The Eye

Question 1

What is the pupil

Answer 1

Opening where light enters eye

Question 2

What is the iris

Answer 2

Colored part that controls amount of light entering eye

Question 3

What is the cornea

Answer 3

Accounts for 2/3 of eye’s refraction (light-focusing)

Question 4

What is the lens

Answer 4

Adjustable light refraction on the retina

Question 5

What is the retina

Answer 5

Lining on back of eye containing photoreceptors

Question 6

What do we need for good vision

Answer 6

receptor surface located at appropriate focal distance for object to be photographed

Question 7

What happens to the eye when focusing light

Answer 7

Lens gets fatter/thinner

Question 8

What happens to the eye when adjusting for light inensity

Answer 8

Pupil opens and closes
Retina’s sensitivity changes

Question 9

How is focal distance manipulated in the human eye (general)

Answer 9

Altering the shape of an adjustable lens

Question 10

How is focal distance manipulated in the human eye (specific_

Answer 10

There is a fixed lens and a flexible lens
The curvature of the flexible lens is changed by the ciliary muscles

Question 11

What are the ciliary muscles

Answer 11

Donut shaped muscles on the top and bottom of the fixed lens that contract in order to manipulate focal distance

Question 12

What is the manipulation of focal distance known as

Answer 12

Accommodation

Question 13

What happens as we get older in terms of accommodation

Answer 13

The flexibility of the lens is reduced, making it harder to achieve accommodation

Question 14

What happens when the ciliary muscles are contracted

Answer 14

Lens becomes more round and a close object is focused onto retina

Question 15

What happens when the ciliary muscles are relaxed

Answer 15

The lens becomes flat and a distant object is focused onto the retina

Question 16

What happens when there is bright lighting

Answer 16

The iris constricts and the pupil becomes smaller

Question 17

What does constriction of the iris prevent

Answer 17

Prevents light sensitive photoreceptors in the retina from becoming saturated by too much light

Question 18

What is another benefit of making the pupil small

Answer 18

Helps focus the image

Question 19

How does a small pupil help focus the image

Answer 19

Reduces the spread of light and area of blur on the retina

Question 20

What is the pigment epithelium

Answer 20

Layer in the very back of the eye which nourishes receptors and is non reflective

Question 21

What is the purpose of the pigment epithelium

Answer 21

Absorbs stray light

Question 22

What are photopigments

Answer 22

Photosensitive chemicals within the rods and cones

Question 23

Describe the process of visual transduction

Answer 23

Light hits the outer segment of rods and cones and changes the molecular properties of the photopigments
The electrical state of the rods/cones is then changed

Question 24

How many cones do we have

Answer 24

5 million

Question 25

How many rods do we have

Answer 25

120 million

Question 26

What are rods the precursors to

Answer 26

Motion perception and sensitivity

Question 27

What are cones the precursors to

Answer 27

Color vision and resolution

Question 28

What is the order of structures in the eye

Answer 28

Cornea -> iris -> pupil/lens/ciliary bodies -> retina -> fovea (rods/cones) -> pigment epithelium -> optic nerve

Question 29

What is the fovea

Answer 29

Pit at the center of the retina with high acuity and reduced light distortion

Question 30

How big is the fovea

Answer 30

1mm

Question 31

Describe the fovea’s cortical representation

Answer 31

Magnified

Question 32

Where is rod density greatest

Answer 32

About 15 degrees away from fovea

Question 33

Where is cone density greatest

Answer 33

In fovea

Question 34

What is the visual search paradigm

Answer 34

A method of investigating visual selection and attention by asking participants to find a visual stimulus amongst other visual stimuli

Question 35

What measures are typically used in the visual search paradigm

Answer 35

Reaction time as a function of set size and slope

Question 36

What is the purpose of the visual search paradigm

Answer 36

Measures the cost of each item in the search

Question 37

What is a feature search

Answer 37

Target differs from distractors in a single way. The target tends to “pop out.” Reaction time and accuracy are independent of set size. (linear slope)

Question 38

What is a conjunction search

Answer 38

Requires identification of a target defined by a combination of two features. Reaction time is dependent on set size (non linear slope)

Question 39

What is an example of a feature search and a conjunction search

Answer 39

Feature: Find the red X in a group of blue Xs and Os
Conjunction: Find the red X in the group of blue Xs and red Os

Question 40

Where is high-acuity vision restricted to

Answer 40

The foveola (~1 degree of our vision)

Question 41

Where is the blind spot on the left eye

Answer 41

Left side underneath the horizontal meridian

Question 42

Where is the blind spot on the right eye

Answer 42

Right side underneath the horizontal meridian

Question 43

What is cortical blindness

Answer 43

Total or partial loss of vision in a normal appearing eye caused by damage to the brain’s occipital cortex

Question 44

How can cortical blindness come about

Answer 44

Can be acquired or congenital, and may also be transient in certain instances