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Human abilities: Perception (Basic human capabilities (Dont change rapidly…
Human abilities: Perception
Basic human capabilities
Dont change rapidly
Have limits that are important to understand
Our understanding of these things does change
Cognitive psychology
We need to understand
How humans percieve the world around them
How humans store and process information and solve problems
How humans physically manipulate objects
Human visual system
Light passes through eyes
Focused on the retina
Retina covered in light-sensitive receptors
Rods
Primarily for night vision and perceiving movement
sensitive to broad spectrum of light
can't discriminate between colours
senses intensity or shades of gray
Very sensitive to light
Allow us to see under a v low level of illumination
about 120 million rods in one eye
Can't resolve fine detail
Subject to light saturation (leaving cinema daytime)
Cones
Used to sense colour (contain photopigments)
Concentrated on fovea of retina
3 types:
64% red
32% green
2% blue
Other colours are a combination
Lens is less sensitive to shorter wavelengths
Distribution of photopigments
No blue cones in center of retina
'disappearance' of small blue objects you fixate on
As we age, the lens (and aqueous humor) yellows and absorbs blues
IMPLICATION
don't rely on blue for text and small objects
good for backgrounds
Colour sensitivity and image detection
Most sensitive to the center of the spectrum
brightness determined by R+G
Shapes detected by finding edges
Hard to deal w/ blue edges and shapes
Center of retina has the most cones
allows for high acuity of objects in focus in the centre
Edge of retina is dominated by rods (peripheral threats)
Focus
Different wavelengths are different distances from lens
Constant refocusing is tiring on eyes
careful about color combinations
Pure (saturated) colours require more focusing than less pure