Sensation & Perception (part 1) Flashcards
The first 5 weeks of the course, so everything for exam 1! (615 cards)
1
Q
What five methods to study sensation and perception does the book mention?
A
- Thresholds
- Scaling
- Signal Detection Theory
- Sensory neuroscience
- Neuroimaging
2
Q
Psychophysics
A
A method to formally describe the relationship between sensation and the energy or matter that gives rise to that sensation.
3
Q
Who named the psychophysics method?
A
Gustav Fechner
4
Q
JND (abbreviation)
A
just noticeable difference
5
Q
Panpsychism
A
The idea that the mind exists as a property of all matter, that all matter has consciousness.
6
Q
Perception
A
Giving meaning or purpose to detected sensations.
7
Q
Who are seen as the founders of experimental psychology?
A
Gustav Fechner (1801-1887) and Wilhelm Wundt (1832-1920).
8
Q
Who made sense of the way in which JND changes?
A
Ernst Weber (1795-1878)
9
Q
What are the Weber fractions concerned with?
A
The systematic way in which the JND changes: a constant ratio between change in stimulus and standard stimulus, which describes the threshold of the detectable change.
10
Q
Weber’s law (formula)
A
[delta].I = K.I
11
Q
Weber’s law (intuitive)
A
The size of the detectable difference is equal to a constant proportion of the level of stimulus.
12
Q
Fechner’s law (formula)
A
S = k * log (R)
13
Q
Fechner’s law (intuitive)
A
The psychological sensation is equal to a constant k times the logarithm of the physical stimulus level, so our experience of intensity increases less than the actual stimulus increases.
14
Q
Absolute threshold
A
The minimum amount of stimulation necessary for a person to detect a stimulus 50% of the time.
15
Q
What three ways os studying thresholds are discussed in the book?
A
- Method of constant stimuli
- Method of limits
- Method of adjustment
16
Q
Method of constant stimuli
A
Many stimuli with different intensities are presented one at a time, to find the smallest intensity that can be detected.
17
Q
Method of limits
A
Stimuli with different intensities. In order of increasing or decreasing intensity until first detected or not detected anymore. Average is taken as threshold.
18
Q
Method of adjustment.
A
Method of limits where the participant adjusts the stimuli intensity herself.
19
Q
Magnitude estimation
A
A task in which participants need to rank a number of sensations based on perceived intensity.
20
Q
Steven’s power law (formula)
A
S = a * (I^b)
21
Q
Steven’s power law (intuitive)
A
The magnitude of subjective sensation S is related to the stimulus intensity I by exponent b. We use constant a to correct for the units used.
22
Q
Cross-modality matching
A
Participants have to adjust a stimulus of one kind to match the intensity of another kind of stimulus.
23
Q
Qualia
A
The experiences when you see/hear something, the qualitative experience.
24
Q
How can we deal with a non-absolute threshold?
A
Signal Detection Theory
25
What is the simplest kind of sound?
A sinus wave.
26
What do we call the time taken for a wavelength in sound?
a period
27
What do we call the height of a wave in sound?
the amplitude
28
What is the phase of a wave in sound?
The position relative to a fixed marker, measured in degress.
29
How many degrees are there across one period in sound?
360
30
Fourier analysis
The process of breaking down a complex sound into individual sine wave components. (or images into spatial frequencies)
31
What are units of spatial frequency?
cycles per degree of visual angle
32
Doctrine of specific nerve energies
We are only aware of the activity in our nerves, not directly of the world itself. It isn't important how nerves are stimulated, but what nerves are stimulated.
33
What cranial nerves are dedicated to sensory information?
1. Olfactory nerve
2. Optic nerve
8. Vestibulocochlear nerve
34
What cranial nerves are dedicated to muscles that move the eyes?
3. Oculomotor nerve
4. Trochlear nerve
6. Abducens
35
Vitalism
The idea that there is a force in life that is distinct from physical entities.
36
Synapse
The tiny gap between the axe of one neuron and the dendrite of the next. Permits information transfer.
37
What happens to the speed of neural transmission at the synapses?
It decreases.
38
EEG
electroencepalography
39
ERP
event-related potential
40
MEG
magnetoencephalography
41
CT
computed tomography
42
MRI
magnetic resonance imaging
43
How does EEG work?
It measures electrical activity with electrodes on the scalp.
44
What are the results of an EEG?
Can roughly localize populations of neurons, but not able to pinpoint area of neural activity. Very good temporal accuracy.
45
What is an ERP?
A measure of electrical activity from a subpopulation of neurons in response to particular stimuli, the average waveform that results from many EEG recordings.
46
What results does an MEG give?
Tiny magnetic field changes, maintains timing of neuron populations and has good image of where in the brain neurons are most active.
47
What results does a CT give?
A 3D picture of the head.
48
BOLD
blood oxygen level-dependent
49
What results does an MRI give?
The BOLD signal is measured, slow and noisy and expensive but still good.
50
PET
positron emission tomography
51
What is PET?
An imaging technique where radioactive material goes into the bloodstream and a camera detects gamma rays.
52
What is the most common tracer in PET?
oxygen-15 with a half-life of +-2 minutes.
53
Electromagnetic radiation
Energy produced by vibrations of electrically charged material.
54
Photons
Tiny particles that each consist of one quantum of energy, demonstrating both particle and wave properties.
55
How do we treat light in the book?
As being made up of waves when it moves around the world, and being made up of photons when it is absorbed.
56
What wavelengths of the spectrum of electromagnetic radiation is light?
Between 400 and 700 nm wavelength.
57
Hue
The perceptual attribute of colors.
58
What portions of the electromagnetic radiation spectrium have a smaller wavelength than light?
Gamma rays, X-rays and Ultraviolet.
59
What portions of the electromagnetic radiation spectrum have a larger wavelength than light?
Infrared, heat, microwaves, FM radio and television.
60
What is the speed of light?
About 186.000 miles per second = 299.792 kilometer per seconde.
61
What wavelength is scattered more strongly?
Short-wavelength.
62
Refraction
When light rays are bent, for example by windows.
63
Where does the light first get to in the eye?
The cornea.
64
What does the aqueous humor do?
Supplies oxygen and nutrients to the cornea and cleans the cornea and the lens.
65
Pupil
A hole in the iris, where the light passes through.
66
What controls the size of the pupil?
The iris.
67
What happens when the pupil is large?
The depth of focus is smaller and image quality poor. Used for low light.
68
Vitreous chamber
Located between the lens and the retina, filled with the vitreous humor.
69
Vitreous humor
The gel-like substance in the vitreous chamber, refracts the light for the fourth time.
70
Transduction
The process in the retina where the light energy is turned into electrical neural signals.
71
What four components of the eye refracts the incoming light?
1. the cornea
2. the aqueous humor
3. the lens
4. the vitreous humor
72
What do the refractive powers of the cornea, aqueous humor, lens and vitreous humor need to be matched to?
The length of the eyeball.
73
What component of the eye has the most refractive power?
The cornea.
74
What three components of the eye have a fixed refractive power?
1. the cornea
2. the aqueous humor
3. the vitreous humor
75
Accomodation
The process of the lens altering the refractive power of the eye by changing shape. Lens gets fatter when gaze directed to nearer objects.
76
What muscle contracts in accomodation in the eye?
The ciliary muscle.
