midtern2 Flashcards
1
Q
univariance
A
An infinite set of different
wavelength-intensity combinations can elicit exactly
the same response from a single type of
photoreceptor
2
Q
Cone photoreceptors
A
S cones 420nm, M cones 534 nm and l cones 565 nm
short middle and long
blue green red, like redshifting
3
Q
Metamers
A
any pair of stimuli that are perceived as
identical in spite of physical differences. In terms of
light: different mixtures of wavelengths that look
identical.
4
Q
Additive colour mixture
A
A mixture of lights. If light A
and light B are both reflected from a surface to the
eye, in the perception of colour, the effects of those
two lights add together
5
Q
Subtractive colour mixture
A
A mixture of pigments.
If pigments A and B mix, some of the light shining on
the surface will be subtracted by A, and some by B.
Only the remainder contributes to the perception of
colour
6
Q
hue
A
Chromatic aspect of color
7
Q
Saturation
A
Chromatic strength of a hue
8
Q
Brightness
A
Distance from black in
colour space
9
Q
Non-spectral hues
A
hues that don’t exist as pure
forms of light but only as mixtures of different
wavelengths
10
Q
Opponent colour theory
A
The theory that
perception of colour is based on the output of
three mechanisms, each of them on an
opponency between two colours; red–green,
blue–yellow, and black–white
11
Q
Does everyone see colours the same way? yes
A
General agreement on colours
– Same metameres.
– Some variation due to age (lens turns yellow)
12
Q
Does everyone see colors the same way No
A
About 8% of male population, 0.5% of female
population have some form of colour vision
deficiency: Colour blindness
– Ishihara test
13
Q
Cone monochromat
A
Only one cone type; truly
colour-blind
14
Q
Rod monochromat:
A
No cones of any type; truly
colour-blind, badly visually impaired in bright light
15
Q
Deuteranope
A
no M-cones
16
Q
Protanope
A
no L-cones
17
Q
Tritanope
A
no S-cones
18
Q
Does everyone see colours the same way? – Maybe
A
English: 11 colour terms (strict definition)
• Other languages have different numbers, e.g. 2/3
– Idea of cultural relativism
19
Q
Unrelated colour:s
A
A colour that can be experienced in
isolation
20
Q
Colour constancy
A
the tendency of a surface to appear
the same colour under a fairly wide range of
illumination.
21
Q
Sensation
A
Illuminant what we dont know and arent intrested in x Reflectance what we dont know and are intrested in
22
Q
Reichardt detector
A
motion detector
23
Q
Apparent motion
A
The illusory impression of smooth
motion resulting from the rapid alternation of objects that
appear in different locations in rapid succession
24
Q
Correspondence problem (motion)
A
The problem faced by
the motion detection system of knowing which feature in
frame 2 corresponds to a particular feature in frame 1
25
Aperture problem
The fact that when a moving object is
viewed through an aperture (receptive field), the direction of
motion of a local feature or part of the object may be
ambiguous
26
LEC 8
Early vs. late selection
27
Early vs. late selection
Early selection
or early with
adaptable filter
system. early is sensory and late is analysis
28
Early vs. late selection
Early selection
or early with
adaptable filter
system. early is sensory and late is analysis. after motion, early is while motion is hapenning
29
“Spotlight” model
attention is
confined to a coherent region of space and can move
from one point to the next.
30
“Zoom lens”
attention expands from fixation…
grows to fill whole region…shrinks to include just cued
location
31
Problems with spotlight and zoom lens models:
```
Attention shifts rather instantly.
Problems with spotlight and
zoom lens models: Attention
can split into more than one
focus; not necessarily coherent
region in space.
Attention
can split into more than one
focus; not necessarily coherent
region in space.
```
32
Biased-competition model of attention (Desimone &
| Duncan, 1995)
```
Competition: Stimuli in the visual field compete for
limited processing capacity & control of behaviour (e.g.,
overlap in RFs).
• Bias: Competition biased
towards certain stimuli
depending on
• bottom-up bias:
salience
• top-down bias (e.g.,
instructions, spatial
cues, feature cues)
```
33
fMRI proof for biased
| competition
```
Competition: Stimuli
presented simultaneously
compete more than
sequential stimuli.
Top-down bias:
Attention to one of the
stimuli (vs. attention to
FP) “overcomes” the
competition.
```
34
Premotor theory of attention
Rizzolatti et al. (1986)
Can you shift attention w/o moving your eyes? SURE!
Can you move your eyes w/o shifting attention? NO!
35
Deubel and Schneider (1996).
Attention and eye movements are closely
coupled, e.g., Deubel and Schneider (1996).
• Digits briefly presented before saccade
• Digit at saccade target is better perceived
36
Corbetta
| et al. (1998).
Shifting attention and eye movements employs largely
overlapping frontoparietal
networks
37
Isaac Newton
o Any single component could not be refracted into a different color (monochromatic colors).
o A second prism combining all the colors would re-create white light.
o We perceive the continuum of wavelengths as qualitatively different phenomena.
