Vision Flashcards
(97 cards)
1
Q
Which sense do we trust the most?
A
Vision
- humans are incredibly reliant on vision
2
Q
The _________ system processes and interprets visual info
A
Visual
3
Q
_________ is a form of electromagnetic radiation that travels as a _______
A
LIGHT is a form of electromagnetic radiation that travels as a WAVE
4
Q
Wavelength
A
The distance b/w successive peaks
- different wavelengths shows different colours
5
Q
Humans are only sensitive to a tiny portion of the total range of wavelengths of light called the _____________ ________________
A
Visible spectrum
6
Q
__________ are the only mammals that see in colour
A
Primates
- primates benefit from colour vision when foraging for food
7
Q
Wavelength is ____________ related to frequency
A
Inversely
- shorter wavelength = higher frequency
- longer wavelength = lower frequency
8
Q
Amplitude is an indication of perceived _____________
A
Brightness
9
Q
The ___________ properties of light determine what we perceive
A
Physical
10
Q
What psychological perception does wavelength/frequency determine?
A
Colour
11
Q
What psychological perception does amplitude determine?
A
Brightness
12
Q
What psychological perception does purity determine?
A
Saturation (richness of colours)
13
Q
A light made up of only one wavelength is known as a ?
A
Pure light
14
Q
How would the colour of a pure light be described?
A
Completely saturated
15
Q
_________ light is a desaturated combination of many wavelengths
- described as desaturated
A
Natural
16
Q
Light first passes through the curved ________ which begins the focusing process
A
Cornea
- the cornea is a transparent window at the front of the eye
- the rest of the eye is covered by the white part called sclera
17
Q
What does the light pass through after the cornea?
A
The pupil
18
Q
What controls the size of the pupil?
A
Iris
- if not enough light reach retina –> muscle causing pupil to dilate
- if too much light reaching retina –> muscle causing pupil to constrict
19
Q
What does the iris consist of?
A
The iris consists of a band of muscles that is controlled by the brain
20
Q
What does light pass through after the lens?
A
The lens
21
Q
What is the transparent structure that does the final focusing of the light onto the retina at the back of the eye?
A
Lens
22
Q
What is the order when light reaches the retina?
A
- Cornea
- Pupil
- Lens
- Vitreous humour
- Retina
23
Q
The _____________ of the lens causes the image to land on the retina upside down and reversed from left to right and slightly smaller
A
Curvature
24
Q
The _____ is a flexible tissue and can alter its shape by surrounding muscles which allow it to focus on objects that are close or far away
A
lens
25
What happens to the shape of the lens if the object is close?
The lens get rounder
26
What happens to the shape of the lens if the object is far away?
The lens gets elongated
27
The lens ___________________ for the distance of object in focus
Accommodates
28
What is the change in lens shape to focus on objects that vary in distance called?
Accommodation
29
What is the neural tissue that lines the back of the eye?
Retina
30
What begins the translation of light into neural impulses?
Retina
31
What are the 3 layers that the retina contains?
1. Photoreceptor layer
2. Bipolar cells layer
3. Ganglion cells layer
32
The retina contains 3 layers with an "______-__-___" arrangement
Inside-to-out
- layer at the very back of the eye (farthest away from light) is where the light-sensitive photoreceptors are located
33
What are the cells in the retina that are responsible for translating the physical stimulus of light into a neural signal that is relayed to the brain called?
Photoreceptors
34
Where do photoreceptors get their nutrients from?
From a layer of cells at the very back of the eye called the Retinal Pigment Epithelium (RPE)
- this is why the photoreceptor layer is at the back of the eye
35
What are the 2 types of photoreceptors
Rods and cones
36
Cones
- around 6 million
- primarily for day vision
- operate at hight light intensities
- provide sensation of colour
- good visual acuity/sharpness of detail
- more concentrated towards the fovea
37
Rods
- around 125 million
- primarily for night vision
- operate at low light intensities
- provide no colour info
- offer poor visual acuity
- concentrated in the periphery
- no rods in the fovea itself but an increase in concentration in the region just surrounding the fovea
38
The photoreceptors sends the information to the next layer of cells in the retina called the ________ ______
Bipolar cells
39
The bipolar cells sends their information on to the next layer of cells in the retina called the _________ ______
Ganglion cells
40
Ganglion cells converge to form the _________ ______ at the optic disc
Optic Nerve
41
The ganglion cells collect info from a larger segment of the retina. The axons of these cells all converge on one point in the eye called the __________ _______. Then eave the eye to join the optic nerve (which then go into the brain)
Optic disk
42
Cells in the retina that allow areas within a retinal layer to communicate with each other are called ___________ _______ and ______________ _______
Horizontal cells & Amacrine cells
- these cells allow info from adjacent photoreceptors to be combined
43
Why do we have a blind spot?
Because the optic disk is like an exit hole in the eye for ganglion axons, this small area contains no photoreceptors at all so it constitutes our blind spot
44
Smaller and more precise receptive field in ______ of retina (fovea)
Center
45
Larger and coarser receptive field in __________ of retina
Periphery
46
The collection of rods and cones in the retina that when stimulated affects the firing of a particular ganglion cell is called the ______________ ________ of that retinal ganglion cell
Receptive field
47
The right and left halves of our visual field are processed by the ___________________ side of our brain
Contralateral
- the input from one visual field is processed on the opposite side of the cortex
48
What is the optic chiasm?
The point at which the optic nerves from the inside half of each eye (closest to the nose) cross over to the opposite hemisphere
49
The axons from the outside, temporal regions of each retina stay on the _________ hemisphere
Same
50
After crossing, most ganglion cell axons synapse with the __________?