77
What happens when the ciliary muscle is relaxed?
The lens is flat and the zonules are stretched. For looking at distant objects.
78
Lens power (formula)
P = 1/f
with f = focal distance in meters.
79
D
diopters, a unit to measure accomodation
80
How does our accomodation change when we get older?
We lose about 1D every 5 years from 8 y/o to 30 y/o.
81
Presbyopia
Old sight, when old people can't see at 2.5D anymore. Happens to almost everyone since lens loses elasticity, they lose accomodation.
82
Why is the lens transparent?
Because it consists of packed together crystallins (proteins).
83
Cataracts
Opacities of the lens that happen when the regularity of crystallins is disturbed.
84
Emmetropia
When the refractive power of the eye is perfectly matched to the length of the eyeball.
85
Refractive errors
When the eyeball is too long or too short relative to the refractive power of the four components, so the image of the world is not clearly focused on the retina.
86
Myopia
Nearsightedness: When the image is focused in front of the retina, so blur far away.
87
Hyperopia
Farsightedness, when the eyeball is too short and the images is focused behind the retina. Near objects seen unclearly.
88
Foveal vision
The central 1.5-2 degrees of the visual field.
89
Peripheral vision
The visual field outside of the foveal vision.
90
How are photoreceptor types distributed over the visual field?
Mostly cones in the fovea and mostly rods in the periphery.
91
How are bipolar cells distributed over the visual field?
Midget bipolar cells in the fovea and diffuse bipolar cells in the periphery.
92
How is convergence distributed over the visual field?
Low convergence in the fovea and high convergence in the periphery.
93
How is receptive field size distributed over the visual field?
Small receptive field size in the fovea and large receptive field size in the periphery.
94
How is acuity distributed over the visual field?
High acuity in the fovea and low acuity in the periphery.
95
How is light sensitivity distributed over the visual field?
Low light sensitivity in the fovea and high light sensitivity in the periphery.
96
Acuity
Detail
97
Astigmatism
When the cornea is not spherical, but more circle-like: vertical lines in front of retina and horizontal lines behind retina or vice versa.
98
How can astigmatism be corrected?
By lenses that have two focal points.
99
LASIK
laser-assisted in situ keratomileusis
100
What is LASIK?
An eye surgery where the cornea is reshaped to correct refractive power.
101
Fundus
The back part of the eye.
102
Optic disc
A white circle on the fundus where the arteries and veins enter the eyes and the axons of ganglion cells leave the eye via the optic nerve. Has no photoreceptors, so it's blind.
103
Fovea
A spot near the center of the macula containing the highest concentration of cones and no rods. Serves as the point of fixation.
104
Pigment epithelium
A layer of darker cells in the retina, the layer furthest back.
105
What does the light need to pass through before making contact with the photoreceptors?
The ganglion, horizontal and amacrine cells.
106
Why are the photoreceptors in their specific location?
The need to be next to the pigment epithelium for nutrition and recycling, as well as next to the other neurons in order to pass along their signals.
107
How many rods and cones does a human have per eye?
About 90 milion rods and 4-5 million cones.
108
Retinal eccentricity
Distance from the fovea.
109
Duplex retina
A retina that consists of both rods and cones.
110
What happens if we look directly at an object whose image is smaller than one degree?
The image will land on a region of the retina that has only cones.
111
For what vision stuff do we use the fovea?
To identify objects, read and inspect fine detail.
112
For what vision stuff do we use the periphery?
When detecting and localizing stimuli that we aren't looking at directly.
113
What photoreceptor type picks up on color?
The cones
114
Photic sneeze reflex
Sneezing in response to being exposed to bright lights.
115
In what four ways does the visual system adjust to changes in illumination?
1. Pupil size
2. Photopigment regeneration
3. The duplex retina
4. Neural circuitry
116
How does the pupil size adjust to changes in illumination?
The diameter can vary by a factor of about 4. Size determines the amount of light that enters the eye. Takes a few seconds to change, but many minutes in dark adaptation.
117
How does photopigment regeneration adjust to changes in illumination?
With low light, there is many photopigment and rods & cones respond to as many photons as possible. Photopigment is bleached when photon is detected and needs to be regenerated. With a lot of light: many photons, photopigment molecules cannot be regenerated fast enough.
118
How does the duplex retina adjust with changes in illumination?
Rods are used when light is low and cones take over when there is too much light for the rods to function well.
119
How does neural circuitry adjust with change in illumination?
Ganglion cells are most sensitive to light differences in their center & surround of receptive fields, not so affected by average intensity of light. Encode patterns of light & dark areas in retinal image.
120
Receptive field
Region on the retina where visual stimuli influence neuron's firing rate.
121
AMD
age-related macular degeneration
122
What happens in age-related macular degeneration (AMD)?
The macula is affected and gradually destroys sharp central vision.
123
RP
retinitis pigmentosa
124
What happens in retinitis pigmentosa?
There's a progressive degeneration of the retina that affects night vision and peripheral vision.
125
What are the 5 classes of neurons in the retina?
1. Photoreceptors
2. Horizontal cells
3. Bipolar cells
4. Amacrine cells
5. Ganglion cells
126
Photoreceptors
Neurons that produce chemical changes that start a neural events chain. Sends signals by synaptic terminals.
127
What do photoreceptors consist of?
An outer segment, inner segment and synaptic terminal.
128
What does the inner segment in a photoreceptor do?
It makes visual pigments.
129
What does the outer segment in a photoreceptor do?
It stores the visual pigments that the inner segment made.
130
What does a visual pigment molecule consist of?
Protein (opsin) and cromophore.
131
Cromophore
Captures light signals, retinal.
132
Rhodopsin
A visual pigment in rods
133
Melanopsin
A photopigment that is sensitive to ambient light. Specifically found in a photosensitive ganglion cell in the retina.
134
Lateral inhibition
Antagonistic neural interaction between adjacent regions of the retina. Enables signals to be based on differences in activation between nearby photoreceptors.
135
What is the role of bipolar cells?
Determine info that is passed from phootreceptors to ganglion cells. Are small, have a specific amount of neurotransmitter release and all the same rate of response.
136
Describe the response pattern of diffuse bipolar cells
Respond to a single point of bright light at the same rate as to several sports of dim light.
137
Midget bipolar cells
what do they do + where?
Pass info from single cones to single ganglion cells and exist only in the fovea.
138
What is the location of the amacrine cells?
Part of the lateral pathway, they're in the inner layers of the retina.
139
What is the role of amacrine cells?
Receive inputs from bipolar cells and other amacrine cells and send signals to bipolar, amacrine,and retinal ganglion cells.
Serve as a switch between rod and cone system.
140
Where are the ganglion cells
The final layer of the retina, can be P or M ganglion cells.
141
Where from do P ganglion cells receive + what do they feed?
Receive from the bipolar cells and feed the parvocellullar layer of the LGN
142
M ganglion cells
Receive from the diffuse bipolar cells and feed the magnocellular layer of the LGN.
143
LGN
lateral geniculate nucleus
144
Photoactivation
Bleaching: the process where a photon is absorbed by a molecule of rhodopsin in the outer segment of a rod and transfers its energy to the chromophore portion of the visual pigment molecule.
145
Hyperpolarization
A change in membrane potential such that the inner membrane surface becomes more negative than the outer membrane surface.
