Sensation and Perception Test 2

Touch, Vestibular system, color perception, and

How to remember slow/ fast for tactile receptor types

fast on the outside ( messi p)

opponent processing is in what step of color detection?

discrimination

color opponent color theory is in what step of color detection

color assignment

why does someone with only one cone see in grey scale

no other cones to make comparisons with

S-cones

A cone that is preferentially sensitive to short wavelengths; colloquially (but not entirely accurately) known as a "blue cone."

M-cone

A cone that is preferentially sensitive to middle wavelengths; colloquially (but not entirely accurately) known as a "green cone."

L-cone

A cone that is preferentially sensitive to long wavelengths; colloquially (but not entirely accurately) known as a "red cone."

spectral sensitivity

the sensitivity of a cell or device to differentiate wavelengths on the electromagnetic spectrum

photopic

light intensities bright enough to stimulate cone receptors and bright enough to saturate rods and bring them to max responses

scotopic

light intensities bright enough to stimulate rods but too dim to stimulate cones

3 steps of color perception

detection, discrimination, appearance

principle of univariance

infinite set of wavelength combinations elicit same response from the same type of photoreceptor

trichromatic solution

the fact that we have types of photoreceptors, relationships between amount of reaction produced- solves principle of univariance

trichomacy / trichormatic theory

theory that the color of any light is defined in our visual system by relation of 3 numbers by 3 receptor types (SML)

metamers

Different mixtures of wavelengths that look identical. More generally, any pair of stimuli that are perceived as identical in spite of physical differences.

example of a metamer

yellow light, red + green light appearing appearing as yellow light

additive color mixture

mix of lights, if A and B reflect to eye, effect and perception is the lights added together ( red + g --\> y)

subtractive color mixing

mix of pigments, if pigments A and B mix, some of the light shining on surface will be subtracted by a, some subtracted by b, only remainder goes to color perception (r and g \---\> brown)

where do cone opponent cells exist?

in retina and LGN

cone-opponent cell

cell type in LGN retina and visual cortex that subtracts 1 type of cone input from another

equivalent stimuli

vary in color, not in luminance

melanopsin

photopigment in class of gang cells that detects light even when photoreceptors absent

mesopic

middle range of light intensities

color space

the 3D space, established because color perception is based on the outputs of three cone types, that describes the set of all colors

what are colors that one wavemlengh cannot produce

mixed- brown, grey- only in comparison and depends on light

opponent color theory

perception of color based on output of 3 mechanisms- each resulting from an oppetency between 2 colors r+g, b-y, b-w (no bluish yellow no greenish red)

which phenomena / illusion does opponent processing explain?

the oppisite color american flag and arch- you wear out one of the colors so the other wins

which phase is opponent color theory in

color assignment

unique hues

only 4 colors that can be described as 1 color term ( r g y b )

archromatopsia

inability to perceive color because of damage to central nervous system

basic color terms

single words that describe colors and have meanings that are agreed upon by speakers of a language

cultural relativism

idea that basic perception experiences may be determined in part by cultural envionment

qualia

In philosophy, private conscious experiences of sensation or perception.

tetrachromatic

Referring to the rare situation (in humans, at least) where the color of any light is defined by the relationships of four numbers—the outputs of those four receptor types. (usually in people w 2 X's)

why are men usually colorblind

they only have one X chromosone, so there is not a spare copy they can use if one is defective

2 factors of colorblindness

type of cone affected, type of defect

duteranope

individual who suffers due to lack of M- cones

protanope

An individual who suffers from color blindness that is due to the absence of L-cones.

tritanopia

An individual who suffers from color blindness due to no S cones

color-anomalous

A better term for what is usually called "color-blind." Most "color-blind" individuals can still make discriminations based on wavelength. Those discriminations are different from the norm—that is, anomalous.

cone monochromat

individual with only one cone type; truly color blind

rod monochromat

no cones of any type; truly color-blind, badly visually impaired in bright light

Agnosia

the inability to recognize familiar objects.

anomia

inability to name objects in spite of the ability to see and recognize them

color contrast

a color perception effect in which the color of one region induces the opponent color in a neighboring region

color assimilation

a color perception effect in which two colors bleed into each other, each taking on some of the chromatic quality of the other

unrelated color

a color that can be experienced in isolation

related color

A color, such as brown or gray, that is seen only in relation to other colors. For example, a "gray" patch in complete darkness appears white.