38
Scotopic
c: dim light levels at or below the level of bright moonlight.
o Rods are sensitive to scotopic light levels.
o All rods contain the same type of photopigment molecule: Rhodopsin.
o All rods have the same sensitivity to wavelength, making it impossible to discriminate light of
different wavelengths.
39
Young-Helmholtz (-Maxwell) theory: theory of trichromatic color vision
Color vision is based on three photoreceptors sensitive to a particular range of wavelengths.
o Maxwell’s color matching technique.
Can recreate monochromatic light by mixing three different monochromatic light
sources.
E.g., blue light can be created from blue, green, and red
40
Color system in V1
blobs primary visual cortex
41
Color system in V2
thin stripes
42
Human V4
color area Achromatopsia: an inability to perceive colors that is due to damage to the CNS.
Can be caused by a stroke in V4.
43
Physical constraints male constancy possible:
o Intelligent guesses about the illuminant
o Assumptions about light sources
Assumptions about surfaces
1 light source only
Light source is broadband (white light)
o Assumptions about surfaces
Surface reflects fairly broadband
Surfaces have mutual reflections
The light from one surface on another surface
44
Animals provide insight into color perception in humans.
ls provide insight into color perception in humans.
o E.g., what’s color perception good for?
Information about food
Colors provide sexual signs
o Color vision is accomplished in different ways in different species but follows similar principles:
Small set of photoreceptor types.
Dogs: dichromats
Chicken: tetrachromats, 1 photopigment covered with different droplet of oil.
45
Motion: change in position over time.
| o Does this mean motion is the same as noticing changes in position?
NO.
Change in position without motion (e.g., Sun),Motion without change in position: water fall illusion.
o Biological motion: dots bouncing that look like a human walking.
o Reichardt detector:
Cells that delay motion onto different receptive fields in a sequence.
Motion perception must be discrete
46
v5
medial temporal and medial superior temporal areas
47
v3
lingual gyrus
48
Global motion task: (Newsome and Pare, 1988)
A normal trained monkey can correctly determine
the direction with only 2-3% of the arrows.
– When you lesioned a monkey’s V5 area it took 10x
more arrows for the monkey to determine direction
accurately.
è global motion perception in MT
49
Silencing by Motion
motion can decrease color change in rotating dots
50
Motion aftereffect, MAE
The illusion of motion of a
stationary object that occurs after prolonged
exposure to a moving object
Existence of this effect implies an opponentprocess system, like that of colour vision
51
Interocular transfer:
The transfer of an effect
| (e.g., adaptation) from one eye to the other
52
• First-order motion
Motion of an object that is
| defined by changes in luminance
53
Second order motion
Motion of an object that is
defined by changes in contrast or texture, but not by
luminance
54
– Optic flow
```
Changing angular position of points in
perspective image that you experience as you
move through the world
– Example of pilot landing plane:
“Radial expansion”
– Focus of expansion
– Focus of constriction
```
55
Motion Binding
lines can appear to move in pairs but with blocks can combine into a diamond
56
Eye Movements
– 6 muscles controlled by cranial nerves
– Oculomotor control
– Different eye movements
– How do we achieve spatial constancy?
57
six muscles a
Inferior/superior/lateral/medial rectus
| – Inferior/superior oblique
58
Superior colliculus:
```
Structure in midbrain
that plays important
role in initiating and
guiding eye
movements
```
59
Smooth pursuit
: Eyes move smoothly to follow
| moving object
60
Saccade
Rapid movement of eyes that change
| fixation from one object or location to another
61
– Vergence eye movements
Type of eye
movement in which two eyes move in opposite
directions, done deliberately
62
• Why do we perceive the pencil to be in motion in the
first case, but perceive the dot to be stationary in the
second case?
– Because in one case there is an eye movement
63
Function of saccades:
: move (rotate) fovea to object
of interest, move as quickly as possible to reduce
travel time during which vision is blurred.
• Yarbus (1967): scanpaths reveal intentions and
interests.
• 3-4 saccades/sec
• False motion &
retinal smear
during saccades
64
Spatial constancy
The task to discriminate motion
across the retina that is due to eye movements vs. object
movements
65
• Saccadic suppression
Reduction of visual sensitivity that occurs when one
makes a saccadic eye movement; eliminates smear from
retinal image motion during an eye movement
– How does the brain know when to suppress?
– Displacements across saccades should result in
apparent motion illusions (but don’t)
66
Compensation theory
: Perceptual system receives
information about the eye movement and discounts
changes in retinal image that result from it
67
• Euclidian geometry
```
Parallel lines
remain parallel as they are
extended in space
– Objects maintain the same size
and shape as they move around
in space
```
68
The two retinal images of a three-dimensional world
| are not the same!
Parallax
69
• Binocular disparity:
The differences between the
two retinal images of the same scene. It is the basis
of stereopsis; a vivid perception of the threedimensionality of the world that is not available with
monocular vision.
