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Psychology Y1 > Perception & Cognition 1/2 > Flashcards

Perception & Cognition 1/2 Flashcards

1
Q

Explain the timeline of understanding of vision

A

Democritus: atoms fro images pass through the eye into the body
Plato: No one will ever be able to explain vision as it is too complex
Alhazen: ‘light rays’ from the surface of an object are carried into your eye
Da Vinci: recognised depth in vision
Helmholtz: founded modern vision science and the ophthalmoscope

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2
Q

What does the ciliary body do in the eye?

A

makes aqueous humour

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3
Q

What is a receptive field?

A

An area of photoreceptors (rods&cones) attached to a single ganglion cell

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4
Q

What is lateral inhibition?

A

Where two stimulated neurones next to each other in a receptive field are activated, the one with stronger stimulation shuts down the response from the other
e.g. negative surround inhibits positive centre

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5
Q

What is myopia?

A

short-sightedness

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6
Q

What is hyperopia?

A

long-sightedness

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7
Q

What is the number one cause of blindness?

A

Age related Macular Degeneration

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8
Q

What is AMD?

A

Age related Macular Degeneration:
parts of the retina start peeling away causing light spots at the back of the eye and vision degeneration from the centre out

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9
Q

What is Glaucoma?

A

Aqueous humour cannot drain so pressure builds up crushing nerves in the optic disc, vision degenerates from outside in

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10
Q

What is diabetic retinopathy?

A

Blood vessels leak into the back of the eye disrupting photoreceptor function, vision loss patchy

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11
Q

What does lateral inhibition cause?

A

Enhanced contrast

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12
Q

Explain the timeline of understanding colour vision

A

Isaac Newton: Prism experiments discovered 3 primary colours of light
Young: Trichromatic theory of vision
Williams: Could look into the back of the eye using adaptive optic system and see proportions of different types of cones

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13
Q

What is the trichromatic theory of vision?

A

Humans posess only 3 types of photoreceptors - L, M & s that when stimulated in correct ratios mean we can see any colour

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14
Q

What are the 3 types of photoreceptors in humans and what light wavelengths do they prefer?

A

L=red cones (long wave sensitive)
M=green cones (medium wave sensitive)
S=blue cones (short wave sensitive) least common cone

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15
Q

Opsins exist inside cones to absorb different wavelengths.

How is colour blindness caused?

A

Missing or abnormal L or M opsin genes

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16
Q

Why are men more prone to colour blindness?

A

L and M opsin genes are carried on the X chromosome, since men only have one, if it is faulty they have no backup unlike women

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17
Q

Why L and M so close to each other on the absorption spectrum? How does this mean we can see colours outside of their spectra?

A

It is more efficient to send the difference between the signals from L and M rather than two signals (one from each receptor) to the brain

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18
Q

What happens to L and M cones in colourblindness?

A

M and L swap or L-M difference disappears causing red-green discrimination to become poorer

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19
Q

What is the opponent processing theory?

A

All receptors have a complex: red-green, blue-yellow, black-white. Therefore cells can only detect the presence of one of the colours in its complex at any one time as they oppose each other. Explains why we do not see ‘greenish-reds’

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20
Q

What part of the brain is concerned with object identity + form (colour)?

A

ventral stream

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21
Q

What part of the brain is concerned with motion, action & location (colourblind)?

A

dorsal stream

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22
Q

What is gain control?

A

How neurones control their sensitivity to light

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23
Q

How does an image get to the brain?

A

Light enters the eye
passes through the retina where luminance is detected
luminance turned into contrast by RFs
enters the LGN - eye of origin determined
enters the cortex - object determined

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24
Q

What sort of gain control does the retina do?