146
S-cones
short-wavelength sensitive cones
147
What do we mean with 'the foveal centre is dichromatic'?
It has only two color-sensitive cone types.
148
L-cones
long wavelength sensitive cones
149
M-cones
medium-wavelength sensitive cones
150
Photopic
Light intensities that are bright enough to stimulate the cone receptors and saturate the rod receptors (drive them to max response)
151
scotopic
Light intensities that are bright enough to stimulate the rod receptors but too dim to stimulate the cone receptors.
152
What type of cones misses from the center of the fovea?
S-cones
153
What cells form a lateral pathway in the retina?
Horizontal and amacrine cells
154
What cells form a vertical pathway in the retina?
Photoreceptors, bipolar cells and ganglion cells.
155
ON-center bipolar cell
Increases firing rate when light in center of RF, decreasing firing rate when light in surround. Depolarizes in response to increase in light.
156
OFF-center bipolar cell
Hyperpolarizes in response to increase in light. Responds to light in the surround, not in the center.
157
RGC
retinal ganglion cell
158
RF
receptive field
159
When does a ganglion cell fire the fastest?
When the spot of light is the same size as the excitatory centre. (just the right size, less when larger or smaller).
160
Center-surround antagonism
lateral inhibition
161
What is the effect of a high degree of convergence in the retinal periphery?
High sensitivity to light, but poor acuity.
162
What is the effect of the low degree of convergence in the fovea?
High acuity, but poor sensitivity to light.
163
Why are images seen more clearly when they fall on the fovea?
Only there there are one-to-one pathways between cones and ganglions.
164
What are our senses?
1. Vision
2. Hearing
3. Taste
4. Smell
5. Touch
165
What is the fancier word for the hearing sense?
Audition.
166
What is the fancier word for the taste sense?
Gustation
167
What is the fancier word for the smell sense?
Olfaction
168
What is the fancier word for the touch sense?
Somatosensation
169
What is the sixth sense according to Harvey?
Balance
170
What is the fancier word for balance?
Vestibular
171
Which of the senses is our primary sense?
Vision (/sight)
172
Sensation
The translation of the external physical environment into a pattern of neural activity (by a sensory organ).
173
What is the method in perceptual threshold detection called where you change the difficulty of the next trial depending on the answer on the previous trial?
The adaptive method.
174
What are the three types of brain activity discussed in lecture 1?
1. Spiking activity
2. Synaptic activity
3. Metabolic activity
175
Spike activity
Brain activity: spikes are action potentials of individual neuron. Can be measured directly from the neuron (ethical issues).
176
What is + how do you measure synaptic activity
Synaptic potentials, can be measured with scans by putting a detector in between two cells and measure results of them firing.
177
What is metabolic activity?
Oxygen and glucose consumption.
178
Describe the cycle of interaction between excitatory and inhibitory neurons:
When excitaroy pool becomes active, it activates the inhibitory pool. The inhibitory pool becomes activated then and inhibits the excitatory pool so that its activity goes down. The excitatory pool stops exciting the inhibitory pool, and thus the injibitory pool stops inhibiting the excitatory pool which then gives rise to activity in the excitatory pool, and back to the start.
179
LFP
Local field potential.
180
What is the influence of the LFP on perception?
When the local field potential is high, you're more likely to perceive than when it is low.
181
How does the measurement of fMRI work?
The human body is mainly water. All the atoms point the same way when in a permanent static magnetic field. But if pushed in another field in a different direction, and that second field is removed, the atoms bounce back in their position and release activity. Now you can measure water density.
182
Where does the translation from photons to electrical signals happen?
In the photoreceptors.
183
How are photons translated to neural signals?
Cross-membrane proteins in the photoreceptors change structure if they catch a photon and then their membrane opens. Potassium can come out then.
184
What type of photoreceptor do we see colors with?
Cones
185
Rhodopsin
The protein in a rod photoreceptor.
186
Horizontal cell (role in chain)
Get input from photoreceptors and output inhibition.
187
Where are they + what do they do? Postreceptoral layers of the retina
In the eyeball, translate the raw light array captured by the photoreceptors into the patterns of spots surrounded by darkness detected by ganglion cells.
188
What do ganglion cells in the retina respond well to?
Spots of light
189
What do neurons in the cerebral cortex respond well to?
Lines, edges and stripes.
190
Contrast
Difference in illuminaton.
191
Wat is a cycle when talking about grating vision?
One repetition of a black and white stripe.
192
Visual angle
The angle that would be formed by lines going from top/bottom or left/right of a cycle on the page, passing through the center of the lens and ending on the retina.
193
How many degrees is one centimeter?
1
194
How many arc minutes is one centimeter/one degree?
60
195
Why is visual acuity poorer in the periphery compared to the fovea?
Rods and cones are less tightly packed together and less receptors converge on each ganglion cell.
196
Horizontal and vertical assymetry
The visual acuity in the peripheral vision is not uniform, it degrades more rapidly along the vertical midline of the visual field.
197
Vertical meridian assymetry
We have a better acuity a fixed distance below the midline of the visual field than above.
198
What type of vision is slower: central or peripheral?
Central vision is slower: foveal cones have longer axons which transmit slow signals better.
199
What does 20/15 vision mean?
THa you're worse than average, because you need to stand at 15m instead of 20m to read the letters.
200
Amblyopia
A developmental disorder with reduced spatial vision in a healthy eye, even with proper correction for refractive error. = Lazy eye
201
List the different forms of acuity:
1. Minimum visible
2. Minimum resolvable
3. Minimum recognizeable
4. Minimum discriminable
202
Minimum visible acuity
The smallest object that one can detect. Limited by our ability to discriminate intensity relative to background.
203
Minimum resolvable acuity
THe smallest angular separation between neighboring objects that one can resolve. Limited by spacing of photoreceptors in retina (foveal vision).
204
Minimum recognizable acuity
The angular size of the smallest feature that one can resolve.
205
Minimum discriminable acuity
The angular size of the smallest change in a feature that one can discriminate.
206
Vernier acuity
The smallest misalignment one can reliably discern when looking at two lines that are aligned.
207
Spatial frequency
The number of times a pattern repeats in a given unit of space.
208
CSF
contrast sensitivity function.
209
Michelson definition of the CSF
C = (Lmax - Lmin) / (Lmax + Lmin)
with L = luminance
210
Geniculate
'bent'
211
What spatial frequency does an ON-center ganglion cell respond well to?
Medium spatial frequency
212
Why does an ON-center cell responds well to medium frequency?
With a low SF, the bright bar of gratings lands in the inhibitory surround and with a high SF, both dark and bright bars fall within the receptive field center.
213
How many layers does the LGN consist of?
6
214
What are the bottom two layers of the LGN called?
Magnocellular layers
215
Why are the bottom two layers of the LGN called 'magnocellular layers'?
Because there are larger neurons there than in the top four layers.
216
Magnocellular layers
Receive input from M ganglion cells in the retina. Responds to large, fast-moving objects.
217
What are the top four layers of the LGN called?
Parvocellular layers
218
Parvocellular layers
The top four layers in the LGN, have smaller neurons than the magnocellular layers. Receive input from P ganglion cells. Responsible for processing details of stationary targets.
219
What do the layers in-between the layers in the LGN consist of?
Koniocellullar cells
220
Contralateral
Left eye
221
What layers of the LGN receive contralateral input?
