SENSATION/PERCEPTION PART II

Color

Physical

hue

brightness

saturation

correspond to different wavelengths

correspond to different amplitudes

manipulate brightness and darkness by adding white or black

language often confuses this - and uses lighter/darker to describe brightness

purity of the color

add or subtract grey to blur the color

eg pink is a less saturated red

psychological

luminance - perceived brightness

Paint and light definition of color is different

eg yellow looks more luminant than blue - stands out more

may be because we live in a blue world

paint

light

red, yellow, blue

red, green, blue

combine to get white

because combine is adding wavelength

combine get brownish black

combine subtrats wavelength bc more colors are absorbed, not reflected

theory of color vision

young-helmholtz trichromatic theory

z3dtf

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

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 level of cones/photoreceptors

explains at the higher mental function level: cells in retina, brain

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

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

Top down: depends on prior experience

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

Figure-ground: what's the focus, what's the background? eg affects the way we perceive mind trick photos - old woman/young woman?

eg impossible dog house - use continuity and closure

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

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

Perceptual Illusions

Ponzo Illusion

Muller Lyer Illusion

Moon Illusion

use distance cue, linear perspective as helpers

horizontal moon looks further away than overhead moon because objects in the city is visibly blocking/overlapping it

box looks larger if further down the road picture, even though it is the same size bc of linear perspective/relative distance

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

color constancy: perceiving familiar objects as having consistent color even if illumination changes wavelength

show experience of stimuli depends on context

brightness constancy

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

local perspective conflict with wholistic perspective

barber pole

auditory barber pole

local: stripes going up/down

wholistic - pole is spinning

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