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
