Exam 3 perception

Why do we perceive the purple bars on the left as lighter than the purple bars on the right? 

The color of the light is perceived differently by our mind because the purple on the left and right has a different context

Additive color mixing occurs when lights mix to create different colors, and Subtractive color mixing occurs when we mix paints together. 1

true 1

The Trichromatic theory of color perception posits that we have three types of color receptors: one that is sensitive to short wavelengths, one that is sensitive to medium wavelengths, and one that is sensitive to long wavelengths.

What concept did we learn about early in the course that explains why it could reasonably be proposed that a combination of only three receptors could cause the perception of the great variety of colors we experience?

pattern codes

The trichromatic theory of color perception is capable of explaining red/green color blindness. 1

false 1

What is a fundamental observation about color that informed the development of the opponent process theory? 

The range of all possible colors can be captured in a circle, with red/green and blue/yellow on opposing sides, When we perceive a surface as having a color, that surface is actually reflecting many different wavelengths of light at the same time, Color is not entirely wavelength dependent, but is a product of our mind

The Trichromatic theory and the Opponent process theory can be combined by having the three color receptors (S, M, L) from the Trichromatic theory differentially activate and inhibit the blue/yellow, red/green, and black/white distinctions from the Opponent process theory. 

 

Why is the Opponent process theory on its own not a satisfactory explanation of color perception until it incorporates aspects of the Trichromatic theory? 

Because the three distinct receptor types that defined the trichromatic theory do exist

Which word combination marks the distinction between the percent of light reflected off a surface, and the appearance of the percent of light reflected off a surface? 

Reflectance and Lightness

Which word combination marks the distinction between the physical amount of light on a surface, and the appearance of the amount of light on a surface? 

Luminance and Brightness

Lightness constancy states the objects will appear to have the same lightness even under different lighting conditions. 

 

Why do we experience lightness constancy? 

Because the ratio of light reflected between the object and what's around it is constant

What did Gilchrist's study demonstrate about perception of lightness? 

Lightness depends on the ratio of objects illuminated in the same way

metamers

different wavelengths yet same color, a pattern code, identity in appearance

trichromatic theory

pattern of activity of three cones determines color. three different cones respond to different wavelengths of light

color circle

it is possible to array all colors in a circle where blue is one one side, yellow on the other, green on one side, and red on the other. all other colors fall between the listed colors

color blindness

Someone who experienced red-green color blindness would experience a purple light as a dull blue, a darker color, or a color that lacks the red component, since purple contains red and those with this color blindness cannot process red or green.

Someone who experienced blue-yellow color blindness would experience a purple light as red, a pinkish or a gray shade, since purple is a mix of red and blue wavelengths, the blue component would not be coming through and those with blue-yellow color blindness cannot process blue or yellow colors.

Someone with complete color blindness would experience a purple light as a shade of gray, since there is no color component that would come through for them to perceive as people with this type of color blindness do not perceive any type of color besides white, black or gray.

color contrast

the difference in lightness or darkness between colors. gray surrounded by yellow, center looks blue. the surroundings changes the appearance of the central square. surrounded by green, center looks reddish.

color aftereffects

an optical illusion where you see the opposite (complementary) color after staring at a specific color, like seeing blue after a red image, caused by your eye's color-sensitive cells (cones) getting fatigued and adapting, explained by the opponent-process theory (red-green, blue-yellow)

opponent processes theory

pattern of activity on two dimensions determines color. three underlying dimensions to the experience of color, blue yellow dimension, red green dimension, black white dimension. any given color falls in between these dimensions. combination of colors within a dimension are not visible, for example, no thing as a reddish green, blue-yellow, white-black;either or

combining trichromatic and opponent process theories

trichromatic theory describes color processing at retina, opponent processes describes color processing upstream in the brain

Wallach ration and Gilchrist update

Lightness is psychological experience of achromatic

color (brightness is how much light)

• Reflectance is actual amount reflected (luminance is

actual amount of light)

• People can judge lightness by ratio of amount of light

• Gilchrist added need to compare ratios of similarly lit

surfaces

Which of the 5 tastes below do we have an evolutionary argument for why we find them particularly enjoyable?

salt, sweet, umami

Which of the 5 tastes below was discovered by a Japanese scientist in 1907, and only recognized in the US in the 1980's? 

umami

salty

sodium ions

sweet

sugars

sour

acid ions (H+)

bitter

molecules with an amine group

umami

glutamate

Which below is an accurate description of a characteristic of a supertaster's tongue? 

their papillae are smaller and more densely clustered

orthonasal flow

Enables us to smell objects out in the world, Odorants flowing into the nose

retronasal flow

Enables us to smell what we are eating, odorants flowing out of the nose

What is one possible explanation for why food can get easily associated with emotionally relevant memories? 