negative afterimage

the image seen after a portion of the retina is exposed to an intense visual stimulus; consists of colors complementary to those of the physical stimulus (r\---\> g) (y\---\>b)

adapting stimulus

a stimulus whose removal produces a change in visual perception or sensitivity

nuetral pointer

the point at which an opponent color mechanism is generating 0 signal. If red green and yellow blue mechanism are at neutral points, a stimulus will appear achromatic

color constancy

the tendency for a color to look the same under widely different viewing conditions (illuminants)

illuminant

the light that illuminates a surface

spectral relative function

percent of wavelength that is reflected from a surface

spectral power distribution

the physical energy in a light as a function of wavelength

reflectant

% of light hitting a surface that is reflected and not absorbed

why is color vision useful

eating and sex (mating prefs)

color is a \____ property

psychophysical

detection step in color perception

wavelengths of light detected by visual system

discrimination step in color perception

we must be able to differentiate between diff wavelengths or mixtures of wavelengths

appearance

perceived colors of light get assigned to the surfaces that reflected the light; those perceived colors should be stable over time + across light sources

t/f all photoreceptors respond to a spectrum of wavelengths

true

which cones are most rare?

S cones

do the cones overlap?

yes

what needs to happen for a photoreceptor to be stimulated

light of its preffed wavelength needs to fall in its receptive field

what solves problem of univariance

having \>1 type of cone

in subtractive color mixture, what color is subtracted of the overall?

the opposite on the color wheel!

example of metamers

R and G light and yellow light

difference between opponent color theory
and opponent processing

opponent processing - signals are fighting for dominance for what we see- American flag thing
opponent color thry: perception of color based on output on 3 mechanisms, each resulting from an oppency of blue and yellow, red and green, and black and white- COMBO of each levels of those colors

realism

a philsophical position arguing that there is a real world to sense

positivism

philisophical position that all we really have to go on is the evidence of the senses, could all just be a hallucination

why do we have 2 eyes?

loose function of one, still have one,
see more of world
190 degrees seen, 110 covered by both
we can see 3D and depth better

binocular

referring to 2 eyes

probability summation

increase in detection probability based on statisctial advantage of having 2 dectectors intead of one
(more likley to be this object)

binocular summation

the combo of signals from each eye in ways that make performance on many tasks better with both eyes than with either eye alone

binocular disparity

the difference in the retinal images of the two eyes looking at same thing

what is the basis for stereopsis?

binocular disparity

monocular

1 eye

can you have stereopsis w one eye?

no

stereopsis

ability to use binocular disparity as a depth cue
a vivid perception of the 3D world unavailable with monocular vision

monocular depth cue

A depth cue available when only one eye is used; it is also available using two eyes.

binocular depth cue

A depth cue that relies on information from both eyes

pictural depth cues

a cue to distance or depth used by artists to depict 3D depth in 2D pics

occlusion

a cue to relative depth order in which, for example, one object obstructs the view of part of another object

non- metrical depth cue

A depth cue that provides information about the depth order (relative depth) but not depth magnitude

metrical depth cue

depth cue that gives quantitative info about objects in the 3rd dimension (can be relative or absolute metrial)

projective geometry

The transformations that occur when the three-dimensional world is projected onto a two dimensional surface

relative size

smaller things further away like trees bigger if closer

texture gradient

A depth cue based on the geometric fact that items of the same size form smaller images when they are farther away. An array of items that change in size smoothly across the image will appear to form a surface tilted in depth.

relative height

A depth cue. Objects that have bases below the horizon appear to be farther away when they are higher in the field of view. Objects that have bases above the horizon appear to be farther away when they are lower in the field of view.

familiar size

A depth cue based on our knowledge of the typical size of objects (hand vs penny)

absolute metrical depth cue

A depth cue that provides quantifiable information about distance in the third dimension
best one is familiar size (how big a hand is)
type of metrical depth cue

relative metrical depth cue

A depth cue that could specify, for example, that object A is twice as far away as object B without providing information about the absolute distance to either A or B.
type of metrical depth cue

haze/ ariel perspective

implicit understanding that light is scattered by the atmosphere - more light scattered \=further

linear perspective

depth cue based on fact that lines are parallel in 3D world will still appear to converge in 2D world

vanishing point

apparent point where parallel lines receding in depth converge

anamorphosis

Use of the rules of linear perspective to create a two-dimensional image so distorted that it looks correct only when viewed from a special angle or with a mirror that counters the distortion.

motion parallax

A depth cue based on the fact that, as an observer moves, the retinal images of nearby objects move more rapidly than do the retinal images of objects farther away.

optic flow

pattern of apparent motion of objects due to relative motion between observer and scene (dots moving toward)

accommodation

change in focus to see near and far