1, 4 and 6
222
Ipsilateral
Right eye
223
What layers of the LGN receive ipsilateral input?
Layers 2, 3 and 5.
224
From what eye does the right LGN receive input?
Left eye
225
Topographical mapping
The orderly mapping of the world in the lateral geniculate nucleus and the visual cortex.
226
What is written about the connections between the LGN and the visual cortex? (direction, ratio)
There are more feedback connections from the visual cortex to the LGN than feed-forward from LGN to visual cortex.
227
What part of the brain is inhibited while sleeping?
the thalamus (LGN is part of thalamus, so no vision while sleeping)
228
Inion
A bump at the back of your head, below which is the primary visual cortex.
229
V1
Primary visual cortex
230
Area 17
Prmary visual cortex
231
How is the striate cortex built up?
Six layers, some having sublayers.
232
What layer of the striate cortex does the LGN project to?
Mostly to layer 4.
233
Where do the magnocellular axons go in the striate cortex?
The upper part of layer 4C, called 4Calpha
234
What part of the striate cortex do the parvocellular axons connect to?
The lower part of layer 4C, called 4Cbeta
235
Name two important features of the visual cortex:
1. Topograhpy
2. Magnification
236
Cerebral cortex
Primary visual cortex
237
Cortical magnification
The process that objects on the fovea get much more processing space in the cortex than objects in the periphery.
->Cortical representation of fovea is magnified compared to that of peripheral vision.
238
Visual crowding
A phenomenon in the periphery when objects are not recognized as well because they appear combined with surroundings.
239
Ocular dominance
The property of striate receptive fields that they have a preference for a stimulus in one eye versus the other eye.
240
Simple cell
The 'line detector'. An edge detector in V1 that has clear ON and OFF regions, is orientation selective and gets input from LGN cells.
241
Edge detector
The three types of cells in V1. Have large receptive fields and are the basis of simple object recognition.
242
Stripe detector
The simple cell. Excited when a line of light with a particular width is surrounded by darkness.
243
Complex cells
The 'motion detector'. No clear ON and OFF regions. Respond best to a moving edge with a particular orientation and direction. Get input from simple cells.
244
End stopping
A property of some cells in the striate cortex. Happens in hypercomplex cells: response rate increases when filling up RF, but decreases as bar extends beyond RF.
245
Perpendicular
Loodrecht op
246
Hypercolumn
A column of 2 sets of columns: each set has one left dominant & one right dominant column that both have every possible orientation. Responsible for all processing of a small part of the visual field.
247
CO
Cytochrome oxidase
248
Cytochrome oxidase blobs
Arranged in a regular array, implicated in processing color and the interblob regions in processing motion and spatial structure.
249
Adaptation
Method where neural firing is measured for a certain stimulus, the stimulus adapted and change in neural firing rate measured. Cells might be fatigues after first representation, so cells next to it are more active the second stimulus.
250
Tilt aftereffect
Fact that there is little to no effect on sensitivity to vertical gratings followeing adaptation to horizontal gratings. Supports that there are individual neurons selective for different orientations.
251
Selective adaptation
Neurons most sensitive to stimulus become fatigued, so then higher contrast is needed after adaptation in order to stimulate these neurons.
252
Interocular transfer
The transfer of adaptation from the adapted to the non-adapted eye.
Shows that selective adaptation must happen in cortical neurons.
253
Spatial frequency channels
Pattern analyzers that are implemented by ensembles of cortical neurons, with each set of cells tuned to a limited range of spatial frequencies and orientations.
254
What do low frequencies emphasize?
The broad outlines
255
What do high rrequencies carry in vision?
Informatino about details.
256
VEP method
Visually evoked electrical potentials.
257
When is the critical period of early visual development?
3-8 years.
258
Steropsis
Lack of binocular depth perception
259
Strabismus
When one eye is turned so that it receives a view from the world in an abnormal angle.
260
Anisometropia
When two eyes have very different refractive errors.
261
Superior colluculus
Gets input from the eyes and is very fast and reflexive.
262
Name the two main classes of retinal ganglion cells:
1. Magnocellular / parasol cells (M cells)
2. Parvocellular / midget cells (P cells)
263
Where are the bistratified cells?
In the koniocellular layers.
264
What is another name for P cells?
Midget cells
265
What is another name for M cells?
Parasol cells.
266
Describe the visual pathway of motion/spatial information.
M cells ->
Magnocellular layers ->
4C alpha ->
4C beta ->
thick stripe and dorsolateral, parietal and temporal cortex.
267
Describe the visual pathway of form information:
P cells ->
parvocellular layer ->
4Cbeta ->
level 2 and 3 interblobs ->
pale interstripe ->
inferior occipitemporal cortex.
268
Describe the visual pathway of color information:
P cells and bistratified cells ->
parvocellular and intralamirro koniocellular layers ->
4C beta ->
layer 2 and 3 blobs ->
thin stripe ->
inferior occipitotemporal cortex.
269
What visual pathways go through layer 4b?
Contrast, motion and orientation.
270
What visual pathways go through the blobs?
Contrast and color
271
What visual pathways go through the interblobs?
Location, motion (semi), color (semi) and orientation.
272
What three cell types in the primary visual cortex are called the edge detectors?
1. Simple cells
2. Complex cells
3. Hypercomplex cells.
273
Where does LGN get input from?
Retinal ganglion cells.
274
What properties does a simple cell have?
Orientation and position selective.
275
Why is the position selectivity lost in the complex cell?
It gets input from 3 simple cells which are lined up. The simple cells are slightly different, so when they are all active the complex cell doesn't know the exast position.
276
How are receptive field size and eccentricity related?
The further in eccentricity, the larger the receptive fields become.
277
What are the four elements that determine a grating?
Phase, orientation, spatial frequency and contrast.
278
Hertz (Hz)
The number of wave cycles per second, the wave's frequency.
279
How do oscillations arise?
From interactions between excitatory and inhibitory neural population. At peaks, excitatory population acitivity is highest incl. spike rate.
280
T1 image
An image of the locations of the atoms, resulting from an fmri procedure.
281
inhomogeneity
distortion
282
PD (in mri)
proton density
283
T1 (in mri)
realignment with magnetic field
284
T2 (in mri)
proton misalignment due to tissue interactions
285
TMS
transcranial magnetic stimulation
286
What are the advantages of EEG?
1. Cheap
2. High temporal resolution
3. Moves with the subject
4. Silent
287
What are the disadvantages of EEG?
1. Poor spatial resolution
2. Poor signal-to-noise ratio
3. Only senses activity near the scalp
4. Slow to set up
288
Give the steps that show why fmri works:
1. Deoxyhemoglobin affects T2*
2. Blood response follows neural activity
3. Step 2 overcompensates
289
What is the stuff called on which the fmri images depend?
deoxygenated haemoglobin
290
What happens with the oxyhemoglobin levels when blood flow increases?
The oxyhemoglobin concentration increases.
291
What happens to the oxyhemoglobin concentration when oxygen is used?
Nothing.
292
What does the BOLD signal look like following neural activity?
There is an early small dip and then a larger increase.
293
Lesion
A damaged area of the brain.
294
What brain area is necessary for motion perception?
Area MT
295
How does transcranial magnetic stimulation work?
