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Flashcards in Block 10 Deck (185)
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1
Q

Changes in luminance across space

A

Spatial vision

2
Q

Changes in luminance over time

A

Temporal vision

3
Q

What is the difference between low and high modulation depth with looking at a graph

A

High modulation depth appear taller than low modulation depth

4
Q

Resolution of low modulation depth

A

Low

5
Q

How does low modulation depth appear: flicker or steady

A

Steady

6
Q

Resolution of high modulation depth

A

High

7
Q

How does high modulation depth appear: flicker or steady

A

Flicker

8
Q

How does high and low temporal frequency differ on a graph

A

High appears as more periods than low

9
Q

Which frequency flickers at a low rate

A

Low temporal frequency

10
Q

Which frequency may flicker at a higher rate

A

Higher temporal frequency

11
Q

Unit for temporal frequency

A

Hertz

12
Q

1 Hz equals

A

1 cycle/second

13
Q

What is the CFF

A

Frequency at which the flicker can no longer be resolved

14
Q

Where the stimulus first appears stead

A

CFF

15
Q

What represents the high temporal resolution limit of the visual system

A

CFF

16
Q

Can be though of as temporal acuity

A

CFF

17
Q

Is CFF higher for photopic or scotopic

A

Photopic

18
Q

Why is the CFF higher under photopic conditions

A

Due to speeding up of retinal processes that occurs at increasing levels of light adaptation

19
Q

What happens to CFF as the retinal illumination increases

A

CFF increases

20
Q

Max TMTF?

A

10 Hz

21
Q

Max sensitive is to what frequencies

A

Moderate

22
Q

Reduced sensitivity to what frequencies

A

Low and high

23
Q

What happens to CFF as the stimulus area increases

A

CFF increases

24
Q

How are temporal properties of the retina related across eccentricity

A

Similar

25
Q

Why do stimuli at the fovea appear steady, but may flicker in the periphery

A

Higher temporal resolution in periphery

26
Q

Flickering does what the nearby retinal blood vessels

A

Dilate

27
Q

Visual system’s reduced sensitivity to low temporal frequencies is the inability to perceive stationary or stabilized retinal images

A

Troxler phenomenon

28
Q

What keeps us aware of our world as we focus on a target

A

Small, involuntary eye movements (saccades)

29
Q

Are we sensitive to low temporal frequencies; what happens to borders

A

No; they disappear

30
Q

Are we sensitive to moderate temporal frequencies? What happens to the border

A

Yes; border stays

31
Q

What frequencies does lateral inhibition affect

A

Low temporal frequencies

32
Q

High frequency TMTF is due to

A

Neural constraints

33
Q

Provides info regarding both spatial and temporal processing

A

Masking

34
Q

Mask and target presented at the same time

A

Simultaneous masking

35
Q

More pronounced in amblyopia patients

A

Simultaneous masking

36
Q

Reduction in acuity caused by surrounding spatial patterns is sometimes referred to as

A

Crowding phenomenon

37
Q

Target precedes the mask

A

Backward masking

38
Q

Mask is brighter and interferes with detection of the target

A

Backward masking

39
Q

Backward masking where mask and target are spatially adjacent

A

Metacontrast

40
Q

Visibility of a briefly presented target is reduced by subsequent presentation of a spatially adjacent mask

A

Metacontrast

41
Q

Mask precedes the target

A

Forward masking

42
Q

Mask reduces the visibility of a subsequently presented, spatially adjacent target

A

Paracontrast

43
Q

When optotypes are surrounded by spatial patterns, the visual acuity

A

Decreases

44
Q

When a mask reduces sensitivity to previously presented spatially adjacent stimuli, the phenomenon is referred to as

A

Metacontrast

45
Q

The VA of amblyopia patients is poorer when measured using a snellen chart than when measured with isolated optotypes because of

A

Simultaneous masking

46
Q

When flicker light falls on retina, nearby vessels

A

Dilate

47
Q

What prevents our visual world from disappearing when we fixate on an object

A

Small, inhibitory eye movements (microsaccades)

