter based on which cognitive demon "yells the loudest"

Front 70

what were the results of the campbell and robson findings

Back 70

detection threshold for square wave gratings were NOT the same as the for sin gratings of the same spatial freq

at threshold, sin gratings and square wave gratings look the same (only the largest sin component of the square wave was visible)

Front 71

what are GEONS

Back 71

GEOMETRIC ICONS
1. non accidental features, equally recognizable regardless of orientation
2. structures composed of geons should be "viewpoint invariant"
3. we recognize objects by recognizing the spatial combo of the various geons

Front 72

in respects to threshold what is the difference between sin and square wave gratings

Back 72

thresholds were typically 1.27x lower for square vs sin gratings of the same spatial freq

Front 73

most eyes growth happens within...

Back 73

the first 6 months

Front 74

what happens with CSF during mild refractive error, visual deprivation and mild amblyopia

Back 74

1. contrast sensitivity same as normal
2. high spatial freq loss

Front 75

what ethinicity tends to be more myopic

Back 75

ASIANS

Front 76

what happens with CSF during multiple sclerosis

Back 76

1. mid to low spatial freq. loss
2. decrease in contrast sensitivity

Front 77

what is the most important factor that leads to emmetropization

Back 77

time spent outdoors is most important for proper emmetropization

Front 78

what happens with CSF during cataracts, severe refractive error and severe amblyopia

Back 78

BOTH contrast sensitivity AND spatial frequency DECREASES!!

Front 79

how does form effect myopia

Back 79

1. depriving the eye of form vision promotes axial elongation and myopia (chronic image degradation can cause myopia)
2. the ocular changes in FDM are similar to those associated with childhood myopia
3. the potential for a clear retinal image is essential for normal refractive development

Front 80

what happens with CSF during paracentral glaucoma

Back 80

looks kinda normal but a little NOTCHED

Front 81

what is the role of optical defocus in treatment of refractive error

Back 81

1. optically imposed myopia:
to compensate, the eye must become more hyperopic
2. optically imposed hyperopia:
to compensate, the eye must become more myopic

Front 82

what are some psychophysical evidence for multiple spatial frequency channels

Back 82

1. SF size adaptation
2. SF size induction
3. SF masking
4. sub-threshold summation

Front 83

what happens with under corrected patients

Back 83

1. under correction DOES NOT prevent myopic progression in children
2. they actually will become more myopic

Front 84

spatial frequency in respects to selective adaptation

Back 84

1. prolonged viewing of a high contrast pattern makes subsequently viewed patterns harder to see

ADAPTATION RESULTS IN:
1. single mech. model: a drop in CS across all SF
2. multi. filter models: a loss in sensitivity limited to a narrow range of spatial freq centered on the adapting SF

Front 85

what is the consequence of traditional correcting lenses

Back 85

as a consequence of eye shape and/or aspheric optical surfaces, "corrected" myopic eyes often experience significant HYPEROPIC DEFOCUS across the visual field

Front 86

what happens if you stare at a specific spatial freq for a while?

Back 86

Adaptation will kick in

LOW SF will appear LOWER
HIGH SF will appear HIGHER

Front 87

AN INTACT FOVEA IS NOT ESSENTIAL FOR NORMAL EMMETROPIZATION

Back 87

AN INTACT FOVEA IS NOT ESSENTIAL FOR NORMAL EMMETROPIZATION

Front 88

what is size (SF) induction

Back 88

two same sized objects:
1. surround one with bigger objects then the original object will look smaller
2. surround one with smaller objects then the original objects will look bigger

Front 89

what are the implications of human studies of emmetropization

Back 89

1. contribution to myopia, concentrate on factors that are very CONSTANT over time
2. peripheral vision should be considered when assessing the effects of visual experience on refractive development
3. peripheral vision should be taken into account in order to optimize optical treatment strategies for myopia
4. inaccurate accommodation is significant risk factor in myopia
5. spending time outdoors is good for emmetropization

Front 90

what is spatial frequency masking

Back 90

1. if you have a low SF object surrounded by a lot of high SF object...the high SF will MASK the low SF object
2. in order to see the low SF object amongst the chaos you have to apply a LOW PASS SPATIAL filter.

vis versa

Front 91

what is a better why to correct myopia

Back 91

by increasing the effective curvature of field it would be possible to correct central errors and either correct peripheral errors or induce peripheral myopic defocus

Front 92

what are evidences of orientation channels

Back 92

1. orientation adaptation
2. orientation induction
3. orientation masking
4. sub-threshold summation

Front 93

photoablation of the fovea does not...

