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SENSATION/PERCEPTION PART II (Signal Detection Theory: predict when and…
SENSATION/PERCEPTION PART II
Color
Physical
hue
correspond to different wavelengths
brightness
correspond to different amplitudes
manipulate brightness and darkness by adding white or black
language often confuses this - and uses lighter/darker to describe brightness
saturation
purity of the color
add or subtract grey to blur the color
eg pink is a less saturated red
psychological
luminance - perceived brightness
eg yellow looks more luminant than blue - stands out more
may be because we live in a blue world
effects
red can mean danger,avoidance OR love,passion,sexual readiness depending on context
study 1: red cover on exam paper - hold exam further away and score worse than green cover and control (grey) color
female with red background/dress more attractive
Paint and light definition of color is different
paint
red, yellow, blue
combine get brownish black
combine subtrats wavelength bc more colors are absorbed, not reflected
light
red, green, blue
combine to get white
because combine is adding wavelength
theory of color vision
young-helmholtz trichromatic theory
suggests red and green developed later, and initially only blue-yellow was needed
explains why r-g blindless is more common
men more common because need 1 x with recessive gene, women need both x to have recessive trait
suggests we have 3 types of detectors - red, green, blue
deficiency in red - protanopia
deficiency in green-deuteranopia
deficiency in blue-tritanopia
both protanopia and deuteranopia are red green deficiencies
deficiency may be bc cone is bad, not always missing
monochromacy - achromatopsia, usually rare and only in one side of the eye
problem with trichromatic theory
primacy of yellow in paint makes it seem really pure
red green are complementary colors, cant possibly be near each other/mixture? ie no such thing as reddish green
explains at the level of cones/photoreceptors
Opponent Process Theory
complementary neural system
red/green
blue/yellow
white/black
if cell stimulated by 1 color, it will inhibit opp color
hence cant see reddish green but can see reddish blue bc that can trigger 2 sets of paths
explains at the higher mental function level: cells in retina, brain
Signal Detection Theory: predict when and how we detect faint stimuli amidst background stimulation
hit - stimulus + hear
miss - stimulus +not hear
false alarm - no stimulus +hear
correct negative - no stimulus +not hear
Response bias
conservative response bias/ high threshold- only say hear if ery sure they heard sth = increase miss, less false alarm
liberal response bias/low threshold - always say hear = more false alarm, less miss
influenced by: expectation - are you expecting a stimuli, motivation or consequence of making an error eg identify tumor in person
Applied in Marley Hypothesis - you are more accurate in detecting real/fake racism when you have been in the situation - higher hit rate without increase in false alarm. And perceive more racism in the culture
Perceptual Organization
Bottom Up: Form Perception
Gesalt: when given cluster of information, organize into form/whole
Gesalt Grouping Principle
proximity eg 3 pairs of lines
continuity
closure eg form closed shape with dotted lines
similarity eg group same shapes together
connectedness
eg impossible dog house - use continuity and closure
Figure-ground: what's the focus, what's the background? eg affects the way we perceive mind trick photos - old woman/young woman?
Depth Cue - binocular
uses retinal disparity: difference in vision from left/right eye help see 3D/depth
closer to eye, harder to perceive 3D with only 1 eye bc 2 eyes receive diff image
Depth Cue - monocular
relative size: closer- bigger, further-smaller
interposition: sth overlap another=closer
texture gradient: if object is nearer, then we see texture, if further then becomes blurry
relative height: see height as longer distance than width even if it is the same size (ppl exaggerate height relative to width)
linear perspective: parallel lines converge when going into the distance
relative brightness/shadow
relative motion: far away objects seem to move with us, close objects seem to move away from sight
Top down: depends on prior experience
priming eg show saxophone player then see it, show woman, the see woman on ambiguous picture
culture - shapes experience
surrounding stimuli - shadow, surrounding color, angle eg black of checker board and shadow on white tile of checker board may be same color but we don't perceive so
Bottom Up: Motion Perception
phi phenomenon: illusion of movement created when 2 or more adjacent lights blink on a off in quick succession
used in moving arrow or stop motion picture
Perceptual Constancy
Shape Constancy: image changes in 2D but we perceive as the same object and not changing shape and size eg door opening
Size Constancy: can see object moving towards us as same size even if it gets bigger in 2D
use distance cue, linear perspective as helpers
color constancy: perceiving familiar objects as having consistent color even if illumination changes wavelength
show experience of stimuli depends on context
brightness constancy
Perceptual Illusions
Ponzo Illusion
box looks larger if further down the road picture, even though it is the same size bc of linear perspective/relative distance
Muller Lyer Illusion
line with inverted arrows look longer than line with normal arrowheads - may be because we cannot help but think extra arrows are included into the line
Moon Illusion
horizontal moon looks further away than overhead moon because objects in the city is visibly blocking/overlapping it
local perspective conflict with wholistic perspective
barber pole
local: stripes going up/down
wholistic - pole is spinning
auditory barber pole
the high, middle and low octaves take turn increasing and decreasing in volume to make it seem like the sound is neverendingly increasing in pitch
local: pitch increase
wholistic: the octave never changes
Inattentional blindness
caused by focusing too much on 1 thing
if did not notice the guy behind the counter changes - caused by not paying attention enough
