W2

Question 1

How can information from the outside world enter our brains for us to have thoughts about it?

Answer 1

Information enters our brains through a process called reception, where physical energy from photons is received by the eyes, interacts with the retina, and is transduced into an electrochemical pattern in neurons. This information is then coded in the brain, correlating physical stimuli with firing patterns of neurons.

Question 2

What is the retina made of?

Answer 2

The retina is made of lots and lots of photoreceptors.

Question 3

What are rods?

Answer 3

Rods are a type of photoreceptor that are sensitive to the amount of light in the environment and are involved in vision in dim light and movement.

Question 4

What are cones?

Answer 4

Cones are a type of photoreceptor that process color and are layered along the back of the eye forming the retina.

Question 5

What is the density of cones and rods in the retina?

Answer 5

Cones have a density of approximately 6 million in the retina, with most concentrated in the fovea, while rods have a density of approximately 125 million in the outer regions of the retina.

Question 6

Why do we see color?

Answer 6

We see color because our eyes respond to specific wavelengths in the electromagnetic spectrum, interpreting them as different colors. Our eyes are most sensitive to green light.

Question 7

What is the Trichromatic Theory?

Answer 7

The Trichromatic Theory proposes that any color can be created by mixing three primary colors of light: red, green, and blue. It suggests that there are three types of color receptors in the eye, each preferring different wavelengths (short = blue, medium = green, long = red).

Question 8

What is the Opponent-Process Theory (Hering)?

Answer 8

The Opponent-Process Theory states that colors cannot be combinations like blueish-yellow or reddish-green; they are opposites. It suggests that colors like red and green cannot be perceived simultaneously; they must fall between.

Question 9

What is color constancy?

Answer 9

Color constancy refers to our brains constructing color based on what something probably is in real life. It indicates that what our cones perceive may differ from what we actually perceive, influenced by top-down processing.

Question 10

What are the two pathways through which information is processed after the retina?

Answer 10

The two pathways are the Parvocellular Pathways (P), which are sensitive to color and fine detail, receiving most of the input from cones, and the Magnocellular Pathways (M), which are sensitive to motion, receiving most of the input from rods.

Question 11

What is the pathway process from the eye to the brain?

Answer 11

The process starts with information in the retina, then goes through the optic nerve, optic chiasm, lateral geniculate nucleus (LGN), and finally reaches the primary visual cortex (cortical area V1).

Question 12

What are receptive fields?

Answer 12

Receptive fields are a property of visual neurons where each neuron is responsible for a different part of space and fires more neurons if something happens in that space.

Question 13

What is Retinotopy?

Answer 13

Retinotopy is another property of visual neurons where neurons that care about nearby spaces are physically close together in the brain, maintaining a spatial organization similar to the retina.

Question 14

What is Lateral Inhibition?

Answer 14

Lateral Inhibition is a property of visual neurons where a neuron inhibits activity in neighboring neurons, enhancing contrast to perceive fine lines and edges.

Question 15

What is the Lateral Geniculate Nucleus (LGN)?

Answer 15

The LGN is part of the thalamus, involved in fast processing of visual information and maintaining a retinotopic map, correlating signals from the retina in space and time. - allows you to respond to a stimulus before its even fully processed eg jump out the way of car

Question 16

What is the primary visual cortex (V1)?

Answer 16

V1 extracts basic information from the visual scene (bottom up), such as edges and orientations - sends this info to other areas of brain for later processing and maintains retinotopy.

Question 17

What happens when there is damage to V1?

Answer 17

leads to a clinical diagnosis of cortical blindness (the patient cannot consciously report objects presented in this region of space) - However, the patient is still able to make some visual discriminations in the “blind” area (e.g. orientation, movement direction) – called *blindsight cant see the thing but can see what its doing
- This is because there are other routes from the eye to the brain not just V1
- The geniculostriate route may be specialized for conscious vision but other routes act unconsciously

Question 18

What is Functional Specialization Theory?

Answer 18

• Different parts of the visual cortex are specialised for different visual functions
• V1/V2 is early stage of visual perception eg shapes
• V3/V3a is responsive to form especially moving objects
• V4 is responsive to colour
• V5/MT is responsive to visual motion

Question 19

What happens to patients with cortical Achromatopsia, and what does it tell us about V4?

Answer 19

Patients with cortical Achromatopsia cannot see colors due to damage to V4, indicating V4’s involvement in color processing, although the link is not perfect.

Question 20

What causes Akinetopsia, and what do patients experience?

Answer 20

Akinetopsia is caused by brain damage to V5/MT, resulting in grossly deficient motion perception despite good color vision and the ability to locate stationary objects.

Question 21

What is the important visual ‘where’ pathway?

Answer 21

the parietal (or dorsal) processing pathway, concerned with movement processing and vision for action, from the occipital to the parietal lobes.

Question 22

What is the important visual ‘what’ pathway?

Answer 22

the temporal (or ventral) processing pathway, concerned with color and form processing and vision for perception, from the occipital to the temporal lobes.

Question 23

How do we perceive an object according to the Model of Object Recognition?

Answer 23

Object recognition involves early visual processing (extracting features), perceptual segregation (grouping visual elements), matching grouped visual description onto a representation of the object stored in the brain (structural descriptions), and attaching meaning to the object based on prior semantic knowledge.

Question 24

What is Perceptual Segregation?

Answer 24

Perceptual segregation is the process of separating visual input into individual objects, thought to occur before object recognition.

Question 25

What is Gestalt Psychology?

Answer 25

Gestalt Psychology is based on the fundamental principle of the “Law of Prägnanz,” which suggests that what you perceive is the most likely explanation for the visual input you are receiving. It assumes a set of rules that operate early in visual processing.

Question 26

What are Gestalt Laws of Perceptual Organization?

Answer 26

The Gestalt Laws of Perceptual Organization include the law of proximity, similarity, good continuation, and closure, which describe how visual elements are grouped together.

Question 27

What are problems with Gestalt Psychology?

Answer 27

Problems with Gestalt Psychology include the fact that segmentation processes aren’t always bottom-up and following the laws of perceptual organization, reliance on introspection and evidence from 2D drawings, descriptive evidence without explanation, and segmentation occurring via top-down prior knowledge.

Question 28

What is Apperceptive agnosia?

Answer 28

Apperceptive agnosia is an impairment in the process of constructing a perceptual representation from vision, associated with seeing parts but not the whole, and typically associated with lateral occipital lobe damage.

Question 29

What is Associative agnosia?

Answer 29

Associative agnosia is an impairment in the process of mapping a perceptual representation onto knowledge of the object’s functions and associations, associated with recognizing something but not knowing its function or meaning, typically associated with occipito-temporal damage.

Question 30

What is Prosopagnosia?

Answer 30

Prosopagnosia is an impairment of face processing that doesn’t come from damage to early visual processing, suggesting that faces are processed differently in the brain compared to other objects.

Question 31

What is the Fusiform Face area?

Answer 31

The Fusiform Face area is an identified area of the ventral (what) visual stream that responds more to faces than other objects in functional imaging experiments, suggesting it plays a role in face processing.

Question 32

What is Holistic Processing in face recognition?

Answer 32

Holistic processing in face recognition refers to the tendency of sighted people to be slower and less accurate at identifying inverted (upside down) faces, interpreted as evidence of spatial-relational information being disproportionately affected by inversion.