Back 93

photoablation of the fovea does not...
1. interfere with normal emmetropization
2. prevent recovery from induced refractive errors
3. prevent form deprivation myopia
4. prevent compensation for optical defocus

Front 94

what is subthreshold summation

Back 94

if the contrast of 2 gratings are below threshold are added together will exceed threshold and become visible...BUT ONLY IF their SF are similiar enough for them to share the same channel

if each stimulate different channels, the sum should NOT be visible

Front 95

what are some normal changes of the pupils and lens with increasing age

Back 95

senile miosis:
1. decreased in retinal illumination
2. increased depth of field

Lens Change:
1. Presbyopia: decrease in AA
2. yellowing of crystalline lens
3. increased light scatter

Front 96

what are some normal changes in refractive error with increasing age

Back 96

1. "with" to "against" the rule shift in astigmatism
2. increase in myopia
3. NO significant change in macular pigment density

Front 97

what happens to luminance to the retina as we age

Back 97

1. reduced light transmittance through smaller pupils
2. less light due to lens change
3. perceptually not tramatic because of light adaptation

Front 98

what happens to spectral sensitivity as we age

Back 98

1. decreased sensitivity for all wavelengths
2. greater decrease for short wavelength sensitivity

Front 99

why does the short wavelength sensitivity decrease more with age

Back 99

1. yellowing of the lens
2. greater sensitivity of SWS cones for metabolic damage (diabetes)

Front 100

how is color vision affected with age

Back 100

1. increase in tritan abnormailities
2. evident in DESATURATED D-15 testing
3. secondary to yellowing of lens, increased macular pigment density and metabolic disease

Front 101

how is contrast sensitivity affect with increasing age

Back 101

1. decrease beginning ~65 yrs.
2. mainly for midrange and high spatial freq
3. due to miosis, lens and vitreous change, as well as increase in density of macular pigment and neural factors

Front 102

how is visual (recognition) acuity impact with age (IMPORTANT)

Back 102

1. mild decrease in high-contrast recognition acuity beginning around 60-65
2. significantly greater decrease found in LOW CONTRAST recognition acuity

*snellen chart DO NOT adequately reflect an older patients loss of visual function in the real world

Front 103

what are two clinical test for disability glare

Back 103

1. brightness acuity tester (BAT)
-high contrast acuity with glare

2. Berkeley Glare Test
-low contrast acuity with glare

Front 104

what happens to disability glare with increasing age

Back 104

1. decreased spatial resolution in presence of bright, surrounding light
2. largely due to LIGHT SCATTER

Front 105

glare recovery with increasing age

Back 105

1. time to read two lines larger than before on the low contrast SKILL card after exposure to bright light
2. ~8x increase from ages 60-80+

Front 106

what happens to flicker perception as we age

Back 106

1. gradual decrease at ~20 years
2. larger decrease at ~70 years
3. both CFF and sensitivity decreases are due to neural factors

Front 107

at birth what does the normal eye look like

Back 107

1. small eye (16.5mm)
2. clear media
3. reasonably good image quality
4. HYPEROPIA and ASTIGMATISM
5. small pupils
6. poor accommdative control
7. photoreceptors are wider and shorter

Front 108

the first eye movements are...

Back 108

1. reflexive
2. saccadic

*existence of these early eye movements is that the neural pathways serving them must exist at birth

Front 109

newborns and tracking

Back 109

MOSTLY SACCADIC TRACKING

-little smooth pursuit tracking

Front 110

what pathway is utilized in OKN and smooth pursuit

Back 110

1. different NEURAL PATHWAYS (subcortical) than those involved with conscious perception
2. OKN can exist in people who are perceptually blind

Front 111

what eye movement bias does newborns exhibit

Back 111

1. NASAL BIAS
2. better OKN and smoother pursuit for T-N motion than N-T
3. normally disappears within first 3-5 months
4. persist in infantile onset strabismic amblyopia

Front 112

spectral sensitivity and color vision in new borns

Back 112

1. scotopic/photopic spectral sensitivity (adult shape by 1 month and adult sensitivity by 6 months)
2. R/G discrimination present at 2months (adult level by first year)
3. B/Y develop more slowly

Front 113

what is the contrast sensitivity timeline for newborns

Back 113

1. 0-10wks: improvement at all spatial freq
2. by 2 months: lateral inhibition
3. by 6 months: peak of CSF at adult position
4. ~5 years: increase sensitivity in high spatial freq and cutoff spatial freq

Front 114

when does stereopsis mainly develop in newborns

Back 114

1. little to no stereopsis before 3 months
2. EXTREMELY rapid development between 3-6 months

Front 115

what happens in the first six months of development

Back 115

1. CFF
2. scotopic/photopic luminosity
3. absolute light sensitivity
4. spatial freq of max contrast sensitivity
5. stereopsis (threshold ~1arc min)

Front 116

what happens within the first year of development

Back 116

red/green color vision development

Front 117

what happens between 3-12 years of development

Back 117

1. fine spatial resolution
2. fine relative spatial localization

Front 118

in art what gives rise to depth

Back 118

THREE DISTINCT CHANNELS:
1. form
2. color
3. movement