WEEK 6 - Sensory Systems and Perception

Question 1

how do we know about our environment?

Answer 1

live in it but we dont perceive it directly,
we continuously interact with it to understand it
as soon as there is a distruption sensory input (vision/hearing) we get lost

Question 2

what is our conscious experience of the environment?

Answer 2

a construction of our minds - the way we see our reality is based on our construction

Question 3

In relation to cameras, what is the human eye?

Answer 3

a digital camera

Question 4

In stead of CCD sensors (in cameras) what do we have

Answer 4

photoreceptors

Question 5

how are eyes like cameras?

Answer 5

lens at one end, receptor layer on the other

Question 6

what does the retina do?

Answer 6

like a camera, they pick up points of light

Question 7

how do we get from seeing points of light to seeing objects / lines / shapes?

Answer 7

we have a system for enhancing edges - discontinuities in adjacent parts of the image (like modern cameras)

Question 8

how does the retina work?

Answer 8

through cells such as the ganglion cell

Question 9

ganglion cells

Answer 9

are in the retina and have a receptive field

Question 10

how can some ganglion cells be excited?

Answer 10

by light inside the receptive field and

Question 11

how can ganglion cells become inhibited

Answer 11

by light outside the receptive fireld

Question 12

what happens in other center-surrounding receptive fields?

Answer 12

illumination of the center is inhibitory while illumination of the surrounding is excitory

Question 13

what does the retinal ganglion cell act as?

Answer 13

edge detectors - where they integrate patterns of lightness over an area and indicate whether that pattern of lightness within an area is different to that in an adjascent area (an edge)

Question 14

Where is the Fovea

Answer 14

exact center of the visual field where light rays enter the eye sight along the axis of the eye.

Question 15

what is the fovea?

Answer 15

the area with the greatest concentration of photoreceptors

Question 16

what are the two types of photo receptors in the fovea

Answer 16

cone cells and rod cells

Question 17

what are cone cells responsible for?

Answer 17

colour vision

Question 18

what is the level of acuity that cone cells process

Answer 18

high acuity as they can see very fine detail with cones as they are densely packed in the fovea,

Question 19

what kind of light does the cone cells work primarily in?

Answer 19

bright light or daylight ‘photopic’ vision

Question 20

what are the rod cells responsible for?

Answer 20

black and white vision

Question 21

what is the level of acuity that rod cells process

Answer 21

low acuity - mostly widely spread throughout the retina, more peripheral visual field)

Question 22

what kind of lights do rod cells work best in?

Answer 22

night time ‘scotropic’ vision

Question 23

what is depth perception

Answer 23

two eyes, two differeny images

Question 24

what side of the brain does the right visual field project to?

Answer 24

left

Question 25

what side of the brain does the left visual field project to?

Answer 25

right

Question 26

where do the nerve cells cross over when projecting images to the brain?

Answer 26

optic chaism

Question 27

where is the optic chaism located

Answer 27

midbrain

Question 28

what is the process of visual information?

Answer 28

travels to laterial geniculate nucleus of thalamus (LGN) then back to occipital cortex and the back of the brain

Question 29

what is another word for the occipital lobe?

Answer 29

primary visual cortex (V1)

Question 30

what are simple cells in the V1?

Answer 30

respond to an edge at a particular orientation in a specific part of the visual field

Question 31

complex cells in the V1

Answer 31

respond to an edge at a particular orientation by falling anywhere within a wider field. May also respond to direction of motion

Question 32

hypercmplex cells in the V1

Answer 32

redpond to a line which ends within the receptve field (end-stopping)

Question 33

what are the higher levels of the ascending visual system?

Answer 33

temporal lobe, colour and orentation combinations AND higher still feature detectors

Question 34

what is the temporal lobes function in relation to vision

Answer 34

detectors for combination of line/edges (squares or cone shapes)

Question 35

agnosia

Answer 35

the inability to recognise objects

Question 36

prospagnosia

Answer 36

inability to recognise faces

Question 37

what happens when there is damage to the parietal lobe?

Answer 37

causes problems of spatial awareness eg visual neglect

Question 38

what is visual neglect?

Answer 38

visual unawareness of half their visual field. therefore lost information form half of both eyes

Question 39

where does information from all levels of the visual system get distributed?

Answer 39

in the multi parallel visal maps

Question 40

retinotopic

Answer 40

mimics the layout of visual field

Question 41

what happens when you move your eyes?

Answer 41

other connections exist with higher cortical levels, including frontal association cortex that tell you where your eyes are pointing to make an internal map of where things are located

Question 42

blindsight

Answer 42

unconscious, but not conscious, awareness of a visual stimulus. this must be observed in sme cases of visual neglect

Question 43

what are the things one would give to a robot?

Answer 43

− A system for detecting light
− System for focussing on the important stuff – fovea, rods and cones
− System for detecting edges (‘stuff’) – ganglion cells and simple cells
− Higher system for identifying objects from the edges and patterns – temporal lobe
− Higher system for identifying where the objects are – parietal lobe system