Changing magnetic fields disrupt electrical activity in a specific part of the brain. It can show that activity in that part is necessary for a certain process/task.
296
Convergence
The way your eyes move together and point inward when you look at nearby objects.
297
Protanopia
When the L-cone is missing.
298
Deuteranopia
When the M-cone is missing
299
Tritanopia
When the S-cone is missing
300
What determines spacial acuity?
The density of receptors.
301
Do we perceive light?
No, we perceive changes in light (intensity) across space and or time.
302
Dualism
The idea that the mind has an existence separate from the material world of the body.
303
Materialism
The idea that the only thing that exists is matter and that all things are the results of interaction between bits of matter.
304
Two-point touch threshold
The minimum distance at which two stimuli are just perceptible as separate.
305
Just noticeable difference (JND)
The smallest detectable difference between two stimuli or the minimum change in a stimulus that enables it to be correctly judged as different from a reference stimulus.
306
Supertaster
An individual who experiences the most intense taste sensations.
307
Signal detection theory
A theory where the response of an observer to the presentation of a signal in the presence of noise is quantified. Uses sensitivity and criterion measures.
308
Criterion (in SDT)
An internal threshold that is set by the observer. If internal response is above criterion, obeserver gives one response and if not, another response.
309
Sensitivity (SDT)
The ease with which an observer can tell the difference between the presence and absence of a stimulus.
310
ROC curve (abbreviation)
Receiver operating characteristic curve
311
ROC curve
The graphical plot of the hit rate as a function of the false alarm rate.
312
Sine wave
A simple oscillation that repeats across space.
313
Wavelength
The distance required for one full cycle of oscillation for a sine wave
314
Period
The time required for a full wavelength of an acoustic sine wave to pass by a point in space.
315
Phase
A fraction of the cycle of a sine wave described in degrees or radians.
316
Cranial nerves
Twelve pairs of nerves that originate in the brain stem and reach sense organs and muscles through openings in the skull.
317
Olfactory/ I nerves
The first pair of cranial nerves. Axons of the olfactory sensory neurons bundled together, conducts impulses from the olfactory epithelia in the nose to the olfactory bulb.
318
Optic / II nerves
Second pair of cranial nerves. Arise from retina and carry visual information to the thalamus and other parts of brain.
319
Vestibulocochlear / VIII nerves
Eigth pair of cranial nerves. Connect the inner ear with the brain, transmitting impulses from hearing and spatial orientation. Composed of cochlear nerve branch and vestibular nerve branch.
320
Oculomotor / III nerves
Third pair of cranial nerves. Connect to the extrinsic muscles of the eye and the elevator muscle of upper eyelid, ciliary muscle and sphincter muscle of the pupil
321
Trochlear / IV nerves
Fourth pair of cranial nerves, connect to superior oblique muscles of the eyeballs.
322
Abducens / VI nerves
Sixth pair of cranial nerves, connect the lateral rectus muscle of the eyeballs.
323
Polysensory
Blending multiple sensory systems.
324
Neurotransmitter
A chemical substance used in neuronal communication at synapses.
325
Neuroimaging
A set of methods that generate images of the structure/ function of the brain.
326
BOLD signal
The ratio of oxygenated to deoxygenated hemoglobin that permits the localization of brain neurons that are most involved in a task.
327
Cornea
The transparent 'window' into the eyeball.
328
Aqueous humor
The watery fluid in the anterior chamber of the eye
329
Lens
The structure inside the eye that enables the changing of focus.
330
Iris
The coloured part of the eye, consisting of a muscular diaphragm surrounding the pupil and regulating the light entering the eye by expanding and contracting the pupil.
331
Retina
A light-sensitive membrane in the back of the eye that contains photoreceptors and other cell types that transduce light into electrochemical signals and transmits them to the brain through the optic nerve.
332
Focal distance
The distance between the lens and the viewed objects, in meters.
333
What are the most common refractive errors?
Myopia, hyperopia, astigmatism and presbyopia.
334
Macula
The pigmented region with a diameter of about 5.5mm near the center of the retina.
335
Rod
A photoreceptor specialized for night vision.
336
Cone
A photoreceptor specialized for daylight vision, fine visual acuity and colour.
337
Eccentricity
The distance between the retinal image and the fovea.
338
Receptive field
The region of the retina in which visual stimuli influence a neuron's firing rate.
339
Synaptic terminal
The location where axons terminate at the synapse for transmission of information by the release of a chemical transmitter.
340
Chromophore
The light-cathing part of the visual pigments of the retina.
341
Graded potential
An electrical potential that can vary continuously in amplitude.
342
Horizontal cell
A specialized retinal cell that contacts both photoreceptor and bipolar cells.
343
Visual acuity
A measure of the finest detail that can be resolved by the eyes.
344
Midget bipolar cell
A small bipolar cell in the central retina that receives input from a single cone.
345
Contrast sensitivity function (CSF)
A function describing how the sensitivity to contrast depends on the spatial frequency of the stimulus.
346
Contrast threshold
The smallest amount of contrast required to detect a pattern.
347
Lateral geniculate nucleus
A structure in the thalamus that receives input from the retinal ganglion cells and has input and output connections to the visual cortex.
348
Koniocellular cell
A neuron located between the magnocellular and parvocellular layers of the lateral geniculate nucleus.
349
Contralateral
Referring to the opposite side of the body
350
Ipsilateral
Referring to the same side of the body
351
orientation tuning
The tendency of neurons in striate cortex to respond optimally to certain orientations and less to others.
352
Extrastriate cortex
A set of visual areas that lie just outside the primary visual (striate) cortex.
353
RGC
Retinal ganglion cells
354
When do receptive fields start to show interest in properties important to object recognition?
Beyond V1.
355
Where are the cells that care about border ownership found?
In area V2.
356
From what lobe to what lobe is the where pathway?
From the occipital lobe to the parietal lobe.
357
From what lobe to what lobe is the what pathway?
From the occipital lobe to the temporal lobe.
358
Lesioned
Surgically removed
359
Agnosia
Having the ability to see without recognizing what is being seen.
360
IT cortex (abbreviation)
Inferotemporal cortex.
361
What cortex is important in agnosia?
The IT cortex.
362
Grandmother cell
Any cell that seems to be selectively responsive to one specific object.
363
Homologous regions
Regions that appear to be equivalent in function, but not identical in different species.
364
Prosopagnosia
The inability to recognize faces.
365
Reverse-hierarchy theory
Argues that the feed-forward processes give you a general categorical impression of the world, but that you become aware of the details only through feedback.
366
What is the goal of mid-level vision?
To organize the elements of a visual scene into groups that we can recognize as objects.
367
Illusory contours
Edges that are perceived even though large parts are missing.
368
What view is challenged by the existence of illusory contour?
The structuralist view: perception cannot be the sum of atoms of sensations if illusory contour exists.
369
Gestalt theory
The perceptual whole is more than the sum of its parts.
370
Gestalt grouping rules
A set of organizing principles that describe the visual system's interpretation of the raw retinal image.
371
What are two of the strongest Gestalt principles?
Similarity and proximity
372
Similarity (Gestalt principle)
Image chunks that are similar to each other will be more likely to group together.
373
Proximity (Gestalt principle)
Items near each other are more likely to group together than items more widely separated.
374
What are two weaker Gestalt principles?
Parallellism and symmetry.
