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PSY 322: Exam 2
Ewald Hering |
-"opponent-color" or "opponent-process" theory of color vision.
-suggests 2 types of cones exist: blue-yellow and red-green sensitive. When 1 color of the cone is stimulated, the other inhibited. therefore, no reddish-green colors exist.
-this is why a green afterimage exists after looking at red for a long time, then looking at white |
Complementary colors |
Colors across from each other on the color wheel or circle. Cancel each other out. |
Afterimages |
firing one half of a pair of opposing color forces repeatedly results in fatigue, this explains the existence of complementary afterimages |
Hue Cancellation |
starting with a yellowish-green color, we can cancel the yellowness by adding its opponent color, blue; can be used to determine wavelength of unique hues |
unique colors |
red, yellow, green, blue. No opponency. All unique colors are pure but not all pure colors are unique. |
Illegal colors |
Reddish- green
Bluish- yellow. Colors that can not be seen together |
Opponent receptive fields |
Respond to differences in signal |
Single surround (in retina, parvocellular layers, cortex) |
Excitatory response to one color in the pair and inhibatory response (in the surround) to the other pair. |
Double surround (in cortex) |
Opposing responses in each section (Center, surround).
Optimized for contrast information |
Area v4 |
Later area in occipital lobe primarily for color processing |
Hue |
name given to a color in the color spectrum based on its unique properties |
Color blindness |
Malfuntion of photopigments
monochromats-1 photopigment
Dichromats-2 photopigments (most common (long and medium mashed together) |
Protanopia |
Long wavelength malfuntion |
deuteranopia |
•Defective or missing medium wavelength cone pigment(red/green)
Missing M cones |
tritanopia |
blue cone pigment absent. Lacking S cone- very rare- |
Tetrachromats |
Have better than normal vision |
Color agnosia |
Inability to perceive color. No awareness of color distinctions |
Color anomia |
Inability to label colors. Perceive the difference but do not know the labels. |
Color constancy |
A certain hue is seen as the same hue under different lighting. |
Illuminant light |
(not simply white light)- The light that shines on surfaces. |
Spectrum power distribution |
The distribution of wavelength on the color spectrum |
Spectral reflectance function |
the tendency for a surface to reflect or absorb certain wavelenghts |
contextual "illusion" of color |
color you perceive is defined by the interpretation of a scene |
Cultural relativism |
cultures may define how we think and perceive a thing. |
The sapir-whor hypothesis |
(verbal labels restraining categories). The language we use constrains the way we conceptualize things |
Euclidean world |
Referring to the geometry of the world, so named in honor of Euclid, the ancient Greek geometer of the third century BCE. In Euclidean geometry, parallel lines remain parallel as they are extended in space, objects maintain the same size and shape as they move around in space, the internal angles of a triangle always add to 180 degrees, and so forth. |
binocular summation |
combining information from both eyes that makes tasks much easier than with one eye alone |
monocular cues |
visual input from a single eye alone that contributes to depth perception |
Binocular Cues |
Visual cues for depth that require both eyes |
Pictoral Cues |
Depth Perception from 2-D pictures |
projective geometry |
investigates the mathematical relationships between objects in the environment and their optical projections on the retina or on a picture |
Occlusion |
When one object partially covers another |
Ametric |
Tells you about the ordering of things in space but not the degree of closeness. |
Metric cues |
(distance) Relative relation of one thing compared to another thing |
Absolute |
How far it is based on the properties of that object. Independent of its surroundings |
anamorphic |
a distorted image that must be viewed by some special means, From a specific perspective, (such as a mirror) to be recognized. |
Vanishing Point |
the point on the horizon line where all lines converge |
straight line projections |
lines must be straight towards the vanishing point |
refraction |
Bending of light as it hits an object |
Familiar size (absolute) |
You take in the size of a retinal image, compare that to how you see it in your memory and use the relationship to judge distance. |
Relative size |
size of retinal image compared to its surrounding |
Motion parallax |
Depth cue that objects further away move less. Things moving in parallel around you. The amount of change on the retina per unit of change on the world is greater for close objects than far objects. |
Overlapping visual field |
The amount of space you can pick up with one glance of the eye |
Binocular disparity |
