CH 5: Vision Flashcards
1
Q
What are Sensations?
A
- Building blocks of an experience (light/dark, bitter etc)
- AKA raw info from the senses
2
Q
What is Perception?
A
-The collection of processes used to arrive @ meaningful interpretations of sensations
3
Q
What are the 5 steps of the Perceptual process?
A
- Environmental stimuli
- Attended stimuli (focus/ attention for observer)
- stimulus on receptors (image of stimulus on receptor cells=your senses)
- Transduction=change from environmental energy to electrical energy in your NS
- Neural processing= propagation of electrical signal from receptor cells throughout the brain
4
Q
What is Sense?
A
-System that translates outside info into NS activity
5
Q
What is the role of our senses?
A
-detect & interpret biologically useful info from our environment
6
Q
What are our 5 senses?
A
- Vision
- Audition
- Touch
- Taste
- Olfaction (smell)
7
Q
What does perception depend on?
A
-Context, expectations, & sensory messages
8
Q
What is Bottom-Up processing?
A
- Processing via physical message delivered to the senses
- AKA raw data from environment & Data-based processing
9
Q
What is Top-Down processing?
A
- Processing based on our previous knowledge
- AKA knowledge-based processing
- Requires higher-level cognitive processes
10
Q
What is Attention?
A
- The internal processes used to set priorities for mental functioning
- Select specific info to further processing
11
Q
What are the 3 qualities of attention?
A
- It improves mental processing
- It takes effort
- It is limited
- ISN’T FOOL PROOF
12
Q
What is a major key to perception?
A
-Attention!
13
Q
What is Inattentional Blindness?
A
-A stimulus is not perceived even when the person is looking directly at it
14
Q
What is Change Blindness?
A
-Inability to detect changes in a scene (even when directly attending to it)
15
Q
What is Selective Attention?
A
-People being selective to what they focus on
16
Q
What are 4 disorders of Visual Attention?
A
- Simultanagnosia
- Ballint’s syndrome
- Oculomotor Appraxia
- Optic Ataxia
17
Q
What is Simultanagnosia?
A
-The inability to perceive more than a single object at a time
18
Q
What is Ballint’s syndrome?
A
-It is the combination of Simultanagnosia & oculomotor apraxia & optic ataxia
19
Q
What is Oculomotor Apraxia?
A
-Difficulting in fixating the eyes
20
Q
What is Optic Ataxia?
A
-Inability to move the hand to a specific object by using vision
21
Q
What are the receptors for vision sensitive to?
A
-Light
22
Q
What is the role of the vision receptors?
A
-They transduce (convert) energy into electrochemical patterns (nerve impulses)
23
Q
What is the Law of Specific Nerve Energies?
A
-States that activity by a particular nerve always conveys the same type of info to the brain
24
Q
How does the brain give us what we see?
A
-Via sensory coding where neurons respond to the Amplitude (amt) of response, the frequency (timing), & the rate of response
25
Where does light enter through the eye?
-In an opening in the center of the iris= Pupil
26
Where is light focused in our eye?
-It is focused by the lens & the cornea onto the rear surface of the eye= Retina
27
What is the Retina lined with?
-Visual receptors
28
What do visual receptors do?
-Send messages to bipolar cells (neurons) located close to the center of the eye
29
What do Bipolar cells do?
-They send messages to the ganglion cells that are even closer to the center of the eye
30
What do the axons of the Ganglion cells do?
-They join together to form the optic nerve that exit through the back of the eye & travels to the brain
31
What are the messages that are sent by the optic nerve like?
-They are in the form of action potentials
32
What are Amacrine Cells?
- They are additional cells that receive info from bipolar cells & then sends it to other bipolar cells, ganglion, or amacrine cells
- They also control the ability of ganglion cells to respond to what they need to respond to
33
What are Ganglion cells?
-They respond to shape, movement, & other aspects of visual stimuli
34
What is the Blind Spot?
- It is the point where the optic nerve leaves the brain
| - AKA has no receptors
35
What is Macula?
-It is the center of the human retina
36
What is the central portion of the Macula?
-It is the Fovea
37
What is the function of the Fovea?
- It allows for acute/ detailed vision
- It is packed tight w/ receptors
- Nearly free of ganglion axons & blood vessels
38
What receptors does the vertebrate Retina consist of?
- Rods
| - Cones
39
What are Rods?
- They are most abundant in Peripheral of the eye= respond to faint light
- There are 120 million per retina
40
What are Cones?
- They are most abundant in Fovea= essential for color vision & bright light
- There are 6 million per retina
41
What are Photopigments?
-Chemicals contained by both rods& cones= releases energy when struck by light
42
What do Photopigments consist of?
11 cis-retinal-bound opsins (proteins)= gets converted into all-trans-retinal via light energy
43
How do we see objects Perceptually?
-We see objects bc of reflectance in the visible spectrum
44
Why do we see color?
-Bc of a specific wavelength reflectance
45
What are the 3 types of Cones?
- Short wavelength=419 nm=Blue
- Medium Wavelength=531nm=Green
- Long Wavelength=558nm=Red
46
What is Color Vision Deficiency?