70
Binocular depth cues (from overlapping visual fields)
| provide:
```
Convergence
– Stereopsis
– Ability of two eyes to see
more of an object than
one eye
```
71
Monocular Cues to Three-Dimensional Space
```
Occlusion
– Relative size
– Position cues
– Familiar size
– Aerial perspective
– Linear perspective
– Motion cues
```
72
Occlusion
A cue to relative depth order when, for
example, one object obstructs the view of part of
another objec
73
Nonmetrical depth cue
provides information
about depth order but not magnitude.
– (Metrical depth cues: Provide quantitative
information about distance)
74
Relative Size
```
A
comparison of
size between
items without
knowing the
absolute size of
either one
```
75
Texture Gradient:
```
: A
depth cue based on the
geometric fact that
items of the same size
form smaller images
when they are farther
away
```
76
– Relative Height:
```
Objects at different
distances from the
viewer on the ground
plane will form images
at different heights in
the retinal image
```
77
Natural scene statistics, natural scence statistics
further things are higher
78
Familiar size
```
: depth
cue based on
knowledge of the
typical size of
objects
• Absolute metrical
depth cue
vs. relative depth
cues
```
79
Aerial perspective:
A depth cue that is based on the
implicit understanding that light is scattered by the
atmosphere
• Reduction in contrast, hue, saturation
80
• Linear perspective
A depth cue based on the fact that
lines that are parallel in the three-dimensional world will
appear to converge in a two-dimensional image
81
Vanishing point
```
: The
apparent point at
which parallel lines
receding in depth
converge
```
82
3-point perspective
discovered after the
invention of photo
cameras.
83
Foreshortening
```
refers to the
visual effect that an object or
distance appears shorter than it
actually is because it is angled
toward the projection screen/
retina/picture plane
```
84
Anamorphosis
```
s: a
distorted projection or
perspective requiring
the viewer to use
special devices or
occupy a specific
vantage point to
reconstitute the image
```
85
Where monocular cues
| fail.
```
Here the depth cues are
removed. The girl on the right is
much further away, but the
perspective cues are
manipulated.
• Only works for a single view
point.
```
86
Motion parallax
Based on head movement; geometric
information obtained from two eyes in different positions
in the head the same time
87
Accommodation
Eye
| changes its focus
88
Convergence
Ability of the
two eyes to turn inward;
reduces the disparity of a
feature to (near) zero
89
Divergence
Ability of the two
eyes to turn outward; reduces
the disparity of the feature to
(near) zero
90
Vergence
angles of eye positions
| • Triangulation
91
Binocular disparity
Differences between the
| images falling on the two retinas due to parallax
92
Stereopsis
“Popping out in depth”
– Most humans are able to see this way
– How exactly does this translation from stimulus
attribute to perception take place?
93
examples
Bob fixates red crayon: corresponding retinal
points: points of retinal images that have the same
distance from the fovea. “Zero binocular disparity
94
Horopter
```
location of
objects in space whose
images lie on
corresponding points.
The surface of zero
disparity
```
95
• Panum’s fusion area:
region of space in front
and behind the horopter
within which binocular
single vision is possible
96
Diplopia
double vision
for points outside
Panum’s fusion area.
97
Free fusion:
The technique of converging (crossing)
or diverging the eyes in order to view a stereogram
without a stereoscope
98
stereoblindness
• Some people do not experience stereoscopic depth
perception because they have stereoblindness
– An inability to make use of binocular disparity as a
depth cue
– Can result from a childhood visual disorder, such as
strabismus, in which the two eyes are misaligned
99
random dot stereograms
s can only be seen
with binocular cues; they contain no monocular depth
cues
• Evidence that disparity is sufficient for
stereopsis. No need for cues from object
perception
100
• Correspondence problem
```
Correspondence
between two apples
that actually are the
same apple (easy).
???
Correspondence
between pixels that
are the same
(hard!!!).
```
101
```
Correspondence
between two apples
that actually are the
same apple (easy).
???
Correspondence
between pixels that
are the same
(hard!!!).
```
Leaving only the low-spatial
| frequency information
102
Uniqueness constraint
t: A feature in the world will be
represented exactly once in each retinal image (1
feature in one eye paired 1 feature in the other eye
103
Continuity constraint
Except at the edges of objects,
neighboring points in the world lie at similar distances
from the viewer
104
How is stereopsis implemented in the human brain?
Input from two eyes converges onto the same cell
– Many binocular neurons respond best when the
retinal images are on corresponding points in the
two retinas: Neural basis for the horopter
– However, many other binocular neurons respond
best when similar images occupy slightly different
positions on the retinas of the two eyes (tuned to
particular binocular disparity)
105
• Absolute vs. Relative disparity information can be
| extracted:
– Absolute disparity: A difference in the actual retinal
coordinates in the left and right eyes of the image
of a feature in the visual scene
– Relative disparity: The difference in absolute
disparities of two elements in the visual scene
106
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
107
Bayesian approach
A statistical model based on
Reverend Thomas Bayes’ insight that prior
knowledge could influence your estimates of the
probability of a current event
• Optimal inference from cues: perception should
choose the solution depending on which one is most
likely.
