Psych 230 Exam 3

color deficiency

the condition of individuals who are missing one or more of their cone system

rod monochromacy

missing all cone systems
- cannot see any color
- univariance
- cannot see clearly in heavily lit environments (sensitive)
- poor visual acuity

cone monochromacy

one type of cone is present in retina
- cannot see color except whites, blacks, grays
- poor visual acuity
- less severe than rod monochromacy
- can perceive different light levels
- light sensitive
- univariance

dichromacy

two working cone systems
- can see color, but at a smaller range than normal people

tritanopia

lack of S-cones
leading to green-yellow color deficiency; this trait is rare and not sex-linked

protanopia

lack of L-cones
lack green and red
sex-linked and more common in men

dueteranopia

lack of M-cones, leading to red-green deficiency
sex-linked and more common in men

cortical achromatopsia

loss of color vision due to damage to the occipital lobe
- V4
- gray, black, white
- hot saturated colors
- lost ability to remember colors

monochromatic yellow light source

only yellow-blue component

brown/blue error

look alike

red/green error

hard to tell apart

yellow/orange error

look alike

blue surface

appears very dark, yellow light kills the blue

brown surface

don't reflect a lot of light, look dark

orange surfaces

yellow + red, yellow is reflected but red is not and cannot be coded by yellow light

yellow surface

reflected and coded - blue channel

red-green surfaces

bit of yellow light, but cannot be coded by yellow channel

constancy

ability to perceive an object as the same object under different conditions

color constancy

ability to perceive the color of an object despite changes in the amount and nature of illumination

lightness constancy

ability to perceive the relative reflectance of objects despite changes in illumination

color-based acuity

1) cones are clustered together around fovea and are in the midget system (one photoreceptor - one ganglion cell) giving us spatial acuity
2) 3 different types of cones respond maximally to 3 different wavelengths (s, m, & l cones)

do we suck at perceiving blue detail?

YES

do we all perceive the same color?

no

cultural relativism

not judging a culture to our own standards of what is right or wrong, strange or normal.

Eleanor rosh

no cultural variations
- found: tribes couldn't use words to differentiate between blue and green
blue and green were easy to say they are different but blue and blue were difficult to choose between

debi roberson

yes cultural variations

synesthesia

accidental association of 2 percepts, with one perception eliciting a secondary perception (2 or more). Stimulation of one sensory or cognitive pathway leads to automatic, involuntary experiences in a second sensory or cognitive pathway
(4% of population)

music/color
taste/color

grapheme

most common form, color synesthesia
color = painted by our brain

motion

change in position over time

Which parts of fovea are seeing motion?

Periphery and retina
-the periphery has good detection of motion bc rods and photoreceptors are located there
-some movements are too slow to detect and others are too fast

real motion

motion in the world created by continual change in the position of an object relative to some frame of reference

apparent motion

the appearance of real motion from a sequence of still images

correspondence problem (motion perception)

how the visual system knows if an object seen at time 1 is the same object as time 2

induced motion

an illusion whereby one moving object may cause another object to look as if it is moving

how does the visual system correctly perceive overall motion of objects?

local information (1 aperture = 1 receptive field) is ambiguous
sets of hypotheses are made by each aperture
motion detection = hypotheses shared by ALL apertures

motion in the retina

- amacrine cells in the retina are sensitive to motion
- optic nerve leaves the retina, beginning of M pathway, which codes for motion in V1 and along the dorsal stream of vision
- P pathway also helps see moving objects in color

Reichardt Detectors

neural circuits that enable the determination of direction and speed of motion by delaying input from one receptive field, to determine speed, to match input of another receptive fields, determine direction

corollary discharge theory

theory that the feedback we get from our eye muscles as our eyes track an object is important to the perception of motion

the motor system tells eyes to move and sends copy to brain

motion in the eyes is ambiguous

saccades

(most common)
jumping from one object to another, your brain knows and stops processing information (short/fast movements)
- looking up from book to see window quickly

smooth-pursuit eye movements

voluntary movements to track moving objects
- tennis match, birds flying across the sky
- dogs do not have this, but we humans do

MT (V5)

the movement area of the brain
- occipital lobe in dorsal pathway
--> between temporal and occipital lobe

Akinetopsia

motion blindness
- rare condition in which and individual is unable to detect motion despite intact visual perception of stationary stimuli, caused by damage to area MT

stimuli used in Newsome and Parè's (1988) Experiment

dots moving in same direction 100%, half dots moving in same direction 50%, 1/5 of dots moving in same direction 20%

Weigelt et. al (2013) Results

motion is coded in area MT

Kaas et al. 2010

motion imager is coded in area MT

motion aftereffects

motion-based visual illusion in which a stationary object is seen as moving in the opposite direction of real or apparent motion just perceived

