Perception (Chap 2, 3 & 4) Flashcards
What is perception?
The acquisiton and processing of sensory information in order to see, hear, taste or feel objects in the world
Size of visual cortex?
20 % of entire cortex
Three major consequences of light hitting the retina?
Reception, transduction, coding
Reception
Absorption of physical energy by photoreceptors
Transduction
Physical energy converted into electro-chemical pattern
Coding
One to one correspondence between physical stimulus and nervous system activity
The order in which light passes in the eye
Cornea, iris (determined by pupil), lens, retina
Describe accommodation when light is from a distant object
Lens is pulled out thin
Accommodation on a close object
Lens is bulged or convex
how many cones
6 million
Where are the most cones?
fovea
How many rods
125 million
Cones
colour and sharp vision
Rods
Dim light and movement detection
Main pathway from eye to visual cortex
retina-geniculate-striate pathway
How does the retina-geniculate-striate pathway transmit information?
From the retina to V1 to V2 (via geniculate in thalamus)
Two channels of RGS pathway
Parvocellular and magnocellular
Parvocellular pathway
Sensitive to colour and fine detail; cone input mostly
Magnocellular pathway
Sensitive to information about movement (rods mostly)
Are the two pathways completely separate?
no
What are the three physiological dimensions of colour?
hue, saturation and lightness
Opponents Process Theory
Opponent-process theory suggests that color perception is controlled by the activity of three opponent systems.