48
Q

When the modulation depth is very small, the screen appears

A

Steady

49
Q

The maximal TMTF value of a young healthy eye is

A

10 Hz

50
Q

At which temporal frequencies does the TMTF show max sensitivity

A

Moderate temporal frequencies

51
Q

The reduction in sensitivity to low temporal frequencies is caused by

A

Lateral inhibition

52
Q

The detection of high temporal frequency is limited by

A

Speed of neural processing

53
Q

As the area of the stimulus increases, the CFF

A

Increases

54
Q

Beyond CFF, the stimuli appears steady bc

A

It cant be resolved

55
Q

A high temporal frequency stimulus may appear flickering at what rate

A

Higher

56
Q

The CFF for a given percentage modulation is 50 Hz. A stimulus of 55 Hz, presented at the given percentage modulation, is seen as

A

Steady

57
Q

Unit for temporal frequency

A

1 Hz

58
Q

1 Hz is equal to

A

1 cycle/second

59
Q

When testing under scotopic conditions, CFF is expected to be closest to

A

20 Hz

60
Q

When testing under photopic conditions, CFF is expected to be closest to

A

60-70 Hz

61
Q

Changes in what can lead to the perception of motion

A

Changes in the spatial distribution of light

62
Q

Which pathway processes motion

A

Dorsal processing stream

63
Q

Tests of motion perception can be useful in the diagnosis of what

A

Certain neurological disorders

64
Q

In real motion, the image slides across

A

The retina

65
Q

What is apparent motion dependent on

A

Spatially separated stimuli AND appropriate time interval

66
Q

Sense of motion elicited by apparent motion is known as

A

Stroboscopic motion (phi phenomenon)

67
Q

Example of stroboscopic motion

A

Movies/tv/computer monitors

68
Q

How many different images are presented per second

A

24 images

69
Q

How many times are each image displayed

A

3 times

70
Q

How many total presentations per second

A

72

71
Q

Why would the a movie flicker

A

If presentation rate is below the CFF

72
Q

Example of a simple first-order stimuli for motion

A

Sine-wave grating

73
Q

Both stroboscopic stimuli, sine-wave gratings and the aperture problem are used to study what

A

Local motion processing

74
Q

Physiological mechanism of first-order stimuli

A

Neurons respond with different latencies

  • initially stimulated (at fovea) respond slower than the following stimulated (in periphery)
  • it is because of this that they are all responding at the same time
  • responses are added together to encode stimulus speed and direction
75
Q

More complex first-order stimuli presented with

A

Random dot kinematograms

76
Q

Smallest percent coherence that results in the perception of motion in a defined direction

A

Coherence threshold

77
Q

Coherence threshold in humans

A

Close to 1%

78
Q

Minimum distance dots must move in a given direction to elicit the perception of motion

A

Dmin (minimum displacement threshold)

79
Q

Maximum distance the dots can move to still elicit motion perception

A

Dmax (maximum displacement threshold)

80
Q

Example of local motion perception

A

Sine-wave grating (billboard)

81
Q

Example of global motion perception

A

Random dot kinematograms (gas molecules in jar)

82
Q

Why is the random dot kinematograms more complicated than stroboscopic and sine-wave stimuli

A

Because visual system must integrate information from many dots over a broad expanse of the retina

83
Q

The aperature problem is caused by

A

Local motion cues

84
Q

How do you resolve the aperture problem

A

Global motion cues (see the entire background)

85
Q

Cues that help your visual system resolve locally ambiguous motion

A

Global motion cues

86
Q

Interocular transfer study proves that the information from 2 eyes are

A

Combined

87
Q

Motion perception for more complex stimuli, such as texture defined contours

A

Second-order stimuli

88
Q

Which path processes high velocity info

A

Magno

89
Q

Which path processes low velocity info

A

Parvo

90
Q

Which pathway processes motion

A

Magno

91
Q

Which pathway processes objects

A

Parvo

92
Q

Which pathway is the “where” system

A

Magno

93
Q

Which pathway is the “what” system

A

Parvo

94
Q

Which pathway is the dorsal path

A

Magno

95
Q

Which path is the parietal lobe

A

Magno

96
Q

Which pathway is the ventral path

A

Parvo

97
Q

Which pathway is the temporal lobe

A

Parvo

98
Q

Lack of percieved movement as we change form one point to another is probably due to suppression of