• Very often perception comes close to
what is optimally possible
108
• Specific distance tendency
When a simple object is presented in an otherwise dark
environment, observers usually judge it to be at a
distance of 2-4 m.
109
Equidistance tendency
Under the same conditions, an object is usually judged
to be at about the same distance from the observer as
-sky
neighbouring objects.
110
What happens when our guesses are wrong?
Illusions
111
What effects does attention have?
| • How can we study attention?
```
– Cues influence/bias attention
– Visual search
– Attention in time
• The physiological correlates of attention
• Scene perception
```
112
How can we measure attention?
```
Reaction times: a measure
of the time from the onset of
a stimulus to a response.
• Perception:
• perceptual thresholds
motor accuracy
Eye movements: overt
shifts of attention but not
covert shifts of attention.
• perceptual biases
• Brain activity
```
113
• How can we study attention?
```
– Cues influence/bias attention
• Posner’s attentional cueing paradigm
• Natural biases
• Feature-based cueing
– Visual search
– Attention in time
```
114
• Simple probe detection
| experiment
```
measures RT (or
perceptual thresholds)
```
115
Posner
```
Cue: A stimulus that might indicate
where (or what) a subsequent stimulus
will be: valid vs. invalid vs. neutral
=> cueing effect
• Cueing effect: the difference (in RT,
brain activity, etc.) between the effect
of a valid and an invalid cue.
```
116
Behaviour
stimulus-driven or voluntary.
117
Stimulus-driven cues:
```
info conveyed through
previous events at the
same location.
(involuntary, reflexive,
peripheral, exogenous)
```
118
• Voluntary cues
```
(spatial)
info conveyed through
cognitions & memory,
often based on language
or other symbols.
(symbolic, central,
endogenous)
```
119
What’s the difference between stimulus-driven/
| peripheral and voluntary/symbolic?
Partially independent neural structures.
• Stimulus onset asynchrony (SOA): the time between the
onset of one stimulus and the onset of another.
– Different time courses of SOAs; slower effects for
voluntary cues.
– Inhibition of return (IOR)
120
• Overt shifts of attention:
A shift of attention
| accompanied by corresponding movements of the eyes
121
Covert shifts of attention
A shift of attention in the
| absence of corresponding movements of the eyes
122
• Perceptual biases
```
Asymmetries
in perception between the left and
right side of a stimulus.
– Vary with task, e.g. listening to
speech.
• Line bisection task
```
123
Gratingscales:
– Which bar has more of the thinner/thicker
stripes?
greater activation of
attention networks in the right hemisphere
124
Space-based cueing
of attention
• Feature-based cueing of attention: attention is
guided based on non-spatial information about
features.
– Cued feature becomes more “visible” throughout
the visual field = outside the focus of attention.
125
How can we study attention?
```
Task and terms
• Feature searches
• Inefficient searches
• (Feature-)conjunction searches
• Models of visual search
```
126
Looking for a target in a display containing distracting
| elements
Target: the goal of visual search
• Distractor: any stimulus other than the target
• Set Size: the number of items in a visual display
– Has no influence on search time for “efficient
searches”.
– Impacts search time for “inefficient searches”.
• How much time does it take to perform a visual
search task, i.e. to tell whether a target is present or
absent? – It depends (of course…).
127
Basic features Less ‘basic’ (it seems) yet
efficiently searched:
salience
parallel
```
Basic features: colour, size,
orientation, motion
• Less ‘basic’ (it seems) yet
efficiently searched: lighting
direction
• Salience: the vividness of a stimulus
relative to its neighbours (feature
contrast “clearly” above JND
threshold)
• Parallel: the processing of multiple
stimuli at the same time
•
“Pop-out”
```
128
Is conjunction search serial?
```
YES
– Serial self-terminating search: items are
examined one after another until target is found or
until all items are checked
– Similar to eye movements scanning a scene but
faster.
• NO
– Limited capacity parallel process:
“adjustable spray nozzle” model
• COMBO?
– Neurophysiological evidence that both
mechanisms co-exist
```
129
Feature Integration Theory
```
.Preattentive Stage: parallel
processing of basic features
across entire visual field before
selective attention is deployed
2. Attentive Stage: spatial
attention binds together features
for one item at a time, serial
search
• Guided search theory (Wolfe):
Attention can be restricted to a
subset of possible items on the
basis of information about the
target’s basic features.
```
130
Illusory conjunctions
Can you recall the letters that
| are present? Can you recall their color?
131
RSVP
Rapid Serial Visual Presentation is a method
of displaying information at one location in which each
piece of information is displayed briefly in sequential
order
– Normal understanding with 250 words per minute.
