Vision

Question 1

How does light travel through the eye?

Answer 1

Cornea –> pupil –> lens

Question 2

What is the cornea?

Answer 2

A clear hard covering that protects the lens

Question 3

What is the pupil?

Answer 3

An opening in the iris in which light enters the eye

Question 4

What is the lens?

Answer 4

The structure behind the pupil that bends light rays to focus images on the retina and allow larger area of visual space in the small eye area

Question 5

What is the iris and it’s function?

Answer 5

• A muscle that makes up the colored part of the eye
• adjusts pupil to control the amount of light that enters
  the eye

Question 6

What is the retina?

Answer 6

• The thin layer of tissue that lines the back of the eye

- The lens bends light rays to focus light on the retina

Question 7

What is the process of Accommodation?

Answer 7

The process by which muscles control the shape of the lens to adjust it to view objects at different distances

Question 8

What are the cells in the retina called?

Answer 8

Photoreceptors called rods and cones

Question 9

What is the purpose of photoreceptors?

Answer 9

These convert light energy to neural impulses

Question 10

Explain the pathway of light through the eye in terms of cells

Answer 10

Ganglion cells –> amacrine cells –> bilayer cells –> horizontal cells –> photoreceptor layer (rods and cones)

Question 11

What are rods?

Answer 11

• One of two photoreceptors
• Located on the outer periphery of the retina
• used in vision at night
• very sensitive to light
• become “bleached” in the morning when sudden bright light hits the eye
• more numerous
• protein contained in these cells called rhodopsin

Question 12

What are cones?

Answer 12

• One of two photoreceptors
• responsible for our colour vision
  3 photosins: short (blue), medium (green), long (red)
• function well in bright light
• give our vision sharpness and detail
• best in bright light
• less numerous
• protein contained in these cells called photopsins

Question 13

What is the fovea?

Answer 13

• A spot in the back of the retina that contains the highest concentration of cones
• Because of this high concentration of cones, when ligh hits the fovea, the clearest image we can see is produced

Question 14

Explain the difference in photoreceptors in humans and dogs and how this affects our vision

Answer 14

While both dogs and humans have more rods than cones, dogs have less cone cells than rod cells compared to humans

This explains why dogs have better night vision that humans ( the more rod cells ) and why they have poor detailed vision and poorer colour vision (less cones than humans)

Question 15

what are the theories of the perception of colour?

Answer 15

The trichromatic colour theory
- colour is perceived by mixing wavelengths of light

The opponent process theory
- cones are linked together in opposing colour pairs
and so when one fires, the other cannot

Question 16

Define the optic nerve and explain its function

Answer 16

Structure made from the axons of ganglion cells that transmits signals from the eye to the brain

Question 17

Define and explain the optic disk

Answer 17

• The small area that contains no photoreceptors where the optic nerve exits the eye
• Forms a blind spot on the retina

Question 18

What are the factors in motion perception?

Answer 18

• size of the background

- size of the object

Question 19

Explain the visual pathways in human vision

Answer 19

• The left side of the retina in each eye senses the right visual field
• The right side of the retina in each eye senses the left visual field
• The two strands from each of the two optic nerves for the right and left side of the retinas meet at a point called the OPTIC CHIASM where the opposite strand crosses over. This leaves us with both right side strands of the optics nerves together and both left side strands of the optic nerves together. The right side and left side strands then continue to the thalamus where signals are then sent to the primary visual cortex in the occipital lobe

Question 20

What is a respective field in terms of vision?

Answer 20

The area of visual space that stimulates specific neurons

Question 21

What are feature detectors in terms of vision?

Answer 21

Neurons in the visual cortex that analyze retinal images and respond to certain aspects of shapes (angles, movement, ect)

Question 22

What is apparent motion?

Answer 22

When you think something is moving when in reality nothing is actually moving

Motion blindness - Akinetopsia

Question 23

What is depth perception?

Answer 23

The ability to distinguish what is near or far and see objects in three dimensions

Question 24

What are binocular depth cues?

Answer 24

• Cues that depend on both eyes
• binocular disparity
• convergence

Question 25

What is convergence?

Answer 25

- binocular depth cue | - determining the distance of an object by messages of how much the muscles contract to focus on an object

Question 26

What is binocular disparity?

Answer 26

- binocular depth cue | - creates depth by using the difference in what one eye sees versus the other

Question 27

What are monocular depth cues?

Answer 27

- motion parallax - detailing of an object - cues that only require one eye

Question 28

What is motion parallax?

Answer 28

comparing sizes of objects in the visual to determine distances objects/ depth

Question 29

How can detailing of an object be of use when determining depth?

Answer 29

The farther away an object is, the fewer details we can see | Details could be: texture, shading, ect

Question 30

What is perceptual constancy?

Answer 30

- The ability of the brain to preserve perception of objects in spite of changes in the retinal image - using shape and size constancy - example of this is the Ames room

Question 31

Gestalt Laws of Perception

Answer 31

The tendency to group things together by: - similarity - continuity - proximity - closure ( holes in a perceived triangle) - figure - ground

Question 32

Visual areas of the cortex

Answer 32

- postier parietal cortex - prestriate cortex - primary visual (striate) cortex - inferotemporal cortex

Question 33

Dorsal and Ventral streams

Answer 33

Ventral stream - What? pathway - moves from occipital lobe to temporal lobe - identifies objects by looking at size, shape, orientation Dorsal stream - Where? pathway - Moves from the occipital lobe to the parietal lobe - locates objects relative to yourself

Question 34

Explain the vegetable face man experiment and what was found as a result of this experiment

Answer 34

Experiment with participants being split-brain patients - the right hemisphere saw a face - the left hemisphere saw vegetables This gave evidence for: right hemisphere is the face processor left hemisphere is the object processor

Question 35

What are feature detectors?

Answer 35

Neurons in the visual cortex that analyze retinal images and responds to certain aspect of shapes such as angles movement and more

Question 36

What is a simple cell in terms of vision?

Answer 36

- A cell that only responds to visual stimuli that are still or are in the middle of the respective visual fields - can only respond to very specific things they are programmed to do

Question 37

What are complex cells in terms of vision?

Answer 37

- Cells that can respond to visual stimuli in different parts of its respective field - can respond to multiple things