A

Magno

99
Q

Spot of integration Magno and Parvo

A

V1

100
Q

Gateway to dorsal and ventral paths

A

V1

101
Q

Biological motion activates

A

Posterior superior temporal sulcus

102
Q

Which photoreceptors are used in parvo path

A

Cones

103
Q

Which photoreceptors are used in magno path

A

Rods

104
Q

Pathway with better spatial resolution

A

Parvo

105
Q

Pathway selective for color

A

Parvo

106
Q

Pathway with better temporal resolution

A

Magno

107
Q

Monochromataic pathway

A

Magno

108
Q

Midget RGC receptive field tilling in which path

A

Parvo

109
Q

Parasol RGCs receptive field tilling in which path

A

Magno

110
Q

High contrast movement on sine-wave grating appears - smooth or stepping?

A

Stepping

111
Q

Low contrast movement appears : smooth or stepping

A

Smooth

112
Q

Do objects move slower or plaster in scotopic

A

Slower

113
Q

How much slower do objects appear to move in scotopic compared to photopic

A

25%

114
Q

Motion perception is impaired under mesopic condition due to

A

Incomplete integration of rod and cone signals

115
Q

As velocity increases, resolution acuity does what

A

Stays pretty constant until about 60-80 degrees/second

116
Q

The ability to resolve a moving stimulus

A

Dynamic visual acuity

117
Q

As you move beyond the velocity of 60-80 degrees/second, what happens to dynamic visual acuity

A

Deteriorates

118
Q

Reduction in dynamic visual acuity as target velocity increases is due to

A

Inability to track: Smooth pursuit movements

119
Q

Higher dynamic visual acutiy is associated with

A

Improved ability to detect hazardous situation while driving

120
Q

Ballistic eye movement between 2 fixation points

A

Saccadic eye movement

121
Q

Vision is suppressed shortly before, during and after saccadic eye movement –> this is called

A

Saccadic suppression/omission

122
Q

Enables u to look form one object to another without smearing of our vision

A

Saccadic suppression

123
Q

Which pathway is suppressed to avoid smearing during saccadic movement and why

A

Magno because it is sensitive to high velocity movement

124
Q

Primary contributor to saccadic suppression is

A

Extraretinal signal

125
Q

7 types of pictorial, monocular cues to depth perception

A
Relative size
Familiar size
Linear perspective 
Texture
Interposition
Clarity
Lighting and shadow
126
Q

Depth cue when comparing object sizes with no reference

A

Relative size

127
Q

When comparing to images, which appears closer due to relative size and why

A

The larger because there is no reference point, so it creates a larger retinal image

128
Q

Cue used when viewing objects of known size

A

Familiar size

129
Q

Illusion of a picture of a railroad

A

Linear perspective

130
Q

Illusion formed because all aspects of the photo are the same distance from your eye, but parts appear farther away

A

Linear perspective

131
Q

Brains consciously ignore the background, even though we unconsciously notice size changes int he backgrounds

A

Texture gradient

132
Q

The distance to any object sitting on the texture can be accurately judged by comparing it to what

A

The part of the texture the objects happens to be sitting on

133
Q

Occurs when the view of a scene is partially obstructed

A

Interposition

134
Q

Obscuring the view of objects causes them to appear ________; what cue is this

A

Farther away; clarity

135
Q

Light falls on an object and casts a shadow; the shadow is interpreted as what; this creates what

A

Falling behind the object; creates a sense of depth

136
Q

Visual system uses the angular declination below the horizon to determine

A

Object distance

137
Q

What type of depth cue is motion parallax

A

Kinetic monocular depth cue

138
Q

When a moving observer fixates on an object while noticing the relative motion of surrounding objects

A

Motion parallax

139
Q

In motion parallax, when fixating on a closer target, what do you notice about the distance target

A

Moves in the same direction of head movement

140
Q

In motion parallax, when fixating on a distant target, what do you notice about the near target

