Visual System

Question 1

What is the difference between sensation & perception?

Answer 1

Sensation is the sensory information received from the environment and translated into the brain’s language. On the other hand, perception is the interpretation by attributing meaning to the sensory information being received.

Question 2

What are the layers of the eye?

Answer 2

The cornea (outer), choroid (middle), inner layer (vitreous humour, iris, pupil, lens).

Question 3

What does the choroid do?

Answer 3

Nourishes the eye through the blood vessels in the eye.

Question 4

Explain the differences between rods and cones.

Answer 4

Rods are photoreceptor cells in the retina that cannot register colour, are in low resolution and activated during the night time. On the other hand, cones are able to register colour, have high resolution and is active during daytime.

Question 5

How are the eyes connected to the cortex?

Answer 5

The eyes are first connected to the subcortex through the lateral geniculate nucleus, which is then connected to the cortex through the V1 stream (area 17 / primary visual cortex / striate cortex)

Question 6

Explain double dissociation in the eyes.

Answer 6

It is the circumstance where a lobe lesion affects function 1 and not 2, but a lesion in another part of the brain impairs function 2 but not 1 (reverse effect). In Mishkin & Ungerleider (1982)’s experiment, monkeys with parietal lobe lesions experience difficulty in landmark discrimination, but do well in object discrimination. However, monkeys with temporal lobe lesions experience difficulty in object discrimination, whilst are capable of landmark discrimination.

Question 7

What is the difference between the ventral and dorsal streams?

Answer 7

The ventral stream involves pattern perception, recognising what the objects are, whilst the dorsal stream engages in spatial awareness, recognising where objects are.

Question 8

What are the kinks of different photoreceptor cells?

Answer 8

Rods & cones - diffused light
Lateral geniculate nucleus cells / Retinal ganglion cells - bright spots against dark background
V1 cells - white lines of different orientation against dark background
Grandmother cells - side profiles

Question 9

What does the Herman Grid illusion illustrate?

Answer 9

It demonstrates the centre-surround architecture of a retinal ganglion cell’s receptive field which engages in lateral inhibition, and enhances contrast.

Question 10

How do we go from dots to lines?

Answer 10

Retinal ganglion cells have centre-surround architectures that multiply downwards when it reaches the V1 cell, creating lines

Question 11

What are the eye disorders that arise from cutting the optic nerves, optic chiasm and optic tract respectively?

Answer 11

Left / right monocular blindness where an entire eye is blind, bitemporal hemianopia, and left / right homonymous hemianopia.

Question 12

Who is patient DB?

Answer 12

He had blindsight, a condition where he was able to localise objects he couldn’t see.

Question 13

How is blindsight possible?

Answer 13

Information from the retina bypasses V1 and the LGN, going through dorsal pathways to V5, transmitting to the parietal lobe only. Hence, one is only spatially aware of where an object is, not what it is.

Question 14

What is achromatopsia?

Answer 14

Damage to V4, causing absence of colour vision.

Question 15

What is akinetopsia?

Answer 15

Damage to V5, causing absence of motion vision.

Question 16

What is apperceptive agnosia?

Answer 16

Unable to recognise objects or copy them due to extreme visual perception failure. Can be caused by mercury / carbon monoxide poisoning that damages pockets of v1, creating scotomas across visual field (peppery mask)

Question 17

What is dorsal simultagnosia?

Answer 17

Ability to recognise objects, but only one at a time. Lack of spatial awareness and cannot see multiple objects.

Question 18

What is ventral simultagnosia?

Answer 18

Ability to be spatially aware, although only one object at a time. Unable to recognise objects.

Question 19

What is associative agnosia?

Answer 19

Unable to determine what an object is, but is able to describe it and provide a somewhat accurate copied drawing. (only capable of drawing assumptions through associations)

Question 20

What is the difference between bottom-up and top-down theories?

Answer 20

The bottom-up theory is receiving information from your external environment, whilst the top-down theory utilises information already existent within your brain.

Question 21

What are some binocular cues of depth perception?

Answer 21

Retinal disparity (both eyes see the world from different angles, so they compensate for the disparity), convergence and divergence (how much rotation the eyeballs do to gauge how near or far something is).

Question 22

What are some monocular cues of depth perception?

Answer 22

Linear perspective (parallel lines converging as they become further away), interposition (object being blocked is further away), height in plane (position relative to horizon), relative size, texture gradient (less details = further away), and light and shadow.

Question 23

What is the Young-Helmholtz Trichromatic Theory?

Answer 23

There are three types of cones maximally sensitive to their respective colours: blue (short), green (medium) and red (long).

Question 24

What is the Opponent-Process Theory?

Answer 24

Working in conjunction with the Young-Helmholtz Trichromatic Theory, this processes colour at a neural level. Red-green and blue-yellow receptor complexes often clash (opponent cells), with red inciting a positive response, while green incites a negative response. Hence, colour-blindness occurs in pairs.

Question 25

What is Rene Descartes’ contribution to psychology?

Answer 25

He jumpstarted the theory of localised function with the belief that the pineal gland was the central executive of the brain. Recognised that the brain consisted of a left and right side.

Question 26

What are Gall and Spurzheim’s contributions?

Answer 26

They developed the theory of phrenology, where well-developed organs formed bulges in the cranial bone, representing certain faculties.

Question 27

What is the Broca and Patient Tan experiment?

Answer 27

Lesions were made on Patient Tan’s Broca’s area, which led to an affectation in speech output, but comprehension remains unharmed. (Broca’s aphasia)

Question 28

What is Wernicke’s aphasia?

Answer 28

Lesions made on the Wernicke’s area resulted in impaired language comprehension, but perfect speech output.

Question 29

What did Fritsch and Hitzig (1870) do?

Answer 29

They electrically stimulated a part of the cortex in dogs’ brains and found that resulted in movement.

Question 30

What does damage to the occipital lobe do?

Answer 30

Blindsight, blindness and apperceptive agnosia.

Question 31

What does damage to the superior temporal gyrus do?

Answer 31

Auditory brain impairment, deafness, Wernicke’s aphasia, auditory agnosia

Question 32

What does damage to the middle & inferior temporal gyri do?

Answer 32

Achromatopsia, akinetopsia, ventral simultagnosia, associative agnosia

Question 33

What happens if you damage the right medial temporal lobe?

Answer 33

Copying is okay, but visual memory is impaired.

Question 34

What happens if you damage the left medial temporal lobe?

Answer 34

Hearing is okay, but verbal memory is impaired.

Question 35

What are the effects of left parietal lobe damage?

Answer 35

Agraphia (hard to organise letters, so writing is difficult), acalculia (calculation signs are in the wrong places, so hard to calculate), left/right confusion, dyslexia, and difficulty in drawing details.

Question 36

What are the effects of right parietal lobe damage?

Answer 36

Difficulty in recognising unfamiliar views of objects, hard to draw overall shape of objects and contralateral neglect (ability to only see right side)

Question 37

What is the difference between ego-centred and object-centred neglect?

Answer 37

Ego-centred neglect is when someone ignores the entire left visual field, whilst object-centred neglect ignores the left side of every object (right side of the object is able to be perceived, even if the object is in the left visual field)

Question 38

What does damage to the frontal lobe do?

Answer 38

Changes in behaviour & personality, Stroop effect, imitation codependency, word & design fluency impairment idk bro i feel like i’ve never seen this lecture wtf

Question 39

What is the order in which signals enter the ear?

Answer 39

Tympanic membrane, ossicles, oval window, hair cells