– 650 wpm: 20% reduction.
– Special case: Visual search in time for a target.
– A V Y W L N F 4 R U X F H V X
– 8-10 items per second
– 2 targets, T1 & T2
132
• Attentional blin
: difficulty in perceiving the second of
two targets within a rapid stream of distractors; depends
on whether the observer responded to the first target
presented 200-500 ms before.
– Reduced attentional blink for smaller/larger time
differences between T1 & T2
133
• The physiological basis of attention
Enhanced processing in striate and extrastriate
areas
– Enhanced processing in higher visual areas
– Attention and single cells
134
RSVP: Rapid Serial Visual Presentation
n is a method
of displaying information at one location in which each
piece of information is displayed briefly in sequential
order
135
Attentional blink
difficulty in perceiving the second of
two targets within a rapid stream of distractors; depends
on whether the observer responded to the first target
presented 200-500 ms before.
– Reduced attentional blink for smaller/larger time
differences between T1 & T2
136
The physiological basis of attention
Enhanced processing in striate and extrastriate
areas
– Enhanced processing in higher visual areas
– Attention and single cells
137
Fusiform face area
| • Parahippocampal place area
```
Functional fMRI studies: different pieces of
cortex are activated by faces vs. places
• O’Craven & Kanwisher, 1999: PPA or
FFA light up depending on which layer is
attended
```
138
potter
```
We can correctly
remember very large
numbers of photos
scenes.
• Potter (1975, 1976) fast
RSVP for scenes.
```
139
• Change Blindness:
: failure to notice a change
between two scenes; perception depends on
meaning of change
• Suggests our scene perception is very poor.
• How does that fit together?
140
Spatial layout of a scene
```
description of the
structure of a scene
• Global vs. local scene analyses
• Global: Oliva & Torralba (2001): scene classification
based on a few easy-to-process scene dimensions:
– Spatial frequency
– Openness
– Naturalness
– Roughness
```
141
Corbetta & Shulman’s DAN and VAN
Dorsal Attentional Network for goal-directed (endogenous)
selection and responses. Associated with both hemispheres.
Ventral Attentional Network for unexpected, salient stimuli,
circuit breaker. Mainly associated with the right hemisphere.
Limitation of fMRI: correlative studies.
142
• Disorders of attention
Spatial neglect
– Extinction
– Balint syndrome
143
Co-morbidities v
Visual field defect: a portion of the visual field
with no vision or with abnormal vision, typically
resulting from damage to the visual nervous
system
– Motor deficits: paralyzed arm etc.
• Spatial neglect: inability to attend to or respond to
stimuli in the contralesional visual field, typically after
right brain damage
144
Extinction
Parietal lesions either in left or right
brain
• Intact detection of single stimuli
• Unable to detect contralesional stimuli when
presented together with ipsilesional one.
145
Balint’s syndrome.
```
Illusory conjunctions:
Friedman-Hill et al.
(1995): Balint’s patient
R.M. shows difficulties
with binding under free
viewing conditions!
Loss of global perception
```
146
1. After viewing a moving visual stimulus for some time with stationary eyes, and then
fixating a stationary stimulus the stationary stimulus appears to move in the opposite
direction to the original stimulus. This phenomenon is called _______.
A) Correspondence problem
B) Aperture problem
C) Motion aftereffect
D) Motion afterimage
C
147
```
2. A patient with no perception of motion is mostly likely has a lesion in (the) ______.
A) MT
B) V4
C) V2
D) PPA
```
A
148
3. Which of the following is FALSE?
A) Colour is a physical property
B) Most of the light we see is reflected
C) Perceivable colours have wavelengths between 400 – 700 nm
D) Typical light sources emit a broad spectrum of wavelengths
A
149
4. What are metamers?
A) Different mixtures of wavelengths that look different
B) Different mixtures of wavelengths that look identical
C) Metamers can be both A and B
D) None of the above
B
150
What is the difference between additive and subtractive color mixture?
A) Additive is a mixture of pigments; subtractive is a mixture of lights
B) Additive is a mixture of lights; subtractive is a mixture of pigments
C) Additive and subtractive are mixtures of lights with pigments
D) There is no physical difference between the two, the difference is psychological
B
151
6. Why is colour space 3-dimensional?
A) Because we have 2 types of cones and 3 types of rods
B) Because we have 3 types of cones
C) Both A and B are true
D) Colour space is 2-dimensional, not 3-dimensional
B
152
7. According to the opponent colour theory, why is “bluish yellow” an impossible
colour?
A) Blue and yellow share the same wavelength
B) Blue has a wavelength that is double that of yellow
C) Blue and yellow are opponent colours
D) Blue and yellow are metamers
C
153
```
8. Which of the following is a type of true colour-blindness?
A) Rod monochromat
B) Deuteranope
C) Protanope
D) Tritanope
```
A
154
11. There are multiple pieces of evidence in support of the Opponent Colour Theory.
Which of the statements below does NOT support the theory?
