PSYCHOLOGY Perceptual Organization
Dec 16, 2015
PSYCHOLOGY
Perceptual Organization
Perceptual Illusions
http://www.yorku.ca/eye/m-lillu.htm
Objectives
1. Understand how illusions help us understand perception
2. Understand perceptual organization principles
Outline A. Intro & illusions B. Organizational Principles
1. Form perception Figure/Ground Gestalt grouping
2. Depth perception Binocular cues - retinal dispartity,
convergence Monocular cues - 8
3. Motion Perception - stroboscopic, phi phenomemon
4. Perceptual Constancy - size & shape, size & distance, light, color
Perception
What can we learn from looking at the visual illusions #1-6 in your textbook?
Illusion reveal the ways we normally organize and interpret sensation.
Perceptual Illusions
Perceptual Organization: Muller-Lyer Illusion
Illusions
Muller-Lyer IllusionWe interpret the arrows as cues for
distance & length The arrows at the ends of the lines
make them appear of different lengths
Room Illusion
Room Illusion
Perceptual Organization: Size-Distance Relationship
Illusions
What assumptions do we make about rooms?
90 degree anglesSize & distance (we make the false
assumption that they are the same distance way)
To fool us they distorted the shape of the room
St. Louis Arch
Taller than wider?Wider than taller?
Perceptual Organization: Depth Perception
Relative Height
St. Louis Arch
Explanation: Relative Height - we perceive
objects higher in our field of vision as farther away
Perceptual Illusions
Illusions
Hans- Wallach’s - glowing blue wormGestalt principles grouping principles
lead you astray in this puzzleApply grouping principles like - continuity
Perceptual Illusions
Illusions
Hoffman - ripple illusion
It is a shading technique using light & shadows
Perceptual Illusions
Illusions
People tend to overestimate distance in the fog Light & Shadow issues Relative Clarity issues
Where can this information be useful in the real world?
Perceptual Illusions
Perception
What can we learn from looking at the visual illusions #1-6 in your textbook?
Illusion reveal the ways we normally organize and interpret sensation.
Which sense dominates?
Visual Capture tendency for vision to dominate
the other senses
Ex. - movie theater, roller coaster
Perceptual Organization: Gestalt
Our brains do more then just register info, we filter & infer to make sense
Gestalt = whole tendency to integrate pieces of
information into meaningful wholes
Necker Cube
The whole may exceed the sum of the parts
8 circles - people tend not to notice the circles but the whole box
Perceptual Organization: Illusory Contours
Fig. 15.2
Is there really a line down the middle?
Your eye perceives one
Outline M15 A. Intro & illusions B. Organizational Principles
1.Form perceptionFigure/GroundGestalt grouping
2.Depth perception Binocular cues - retinal dispartity,
convergence Monocular cues - 8
3.Motion Perception - stroboscopic, phi phenomemon
4.Perceptual Constancy - size & shap, size & distance, light
Form perception
Our brains do more then just register info, we filter & infer to make sense by discriminating what it is - form
We organize and interpret meaning
What is it?
Perceptual OrganizationForm perception
Figure and Ground--organization of the visual field into objects (figures) that stand out from their surroundings (ground); Reversible figures
What is it?
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What is it?
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Perceptual Organization: Gestalt
Grouping the perceptual tendency to organize
stimuli into coherent groups
Gestalt grouping prin.
Grouping Principlesa) proximity--group nearby figures togetherb) similarity--group figures that are similarc) continuity--perceive continuous patternsd) closure--fill in gapse) connectedness--spots, lines, and areas are
seen as unit when connected
Perceptual Organization: Grouping Principles
Perceptual Organization: Closure
Gestalt grouping principles are at work here.
Perceptual Organization: Grouping Principles
Gestalt grouping principles are at work here
Perceptual Organization: Grouping Principles
Impossible doghouse
Perceptual Organization:
Depth Perception ability to see objects in three
dimensions allows us to judge distance Somewhat innate ability as shown by
infants
Perceptual Organization: Depth Perception
Visual Cliff
Depth perception
1. Binocular cuesa) retinal disparity
images from the two eyes differ closer the object, the larger the
disparity(floating finger sausage)
b) convergenceneuromuscular cue - two eyes move inward for near objects
2. Monocular Cues
a) relative sizesmaller image is more distant
b) Interposition (overlay)closer objects blocks distant
object
Perceptual Organization: Depth Perception
Relative Size
Perceptual Organization: Depth Perception
Interposition
Monocular cues
c) relative clarityhazy object seen as more distant
d) texture coarse --> closefine --> distant
Perceptual Illusions
Monocular cues
e) relative heighthigher objects seen as more
distant
Perceptual Organization: Depth Perception
Relative Height
Monocular cues
f) relative motioncloser objects seem to move faster
g) linear perspectiveparallel lines converge with distance
h) relative brightnesscloser objects appear brighter
Perceptual Organization: Depth Perception
Light and Shadow
Perceptual Organization: Depth Perception
Perspective Techniques
Perceptual Organization: Depth Perception
Illusory Depth
Perceptual Organization: Depth Perception
Illusory Depth Explanation
Motion Perception
1. Stroboscopic movement - still pictures can be perceived as moving ( cartoons & film)
2. Phi phenomenon - 2 adjacent stationary lights blink on/off in succession are perceived as moving
Perceptual Constancy Perceptual Constancy
perceiving objects as unchanging even as illumination and retinal image change color shape size
Size & distance p.239
Monster & Ponzo illusions
Monster - linear perspective, relative height; cues to distance & size
Ponzo - we perceive the bar as farther away as being larger based on experience
Moon illusion
Moon looks larger at the horizon then it does high in the sky
Explanation: cues to objects distances at the horizon make the moon seem farther away
Similar to the monster & ponzo illusion
Perceptual Organization-Brightness Contrast
Perceptional Constancy
1. Shape2. Size & distance3. Color4. Lightness/Brightness
Concentrate on the 4 dots in the middle for 30 sec.
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Which is line is longer?
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