Test 1, Perception Flashcards
Spectral colors:
a color comprised of a single wavelength
Non-spectral colors:
a color comprised of more than one wavelength
Hue:
variations described by names such as red, purple, blue, orange, etc.
Saturation:
apparent purity, vividness, or richness
Two theories help explain human color perception
Trichromatic theory
Opponent process theory
Trichomatic Theory
Theory proposes there are 3 types of photoreceptors, corresponding to blue, green, and red, that determine our color perception
Supported by the fact that there are 3 types of cones in the retina
Opponent process theory
Suggests that color perception is controlled by the activity of two opponent systems: blue-yellow and red-green
In these systems, only one color can be signaled at a time
Ex. Red light will increase their firing rates and green light will decrease it, staring at red, then looking away we see green.
Short wavelength (blue) receptors
Photopigment: cyanolabe
Medium wavelength (green)
Photopigment: chlorolabe
Long wavelength (red)
Photopigment: erythrolabe
Dichromatic vision:
missing one photopigment
Protanopia:
the long wavelength (red) cones do not contain the erythrolabe
Deutanopia:
the medium wavelength (green) cones do not contain chlorolabe
Contrast Sensitivity
Represents the ability of the visual system to distinguish bright and dim components of a static image
A function of both the contrast and the spatial frequency of what is being viewed
E.g. being able to read light gray letters on a dark gray background; night driving
Perceptual Organization
The process by which we apprehend particular relationships among potentially separate stimulus elements (e.g., parts, features, dimensions)
The world we perceive is constructed by cues such as similarities and differences of color
Gestalt means
“essence or shape of an entity’s complete form”
Proximity:
elements close together are perceived as a group
Similarity:
similar elements (in terms of color, form, or orientation) are perceived together
Continuity:
points connected in straight or smoothly curving lines are perceived together
Closure:
open curves are perceived as complete forms
Common fate:
elements moving in the same direction at the same speed are perceived as together
Accomodation:
automatic adjustments of the lens that maintain a focused image on the retina
Vergence:
degree to which the eyes are turned inward to maintain fixation on an object
Interposition:
nearer objects will block the view of more distant objects if they are in the same line of vision
Perspective:
angles such as when you know something is rectangular but it appears trapezoidal
Motion Parallax:
apparent displacement or difference in position of an object viewed along two different lines of sight
Binocular disparity:
each eye receives a slightly different image of the world because of the eye’s location
Object motion:
external object is moving
With a single stimulus moving in a stationary background, we can detect movement as slow as 0.5mm per second
Induced motion:
a stationary background causes movement to be attributed to the wrong part of a scene
After staring at a waterfall, other objects appear to be moving up
Apparent motion:
discrete jumps of retinal images can produce the appearance of smooth motion
Ex. Television frames are perceived as smooth motion
Integral dimensions:
cannot specify a value on one feature dimension without specifying the value on the other dimension
Ex. The stretching or bending of an object
Separable dimensions:
dimensional combinations that exist independently of one another
Ex. The color and form of an object
Configural dimension:
dimensions that interact to create new features. These new features can interact or interfere with the pattern recognition
Expectancies:
perception of the object is induced by context
