Visual system, colour and depth perception (Sensation vs perception )

light passes through several structure before

the brain process the info

Cornea

transparent outer covering that helps focus light

pupil

opening through which light enters

lens

focuses light onto the retina

retina

light-sensitive lining containing photoreceptors

optic nerve

carries visual info toward brain

occipital lobe

processes visual info

iris

coloured part of the eye , muscles control pupil size

pupil dilation

pupil expands in low light to let more light enter

pupil constriction

pupil becomes smaller in bright light

fovea

small region of retina where images are normally focuses, contains densely packed cones and provides high visual acuity

rods work best in

dim light

rods dont provide

color vision

rods have lower … than cones

spatial resolution than cones

rods helos with

peripheral vision and movement

cones work best in

bright light

cones responsible for

color vision

cones provide sharp

visual details

cones concentrated in

fovea

dark adaptation

in dark space, struggle to see initially. After few minutes, your vision adjusts as rodactivity becomes more dominant

blind spot

region of visual field where an object cant be seen when image falls on corresposnding area of the retina

each eye receives slightly different view so

their blind spots dont overlap

visual system fills in missing info making

the gap less noticeable

optic chiasm

x-shaoed point where optic nerves meet

Info from right visual field of both eyes is sent to

left side of brain

Info from left visual field of both eyes is sent to

right side of brain

Trichromatic theory states that color vision depends on 3 types of cones that are maximally

sensititve to different wavelengths, associated with red, green and blue

our perception of different colours comes from combinations of

activity across these 3 cones types

Opponent-process theory states that

color is coded in opposing pairs

some cells are excited by one color in a pair and …, explains ….

inhibited by others, explains negative afterimages

depth perception is the ability to

perceive spatial relationships in 3D shape including whether objects are in front of, behind, above, below or beside one another

binocular cues require

both eyes

Binocular disparity

each eye receives a slightly different image of the world.

Brian combines the mages to help perceive depth

monocular cues require

only one eye

Interposition

one object partially overlaps another, suggesting it is closer

relative size

objects that appear smaller may be perceived as farther away

Closness to horizon

position of images relative to horizon can provide depth info

Stereo blindness

inability to respond to binocular depth cues

where/how pathway processes

where an object is in space

where/how pathway helps you undrestand

how to

damage to visual processing areas can cause

agnosia

what is agnosia

difficulty recognizing or identifying objects despite having basic sensory info available