PSYCHOLOGY (8th Edition, in Modules) David Myers PowerPoint Slides Worth Publishers, © 2007 Psychology 7e in Modules

Perceptual Organization Module 16 Psychology 7e in Modules

Perceptual Organization Perceptual Illusions Form Perception Motion Perception Perceptual Constancy Psychology 7e in Modules

Perceptual Illusions To understand how perception is organized, illusions provide good examples. It is as good to study faulty perception as other perceptual phenomena. OBJECTIVE 16-1| Explain how illusions help us understand some of the ways we organize stimuli into meaningful perceptions. Line AB is longer than line BC. Psychology 7e in Modules

Tall Arch Vertical dimension of the arch looks longer than the horizontal dimension when both are equal. Rick Friedman/ Black Star Psychology 7e in Modules

Illusion of a Worm © 1981, by permission of Christoph Redies and Lothar Spillmann and Pion Limited, London Figure on the right gives us the illusion of a blue hazy “worm” when it is nothing else but blue lines identical to the picture on the left. Psychology 7e in Modules

3-D Illusion Reprinted with kind permission of Elsevier Science-NL. Adapted from Hoffman, D. & Richards, W. Parts of recognition. Cognition, 63, 29-78 To perceive this figure in two dimensions takes a great deal of effort. Psychology 7e in Modules

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 psychologists showed that a figure formed a “whole” different than its surroundings. OBJECTIVE 16-2| Describe Gestalt psychology's contribution to our understanding of perception. Psychology 7e in Modules

Form Perception Organization of the visual field into objects (figures) that stand out from their surroundings (ground). OBJECTIVE 16-3| Explain the figure-ground relationship and identify principles of perceptual grouping in form perception. Time Savings Suggestion, © 2003 Roger Sheperd. Psychology 7e in Modules

Gestalt Psychology In the beginning of the 20th c. a group of researchers described the principles that govern how we perceive groups of objects. Closure/Connectedness Proximity Continuity Similarity Psychology 7e in Modules

Grouping Having discriminated figure from ground our perception needs to organize figure into meaningful form using grouping rules. Psychology 7e in Modules

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 Psychology 7e in Modules

Depth Perception Depth 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. OBJECTIVE 16-4| Explain the importance of depth perception, and discuss the contribution of visual cliff research to our understanding of this ability. Innervisions Visual Cliff Psychology 7e in Modules

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. © The New Yorker Collection, 2002, Jack Ziegler from cartoonbank.com. All rights reserved. Psychology 7e in Modules

Monocular Cues Relative Size: If two objects are similar in size, we perceive one that casts a smaller retinal image as farther away. OBJECTIVE 16-6| Explain how monocular cues differ from binocular cues, and describe several monocular cues for perceiving depth. Psychology 7e in Modules

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 Psychology 7e in Modules

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. Psychology 7e in Modules

Monocular Cues Relative Clarity: Because light form distant objects passes through more air, we perceive hazy objects as farther away than sharp clear objects. Psychology 7e in Modules

Monocular Cues Texture Gradient: Indistinct (fine) texture signals increasing distance. © Eric Lessing/ Art Resource, NY Psychology 7e in Modules

Monocular Cues Light and Shadow: Nearby objects reflect more light to our eyes. Given two identical objects, the dimmer one seems further away. From “Perceiving Shape From Shading” by Vilayaur S. Ramachandran. © 1988 by Scientific American, Inc. All rights reserved. Psychology 7e in Modules

Monocular Cues: Review Linear Perspective Relative Size / Height Interposition Texture Gradient Relative Clarity Shadowing Psychology 7e in Modules

Monocular Cues Relative motion: Objects closer to a fixation point move faster and in opposing direction to objects farther away from a fixation point, which move slower and in the same direction. Psychology 7e in Modules

Binocular Cues Retinal disparity: Images from the two eyes differ. Try looking at your two fingers half an inch apart about 5 inches away. You will see a “finger sausage” as shown in the inset. Psychology 7e in Modules

Binocular Cues Convergence: Neuromuscular cues. When two eyes move inward (towards the nose) to see near objects, and outward (away from the nose) to see far away objects. OBJECTIVE 16-5| Describe two binocular cues for perceiving depth, and explain how they help the brain to compute distance. Psychology 7e in Modules

Motion Perception Motion Perception: Objects that tend to travel towards us grow in size and ones that move away shrink in size. The same is true when the observer moves to or from an object. OBJECTIVE 16-7| State the basic assumption we make in our perceptions of motion, and explain how these perceptions can be deceiving. Psychology 7e in Modules

Apparent Motion Phi Phenomenon: When lights flash at certain speed they tend to present illusions of motion. Neon signs use this principle to create motion perception. One light jumping from one point to another: Illusion of motion. Two lights flashing one after the other. Psychology 7e in Modules

Perceptual Constancy Perceiving objects as unchanging even as illumination and retinal image change. Perceptual constancies include constancies of shape and size. OBJECTIVE 16-8| Explain the importance of perceptual constancy. Shape Constancy Psychology 7e in Modules

Stable size perception amid changing size of the stimuli. Size Constancy Stable size perception amid changing size of the stimuli. OBJECTIVE 16-9| Describe the shape and size constancy, and explain how our expectations about perceived size and distance to some visual illusions. Size Constancy Psychology 7e in Modules

Size-Distance Relationship The distant monster and the top red bar appear bigger because of distance cues. Alan Choisnet/ The Image Bank From Shepard, 1990 Psychology 7e in Modules

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 Psychology 7e in Modules

An Ames room is designed to give size-distance illusion. Psychology 7e in Modules

The color and brightness of square A and B are the same. Lightness Constancy OBJECTIVE 16-10| Discuss lightness constancy and its similarity to color constancy. Courtesy Edward Adelson The color and brightness of square A and B are the same. Psychology 7e in Modules

Color Constancy Perceiving familiar objects as having consistent color, even if changing illumination filters the light reflected by the object. Color Constancy Psychology 7e in Modules