375
Ambiguous figure
A figure that generates two or more plausible interpretations.
376
Necker cube
A cube where mid-level vision shows two different interpretations, but does not show other interpretations that are also possible.
377
Accidental viewpoint
When you have to view a scene from one very precise location in order to see a certain interpretation, produces some regularity in the visual image that is not present in the world.
378
Figure-ground assignment
The process of assigning regions that we see to figure/foreground or background.
379
Relatability
Whether two contour segments look like they belong to the same edge.
380
Global superiority effect
Global stuff interferes more with recognition of local stuff than vice versa.
381
Subtraction method
Used to show the special activation of regions of the cortex to specific stimuli. Sets of stimuli that share one region, then subtract brain activation.
382
FFA
fusiform face area
383
EBA
extrastriate body area
384
Structural description
A specification of an object in terms of its parts and the relationship between parts
385
Entry-level category
The first word that comes to mind when asked to name a category.
386
Holistic processing
You don't recognize parts of a face like someone'sn ose, but the face as a whole.
387
Congenital prosopagnosia
When someone is born wiht an impariment to recognize faces.
388
5 principles of mid-level vision
1. Bring together wat should be brought together.
2. Split what needs to be split.
3. Use what you know.
4. Avoid accidents.
5. Seek consensus and avoid ambiguity.
389
Recognition-by-components model
A set of geons (geometric ions) could be the basis building blocks of object perception in the world. Visual system recognizes objects by the relationship of its geons.
390
IT cortex
Part of the cerbral cortex in the lower portion of the temporal lobe, important in object recognition.
391
Good continuation
A Gestalt grouping rule stating that two elements will tend to group together if they seem to lie on the same contour.
392
Closure
The Gestalt principle stating that a closed contour is preferred to an open contour.
393
Texture segmentation
Carving an image into regions of common texture properties.
394
Parallellism
A rule for figure-ground assignment stating that parallel contours are likely to belong to the same figure.
395
Symmetry (Gestalt)
A rule for figure-ground assignment stating that symmetrical regions are more likely to be seen as figure.
396
Surroundedness
A rule for figure-ground assignment stating that is one region is entirely surrounded by another, it is likely that the surrounded region is the figure.
397
Nonaccidental feature
A feature of an object that is not dependent on the exact viewing position of the observer.
398
PPA
parahippocampal place area
399
Parahippocampal place area
A region of extrastriate visual cortex in humans that is specifically and reliably activated more by images of places than by other stimuli.
400
Fusiform face area
A region of extrastriate visual cortex in humans that is specifically and reliably activated by human faces.
401
Extrastriate body area
A region of extrastriate visual cortex in humans that is specifically and reliably activated by images of the body other than the face.
402
Decoding
The process of determining the nature of a stimulus from the pattern of responses measured in the brain or potentially in an ai system.
403
Template
The internal representation of a stimulus that is used to recognize the stimulus in the world.
404
Name the three steps to go from physical wavelengths to perception of color:
1. Detection
2. Discrimination
3. Appearance
405
How many types of cone photoreceptors do we have?
3
406
At what wavelength do S-cones peak?
420 nm
407
Around what wavelength do M-cones peak?
535nm
408
Around what wavelength do L-cones peak?
565 nm
409
At what light levels do cones work?
Photopic
410
At what light levels do rods work?
Scotopic light
411
Around what wavelength do rods peak?
500nm
412
Principle of univariance
The fact that one type of cone is color blind because it has the same response for different wavelengths, gives ambiguous output.
413
Trichromacy
The idea that ability to discriminate one light from another is defined in our visual system by the relationships among three numbers.
414
Metamers
MIxtures of different wavelengths that look identical. Any pair of stimuli that are perceived as identical in spite of physical difference.
415
What is trichomatric theory often called?
the Young-Helmholtz theory
416
Additive color mixture
Taking one wavelength or a set of wavelengths and adding it to another, for example red + green = yellow.
417
Subtractive color mixture
When substance absorbing wavelengths are mixed, thus absorbing more wavelengths and showing a different color.
418
Maxwell's color-matching experiment
A color is presented and participants adjust a mixture of three lights (blue, green & red) to obtain the presented color.
419
What does the nervous system do in order to discriminate colours?
It looks at differences in activity of the three cone types.
420
Yellow light is equivalent to a mix of...
Long and medium wavelength.
421
Blue plus yellow light results in a mix of .... and looks ...
short, medium and long wavelengths
white
422
What two differences in cone photoreceptor activity does the nervous system compute?
1. (L-M)
2. ([L+M]-S)
423
Cone-opponent cell
A cell where different sources of chromatic information are pitted against each other.
424
Where do S-cone signals go to?
Through the koniocellular layers in the LGN.
425
Where do M- and L-cone signals go?
Mostly through the parvocellular layers.
426
Equiluminant stimuli
Stimuli that vary in color but not in luminance. Bad spatial resolution
427
Mesopic range
The middle range of light intensities.
428
HSB (color)
Hue, Saturation and Brightness
429
CMYK (color)
Cyan, Magenta, Yellow and blacK.
430
Hering's opponent colour theory
Has four basic opponent colours: red vs green and blue vs yellow. 3rd pair might be blak vs white. Perception of colour is based on the output of three mechanisms, these opponencies.
431
Hue cancellation
When you start with a light that appears one colour and add the opponent colour to it, it cancels out the colour it appeared to be.
432
Unique hue
A hue that can be described with a single colour term.
433
How many unique hues exist?
4
434
List the four unique hues
1. Red
2. Green
3. Yellow
4. Blue
435
What colour do very long wavelengths look like?
red
436
Globs
Colour hot spots in the visual cortex of monkeys
437
Achromatopsia
Loss of colour vision after brain damage. Vision is largely intact, except for colour experience.
438
Tetrachromatic colour vision
Is based on four numbers per patch of light, happens in women that have 4 different cone pigments.
439
Deuteranope
Someone who has no M-cones.
440
Protanope
Someone who has no L-cones
441
Tritanope
Someone without S-cones.
442
Color-anomalous
When someone has three cone photopigments, but two of them are so similar that it is close to having only two cone types.
443
Cone-monochromat
Someone who has only onte type of cone in the retina.
444
Rod monochromat
Someone who misses cones altogether. They fail to discriminate colours, have poor acuity and difficulties seeing in daylight conditions.
445
Anomia
Inability to name.
446
Color contrast
When the color of one region induces the opponent color in a neighbouring region.
447
Color assimilation
When two colours bleed into each other, each taking on some of the chromatic quality of the other.
448
Isolated colour
Unrelated colour
449
Negative afterimage
If you look at one colour for a few seconds, a subsequently viewed achromatic region will appear to take on a colour opposite to the original colour. First colour is adapting stimulus.
450
Colour constancy
The tendency for colour of objects to appear relatively unchanged in spite of substantial lighting changes.
451
Illuminant
The light that illuminates the surface.
452
Spectral reflectance function
The percentage of each wavelength that is reflected from a particular surface.
453
Spectral power distribution
The relative amount of light at different visible wavelenghts.
454
Spectral sensitivity
The sensitivity of a cell or a device to different wavelengths on the electromagnetic spectrum.
455
Colour space
The three-dimensional space that describes the set of all colours. Established because colour perception is based on outputs of three cone types.