A) The phenomenon of negative afterimage supports the theory.
B) The fact that LGN has colour-opponent cells supports for the theory.
C) Each type of photoreceptors is sensitive to particular ranges of wavelengths.
D) Human colour vision is based on the output of three pairs of basic colour dimensions
C
155
```
12. A person with no ‘S cones’ is known as a _______.
A) Tritanope
B) Protanope
C) Deuteranope
D) Monochroma
```
A
156
13. What is the term used to describe when you look at one colour for a few seconds and
a subsequently viewed achromatic region will appear to take on a colour opposite to the
original colour?
A) Adapting stimulus
B) Negative afterimage
C) Unrelated colour
D) Neutral point
B
157
14. The problem faced by the motion detection system is knowing which feature in an
image or frame matches a particular feature in another image or frame is known as the
________.
A) Problem of direction
B) Problem of univariance
C) Correspondence problem
D) Aperture problem
C
158
```
15. Point A provided in the figure below is called the _______________.
A) Binocular point
B) Perspective point
C) Vergence point
D) Vanishing poin
```
D
159
16. Binocular depth cues from overlapping visual fields provide _____________.
A) Convergence
B) Stereopsis
C) The ability to see more of an object than one eye
D) All of the above
C
160
18. The competition between the two eyes for control of visual perception, which is
evident when completely different stimuli are presented to the two eyes, is called
___________.
A) Binocular rivalry
B) Binocular disparity
C) Binocular cue
D) Binocular competition
A
161
19. Which is NOT a method to solve the correspondence problem?
A) Focusing on low-spatial frequency information
B) Searching for correspondence within high-spatial frequency information
C) Uniqueness constraint
D) Continuity constraint
A
162
20. The superior colliculus is known to play a role in:
A) Inhibiting proprioceptive signals from the eye muscles
B) Initiating and guiding eye movements
C) Filtering visual input by colour
D) Matching visual input with memory
B
163
21. Quick saccadic eye movements, occurring 3-4 times per second, cause the eye to
rotate so quickly that the photoreceptors of the retina produce signals reflecting a
smeared image. The function of these saccades is to:
A) Place the high-resolution fovea over features of interest in the visual scene
B) Reduce the proportion of time where the retinal image is smeared
C) Avoid damage to the eyes’ musculature
D) A & B
D
164
```
22. Imagine a fruit fly is lazily flying around you and you track it with your eyes. This is
an example of _________.
A) Saccade
B) Smooth pursuit
C) Vergence
D) Reflexive eye movements
```
B
165
23. You look into a mirror and look from one eye to the other. You can never observe
your eyes in motion, yet an external observer can clearly see the motion of your eyes.
This is an example of ____________.
A) Spatial constancy
B) Saccadic suppression
C) Binocular disparity
D) Change blindness
B
166
```
24. Which of the following brain areas is least likely to be involved in eye movements?
A) Frontal eye fields
B) Parietal cortex
C) Inferior colliculus
D) Superior colliculus
```
C
167
```
25. How many muscles control the movement of each eye?
A) 2
B) 3
C) 6
D) 8
```
C
168
```
26. Which MIDbrain structure is especially important for initiating eye movements?
A) The frontal eye fields
B) The interpeduncular fossa
C) The intraparietal sulcus
D) The superior colliculus
```
D
169
```
27. What sort of eye movement is used, for instance, to shift your gaze from a moving car
to a stationary face?
A) Fixational eye movements
B) Vergence
C) Saccade
D) Smooth pursuit
```
C
170
28. The competition between the two eyes for control of visual perception, which is
evident when completely different stimuli are presented to the two eyes is called
___________.
A) Binocular rivalry
B) Binocular disparity
C) Binocular difference
D) Binocular competition
A
171
```
29. Which theory suggests that “efference copy” is an explanation for spatial constancy
across eye movements?
A) Compensation theory
B) Feedback theory
C) Saccadic suppression theory
D) Free fusion theory
```
A
172
30. Which of the following options is a method to solve the correspondence problem?
A) Blurring the image
B) Leaving only the high-spatial frequency information
C) Presenting multiple features in each eye
D) The fact that neighbouring points in an image tend to have very different distances
from the viewer.
A
173
31. A new task using the image from the previous question: You are asked to study the
image, and then the bars disappear. You are then asked to point to the prior location of
the horizontal black bar, but instead you point to the location of the horizontal grey bar.
What sort of error has been demonstrated?
A) A distractor error
B) A type I error
C) A matching problem
D) An illusory conjunction
D
174
32. Which of the following is a good example of 'inhibition of return' as discussed in
class?
A) A stimulus cueing the location of a target is shown. One second later, the target
appears at the cued location - The participant is slower to respond than when they receive
no cueing at all.
B) In a computerized maze task, a participant goes down a hall that leads to a dead-end.
