chapter 5 part2: the visual system

Question 1

what is electromagnetic energy?

Answer 1

fluctuating electrical and magnetic waves

Question 2

wave length of visible light

Answer 2

400-700nm (ROYGBIV)

Question 3

how can someone alter their visible spectrum of light?

Answer 3

change their diet drastically

Question 4

sclera

Answer 4

white in the eye

Question 5

iris

Answer 5

coloured by pigments
(melanin = brown, lipochrome = yellow brown)
- muscle controls how much light
- equivalent to camera shutter

Question 6

limbal ring

Answer 6

• darker around eye in youth
• site of stem cells
• border of cornea and sclera

Question 7

what is the limbal ring also known as?

Answer 7

the limbus

Question 8

the limbus is a common site for. the occurrence of

Answer 8

corneal epithelial neoplasm

Question 9

what does the limbus contain?

Answer 9

fribovascular ridges
aka
palisades of Vogt

Question 10

Pupil

Answer 10

hole through which light enters

Question 11

closing of pupil

Answer 11

(closing)
in response to light, pupillary reflex
- opens also in response to objects approaching fast

Question 12

dilation of pupil

Answer 12

(opening)
arousal / sexual
processing complex information (even math)
increases sex appeal

Question 13

cornea

Answer 13

curved, transparent, bends incoming light, focus incoming visual image to back

Question 14

what does the cornea cover?

Answer 14

the iris and pupil

Question 15

where does the lens focus/ bend light onto?

Answer 15

the back of the eye

Question 16

when the lens is fat, how far is the object?

Answer 16

it is near

Question 17

when the lens is flat and skinny, how far is the object/

Answer 17

far

Question 18

Myopia (nearsightedness) affects on cornea, eyes, lens

Answer 18

cornea is too steep
eyes too long
lens focuses image in front of rear of the eye.

Question 19

Hyperophia (farsighted)

Answer 19

cornea too flat
eye too short
lens does not thicken

Question 20

Presbyopia

Answer 20

lens loses flexibility
eyeball becomes shorter
this comes with age.

Question 21

two kinds of photoreceptors

Answer 21

rods and cones

Question 22

where are rods and cones found in the eye?

Answer 22

outermost layer of the retina.

Question 23

which are more abundant in the typical human eye, rods or cones?

Answer 23

rods

Question 24

what are rods insensitive to?

Answer 24

red light

Question 25

the photoreceptors, rods, are responsible for…..

Answer 25

basic shapes and forms
dark adaptation
peripheral vision (not in fovea)

Question 26

the photoreceptors, cones, are responsible for….

Answer 26

colour vision

sensitivity to detail

Question 27

Cones require more light than rods. Which colours are they more sensitive too?

Answer 27

Green, yellow

Question 28

Where the cones highest in density?

Answer 28

fovea

Question 29

site of visual transduction

Answer 29

retina

Question 30

What are light receptor cells comprised of?

Answer 30

bipolar and ganglion cells

bipolar convergence

Question 31

True or false: some scientists believe that the retina is actually part of the brain.

Answer 31

True, however this is heavily debated.

Question 32

The fovea is a central part of the …..

Answer 32

the retina.

sharpness, fine detail

Question 33

photopigments

Answer 33

difference in light perception comes from chemical changes post light exposure

Question 34

photopigments come from

Answer 34

rhodopsin in rods

Question 35

what vitamin affects photopigments

Answer 35

vitamin a

Question 36

what kind of cells is the optic never comprised of?

Answer 36

bundled retinal ganglion cells

Question 37

point at which the optic nerves cross

Answer 37

optic chiasm

Question 38

where do most optic nerves go through?

Answer 38

the LGN V1 (cortex) , part of thalamus

some nerves go through superior colliculus

Question 39

what causes a blind spot in your eye?

Answer 39

this is where your optic nerve is formed (ganglion cells)

Question 40

trichromatic theory of colour

Answer 40

young and hemoltz

- vision sensitive to 3 primary colours since we have 3 types of cones (blue, green, red)

Question 41

Colour blindness and the types

Answer 41

• monochromats (no colour)
• dichromats (2 types of cones, only see red and green. Can’t distinguish reds, this is what dog and cats have)
• more common in males because it’s linked to x genes.

Question 42

opponent processing theory

Answer 42

the theory that afterimage hapens because cones for colour get saturated, give off signal for opposite colour as a result.

Question 43

hubel and wiesel

Answer 43

• studied cats and similar vision in humans

- mapped V1// found that cells respond best to lines of particular orientations.

Question 44

v1 cells

Answer 44

• respond to simple features of environment (build perception of visual world)
• simple cells (responds to vertical lines of preferred position)

Question 45

complex cells

Answer 45

respond to oriented bar over range of positions

- some only respond to oriented bars in motion

Question 46

feature detection

Answer 46

• use minimal patterns to detect object features
• complex cells do this (detect lines and edges)
• found in temporal lobes/ parietal lobe)

Question 47

gestalt principles

Answer 47

how we perceive whole objects rather than parts

- governed by 6 main principles

Question 48

6 main principles of gestalt (kohler and kafka)

Answer 48

proximity - close to eachother looking likea whole
similarity - comprise a whole more than dissimlar
continuity- perceived as whole even if blocked
closure - fill in whats missing when partial info present
figure and ground- focal point against background.
symmetry - whole rather than parts