456
Related colour
A colour that is seen only in relation to other colours. Ex: a gray patch in complete darkness appears white.
457
Adapting stimulus
A stimulus whose removal produces a change in visual perception or sensitivity.
458
Neutral point
The point at which an opponent colour mechanism is generating no signal.
459
`What light colour do S-cones generally respond to?
Blue
460
What colour of light do M-cones generally respond to?
Green
461
What colour of light do L-cones generally respond to?
Red.
462
What is the distribution of cone types in the retina?
About 60% L-cones, 30% M-cones and 10% S-cones.
463
What does the ratio of activation of cone types tell us?
It gives a description of the of the colour that falls on the retina regardless of brightness.
464
What does the height of cone activity tell us?
How intense the light is.
465
What is another term for the magnocellular cells?
Parasol cells
466
What is another term for the parvocellular cells?
Midget cells
467
What is another name for the parasol cells?
Magnocellular cells
468
What is another name for the midget cells?
Parvocellular cells
469
What is the difference in receptive field size between the two main classes of RGCs?
Magnocellular/parasol cells have large RFs and parvocellular/ midget cells have smaller RFs.
470
What is the difference in response time for the two main classes of RGCs?
M/parasol cells respons quickly and are good for motion/low-light conditions. P/midget cells respond slowly and give good info about form/shape.
471
Visual word form area
A brain area that responds to written word.
472
What is the parvocellular/magnocellular difference in terms of what/where?
Parvocellular is the what-pathway and magnocellular is the where-pathway.
473
What is the parvocellular/magnocellular difference in terms of the visual info they process?
Parvocellular processes form and color, magnocellular processes motion and space.
474
What is the parvocellular/magnocellular difference in terms of their function?
Parvocellular serves recognition, magnocellular action.
475
What is the parvocellular/magnocellular difference in terms of their location?
Parvocellular is ventral, magnocellular is dorsal.
476
What is the parvocellular/magnocellular difference in terms of their lobes?
Parvocellular through the temporal lobe, magnocellular through the parietal lobe.
477
What pathway does a ventral lesion affect?
The what-pathway (parvocellular)
478
What part of the brain is activated in response to objects and faces?
The bottom of the temporal lobe: inferior temporal lobe or IT.
479
Decoding
THe approach of associating a pattern of brain activity with a particular stimulus or task.
480
Hypnagogia
The transition to sleep in which people often experience visual imagery much like dreams.
481
What is the first step between early visual processing and object processing?
Grouping edges.
482
How does sensitivity to groups of edge patches develop during our life?
Is not present at birth, learned through statistical correlations and increases into the 20s.
483
Where is the mid-level shape processing area?
The hV4 area and LO1
484
hV4 area
Lies on or near the inferior occipital gyrus and contains a face selective region.
485
LO1
Lateral occipital area 1
486
Distributed encoding
When the activity from a group of neurons yields a result that is interpreted, so one group can create multiple combinations.
487
Exclusive encoding
When the activation of a single neuron is taken to be interpreted.
488
Graceful degradation
The ability to (largely) maintain function even though parts are destroyed (in neuron populations)
489
Deep convolutional network
Tries to imitate the brain's structure over many levels. Each layer uses input from prior layer and gives input to the next layer.
490
DCNN
Deep convolutional neural network
491
List the Gestalt laws of organisation:
1. Proximity
2. Similarity
3. Good continuation
4. Closure
5. Common fate
6. Pragnantz / law of simplicity
492
Pragnantz
Law of simplicity: group objects because simple or familiar.
493
Why do Gestalt laws work?
They reflect assumptions about the nature of real-world surfaces and objects.
494
Realism
The philosophical position that there is a real world to sense.
495
Positivism
The philosophical position that all we really have to go on is the evidence of our senses, so the world could be an elaborate hallucination.
496
What happens to the retinal image of an object as the object gets further away from the eye?
It gets smaller.
497
Lateral eyes
Eyes on the side of the head, some animals have this.
498
Frontal eyes
When eyes are positioned like humans, facing one direction.
499
How many degrees is our human visual field from left to right?
190 degrees
500
What part of our horizontal visual field can be seen by both eyes?
110 degrees out of the 190 degrees.
501
How big is our human visual field from up to down?
140 degrees
502
How is our vertical visual field partitioned?
Abot 60 degrees up untill your eyebrows block the view, and 40 degrees down to the cheeks.
503
Binocular
Referring to two eyes.
504
Probability summation (vision)
The increased detection probability based on the statistical advantage of having two (or more) detectors rather than one
505
Binocular summation
the combination of signals from both eyes in ways that make performance on many tasks better than with either eye alone.
506
Binocular disparity
the differences between the two retinal images of the same scene.
507
Stereopsis
A vivid perception of the three-dimensionality in the world, the binocular perception of depth.
508
Is stereopsis available with monocular vision?
no
509
Monocular
Referring to one eye
510
Monocular depth cue
a depth cue that is availble even when the world is viewed with one eye alone
511
Binocular depth cue
a depth cue that relies on information from both eyes.
512
Pictorial depth cues
A cue to distance or depth used by artists to depict three-dimensional depth in two-dimensional pictures.
513
Why is it we can see depth in two-dimensional pictures?
The retinal image formed by the two-dimensional picture is the same as the one that would have been formed by the 3d world + depth cues.
514
Occlusion (depth cue)
A nonmetrical depth cue to relative depth order, present in almost every visual scene.
515
Nonmetrical depth cue
A depth cue that provides information about the depth order (relative depth), but not the absolute depth.
516
Projective geometry
the geometry that describes the transformations that occur when the three-dimensional world is projected onto a two-dimensional surface.
517
Relative size (depth cue)
The comparison between items without knowing the absolute size of either one.
518
Texture gradient
A depth cue based on the geometric fact that items of the same size form smaller images when they are further away.
519
Metrical depth cue
A depth cue that provides quantitative information about distance in the third dimension.
520
Familiar size (depth cue)
A depth cue based on knowledge of the typical sizes of objects.
521
Relative metrical depth cue
A depth cue that could specify the relationship between distances bt not the absolute distance.
522
Absolute metrical depth cue
A depth cue that provides quantifiable information about distance in the third dimension.
523
What is another word for aerial perspective?
Haze
524
What is another word for haze?
Aerial perspective
525
Aerial perspective
A depth cue based on the implicit understanding that light is scattered by the atmosphere. More light is scattered when we look through more atmosphere so more distant objects are subject to more scatter and appear fainter, bluer and less distinct.
526
Linear perspective
A depth cue based on the fact that lines are parallel in the three-dimensional world will appear to converge in a two-dimensional image.
527
Vanishing point
The apparent point at which parallel lines receding in depth converge.
528
Anamorphic art
Art where the two-dimensional image is recognizable only from an unusual vantage point.
529
Anamorphosis
The use of the rule of linear perspective to create a two-dimensional image so distorted that it looks correct only from a special angle or with a mirror.
530
Triangulation cues
Depth cues that cannot be reproduced in a static two-dimensional picture.
531
Motion parallax
A depth cue based on head movement. Geometric information from one eye in two positions at two times is similar to the info from two eyes in two positions at one time.
532
Optic flow
The pattern of apparent motion of objects in a visual scene produced by the relative motion between the observer and the scene.
533
Divergence
The ability of the eyes to turn outward.