- Impairment in perceiving color differences due to lack of a type of cone or it has abnormalities
- It is sex-linked on X chromosome
- Common form is distinguising between red & green
47
What is the Trichromatic Theory of Color Vision?
- Any color can be produced by mixing pure versions of blue, green & red in different ratios
- CAN'T EXPLAIN negative color afterimage
48
What is the Opponent Process Theory of Color Vision?
- We perceive color in terms of paired opposites
- Red/green
- Blue/Yellow
- Black/white
49
How does the Opponent Process Theory of Color Vision work?
- Bipolar cells are excited by one set of pairs & inhibited by another
- So when one member of the pair is no longer stimulated, the other is activated
50
What isn't explained by both of the color theories?
-Color constancy= the ability to recognize color despite changes in lighting
51
What is the Retinex Theory?
-Suggests the cortex compares info from various parts of the retina to determine the brightness & color of each area
52
What 3 lightness perception phenomena is explained by Lateral Inhibition?
- Hermann Grid=seeing grey spots @ intersections
- Mach Bands=seeing borders more sharply
- Simultaneous Contrast=seeing areas of different brightness due to the surrounding areas
53
What is Lateral Inhibition?
- The reduction of activity in one neuron by activity in neighboring neurons
- It is the retina's way responsible of sharpening contrast to emphasize the borders of objects
54
Who do Rods & Cones make synaptic contact with?
-Horizontal cells & Bipolar cells
55
What are Horizontal cells?
-They are cells in the eye that make inhibitory contact onto bipolar cells
56
What are Bipolar Cells?
-They make synapses onto amacrine cells & ganglion cells
57
What is the Optic Chiasm?
-The place where the 2 optic nerves leaving the eyes meet
58
Where do most Ganglion Cells go?
-They go the Lateral Geniculate Nucleus (LGN)
59
What is the pathway beyond the Retina?
- Retinal Receptors= RP's
- Optic Nerve generates action potentials
- LGN
- Primary Visual Cortex (back of brain)
- Further processing (ventral/dorsal stream)
60
What is the Lateral Geniculate Nucleus (LGN)?
- It is part of the thalamus specialized for visual perception
- Composed of 6 layers
- Sends axons to other parts of the thalamus & to occipital cortex
61
What are the layers is the LGN made of?
- Layers 1 &2= M cells (larger neurons)
| - Layers 3-6= P cells (smaller neurons)
62
What are the 3 categories Ganglion cells primarily fall into?
- Parvocellular (P cells) neurons
- Magnocellular (M cells) neurons
- Konicellular neurons
63
What are Parvocellular Neurons?
- Highly sensitive to color detection & visual detail
- Mostly located in/near fovea
- Have smaller cell bodies & recpetive fields
- Connect ONLY to LGN
64
What are Magnocellular Neurons?
- Highly Sensitive to large overall pattern & motion
- Distributed evenly throughout retina
- Have larger cell bodies & receptive fields
- Mostly connect to LGN but also other visual areas of thalamus
65
What are Koniocellar Neurons?
- Some are color sensitive but function if not fully known
- They have small cell bodies
- Connect to LGN & other parts of the thalamus & superior colliculus
- These are interspersed between all 6 layers
66
What are the 3 visual pathways in the cerebral cortex?
- Mostly P-Cell pathway= details & shape
- Mostly M-Cell pathway=movement
- Mixed pathway= sensitive to brightness & color
67
What do neurons have?
- Receptive fields= affects the firing of the neuron
| - They can be excitatory or inhibitory
68
What does Neuronal firing depend on?
- Specific location
- Orientation of the line
- Movement in a particular direction
69
What are the 3 types of cells in the visual cortex & what makes them that?
- Simple cells= have fixed excitatory/inhibitory zones
- Complex Cells= can repond to certain pattern/ orientation
- End-Stopped/Hypercomplex cells= have strong inhibitory area in one end
70
What is the Primary Visual Cortex (area V1)?
-Recieves info from the LGN & is the area responsible for the first stage of visual processing
71
What happens if area V1 is damaged?
-People may show blindsight= Ability to respond to visual stimuli & movement that they report not seeing
72
What is the Secondary Visual Corex (area V2)?
-Receives info from area V1, processes it further, & then sends it to other areas
73
What is the relationship between V1 & V2?
-Info is transferred in a reciprocal nature
74
What are Feature Detector Neurons?
-Cells in the visual cortex= their response indicate the presence of a particular stimuli/ feature
75
What is the Ventral Stream?
- What pathway= identifies & recognizes objects Tambien color & form
- Composed of P-cell inputs
- Projects further to inferior temporal cortex
76
What is the Dorsal Stream?
- Where/How pathway=Helps motor system find objects & move towards them
- Composed of M-cells
- Projects further to parietal cortex
77
What is Visualagnosia?
- Inability to recognize objects despite having good vision
| - Caused by damage to pattern pathway in temporal cortex
78
What is Prosopagnosia?
- The inability to recognize faces
| - Caused by damage to fusiform gyrus of the inferior temporal cortex