Waterfall illusion

point-light walker display

an experiment in which small lights are attached to the body of a person or animal, which is then filmed moving in an otherwise completely dark environment
- we can tell gender, action, age, emotional states

affordance

information in the visual system world that specifies how that information can be used
- Jackie chan using a hat as a weapon

optic flow

motion depth cue that involves the relative motion of objects as an observer moves forward or backward in a scene (combination of signals)

gradient flow

difference in perception of speeds of objects moving past us in an optic flow display
- things near us --> slowly
- things far from us --> moving fast

focus of expansion

destination point in an optic flow display from which point perceived motion derives

lateral intraparietal (LIP) area

area of the primate parietal cortex involved in the control of eye movements

visually guided eye movements

an experiment showing the function of the LIP region of the parietal lobe
- preparing & controlling deployment of the eye movement

medial intraparietal area (MIP)

area of the posterior parietal lobe involved in the planning and control of reaching movements of the arms
--> direct movements

anterior intraparietal area (AIP)

region of the posterior parietal lobe involved in the act of grasping
--> prepares grasp (grab, throw, or write with)

oculomotor cues

accommodation
vergence

monocular depth cues

occlusion
relative height
relative size
familiar size
linear perspective
texture gradients
atmosphere perspective
shadows & shading

motion cues

motion parallax
deletion
accretion
optic flow

binocular cues

stereopsis
binocular disparity
3-d movies
horopter
corresponding points
corresponding locations on the retina

accommodation

process of adjusting lens of the eyes so that one can see both near & far objects easily

vergence

inward bending of the eyes when looking at close objects
convergence- eyes turn inward
divergence- eyes uncross when looking further away

occlusion

monocular depth cue
happens when one object partially hides or obstructs the view of a second object

relative height

monocular depth cue
objects closer to horizon are seen as more distant

relative size

monocular depth cue
the more distant the object, the smaller the image will be on the retina

familiar size

monocular depth cue
we judge distance based on existing knowledge of the sizes of objects

linear perspective

monocular depth cue
arises from the fact that parallel lines appear to converge as they recede into the distance

texture gradient

monocular depth cue
become finer as they recede into the distance

atmosphere perspective

monocular depth cue
objects in the distance appear blurred and tinged with blue
(mountains, knobby rock)

shadows & shading

monocular depth cue
an object in front of its shadow and the angle of shadow can provide information about how far the object is in front of the background

motion parallax

motion cue
arises from the motion of a person in the environment
faster moving objects are closer, slower objects are farther away
--> appear to be moving backwards if close, far move in same direction

deletion

motion cue
gradual occlusion of a moving object as it passes behind another

accretion

motion cue
gradual reappearance of a moving object as it emerges from behind another object

optic flow

motion cue
refers to relative motion of objects as a person moves forward or backward
- all points move coherently with my motion

stereopsis

binocular cue
sense of depth that we perceive from the visual system's processing of the comparison of 2 different images from each retina

binocular disparity

binocular cue
view from left eye and view from right eye

3-D movies

binocular cue
both eyes get separate frames
mimic the standard vision and binocular disparity

horopter

binocular cue
region in space where the 2 images from an object fall on corresponding locations on the 2 retinae

corresponding points

binocular cue
refers to a situation in which a point of the left retina and a point of the right retina would coincide if the two retinae were superimposed

noncorresponding points

binocular cue
refers to a situation in which a point on the left retina and a point on the right retina would not coincide if the two retinae were superimposed

Panum's area of fusion

binocular cue
region of small disparity around the horopter where the two images can be fused to a single perception

diplopia

binocular cue
double images, or seeing two copies of the same image; usually results from images of an object having too much disparity to lead to fusion

crossed disparity

binocular cue
direction of disparity for objects closer to the viewer than the horopter (image in left eye is to the right of image of the object in the right eye)

zero disparity

binocular cue
situation in which retinal images fall along corresponding points, which means that the object is along the horopter

correspondence problem (depth perception)

problem of determining which image in one eye matches the correct image in the other eye

uncrossed disparity

The direction of disparity for objects that are behind the horopter (the image of the object in the left eye is to the left of the image of the object in the right eye)

stereograms

An image made up of two different images, one for each eye

wheatstone stereograph

viewer looks at mirrors and images for each eye are off to the side

anaglyph

made by taking 2 photographs of a scene from cameras separated 6 cm apart, one is blue, one is red. made into a common image

random-dot stereograms

stereograms in which the images consist of randomly arranged set of black and white dots, left & right eye images arranged identically except that some of the dots are moved to the left or right in one of the images, creating either crossed or uncrossed disparity

binocular cues

cells with two receptive fields, one for each eye; their main function is to match the images coming to each eye

virtual reality

computer-generated photograph, image, or environment that can be interacted with in an apparently real way

Eyes are shown two different objects so why it seems so real

forced perspective illusions

Makes a person looks smaller or larger than they are by using angles
-must only be focusing on object part of the picture

binocular cells

cells w two receptive fields, one for each eye; their main function is to match the images coming to each eye

development of stereopsis

Need to be exposed to normal visual experiences in order for eye sight to develop properly
* critical period

strabismus

Abnormal alignment of the eye; the condition of having a squint
-crossed or lazy eye
-eye suppresses what the lazy eye sees bc seeing two different images
-can be corrected by wearing special glasses and if not corrected lose depth perception

size-distance invariance

relation between perceived size and distance, whereby the perceived size of an object depends on its perceived distance, and the perceived distance of an object may depend on its perceived size

size constancy

the perception of an object as having a fixed size, despite the change in the size of the visual angle that accompanies changes in distance

ponzo illusion

illusion in which two horizontal lines are drawn one above the other; both lines are on top of two inwardly angled vertical lines; the top line, where the two vertical lines are closer together, looks longer

muller-lyer ilusion

illusion where a line that has two lines going away at an angle looks longer than a line of the same length but the end lines angle back across the main line

ames room

specially constructed room where two people of the same size standing in the two back corners will look very different in height