After searching unsuccessfully for some time, the participant stumbles into the same area
once-again, and is about to re-enter the dead-end hallway. However, the alignment of the
various edges from a certain perspective causes them to notice that they have been there
before, so they move on to a different area.
C) A rat walks into an orange chamber with an electrified metal floor and receives a
shock. The rat never re-enters the orange chamber, even though the current has been
turned off.
D) A baby is shown a picture of a face for two minutes, and then another picture is placed
beside the original one. The baby focuses its attention on the new picture
B
175
33. The image to the right shows the three
stages of a task where a participant is asked to
indicate the location of a target relative to the
center of a computer screen. The stimulus
onset asynchrony (SOA) in this example is the
interval between _________, and the cue is
_________.
A) Time 1 and Time 3, the asterisk
B) Time 2 and Time 3, the outlined box
D) Time 1 and Time 3, the X
C) Time 1 and Time 2, the outlined box
B
176
34. In a task that exploits the 'attentional blink' phenomenon, success rates for locating a
second target within a sequence of rapidly changing distractors is worst for which of the
following time periods following the first target?
A) 0.2 to 0.5ms
B) 2 to 5ms
C) 20 to 50ms
D) 200 to 500m
D
177
35. What is the difference between overt and covert shifts of attention?
A) Overt shifts of attention involve movements of the head, whereas covert shifts do not.
B) Overt shifts of attention involve fixations of the eyes, whereas covert shifts do not.
C) Overt shifts of attention involve movements of the eyes, whereas covert shifts do not.
D) Overt and covert shifts of attention do not differ
C
178
```
36. In the gratingscales task with EEG, pronounced negativity over the right brain after
280 ms is associated with what?
A) An upward bias
B) A leftward bias
C) A downward bias
D) A rightward bias
```
B
179
```
37. What sort of neuronal responsiveness change does the following
image illustrate?
A) Centralized tuning
B) Cross tuning
C) Enhancement
D) Sharper tuning
```
D
180
38. Which of the following would be true of a participant’s brain activity when shown
images of a house and a face with attention on the house?
A) More activity in FFA than PPA
B) More activity in PPA than FFA
C) Equal activity in FFA and PPA
D) None of the above are true
B
181
39. In the Posner paradigm, what is the name of the condition where a target appears with
no preceding cue?
A) Neutral cueing
B) Valid cueing
C) This is not a condition type used in the Posner paradigm
D) Invalid cueing
A
182
40. In visual search, which of the following is true?
A) Set size has no influence on search time for ‘efficient searches’
B) Set size impacts search time for ‘efficient searches’
C) Set size has no influence on search time for ‘inefficient searches’
D) Set size impacts search time for both ‘efficient searches’ and ‘inefficient searches’
A
183
```
41. There are three ways responses of a cell could be changed by attention. Which of the
following is NOT one of these ways?
A) Response enhancement
B) Attention enhancement
C) Altered tuning
D) Sharpened tuning
```
B
184
42. The biased-competition model of attention states that:
A) There is a strict link between covert and overt attention
B) Top-down effects bias processing of sensory inputs.
C) Salient stimuli bias processing from top-down.
D) There is competition between attentional biases
B
185
43. Which of the following statements is FALSE?
A) Support for the premotor theory of attention comes from the finding that the shifting
of attention and eye movements employs overlapping frontoparietal networks
B) Endogenous attentional cueing involves a parieto-frontal network
C) The ventral attentional network is associated more with the right hemisphere
D) The dorsal attentional network is for circuit breaking
D
186
```
44. The Dorsal Attentional Network is usually:
A) associated with the left hemisphere
B) associated with the right hemisphere
C) A & B
D) none of the above
```
C
187
45. The premotor theory of attention states that:
A) covert orienting of attention is achieved by inhibiting the execution of the eye
movement.
B) there is no link between overt and covert attention
C) attention is always independent of where we move our eyes
D) all of the above
A
188
46. Deubel and Schneider (1996) found that when numerical digits are presented before a
saccade, the digit at the saccade target is better perceived. This finding suggests that:
A) Attention and eye movements never occur together
B) We can move our eyes without shifting attention
C) We are able to track multiple objects with our eyes
D) Attention and eye movements are closely coupled
D
189
```
47. We are usually able to process relevant sensory inputs while ignoring others that are
less important. This is called:
A) multiple-object tracking
B) selective attention
C) arousal
D) premotor exogenous attention
```
B
190
48. A patient has suffered a stroke and is displaying unusual behaviour; when asked to
draw picture #1, they produce picture #2. Where could the
patient's brain be lesioned?
