midterm

Question 1

myopia

Answer 1

axial: eyeball is too long = focus before the retina = cannot see far
refractive: too much refraction = focus before the retina = cannot see far

Question 2

hyperopia

Answer 2

eyeball is too short = focus beyond the retina = cannot see close

Question 3

astigmatism

Answer 3

irregular lens = cannot see close/far depending on where light falls on the retina

Question 4

presbyopia

Answer 4

lens hardens with age and has difficulty accommodating = cannot see close

Question 5

isomerization

Answer 5

light binds to opsin, retinal changes shape = electrical signals
- retinal detaches from opsin = visual pigment bleaching
- visual pigment regeneration = retinal must return to bent shape and re-attach to opsin to become light-sensitive again

Question 6

detached retina

Answer 6

separated retinal and opsin cannot re-combine to become light sensitive = blindness in that area of the visual field

Question 7

purkinje shift

Answer 7

rods are most sensitive to shorter wavelengths and have lower thresholds = during dark adaptation, we become more sensitive to shorter wavelengths (things appear more blue/green)

Question 8

ratio of Na+ to K+ inside and outside the cell

Answer 8

Na+ is 10x more concentrated outside the cell
K+ is 20x more concentrated inside the cell

Question 9

convergence

Answer 9

rods converge onto RGCs = compression of information, higher sensitivity
cones do not = visual acuity, less sensitivity

Question 10

what does lateral inhibition explain?

Answer 10

• how RGCs are excitatory-enter inhibitory-surround using photoreceptors and horizontal/amacrine cells
• the Hermann Grid illusion (lateral inhibition on four sides in the periphery because of larger receptive fields)
• Mach bands/Chevreul illusion

Question 11

describe how light reaches the retina and each hemisphere

Answer 11

• left side of left visual field - nasal retina of left eye - right area V1
• right side of left visual field - temporal retina of right eye - right area V1
• left side of right visual field - temporal retina of left eye - left area V1
• right side of right visual field - nasal retina of right eye - left area V1

Question 12

feature detectors

Answer 12

• in area V1
  simple cortical cells - orientation
  complex cells - orientation-specific moving in a certain direction
  end-stopped cells - angles/corners/lines of a particular length with a particular direction of movement

Question 13

inverse projection problem

Answer 13

an image on the retina can correspond to many different stimuli (different shapes can project the same image)
so the brain has to guess, computer is bad at solving this

Question 14

what can’t structuralism explain?

Answer 14

apparent movement (sensation not present)
illusory contours

Question 15

Gestalt grouping principles

Answer 15

• similarity
• proximity
• good continuation
• closed forms
• common fate
• simplicity/pragnanz
• common region
• uniform connectedness
• symmetry

Question 16

global image features

Answer 16

• naturalness
• roughness (small elements vs. smooth)
• openness
• expansion (convergence of lines)
• colour

Question 17

Helmholtz’s Theory of Unconscious Inference

Answer 17

perceptions comes from unconscious assumptions (likelihood principle, Bayesian inference)
to solve the inverse projection problem

Question 18

apparent motion

Answer 18

Phi phenomenon, movies
still activates area MT

Question 19

motion aftereffects

Answer 19

waterfall effect, short-term selective adaptation

Question 20

induced motion

Answer 20

clouds over moon = moon appears to move (larger object passes over a small object = small object appears to move

Question 21

eyes following a moving object according to Gibson’s approach

Answer 21

local disturbance in optic array (background objects getting occluded, background stays stationary = object moving)

Question 22

eyes stationary, object moves across field according to Gibson

Answer 22

local disturbance in optic array

Question 23

eyes scan a scene according to Gibson

Answer 23

global optic flow (everything moves at once = no movement)

Question 24

eyes following an object in movement according to corollary discharge

Answer 24

motor signal to eyes = corollary discharge signal to comparator (no image displacement signal) = movement perceived (receives only one signal)

Question 25

object moves across field while eyes are stationary according to corollary discharge

Answer 25

image displacement signal to comparator (no motor signal to eyes = no corollary discharge signal) = movement perceived (one signal)

Question 26

eyes scan a scene according to corollary discharge

Answer 26

motor signal to eyes = corollary discharge to comparator + image displacement signal to comparator = no movement perceived (receives two signals)

Question 27

Reichardt detector

Answer 27

• direction-sensitive circuit
• output unit multiplies signals from A and B
• A has a delay unit (first cell in the circuit)
• signals must reach the output unit at the same time for movement to be perceived
• found in area MT

Question 28

inferotemporal cortex

Answer 28

complex objects (end-point of ventral pathway)

Question 29

fusiform face area (FFA)

Answer 29

part of area IT
faces/expertise hypothesis

Question 30

lateral occipital complex (LOC)

Answer 30

part of area IT
any kind of object (not textures or scrambled parts)

Question 31

parahippocampal place area (PPA)

Answer 31

part of area IT
spatial layout, navigation, locations, familiar places

Question 32

extrastriate body area (EBA)

Answer 32

part of area IT
bodies and body parts

Question 33

middle temporal area

Answer 33

part of the dorsal stream of visual processing (area V5)
motion

Question 34

superior temporal sulcus

Answer 34

biological motion

Question 35

medial temporal lobe (MTL)

Answer 35

memory (hippocampus, entorhinal cortex, parahippocampal cortex)
extensions from IT cortex reach MTL

Question 36

anterior auditory cortex

Answer 36

most responsive to pitch (pitch neurons)

Question 37

superior olivary nucleus

Answer 37

contains ITD detectors/coincidence detectors for the Jeffress model

Question 38

ventrolateral/ventral posterior nucleus of the thalamus

Answer 38

touch relay area in the thalamus
contains centre-surround neurons

Question 39

nucleus of the solitary tract

Answer 39

part of the brain stem for processing taste