Visual perception

Question 1

Visual perception impatcs

Answer 1

-Impacts all areas of perception as it is processed in each sensory area, flavor perception is most impacted e.g. blue steak and white wine dyed red fooled flavour perception.

Question 2

Importance

Answer 2

-Finding food, detecting danger etc.

Question 3

Iconic duration

Answer 3

-1/10th of a second as seed when making circles with sparklers.

Question 4

Visual sensory memoyr

Answer 4

• Visual stimuli detected by the eyes is stored in the sensory store
• If given attention it is encoded into the short-term memory where it is processed.
• With rehearsal will be encoded into the long-term memory

Question 5

Structuralists

Answer 5

-Focus on shape, form and orientation of objects

Question 6

Gestalt

Answer 6

-Considers how context impacts perception

Question 7

Stages of visual process

Answer 7

1. Light energy
2. Focusing
3. Blind spot
4. Transduction
   5&6. Cortical pathways
   7&8. Subcortical pathways

Question 8

Light energy

Answer 8

• Light energy depends on the object’s reflectors, brightness and atmosphere.
• Light enters the eye through the cornea (outer transparent dome) then pupil which is a hole in the eye which contracts or relaxes ciliary muscle to control light intensity. Light then passes through the lens which is biconvex.
• Light is an electromagnetic wave we can perceive light from 400 (P) to 700 (R) nm.

Question 9

Focusing

Answer 9

• Cornea focuses 80% of light energy (fixed), lens focuses 20% and can change shape by contracting (round and fat = close) or relaxing (long and flat = distant) ciliary muscles.
• Light energy hits the retina which is a thin layer of neurones at the back of the eye

Question 10

Blind spot

Answer 10

• Neural signal leaves the retina via the optic nerve through a gap in the receptors known as the optic disk which is a blind spot.
• We don’t notice the blind spot as our brains fill the gap with guesses based on surrounding stimuli.

Question 11

Transduction

Answer 11

• When light energy hits the retina, the rod cells in the periphery and cone cells in the fovea contains photosynthetic chemicals so absorb photos of light, this induces a change in current across the cell membrane which triggers the release of neurotransmitter that activates neighbouring cells which activates the horizontal and bipolar cells which in turn activates the amacrine and ganglion cells.
• Ganglion cell fibres then become optic nerve fibres.

Question 12

rod and cone cells

Answer 12

• Rod cells are highly sensitive so produce low acuity vision in dim light, but only have one photopigment so only register black and white.
• Cone cells are less sensitive so are effective in bright light, they have high acuity and three photopigments so perceive colour.

Question 13

sub cortical pathways

Answer 13

• Medial parts of the optic nerve fibres cross at the optic chiasm and lateral parts of the optic nerve don’t cross, this means vision is processed contralaterally.
• 10% of the optic nerve fibres go to the superior colliculus which controls eye movements (explains blind sight).
• 90% go to the lateral geniculate nucleus in the thalamus which has six neural layers that process movement in the magnocellular layer and colour and detain in the parvocellular layer.

Question 14

Cortical pathways

Answer 14

• Signals from the lateral geniculate nucleus go to the striate cortex (primary visual cortex) in the occipital lobe, if this area is damaged vision loss may be experienced. This pathway allows us to describe what we are seeing.
• Signals from the sirate cortex can take the ventral path to the parietal lobe to process form and colour for recognition, planning and memory (damage = prosopagnosia).
• Signals could also take the ventral path or dorsal path to the extrastriata which processes action using size and position which is rapid (damage=optic ataxia - spatial neglect)