Visual perception & action

Question 1

LGN pathway

Answer 1

eye -> LGN -> v1 -> occipital lobe (&v areas)

used 80% of the time

Question 2

Retino tectal route

Answer 2

eye -> superior colliculus -> pulvinar -> temporal & parietal lobe
used 10% of the time

Question 3

Functional Specialisation

Answer 3

the suggestion that different cortical areas are specialised for different functions (Zeki, 2001)

Question 4

What are the two names for the V1?

Answer 4

striate cortex & primary visual cortex

Question 5

3 kinds of cell in the visual system 1 (v1)

Answer 5

• simple cell
• complex cell
• hypercomplex cell

Question 6

Simple cell?

Answer 6

On/off sensors
Responds to EDGES AND BARS
Light must be at a particular ANGLE for the cells to fire

Question 7

Complex cell

Answer 7

Prefer the WIDTH of the light > angle
When width fits in the receptive field - will fire
BARS NOT SPOTS

Question 8

Hypercomplex cell

Answer 8

Prefers LENGTH of light

BARS NOT SPOTS

Question 9

what is the receptive feild?

Answer 9

individual sensory neurone’s region of sensory SPACE by which a stim will trigger firing if hit

Question 10

Extra Striate cortex

Answer 10

Gateway to rest of the ‘v’ regions - striped

“the sorting room”

Question 11

What cells are in the V2

Answer 11

Magnocellular cells: THICK & project to V3 and V5

Parvocellular cells: THIN cells, priject to V4

Question 12

V3

Answer 12

input from v1 & v2. - magnocellular

FORM, ORIENTATION & MOVEMENT

Question 13

v4

Answer 13

input from v2: parvocellular cells

COLOUR, PATTERN DISCRIMINATION

Question 14

v5

Answer 14

Input from MAGNO cells of v2,3,1

MOVEMENT

Question 15

the binding problem

Answer 15

Zeki: All breaks down for perception BUT how does it come together again?

Question 16

Solutions for the binding problem (4)

Answer 16

• Weaker specialisation of function than zeki thought ie 1 cell can do more than 1 job
• Synchrony
  a) precise synchrony: tag each info as comes in and use tag to produce output - v expensive
  b) General synchrony: use general pattern of cell firing to bind - loss of detail
• Gestalt laws: similar things go together
• Selective attention : choose the things to attend to & they’re grouped together

Question 17

Dorsal & Ventral Stream - Who?

Answer 17

Milner & Goodale (1992) - dual route hypothesis

Question 18

What is the dorsal stream? up and around

Answer 18

• Dynamic (must be or action will not be correct)
• visual ACTION
• eg returning of a ball

Question 19

What is the VENTRAL stream - downwards

Answer 19

• visual perception & recognition - identifies
• egocentric ie is that object and cat or a dog
• static

Question 20

Optic ataxia

Answer 20

• can SEE but cant INTERACT
  a) perception = good
  b) action = impoverished
  ~~ dorsal stream impaired~~
  damage to posterior parietal lobe

Question 21

Visual Agnosia

Answer 21

• cant SEE but can INTERACT
  a)perception = poor
  b) action = fine
  ~~damaged ventral stream~~
  damaged temporal lobe

Question 22

Blindsight

Answer 22

~ACTION WITHOUT AWARENESS~
RT route in tact, LGN not - i.e. damage to v1
-RT route = unconscious

Question 23

evidence for the dual route hypothesis

Answer 23

Ebbinhaus’ circle size illusion

• ventral stream = tricked by it
• dorsal stream = not tricked by it

Question 24

Planning and control model of percetion

Answer 24

early: planning stage: automatic: context matters
later: control stage: online: corrections made