4-Vision

Question 1

Range of wavelengths of light that humans can see

Answer 1

360nm (~400nm)
to
750nm (~800nm)

Question 2

Which mammals have colour vision?

Answer 2

Primates

Question 3

Which traits of light waves correspond to hue, brightness or saturation?

Answer 3

Wavelength/Frequency: hue
Amplitude: brightness
Purity: saturation

Question 4

Eye anatomy

label diagram “Eye anatomy - 1”

Answer 4

1. Iris
2. Cornea
3. Pupil
4. Sclera
5. Lens
6. Retina

Question 5

In what orientation does an image land on the retina?

Answer 5

Upside down
and
Reversed left to right

Question 6

Which part of the eye controls light intake?

Answer 6

the muscles of the iris controlling the pupil size

larger pupil –> more light

Question 7

Which part of the eye allows us to focus on objects that are far vs close?

Answer 7

the muscles controlling the lens

constricted lens –> close objects
elongated long lens –> far objects

This is called accomodation

Question 8

Name for the fluid inside of the eye

Answer 8

vitreous humor

Question 9

Retina anatomy

layers + purpose + label diagram

Answer 9

Back
1. Photoreceptors: translate physical stim. to neural impulse
2. Bipolar cells: send info to next layer
3. Ganglion cells: neurons sending info to the brain
Front

Question 10

Part of the retina which provides nutrients

Answer 10

Retinal Pigment Epithelium (RPE)

Question 11

Photoreceptors

types + purpose + location

Answer 11

Rods:
- night vision
- black and white
- concentrated in periphery

Cones
- day vision
- colour sensing
- concentrated in the fovea

we have more rods than cones

Question 12

Blind spot of the eye

name + why it exists/what it’s made of

Answer 12

Optic disc: composed of ganglion cell axons

Question 13

Cells which combine information in the retina

names + location

Answer 13

Horizontal cells: between layers 1&2

Amacrine cells: between layers 2&3

Question 14

Fovea

description

Answer 14

small depression in the retina where visual acuity is highest

Question 15

Visual processing diagram

draw diagram + pathway labels

Answer 15

• optic chiasm
• optic tracts
• lateral geniculate nucleus (part of thalamus)
• primary visual cortex (occipital lobe)

Question 16

Alternate names for the primary visual cortex

Answer 16

• Area V1
• Striate cortex

Question 17

Area of the occipital lobe outside the primary visual cortex

name + what it contains + purpose

Answer 17

extrastriate cortex

contains: areas V2 through V5

purpose: processing colour, motion and object recognition

Question 18

Streams of visual processing after the occipital lobe

names + purpose + location

Answer 18

Dorsal stream: where pathway - depth and motion
- ‘up’ to parietal lobe

Ventral stream: what pathway - colour and form
- ‘down’ to temporal lobe

Question 19

what happens to visual information as it is processed?

Answer 19

it becomes compressed
(input from many cells condenses to few cells)

Question 20

Evolution of the eye

basic stages, name + features

Answer 20

• light sensitive patch: detect *presence *of light
• curved “cup” eye: direction of light
• pinhole eye: help focus light
• crude lens: increase focusing
• adjustable lens: allows for accomodation to change focus with distance

Question 21

Cumulative selection

Answer 21

elvolutionary process where adaptations are layered upon old adaptations

eg: the evolution of the eye –> gradual progression to a highly complex organ

Question 22

2 broad categories of eyes

name + which creatures have them + basic features

Answer 22

Simple eyes
- found in vertebrates and mollusks
- eyeball, lens and retina

Compound eyes
- anthropods (insects and crabs)
- ommatidia, lens retina

Question 23

Main two functions of the eye

Answer 23

• Resolution (acuity)
• Sensitivity (ability to get sufficient light)

Question 24

What are the two features of vision that eye size can benefit?

Answer 24

Acuity or Night Vision

Eyes will typically evolve to either have more cones OR more rods

Question 25

What are the two features of vision that eye placement can benefit

Answer 25

Depth perception or Field of view

Eyes on the front of the head have better depth perception and eyes on the sides of the head have a wider field of view

Question 26

Eye development in humans
Prenatal events

Answer 26

2nd prenatal month
- eyes form

6th prenatal month
- eyes react to light
- random firing of retinal cells

Question 27

Eye development in humans
Events after child is born

Answer 27

Newborn
- weak lense muscles
- inconsistent pupil reactions
- low cell density in retina
- retina cells are immature

3 months old
- almost adult-like focusing

11 years old
- complete visual brain area development