LGN (lateral geniculate nucleus)
- LGN is part of the thalamus that receives visual info
51
Each optic tract (left and right) contains only info from the ________________ visual field
Contralateral
52
After the visual signals are processed at the LGN, they are send to areas in the occipital lobe that make up the ____________ _________ ________
Primary visual cortex
53
Where does early visual processing occur in?
Occur in the primary visual cortex
54
What is the primary visual cortex also known as?
Striate cortex
Area V1 of the occipital lobe
55
What is the visual processing areas in the occipital lobe outside the striate cortex known as?
Extrastriate cortex
56
The extrastriate cortex can be further divided into Area ___ through ____
Area V2 through V5
- these are thought to subserve functions related to colour, motion and object recognition
57
From the primary visual cortex, processed visual info are sent on to the extrastriate cortex and gets separated into the _______ & ___________ ________
Into the DORSAL & VENTRAL STREAM
58
What is the dorsal stream referred to as?
The where pathway
59
What does the dorsal stream process?
Processes where objects are (include depth, motion in field)
60
Where does the dorsal stream progress from and to?
Progresses from the extrastriate cortex to the parietal lobe
61
What is the ventral stream referred to as?
The what pathway
62
What does the ventral stream process?
Processes what the object is (include colour and form)
63
Where does the ventral stream progress from and to?
Progresses from the extrastriate cortex to the temporal lobe
64
The receptive field of the LGN is made up of many __________ ___________ cells
Retinal ganglion cells
65
Neurons converge their input as they travel down the visual system. What is the order?
Many
PHOTORECEPTOR CELLS
v
GANGLION CELLS
v
LGN CELLS
v
VISUAL CORTICAL CELLS
Fewer
66
What might eyes have started as?
May have started as a simple light sensitive patch
67
What can a simple light sensitive patch eye do?
Able to detect the presence or absence of light
68
After the light sensitive patch, what did the eye evolve into?
Curved "cup" eyes
- a light sensitive patch formed into a slight depression
69
What can curved cup eyes do?
May have evolved to detect the direction of light
70
What did the curved cup eyes evolve into?
Pinhole eye/curved eye
71
What can pinhole eyes/curved eyes do?
May have developed a pinhole to help focus light
- allow organisms to resolve the detail of an image by changing the amount of light that enters the eye
72
What evolved after pinhole eyes?
Crude lens
73
What can crude lens do?
May have evolved to increase focusing
- relatively solid so its shape changes very little
- best suited for animals that do not rely heavily on visual acuity
74
What evolved after crude lens?
Adjustable lens
75
What can adjustable lens do?
An adjustable lens allows for accommodation
- quite flexible and can adjust focus to process things at varying distances by changing lens shape
- commonly found in vertebrates
76
Cumulative selection
An evolutionary process whereby new adaptations are layered upon old adaptions
- example: eye evolution
77
Factors that affect the architecture of eyes across species
- do they live in an area with light or not?
- does food come from above or below?
- movement, shape and colour of prey
78
WHat are the two broad categories of eyes?
Simple eyes & compound eyes
79
Simple eyes are mostly found in ___________
Vertebrates
- the vertebrae eye can vary quite a bit in its design according to the environment the species live in
80
Compound eyes are good for detecting movement at __________ distances
Close
81
What are compound eyes made up of?
Made up of an arrangement of individual tubular units called ommatidia
- each points at a slightly different direction to gather the light that lays directly in front of it
- they form a single image by putting together many separate signals from each ommatidium
- found in arthropods (eg. insects, crabs)
82
What are the 2 functions of the eye?
Resolution (acuity) & sensitivity (ability to get enough light)
83
Resolution and sensitivity of the eye depends on its ___________
Shape
- larger eyes tends to have better acuity and sensitivity
84
Eye _______ can benefit either acuity or night vision
Size
- large eyes can either be filled with more rods for excellent night vision or more cones for excellent acuity
85
What are laterally-directed eyes?
Eyes located on either side of the head
- mostly prey animals so they can scan continually for predators
86
Pros & cons of laterally-directed eyes
Pros
- wide total view
Essentially two separate fields of view
Con
- poor depth perception
*laterally-directed eyes sacrifice depth perception for field of view
87
Front facing eyes
Both eyes directed towards the front
- typically for predators
- narrow total view
- more binocular overlap
- excellent depth perception
- essentially a single field of view
*front facing eyes sacrifice field of view for depth perception
88
Eyes begin developing __________
Prenatally
- formed during 2nd month of pregnancy
89
The eyes are capable of reacting to light in the __ month of pregnancy
6th
- random firing of retinal cells also occur ( critical for the organized wiring of the retina cells, determining how neighbouring cells will be connected to each other)
90
Visual development relies heavily on visual __________
Input
91
_____________ interprets nerve impulses
Perception
- perception is (unconscious) inference
92
Active adaption
Have to actually do things (interact with the world)
- Our brains can adapt to changes in vision but it takes quite a bit of time for it to adapt
93
What are some brain assumptions on vision?
- single light source
- light from above
- like objects are grouped together
- objects grouped together, move together
94
__________ functions by subconscious activity in secondary visual pathway (if the eyes are still intact)
Blindsight
- Secondary visual pathway is unconscious
- Get you to react before you're consciously aware of it
- Conscious visual pathway requires time
95
Visual processing involves a ____________ and _____________ visual pathway
Primary & secondary visual pathway
96
Conscious visual pathway
Photoreceptors --> ganglion cells --> V1
- conscious visual perception
- primary visual pathway
97
Unconscious visual pathway
SC (superior colliculus) --> pulvinar --> extrastriate cortex
- unconscious, automatic attention orientation
- secondary visual pathway
