Vision 1

Question 1

What is light?

Answer 1

Electromagnetic radiation: ripples in an electric field .

Question 2

What determines the colour of light?

Answer 2

The frequency composition

Question 3

How is an image produced on the retina?

Answer 3

Light from source reflected off object is focused onto the retina by the cornea and the lens

Question 4

What happens to the eye for distant vision?

Answer 4

Ciliary muscles relax, fibres taut and lens at a minimum

Question 5

What happens to the eye . for close vision?

Answer 5

Tightening of ciliary muscles, allowing the . pliable . crystalline lens to become more rounded

Question 6

What are light rays like for distant objects?

Answer 6

nearly parallel and don’t need as much refraction to bring them into focus .

Question 7

what are light rays like for close objects?

Answer 7

they diverge and require more refraction for focusing

Question 8

What are quick eye movements called?

Answer 8

Saccades

Question 9

What happens in visual transduction?

Answer 9

signals carried by light waves are converted into electrical impulses in neurons: the language of the brain.

When light strikes the cells, a chemical reaction occurs that generates electrical signals that are carried to the brain via the optic nerve .

Question 10

How many different types of cones are there?

Answer 10

3, containing three different colour-sensitive pigments (roughly red, green, blue)

Question 11

What are rods?

Answer 11

Scotopic (nightime) vision- high sensitivity allowing for vision to dim light. More convergence than the cone system, increasing sensitivity while decreasing activity.

Question 12

What are cones:

Answer 12

Photopic (daytime) vision –> High acuity colour information in good lighting, only cones are found in the fovea.

Question 13

What are ganglion cells?

Answer 13

Optic nerve fibres

Question 14

What do ganglion cells do?

Answer 14

Combine the electrical outputs of the rods and cones

Question 15

What is visual coding form?

Answer 15

The ganglion cells combine the outputs of the rods and cones to form receptive fields with a centre-surround antagonism.

Question 16

What are receptive fields?

Answer 16

the region of the visual field in which light stimuli evoke responses in the ganglion cell

Question 17

What are neural pathways?

Answer 17

• The optic nerve carries info to the thalamus (lateral geniculate nucleus)
  
  • The LGN projects the primary visual cortex with different neurons carrying information about different places in the image on the retina.

Question 18

What is orientation sensitivity?

Answer 18

In the primary visual cortex, the outputs of the neurons from the eye are combined to produce neurons that respond best to edges and bars at particular orientations.

Question 19

What is the primary visual cortex?

Answer 19

Ø In the primary visual cortex, the shapes of objects are well represented, and the brain has already started analysing features, such as edges at particular orientations.

Question 20

What is perception of depth: convergence?

Answer 20

When the position of the two eyes required to focus the image on the fovea is a cue to depth (works only for close objects)

Question 21

What is perception of depth: Stereopsis?

Answer 21

The two eyes get slightly different views of the world, providing another cue to depth (used to make 3D)

Question 22

What is the flow of visual information?

Answer 22

Primary visual cortex
Secondary visual cortex
Visual association cortex

Question 23

What happens to receptive fields of neurons as information flows through the hierarchy?

Answer 23

They become longer and they respond to more complex and specific stimuli

Question 24

According to the what vs where theory what does the dorsal stream specialise in?

Answer 24

Visual Spatial perception

Question 25

According to the what vs where theory what does the ventral stream specialise in?

Answer 25

Visual Pattern recognition

Question 26

According to the control of behaviour vs conscious perception theory what does the dorsal stream specialise in?

Answer 26

Visually guided behaviour

Question 27

According to the control of behaviour vs conscious perception theory what does the ventral stream specialise in?

Answer 27

Visual perception