534
Corresponding retinal points
Two monocular images of an object in the world are said to fall on corresponding points if those points are the same distance from the fovea in both eyes. The two foveas are also corresponding points.
535
Vieth-Müller circle
The location of objects whose images fall on geometrically corresponding points in the two retinas.
536
Horopter
The location of objects whose images lie on corresponding points.
537
Surface of zero disparity
the horopter
538
Are the horopter and the Vieth-Müller circle the same?
Not quite.
539
Diplopia
Double vision
540
Panum's fusional area
The region of space in front of and behind the horopter within which binocular single vision.
541
Crossed disparity
The sign of disparity created by objects in front of the horopter.
542
Uncrossed disparity
The sign of disparity created by object behind the horopter.
543
What happens to the horopter if we change our fixation?
It moves to a different location in space.
544
Stereoscope
A device for simultaneously presenting one image to one eye and another image to the other eye.
545
Free fusion
The technique of converging (crossing) or diverging the eyes in order to view a stereogram without a stereoscope.
546
Stereoblindness
An inability to make use of binocular disparity as a depth cue.
547
RDS (abbreviation)
random dot stereogram
548
Random dot stereogram (RDS)
A stereogram made of a large number of randomly placed dots, contains no monocular cues to depth.
549
Cyclopean stimuli
Defined by binocular disparity alone.
550
Correspondence problem
The problem of figuring out which bit of the image in the left eye should be matched with which bit in the right eye.
551
Uniqueness constraint
The observation that a feature of the world is represented exactly once in each retinal image.
552
Continuity constraint
The observation that, ecept at the edges of objects, neighbouring points in the world lie at similar distances from the viewer.
553
Binocular rivalry
The competition between the two eyes for control of visual perception, which is evident when completely different stimuli are presetnted to the twoeyes.
554
Until when are infants blind to disparity?
Until 3-4 months
555
When are infants sensitive to depth based on pictorial cues?
From 6 months and on.
556
Stereoacuity
A measure of the smallest binocular disparity that can generate a sensation of depth.
557
Esotropia
Strabismus in which one eye deviates inward.
558
Exotropia
Strabismus in which one eye deviates outward.
559
Tilt aftereffect
the perceptual illusion of tilt, produced by adaptation to a pattern of given orientation.
560
Interocular transfer
Transfer of the effect from one eye to the other.
561
Surpression (vision)
INhibition of unwanted images.
562
What are the monocular depth cues?
1. Occlusion
2. Various size and position cues
3. Aerial perspective
4. Linear perspective
5. Motion cues
6. Accomodation
7. Convergence
563
External attention
Attention to stimuli in the world
564
Internal attention
Our ability to attend to one line of thought as opposed to another, or to select one response over another.
565
Overt attention
Directing a sense organ at a stimulus.
566
Covert attention
For example, looking at a page while directing attention to a person at your side
567
Attention
Any of the very large set of selective processes in the brain.
568
Selective attention
The form of attention involved when processing is restricted to a subset of the possible stimuli
569
RT (abbreviation)
reaction time
570
Reaction time
A measure of the time from the onset of a stimulus to a response.
571
Cue (in RT experiments)
A stimulus that might indicate where (or what) a subsequent stimulus will be. Can be valid, invalid or neutral.
572
What is the difference in reaction time for valid vs invalid cues?
RT decreases with valid cues and increases with invalid cues.
573
Exogenous cue
A cue that is located out (exo) at the desired final location of attention.
574
Endogenous cue
A cue that is located in (endo) or near the current location of attention
575
Peripheral cue
Exogenous cue
576
Symbolic cue
Endogenous cue
577
SOA (abbreviation)
stimulus onset asychrony
578
Stimulus onset asychrony (SOA)
The time between the onset of one stimulus and the onset of another.
579
Probe
Target stimulus
580
Inhibition of return (in attention)
The relative difficulty in getting attention (or the eyes) to move back to a recently attended (or fixated) location.
581
Visual search
A search for a target in a display containing distracting elements.
582
Target (in visual search)
The goal of a visual search.
583
Distractor (in visual search)
Any stimulus other than the target.
584
Set size (in visual search)
The number of items in a visual display.
585
How is the efficiency of a search task described?
By the slope of the function relating RT to set size. Higher slope = lower efficiency.
586
Feature search
Search for a target defined by a single attribute (ex: color or orientation).
587
Salience
The vividness of a stimulus relative to its neighbors.
588
Parallel search
A search in which multiple stimuli are processed at the same time.
RT does not change with the set size, thus the slope relating RT to set size is about flat, 0ms per item.
589
Serial self-terminating search
A search from item to item, ending when a target is found.
590
What does it mean when a visual search is inefficient?
Each additional item in the display imposes a significant cost on the researcher.
591
Guided search
A search in which attention can be restricted to a subset of possible items on the basis of information about the target item's basic features (ex: color).
592
Conjunction search
A search for a target defined by the presence of two or more attributes.
593
Scene-based guidance
Information in our understanding of scenes that helps us find specific objects in scenes.
594
Binding problem
The challenge of tying different attributes of visual stimuli which are handled by different brain circuits to the appropriate object so that we perceive a unified object.
595
Feature integration theory
Anne Treisman's theory of visual attention, which holds that a limited set of basic features can be processed in parallel preattentively, but other properties including the correct binding of features to objects, require attention.
596
Preattentive stage
The processing of a stimulus that occurs before selective attention is deployed to that stimulus.
597
Illusory conjunction
An erroneous combination of two features in a visual scene (ex: seeing red X when display has red letters and Xs but no red Xs).
598
RVSP (abbreviation)
rapid serial visual presentation
599
Rapid serial visual presentation (RSVP)
An experimental procedure in which stimuli appear in a stream at one location at a rapid rate.
600
AB (abbreviation)
attentional blink
601
Attentional blink (AB)
The tendency not to perceive or respond to the second of two different target stimuli amid a rapid stream of distracting stimuli if the observer has responded to the first target stimulus 200-500 ms before the 2nd stimulus is presented.
602
Response enhancement
An effect of attention on the response of a neuron in which the neuron responding to an attended stimulus gives a bigger response
603
Sharper tuning
An effect of attention on the response of a neuron in which the neuron responding to an attended stimulus responds more precisely.
604
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.
605
Neglect
The inability to attend or respond to stimuli in the contralesional visual field, or ignoring half of the body or half of an object.
606
Contralesional field
The visual field on the side oppsite a brain lesion
607
Extinction
The inability to perceive a stimulus to one side of the point of fixation in the presence of another stimulus, typically in a comparable position in the other visual field
608
Ipsilesional field
The visual field on the same side as a brain lesion
609
ADHD (abbreviation)
Attentional deficit hyperactivity disorder
610
Ensemble statistics
The average and distribution of properties like orientation or color over a set of objects or over a region in a scene. Our estimates of ensemble statistics are surprisingly accurate.
611
Spatial layout
The description of the structure of a scene without reference to the identity of specific objects in the scene.
612
Change blindness
The failure to notice a change between two scenes. If the gist, or meaning, of the scene is not altered, quite large changes can pass unnoticed.
613
Inattentional blindness
A failure to notice -or at least to report- a stimulus that would be easily reportable if it were attended.
614
Hypercomplex cell
The 'angle detector'. Is orientation selective, has endstopping and gets input from the complex cells.
615