A) The left striate cortex
B) The left fusiform area
C) The right striate cortex
D) The right temporo-parietal junction
D
191
49. The Milan Cathedral experiment demonstrates:
A) Visual imagery impairment in spatial neglect patients
B) Visual imagery impairment in Balint syndrome patients
C) The reduction of neglect symptoms with caloric stimulation
D) Motor control impairments in Balint syndrome patient
AA
192
```
50. The perception of the following stimulus as “K,” but not “L,” could be symptomatic
of
A) Balint’s syndrome
B) loss of global perception
C) Stroop Effect
D) A & B
```
D
193
```
51. Which of the following brain areas is NOT likely to be involved in spatial neglect?
A) Superior occipital cortex
B) Inferior parietal cortex
C) Temporo-parietal junction
D) Superior temporal gyrus
```
A
194
52. After a stroke in the left hemisphere a patient is tested with a battery of cognitive
tests. He/she can see objects presented individually in the left or right visual fields. But
the patient fails to see the object on the right when both objects are presented
simultaneously in his/her left and right visual fields. What kind of disorder is this most
likely?
A) Memory
B) Topographical mapping
C) Visual hemifield
D) Attention
D
195
```
53. ___________ postulates that attentional deployment can vary from a sharp focus to a
broad window.
A) Search light model of attention
B) Zoom lens model of attention
C) Biased-competition model of attention
D) Premotor theory of attention
```
B
196
54. Activity related to both attentional shifts and eye movements overlaps in several brain
areas – which of the following is included?
A) Medial temporal lobe
B) Occipital lobe
C) Insula
D) Precentral sulcus
D
197
55. If you subtract fMRI signals of participants not shifting attention from a condition
where they perform attention shifts, what significant activity remains?
A) INS and MTL
B) LGN and LO
C) SC and FFA
D) FEF and parietal eye fields
D
198
```
56. When a flash of lightning catches your attention, what network is highly engaged
according to Corbetta and Shulman?
A) The ventral attentional network
B) The dorsal attentional network
C) Superior longitudinal fasciculus
D) The fusiform face area
```
A
199
57. Which of the following statements regarding the premotor theory of attention is NOT
true?
A) There is a strict link between covert attention and overt attention.
B) Shifting attention and eye movements employs largely overlapping frontoparietal
networks.
C) It is possible to move your eyes without shifting attention.
D) It is possible to shift your attention without moving your eyes.
C
200
What is the problem of univariance in colour vision? Please explain.
An infinite set of different wavelength-intensity combinations can elicit exactly the same response from a single type of photoreceptor
201
What does it mean for vision based on a single type of colour-sensitive cone?
everything is perceived as black and white (no colour discrimination is possible)
202
How can the problem of univariance be solved?
more than one type of cone
203
How is Panum's fusion area defined? What happens perceptually?
Definition: location of objects in space whose images lie *nearly* on corresponding points on the retina (almost zero disparity) such that the brain still can fuse the 2 retinal images (no double vision)
204
What lies inside? Please define
name: horopter, definition: region in space composed of points with zero disparity
205
How is an object perceived when it is placed outside the two regions?
double vision (diplopia)
206
What does the term inhibition of return reflect?
an increase in reaction time to a target stimulus that was correctly (validly) predicted by a cue
207
In what experimental paradigm is inhibition of return observed?
Posner's attentional cuing paradigm
208
Which two features of the paradigm are crucial for IOR to occur?
1. stimulus-driven attentional cue; 2. longer delays in stimulus-onset asynchrony
209
In the biased-competition model by Desimone and Duncan, where does competition come from?
Stimuli in the visual field compete for limited processing capacity & control of behaviour
210
What is a bottom-up bias?
A bias that reflects preferred processing due to stimulus salience.
211
What other biases exist?
Top-down biases that reflect preferred processing due to cognitive factors such as instructions or attentional cues.
212
What is the name of the theory that proposes that attention and eye movements are closely related?
premotor theory of attention
213
According to that theory, what does a spatial shift of attention reflect?
an oculomotor program that is ready to be executed
214
... and why can attention shift with as well as without eye movements (whereas eye movements without shifts of attention aren’t possible)?
the actual execution of the eye movements can be inhibited
215
More recent fMRI + EEG research (Grent-’t-Jong & Woldorff, 2007) supports the main claims of the theory. According that study which areas are involved in shifts of attention, and which of them first?
FEF & LIP, FEF first
216
Which attentional network do these areas overlap with according to Corbetta?
dorsal attentional network (DAN=0.5 points)
217
Motion sensitive areas:
Lesions in magnocellular layers of LGN impair perception of large, rapidly moving objects
Vast majority of neurons in MT (V5 = hMT) are selective for motion in particular direction (tuning
functions for motion)
218
Superior colliculus
structure in the midbrain that plays and important role in initiating and
guiding eye movements.
o When stimulated with electrical signals, eye movements can be observed
219
Spatial constancy
the task to discriminate motion across the retina that is due to eye movements vs.
object movements.
o E.g., closing one eye and tapping the other: perceive the world as shaking.
220
Nonlinear relationship between attention and arousal however, they do go in tandem
o Examples:
You are tired, so you drink coffee, which increases arousal for the exam.
You drink too much coffee leading to an arousal state too high for the exam in which
everything is vivid and salient so focusing on one thing is difficult.
