5.2 - How Do We See? Flashcards
Cornea
- where light first passes through
- thick outer layer of eye
Lens
- receives focused light from cornea
- bends light further inwards
- forms a picture on the retina
Retina
Inner surface of the back of the eyeball
Contains sensory receptors that transduce light into neural signals
Pupil
hole in the middle of the eye
small opening in front of the lens
Iris
Donut muscle that relaxes or contracts and makes the pupil smaller or bigger depending on the environment
What are the two types of receptor cells in the retina?
Rods and Cones
Rods
retinal cells that respond to low levels of light and result in black and white perception
- primarily for night vision
- don’t support colour vision
- poor at fine detail
Cones
retinal cells that respond to higher levels of light and result in colour perception
Fovea
centre of the retina where cones are densely packed
Ventral Stream of Processing “what stream”
- occipital lobe to temporal lobe
- specialized for perception and recognition of objects (ex. determining colours and shapes)
Dorsal Stream of Processing “where stream”
- occipital lobe to parietal lobe
- spacial perception (where an object is in relation to other objects)
Object Agnosia
- condition where someone is unable to identify objects (likely caused by damage to the “what” pathway)
Q: Does fovea have more rods or cones?
fovea only has cones
What is the most common form of colour blindness?
Red-green caused by a missing protein in green or red receptor
Myopia
- nearsighted
- eyeball slightly elongated
Hyperopia
- farsighted
- eyeball slightly shortened
Astigmatism
uneven curvature of the cornea that leads to distorted images
5.4
How is the colour of light determined?
The wavelength of the electromagnetic wave that reaches the eye
How does the trichromatic theory explain colour blindness?
Some people may be missing the photopigment that is sensitive to some of the wavelengths and therefore they can’t process that colour
Photopigments
protein molecules that become unstable and split apart when exposed to light
- absorb certain wavelengths
Opponent-Process Theory of colour perception
States that we perceive colours in opposing pairs (ex. red to green, yellow to blue, white to black)
- complimentary colours
- compliments the trichromatic theory
Hue of colour
colour on the spectrum