The Visual System

Question 1

Lens

Answer 1

clear structure that focuses light onto back of eye

Question 2

Accommodation

Answer 2

lens can change shape to focus light

Question 3

Retina

Answer 3

lines inner surface, consists of specialized receptors that absorb light and send signals to brain

Question 4

Photoreceptors

Answer 4

Specialized receptors at back of retina

Made of rods and cones

Question 5

Ganglion Cells

Answer 5

Gather info from photoreceptors, fires signal

Question 6

Optic Nerve

Answer 6

dense bundle of fibres that connect to brain, signal from ganglion cells sent out of eye through here

Question 7

Optic Disc

Answer 7

area on back of retina with no photoreceptor, creates blind spot

Question 8

Trichromatic Theory-/ Young- Helmholtz Theory

Answer 8

colour vision is determined by three different cone types that are sensitive to short medium and long wavelength of light

Question 9

Opponent Process Theory

Answer 9

we perceive colour in terms of opposing pairs (red/green, yellow/blue, white/black)
-See red, then when red is no longer being seen, green (which was inhibited before) is free to fire

Question 10

Rods

Answer 10

occupy peripheral regions of retina, highly sensitive under low light levels, very sensitive to black and gray
10-1 ratio between rods and ganglion cells

Question 11

Cones

Answer 11

sensitive to different wavelengths of light (colours), clustered around fovea (central region of retina)
1-1 ratio between cones and ganglion

Question 12

Dark Adaptation

Answer 12

rods and cones become increasingly sensitive to light under low levels of illumination

Question 13

Colour Blindness

Answer 13

Proteins in cones sensitive to red and green, colourblind people have green cones that contain red cone protein instead

Question 14

Nearsightedness/Myopia

Answer 14

Elongation of eyeball, causing image to fall short of retina

Question 15

Farsightedness/Hyperopia

Answer 15

Image focused behind Retina

Question 16

Optic Chiasm

Answer 16

Point at which optic nerves cross at midline of brain

Question 17

Lateral Geniculate Nucleus

Answer 17

Sends message to visual cortex

Question 18

Feature Detection Cells

Answer 18

cells in visual cortex that respond selectively to simple and specific aspects of a stimulus, such as angles and edges

Question 19

Ventral Stream

Answer 19

Part of secondary visual cortex

• From visual cortex to lower part of temporal lobe
• Responsible for object recognition, and names object

Question 20

Dorsal Stream

Answer 20

Part of secondary visual cortex

• From visual cortex to parietal lobe
• Locates object in space, allows you to interact with it

Question 21

Perceptual Constancy

Answer 21

ability to perceive objects as having constant shape, size, and colour despite changes in perspective

Question 22

Binocular Dept Cues

Answer 22

Distance cues based on differing perspectives of both eyes

Question 23

Binocular Dept Cues: Convergence

Answer 23

eye muscles contract so that both eyes focus on a single object

Question 24

Binocular Dept Cues: Retina Disparity/ Binocular Disparity

Answer 24

difference in relative position of an object as seen by both eyes- provides brain information about depth

Question 25

Binocular Dept Cues: Stereoscopic Vision

Answer 25

overlapping visual fields

Question 26

Monocular Cues

Answer 26

Dept cues perceived with one eye

Question 27

Monocular Cues: Motion Parallax

Answer 27

Provides info about depth based on how quickly stationary objects appear to move

Question 28

Thalamocortical Pathways

Answer 28

-Connetcs eyes to thalamus to cortex
Each stage builds on processing in previous stage
Eyes-> Thalamus-> Cortex

Question 29

Cortical Blindness

Answer 29

Damage to cortex

Loss of conscious vision

Question 30

Parts of Secondary Visual Cortex

Answer 30

Dorsal Stream

Ventral Stream

Question 31

Dorsal Stream

Answer 31

goes upwards towards top of brain

-In charge of locating and interacting with objects

Question 32

Ventral Stream

Answer 32

goes downwards towards bottom of brain

-identifies objects