A

Short range, untuned, dependent on the eyes

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25
What sort of gain control does the cortex do?
longe range, tuned, works on complex features (e.g.facial expressions)
26
When a response curve shifts in gain control where does the steep part of the curve go?
around the average to form a baseline for adaptation
27
What can happen if gain control fails?
can cause schizophrenia, epilepsy and Parkinson's
28
Explain how motion detection occurs. What is this process called?
Reichardt detector: Dark spot hits one RF which sends a signal which is delayed dark spot moves across and hits an RF to the side of the first one sending another signal these two signals together cause a neurone to fire IF the time it takes for the ds to move from RF1 to RF2 is equal to the delay of RF1's signal
29
How does the brain process motion?
motion signal sent to VI then middle temporal and medial superior temporal
30
What is Helmoltz's outflow theory?
His theory on how we compensate for eye movements (i.e. not everything is moving when we move our eyes) An efferent signal from the brain moves the eye muscle COPY of said signal is sent to the cortex visual cortex knows about eye movement and cancels it out
31
What is Sherrington's inflow theory?
His theory on how we compensate for eye movements an efferent signal from the brain moves the eye muscle EYE MUSCLE sends signal to the cortex cortex aware of eye movement and cancels it out
32
Who is correct - Helmholtz or Sherrington - why?
Helmholtz If you move your eye with your finger the world still stays still, therefore the signal cannot be sent from the eye muscle twitching
33
How does motion blindness occur?
damage to the middle temporal area
34
What is the motion after-effect?
Where neurones adapt to a movement The 'up' neurone gets tired, 'down' neurone is still firing at a base level so no upwards motion is detected and there appears to be a downward movement instead e.g. watching a waterfall after a while rocks at the side appear to move upwards
35
How does the eye determine how far away something is?
The visual system senses the degree of strain on the lens
36
What is a horopter?
The circle of vision that is the set of points in space that fall on the same place on the retina in both eyes
37
What is it called if an object is further away from the eye than the horopter?
uncrossed disparity - represented on the retina closer together than a point on the horopter
38
What is it called if an object is closer to the eye than the horopter?
crossed disparity - points on the retina are further away than those on the horopter
39
What is stereopsis?
The perception of depth in 3D space with 2 eyes
40
When crossed of uncrossed disparity occurs how does the eye solve the problem of determining depth?
Images from both eyes analysed in correspondence by the brain to determine the disparity between them, gauging depth
41
What happens in cortical depth processing?
input from both eyes needed Reichardt detector senses that inputs are not lined up motion wise disparity selective cells sense inputs are not lined up depth wise
42
What are disparity selective cells?
Cells with different sizes of separations between the receptive field centres allowing for different amounts of disparity to be detected signalling relative depth
43
What is amblyopia?
Where the brain shuts down the signal from one eye in children born with one weak eye impairing stereo vision
44
What is opponency?
Where the eye adapts to motion: 'up' neurone fires much faster than 'down' neurone
45
What is Presbyopia?
Stiffening of the lens with age causing vision blurring as less able to focus
46
Where is the blind spot located?
12-15 degrees in the nasal retina
47
What is 2 degrees of a visual angle roughly equal to?
The width of your thumb joint at arms length
48
What is photopic vision and what type pf photoreceptor does it use?
Daytime vision that uses cones
49
What is luminance?
A measure of the amount of light coming from an object
50
What is contrast?
Any change in luminance over space or time
51
How often to ganglion cells fire in total darkness?
A few times every second
52
What is protanopic vision?
Only blue and green cones function (S&M) BUT still has red cones
53
What is deuteranopic vision?
Only blue and red cones function (S&L)
54
What is tritanopic vision?
Only green and red cones function (M&L)
55
How many types of photopigments do normal people have?
4 (S,L,M and rods)
56
What wavelength spectrum can the normal human eye see?
400-700nm
57
What are individual cone cells unable to do?
distinguish one wavelength from another
58
LGN cells project primarily to...
The V1 cortex area
59
What is a hemifield?
The general area around the left or right eye
60
How does blurring an mage affect spatial frequency?
Removes high spatial frequencies
61
What is basilar membrane velocity measured in?
dB
62
What is each auditory nerve fibre connected to?
a single inner hair cell
63
What is the speed of sound in air?
330m/s
64
What is the speed of sound in water?
1500m/s
65
In what order does sound travel through parts on the brain?
auditory nerve --> cochlear nucleus --> superior olive --> inferior colliculus --> auditory area in cerebral cortex
66
What does the superior olive do?
detect direction of sound, timing and intensity
67
What does the inferior colliculus do?
Has nerve fibres and synapses
68
Where is the auditory cortex?
In the Sylvian fissure
69
What does the medial geniculate body do?
Send the signal on to the auditory cortex
70
What is amplitude?
The intensity of sound
71
What is period?
The frequency of sound, i.e. pitch
72
What is the normal human hearing range?
0-140dB
73
What is timbre?
Different frequencies of the same pitch and loudness
74
What is the cochlea?
A frequency analyser
75
What happens once the basilar membrane vibrates?
hair cells move --> tectorial membrane moves --> impulse is sent to the auditory nerve
76
What is frequency selectivity?
The ability to separate out sounds of different frequencies occurring at the same time
77
What is tonotopicity?
The spatial representation of frequency in the brain
78
What is a harmonic complex tone?
A set of pure tones that are multiples of each other
79
What is fundamental frequency?
The pitch you perceive a harmonic complex tone to be at
80
What is azimoth?
Where a sound is in terms of degrees around the head on a horizontal plane
81
What is elevation?
The height of the sound (where it is coming from)
82
What is the minimum audible angle (to be able to distinguish left from right)
1 degree
83
What is interaural timing difference?
The time it takes for a sound to come round to the opposite side of your head 0.65 milliseconds
84
What is interaural level difference?
The level of sound in one ear will be louder as it is coming from that direction
85
What is Rayleigh Duplex theory?
When ITD and ILD are used together to determine reasonable spatial resolution across pure tone frequencies
86
What frequencies is ITD more sensitive to?
High frequencies
87
What frequencies is ILD more sensitive to?
Low frequencies
88
What is the cone of confusion?
The area of the cone all had the same ITD
89
How is the cone of confusion solved?
The pinna can distinguish elevation, placing the sound
90
What is the precedence effect?
Ability to suppress echoes
91
What is the most common reason for hearing loss?
outer hair cells are damaged
92
What is sensorineural/cochlear loss of hearing?
Where the inner ear is damaged and loss of hearing at high frequencies
93
What is conductive loss of hearing?
Where the middle ear is damaged and there is equal hearing loss across all frequencies
94
What is Temporal Fine Structure?
The individual pressure variations of a sound wave in response to the temporal pattern of vibration of the basilar membrane
95
what does hearing with a cochlear implant sound like?
Very muffled, learning that way is very hard
96
What is the difference between language abilities for children born deaf and adults who acquire hearing loss?
Children tend to be able to learn to read and speak very well ~80% adults can hear quiet speech after implant

Psychology Y1 (11 decks)

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