day vision. color vision facts color mixing: “rule of 3”
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Day Vision
Color Vision Facts
• Color Mixing: “Rule of 3”
http://www.exploratorium.edu/exhibits
The Color Circle
Subtraction
Color Vision Facts
• Color Mixing: “Rule of 3”
• Color Aftereffects: R and G, B and Y
Color Vision Facts
• Color Mixing: “Rule of 3”
• Color Aftereffects: R and G, B and Y
• Color Blindness
Are You Colorblind?
Red-Green
Trichromatic Theory
• Young and Helmholtz
• Blue, green, and red input channels
• True at receptor level
• Explains “Rule of 3”
Opponent-Process Theoryof Color Vision
• Ewald Hering
• Color-sensitive visual pairs.– Red or green, blue or yellow– Explains aftereffects and blindness
R G B Y
Combined
R G B Y (R + G)
Perception
How do sensations become perceptions?
Perceptual Constancy
• Objects maintain their size, shape, color, and other properties despite changes in their retinal image.
• Allows experience where solid objects do not continuously change
Nonconstant World
Shape Constancy
Saul Kassin, Psychology. Copyright © 1995 by Houghton Mifflin Company. Reprinted by permission.
Depth and Distance
• 3-D experience from 2-D information?
• Cues
Monocular (One Eye)
Binocular (Two Eyes)
Monocular Cues
• Relative Size• Height in the Visual
Field• Interposition• Linear Perspective• Reduced Clarity• Textural Gradient• Light and Shadow
Binocular Cues
Convergence
James D. Laird and Nicholas S. Thompson, Psychology. Copyright © 1992 by Houghton Mifflin Company. Reprinted by permission.
Binocular (con’t)
• DisparityClose – Disparity High
Far – Disparity Low
Douglas A. Bernstein, Alison Clarke-Stewart, Louis A. Penner, Edward J. Roy, and Christopher D. Wickens,
Psychology, Fifth Edition. Copyright © 2000 by Houghton Mifflin Company. Reprinted by permission.
Misperceiving Reality
Which Line Is Longer?
Impossible Figures
Magic Eye
Motion
http://www.exploratorium.edu/exhibits
Perception of Motion
• Looming stimulus (rapid expansion)
• Images moves, but eyes and head do not
• Image moves, but can’t be caused by movement of the body, eyes, or head.– Visual flow without appropriate sensations can
result in motion sickness.
• Stroboscopic Motion
http://www.rpi.edu/~brings/PHI/phi3.html
Recognizing the Perceptual World
How do I recognize familiar people?
How Does Recognition Occur?
• Bottom-Up Processing: Basic features of the stimulus are analyzed to create the perceptual experience.
• Top-Down Processing: Reliance on one’s knowledge, especially when sensory information is vague or ambiguous.
What Can InfluenceTop-Down Processing?
• Schemas– Readiness to perceive a stimulus in a certain
way
• Motivation
• Expectancy or prior context
Expectancy
Organizing the Perceptual World
What determines how I perceive my world?
Principles of Perceptual Organization: Figure and Ground
• Figure: The part of the visual field that has meaning.
• Ground: The contourless part of the visual field.
Figure 3.19: Reversible Images
Gestalt Grouping
• Stimuli are grouped together
• “Gestalt” is the German word meaning (roughly) “whole figure.”
Gestalt Principles of Perceptual Grouping
Categorizing Perceptions
What Do You See Here?
Another Version With Line Grouping
Now Do You See It?