A

It appears to move in the opposite direction of your head

141
Q

What area of the brain encodes motion parallax info

A

MT/V5

142
Q

During accommodation, what happens to the power of the lens

A

It increases

143
Q

2 binocular depth cues

A

Retinal disparity

Convergence

144
Q

In regards to retinal disparity, light rays from a distant target hit what part of the retina

A

Nasal to fovea

145
Q

In regards to retinal disparity, light rays from a near target hit what part of the retina

A

Temporal to fovea

146
Q

Retinal disparity of a distant target is said to be

A

Uncrossed

147
Q

Retinal disparity of a near target is said to be

A

Crossed

148
Q

Important contributor to depth perception at near distance

A

Stereopsis

149
Q

Is stereopsis important at far distances and why?

A

No bc the threshold for retinal disparity requires objects to be separated by great distances

150
Q

Retinal disparity produces stereopsis only if it is small enough to

A

Allow fusion

151
Q

If disparity is too large, the images fall on retinal positions that signal grossly different directions, resulting in

A

Physiological diplopia

152
Q

Illusions when pictorial depth cues are used to determine object size

A

Size illusions

153
Q

Visual system compensates for differences in retinal image size by taking into account the relative distance of an object

A

Size constancy

154
Q

When judgements of distance are erroneous, such as when viewing a flat picture, size constancy may fail causing

A

Size illusion

155
Q

Size constancy fails because monocular depth cues provide incorrect info regarding relative distance

A

Corridor illusion

156
Q

Moon viewed on the horizon appears

A

Larger (moon illusion)

157
Q

Illusion with vertical lines

A

Muller-layer illusion

158
Q

Line with an outgoing corner appears

A

Farther –> looks longer

159
Q

What does a typical stereopsis test test

A

The minimum amount of disparity required to perceive depth

160
Q

Threshold disparity is known as the patient’s

A

Stereoacuity

161
Q

Stereoacuity can be as small as

A

3 seconds of arc

162
Q

Correcting one eye for near and one eye for distance

A

Monovision

163
Q

Is a patients stereo messed up with monovision

A

Yes

164
Q

Will a patient still have depth perception with monovision correction and why

A

Yes bc many important depth cues are monocular

165
Q

Stereopsis is important for depth at which distance

A

Near

166
Q

Will monovision affect driving

A

Many judgements required in driving are for far distances, in which stereo is less important, but other judgements are for relatively near distances

167
Q

A depth cue that compares sizes of objects to each other

A

Relative size

168
Q

The object that produces the smaller retinal image is percieved at what distance

A

Farther away

169
Q

Which depth cue is experienced when viewing a photo

A

Texture

170
Q

When viewing a railroad, we experience a strong sense of depth because of

A

The retinal image size of the separation in the background is smaller than the foreground

171
Q

The distance to any object could be accurately determined by which depth cue

A

Texture gradient

172
Q

Interposition occurs when the view of the scene is _____ obstructed

A

Partially

173
Q

Which are the only binocular depth cues

A

Retinal disparity and convergence

174
Q

Which of the monocular depth cues are not pictorial

A

Motion parallax
Accommodation
Angular declination

175
Q

If an object is closer than the fixated target, the retinal disparity is

A

Crossed

176
Q

If there is with motion when you focus on an object

A

It is farther away that what you are focusing on

177
Q

If there is against motion when you are fixating

A

It is closer to you than whatever you are fixating on

178
Q

As the viewing distance increases, the usefulness of stereopsis

A

Decreases

179
Q

A monocular individual may use what cues when determining the distance

A

Angular declination and motion parallax

180
Q

Is stereo impaired in anisometropia

A

Yes

181
Q

Is stereo impaired in strabismus

A

Yes

182
Q

Monovision CL typicallly cause stereo to

A

Worsen bc only 1 eye is working at near, and you need both eyes working together for good stereo

183
Q

The appearance of the moon in the horizon being bigger than at the zenith is due to

A

Interposition

184
Q

Test to determine minimum amount of disparity required to perceived depth

A

Stereopsis

185
Q

3 types of first order stimuli for motion

A
Local
- sine wave grating
- stroboscopic stimuli
Global
- random dot kinetomatogram