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Unit IV: Sensation & Perception › cms › lib › WA01001541...Sensation & Perception Module 18...
Transcript of Unit IV: Sensation & Perception › cms › lib › WA01001541...Sensation & Perception Module 18...
Unit IV:Sensation & Perception
Module 18
Vision
The Eye 18-1
Visible Light
What we see as visible light is but a thin slice of the whole spectrum of electromagnetic radiation.
VisibleSpectrum
18-1
Physical Characteristics of Light
Two physical characteristics of light help determine our sensory experience of them:
1. Wavelength (the distance from one wave peak to the next) determines hue or color
2. Intensity (the amount of energy in light waves) influences brightness
18-1
Wavelength (hue/color)
Blue color with varying levels of intensity.As intensity increases or decreases, blue color
looks more “washed out” or “darkened.”
Violet Indigo Blue Green Yellow Orange Red
Short wavelengths
Long wavelengths
Intensity (Brightness)
18-1Wavelength & Intensity
Structure of the Eye 18-1
The Retina’s Reaction to Light 18-1
Visual Information Processing 18-2
Visual Processing 18-2
Shape Detection
Specific combinations of temporal lobe activity occur as people look at shoes, faces, chairs and houses.
18-2
Visual Information Processing
Processing of several aspects of the stimulus simultaneously is called parallel processing.
The brain divides a visual scene into subdivisions such as color, depth, form, movement, etc.
18-2
Summary of Visual Processing 18-2
Visual Information Processing 18-3
Color Vision
Young-Helmholtz trichromatic theory: Thomas Young and Hermann von Helmholtz suggested that the eye must contain three receptors that are sensitive to red, blue and green colors in the 19th century. Years later, researchers confirmed this theory.
The retina has three types of color receptors, each sensitive to one of three colors.
When we stimulate combinations of these cones, we see other colors.
For example, when both red-sensitive and green-sensitive cones are stimulated, we see yellow.
18-3
Color Blindness
Genetic disorder in which people are blind to green or red colors.
This supports the Trichromatic theory.
18-3
Opponent Colors
Gaze at the middle of the flag for about 30 seconds. When it disappears, stare at the dot and report
whether or not you see Britain's flag.
18-3