The retinal image of overlapping region is not the same for both eyes. |
Binocular disparity |
The retinal image of overlapping region is not the same for both eyes. |
stereopsis |
the impression of depth that results from information provided by binocular disparity (our ability to use disparity) |
Accomodation |
Which the eyes lens changes shape to focus near or far objects on the retina. |
Fused image |
You do not experience double image. Corresponding retinal points makes them fuse. The position of that point on the retina is the same in both eyes |
Veith Muller circle |
(outside) the location of objects whose images fall on geometrically corresponding points in the two retinas |
horopter |
(on the eye) objects along an imaginary line fall on corresponding points on both retinas |
panums area |
(fudge factor) the area of the visual world around the horopter in which the retinal images are fuse and perceived as a single object |
Diplopic image |
Double image |
Crossed disparity |
(close) Closer to you than the horopter. In order to see the image you must cross your eyes. |
uncrossed disparity |
Includes things farther from you than the horopter. In order to fuse the image you must uncross your eyes. |
Stereoscope |
(device)
produces a convincing illusion of depth by using two slightly different pictures, one for each eye. 2 flat images seen as having depth |
stereogram |
(the 2 flat images) two pictures of the same scene taken with slightly different disparity so that they can fuse into a single 3D image |
free fusion |
the techhique of converging (crossing or diverging the eyes in order to view a stereogram w/out a stereoscope |
Binocellular cells in visual cortex |
Cells that integrate info from both eyes. Can track correspondence of retinal points |
Correspondence Problem |
the problem of figuring out which bit of the image in the left eye should be matched with which bit in the right eye. The problem is particularly vexing when the images consist of thousands of similar features like dots in random dot stereograms. |
uniqueness constraints |
You assume that one retinal image in one eye, should belong to the same retinal image in the other eye, whenever possible assume there is the same thing in both eyes |
continuity restraint |
In the visual field, changes in depth should be as gradual as possible. |
Binocular rivalry |
A phenomenon of visual perception in which perception alternates between different images presented to each eye. (Disparity between both eyes can be competing) |
stribismus |
A disruption early on in life of the ability to use binocular cues. |
Estropia |
One eye points inward too much-lazy eye |
Extropia |
one eye turned outward |
Bayes rule |
A way fro understanding how we get info in our world based on likelihood and expectations. |
mueller-Lyer Illusion |
a visual test in which two lines appear to be different sizes, when they in fact are the same size. |
Ames room |
Shows perception of size can be distorted by changing depth cues |
Optic array |
Thinking about the world around you as a whole field of light with information in it. Gives you a description of the environment. Can be static. NOT patterns of motion |
optic flow field |
complex pattern of motion on your retina that helps distinguish self motion from motion in the world. (Pattern of change in the optic array.) |
Optic flow for self motion |
(Particular kind of optic flow.) Happens if you are moving forward. |
Streaming perspective |
(Kind of self motion) When you are moving forward and looking where you are going. |
Focus of expansion |
The point in the flow field that has no change- tells you where you are going. |
motion-after effect |
the perceptual illusion of movement of a physically stationary visual stimulus following exposure to visual motion, the stationary stimulus appears to move in the opposite direction to the original stimulus |
Opponent process |
( like motion specific cells used for motion after effect) Ewald Heiring. In the theory, he postulated about three independent receptor types which all have opposing pairs: white and black, blue and yellow, and red and green. |
Interocular transfer (cortical) |
Transfer of adaptation effects from one eye to the other (if only one eye is adapted to certain movement, the other eye will still show a negative aftereffect)
- shows that opponent cells receive input from both eyes |
Reichardt detector |
the integrator cell "and gate" will only fire when it receives information from BOTH receptors at exactly the same time |
apparent motion |
(not the same as induced motion!) When you have a series of stationary images that give the illusion of movement between the images. |
aperture problem |
observing a small portion of a larger stimulus leads to misleading informational perception |
Global motion processing |
Large scale space and time.
V5- middle temporal area.
Accounts for sensitivity to biological motion and second order motion |