Perceptual Organization Unit 3 – RG 4e Modified PowerPoint from: Aneeq Ahmad -- Henderson State...
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Transcript of Perceptual Organization Unit 3 – RG 4e Modified PowerPoint from: Aneeq Ahmad -- Henderson State...
Perceptual Organization
Unit 3 – RG 4eModified PowerPoint from: Aneeq Ahmad -- Henderson State University. Worth Publishers © 2007
Perceptual Illusions
To understand how perception is organized,
illusions provide good examples. It is as good to
study faulty perception as other perceptual
phenomena.
Line AB is longer than line BC.
Tall Arch
Vertical dimension
of the arch looks
longer than the
horizontal
dimension when
both are equal.
Rick Friedman/ Black
Star
Perceptual Organization
When vision competes with other senses vision usually wins – a phenomenon called visual
capture.
How do we form meaningful perceptions from sensory information?
We organize it!
Gestalt psychology helps us organize information into meaningful wholes…
but remember…the “whole is different from the sum of it’s parts”
Figure-Ground
Organization of the visual field into objects
(figures) that stand out from their surroundings
(ground).
Time Savings Suggestion, © 2003 Roger
Sheperd.
Gestalt Grouping
Having discriminated figure from ground our
perception needs to organize figure into
meaningful form using grouping rules.
Grouping & Reality
Usually grouping principles help us construct
reality but at times lead us astray.
Both photos by Walter Wick. Reprinted from
GAMES
Magazine. .© 1983 PCS Games Limited
Partnership
Depth PerceptionDepth perception enables us to judge distances. Gibson and Walk (1960) suggested that human
infants (crawling age) have depth perception. Even new born animals show depth perception.
Visual Cliff
Innervision
s
Monocular Cues
Interposition: Objects that occlude (block) other
objects tend to be perceived as closer.
Rene Magritte, The Blank Signature, oil on
canvas,
National Gallery of Art, Washington. Collection of
Mr. and Mrs. Paul Mellon. Photo by Richard
Carafelli.
Monocular Cues
Linear Perspective: Parallel lines like rail road
tracks, appear to converge with distance. The
more the lines converge, the greater their
perceived distance.
Monocular Cues
Relative Size: If two objects are similar in size, we
perceive one that casts a smaller retinal image as
farther away.
Monocular Cues
Relative Height: We perceive objects higher in our
field of vision as farther away.
Image courtesy of Shaun P. Vecera, Ph. D.,
adapted from stimuli that appered in Vecrera et al.,
2002
Monocular Cues
Texture Gradient: Indistinct (fine) texture signals
increasing distance.
© Eric Lessing/ Art Resource,
NY
Binocular CuesConvergence: When two eyes move inward (towards the nose) to see near objects, and
outward (away from the nose) to see far away objects…object is perceived as closer the more
eyes turn inward
Binocular Cues
Retinal disparity: Images from the two eyes differ…the greater the difference between the two objects, the closer
the objectTry looking at your two fingers half an inch apart about 5 inches away.
You will see a “finger sausage” as shown in the inset.
Perception of Movement
Stroboscopic motion: our tendency to perceive
motion in a series of slightly varied still images
flashed in rapid succession
Perception of Movement
Phi Phenomenon: When lights flash at certain
speed they tend to present illusions of motion.
Neon signs use this principle to create motion
perception.
Two lights flashing one after the other.One light jumping from one point to another: Illusion of
motion.
Perceptual Constancy
Perceiving objects as unchanging even as
illumination and retinal image change. Perceptual
constancies include constancies of shape and
size.
Shape
Constancy
Size Constancy
Stable size perception amid changing size of the
stimuli.
Size
Constancy
Size-Distance Relationship
Moon Illusion
What makes this happen?
Cues to the objects’ distances at the horizon make the Moon
behind them seem farther away than the moon in the
night’s sky.
Actually…there are various explanations, yet no ONE
“right” answer
Size-Distance Relationship
The distant monster and the top red bar appear bigger because of distance cues.
Ponzo Illusion
From Shepard,
1990
Alan Choisnet/ The Image
Bank
Depth Perception Webquest
1. Go to class website, under Unit 4, Perceptual Organization Notes, click on “Depth Perception Webquest- website”
2. Go through the web page, filling in the chart a quick description of each depth cue
3. Come up with your own example of each depth cue- must be your own, not from the website, book, or notes
Size-Distance Relationship
Muller-Lyer Illusion
Are these vertical lines the same length?
Size-Distance Relationship
Both girls in the room are of similar height,
however we perceive them of different heights
as they stand in the two corners of the room.
Both photos from S. Schwartzenberg/ The
Exploratorium
Ames Room
An Ames room is designed to give size-distance
illusion.
Visual Illusions…
Straight lines or bowed? Stationary or moving?
Visual Illusions…
A spiral right?How many people/faces
do you see?
Visual Illusions…
Which line matches with C?
It’s actually B…
Poggendorf Illusion
Old woman or young woman?
Visual Illusions…
These are on drawn on flat surfaces (sidewalks)!
Visual Illusions…
Julian Beever has made pavement drawings for over ten years. He has
worked in the U.K., Belgium, France, The Netherlands, Germany, the
USA and Australia.
Visual Illusions…
For more go to…
http://users.skynet.be/J.Beever/pave.htm