Smell is integral to taste, and our sense of smell can reinstate emotions

Taste is the result of taste receptors and our sense of smell ONLY. 2

false 2

What is one theory for why humans like spicy food? 

Humans derive enjoyment from simulating threat arousal

5 taste receptors and what they detect

sweet, bitter, salty, umami, sour. sugars, amine group, sodium Na+, glutamate, acid H+ ions

variations in taste

Eskimos>others in salt

Females>males

Pregnant females>non-pregnant females

Supertasters>normals

supertasters

Fat & sugar taste bad, Alcohol tastes bad, Bitter greens taste bad (at risk for colon and gynaecological cancer), Chefs

What is the best description of the difference between perceived depth and perceived distance? 

Depth is a relative perception of how near or far an object is, distance is an exact perception of how near or far an object is

depth and distance

familiar size, texture gradient, atmosphere

only depth

relative size, interposition, linear perspective, height of the object

lenses in eye change shape

accomodation

eyes rotate

convergence

indicates distance

accommodation and convergence

indicates depth

neither

Motion parallax is a depth cue that depends on how objects move relative to both our motion and our fixation point. 

Let's say you were walking up a trail to a waterfall, and you had a view of the waterfall while walking. You were looking at the waterfall even as the trail turned left. Which way would a nearby bush in your field of vision move when you are walking after having turned left? 

right

There are cells that process differences between activity on the retina of our left eye and the retina of our right eye in order to give us depth and distance cues. 

true

How do we infer the size of an object from distance? 

We infer from a consistent ratio between proximal size and distance with distal size and distance

Why does the moon look larger when it is on the horizon than when it is overhead? 

Overhead, without distance cues we can't apply the size/distance ratio. On the horizon, with distance cues, we can so it appears bigger. 

Which theory of size perception is similar to the affordance theory of object recognition? 

Size from texture gradients

occulomotor cues to depth

accommodation refers to the fact we need to focus on something, the muscles that connect to the lens and the eye need to pull on that lens to focus on things. when objects are far, muscles are relaxed. when muscles are close, the muscles need to be contracted to change the shape of the lens so you can focus on the near object. amount of pull required to focus is accommodation, distance cue, ordinal, near or far but not precisely how far distance as a metric judgement.

convergence refers to the amount the eyes need to rotate inwards for an object. nearer the object is, the more the eyes need to rotate so that the foveas point of both eyes is pointing right at the object, distance cue because there is a specific angle of rotation inwards for each distance from the person

pictorial cues

height in image, relative size, familiar size-w/ distance, linear perspective, interposition, atmosphere-w/ distance (color, contrast, blur) [shadows aid in interpreting pictorial cues], texture gradient-w/ distance. rest is depth

height in image

further up in image, further away objects are

relative size

small object will be more distant

familiar size

when you know something about the size of an object

linear perspective

as things are further away, they get closer together. more narrow

interposition

when you can tell when one object is front of another

atmosphere

the further away is something it is more likely to be it is likely to be changed

texture gradient

all ground surfaces have some material that make up that surface

motion parallax distance cue

refers to changes in motion that occur when an observer moves. - Parallax –distance (if know distance to fixation point) closer to the fixation point, the less the motion is in the opposite direction, past the fixation point, objects appear to move in the same direction as you

Stereo disparity

the horizontal shift of the same object's location between two images taken from slightly different viewpoints (like human eyes or two cameras). p is further than q, left eye is lined up so they fall at exactly the same location on the retina. right eye, p is that one location but q is moved away from being lined up with p and it’s off to the right. closer q is further off to the right if q were more distant than the point of fixation, left

size from distance

proximal distance/proximal size = distal distance/distal size

Size from texture gradients

can directly look at the world and know how far away and know what aspects of the world, how far and big. look at a scene and tell from the relationships within the scene. texture gradients are critical to determine how far and big an object is

moon on horizon

Size from distance needs registered and perceived distances

Texture can give absolute size

Warren door & stair studies, looked at doorways, size is a property relative to your body. people can estimate if they could fit through doors. w/ stairs could estimate optimal stair height compare objects relative. to our body

Kindergarten furniture size, tiny from memories, relative to body proportion and estimate/experience changes