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PSYCHOLOGY (8th Edition) David Myers

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1 PSYCHOLOGY (8th Edition) David Myers
PowerPoint Slides Aneeq Ahmad Henderson State University Worth Publishers, © 2006

2 Perception Chapter 6

3 Perception Selective Attention Perceptual Illusions
Perceptual Organization Form Perception Motion Perception Perceptual Constancy

4 Perception Perceptual Interpretation
Sensory Deprivation and Restored Vision Perceptual Adaptation Perceptual Set Perception and Human Factor

5 Perception Is there Extrasensory Perception? Claims of ESP
Premonitions or Pretensions Putting ESP to Experimental Test

6 Perception The process of selecting, organizing, and interpreting sensory information, which enables us to recognize meaningful objects and events.

7 Selective Attention The focusing of our conscious awareness on a particular stimulus, while ignoring the other stimuli that we are sensing (outside our awareness). Perceptions about objects change from moment to moment. The cocktail party effect (paying attention to only one voice out of many that may be speaking) is an example of selective attention. OBJECTIVE 1| Describe the interplay between attention and perception. Necker Cube

8 Inattentional Blindness
Inattentional blindness refers to the inability to see an object or a person in our midst. Simmons & Chabris (1999) showed that half of the observers failed to see the gorilla-suited assistant in a ball passing game. Daniel Simons, University of Illinois

9 Change Blindness Change blindness is a form of inattentional blindness in which a gradual change goes un-noticed, or a person giving directions fails to notice a change in the individual asking for directions. Change deafness refers to the failure to notice a change in auditory stimuli. Choice blindness is the failure to notice that the choice defended (as in a line-up) is not the original choice. The opposite of these might be, pop-out (pg 239), in which a strikingly distinct stimulus draws your eye. © 1998 Psychonomic Society Inc. Image provided courtesy of Daniel J. Simmons.

10 Perceptual Illusions Illusions provide good examples in understanding how perception is organized. Studying faulty perception is as important as studying other perceptual phenomena. OBJECTIVE 2| Explain how illusions help us understand some of the ways we organize stimuli into meaningful perceptions. Line AB is longer than line BC.

11 Tall Arch In this picture, the vertical dimension of the arch looks longer than the horizontal dimension. However, both are equal. Rick Friedman/ Black Star

12 Illusion of a Worm © 1981, by permission of Christoph Redies and Lothar Spillmann and Pion Limited, London The figure on the right gives the illusion of a blue hazy “worm” when it is nothing else but blue lines identical to the figure on the left.

13 3-D Illusion Reprinted with kind permission of Elsevier Science-NL. Adapted from Hoffman, D. & Richards, W. Parts of recognition. Cognition, 63, 29-78 It takes a great deal of effort to perceive this figure in two dimensions.

14 Perceptual Organization
When vision competes with our other senses, vision usually wins – a phenomena called visual capture (vision dominates our other senses). Gestalt (our tendency to integrate meaningful pieces into an organized/unified whole) psychologists showed that a figure formed a “whole” different than its surroundings. OBJECTIVE 3| Describe Gestalt psychology's contribution to our understanding of perception.

15 Figure-Ground Organization of the visual field into objects (figures) that stand out from their surroundings (ground). Time Savings Suggestion, © 2003 Roger Sheperd. OBJECTIVE 4| Explain the figure-ground relationship and identify principles of perceptual grouping in form perception.

16 Grouping After distinguishing the figure from the ground, our perception needs to organize the figure into a meaningful form using grouping rules.

17 Grouping & Reality Although grouping principles usually help us construct reality, they may occasionally lead us astray. In closure, we fill in the gaps to create a complete and whole object Both photos by Walter Wick. Reprinted from GAMES Magazine. .© 1983 PCS Games Limited Partnership

18 Depth Perception Depth perception enables us to judge distances. It works best when both eyes are used, but can still be perceived with only one. Gibson and Walk performed their visual cliff experiments (1960) proving that human infants (crawling age) have depth perception. Even newborn animals show depth perception. OBJECTIVE 5| Explain the importance of depth perception, and discuss the contribution of visual cliff research to our understanding of this ability. Innervisions Visual Cliff

19 Binocular Cues Binocular cues help us to judge distances in the most accurate way possible. Retinal disparity: Images from the two eyes differ because they are approximately 2.5 inches apart. Try looking at your two index fingers when pointing them towards each other half an inch apart and about 5 inches directly in front of your eyes. You will see a “finger sausage” as shown in the inset.

20 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 faraway objects. OBJECTIVE 6| Describe two binocular cues for perceiving depth, and explain how they help the brain to compute distance.

21 Monocular Cues Monocular cues also help us to judge distance, especially of objects that are straight ahead, and further away. Relative Size: If two objects are similar in size, we perceive the one that casts a smaller retinal image to be farther away. OBJECTIVE 7| Explain how monocular cues differ from binocular cues, and describe several monocular cues for perceiving depth.

22 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.

23 Monocular Cues Relative Clarity: Because light from distant objects passes through more air than closer objects, we perceive hazy objects to be farther away than those objects that appear sharp and clear.

24 Monocular Cues Texture Gradient: Indistinct (fine) texture signals an increasing distance. © Eric Lessing/ Art Resource, NY

25 Monocular Cues Relative Height: We perceive objects that are higher in our field of vision to be farther away than those that are lower. Image courtesy of Shaun P. Vecera, Ph. D., adapted from stimuli that appered in Vecrera et al., 2002

26 Monocular Cues Relative motion: Objects closer to a fixation point move faster and in opposing direction to those objects that are farther away from a fixation point, moving slower and in the same direction. Motion can also be mimicked through slightly altering a series of still pictures, and then rapidly flipping through them causing stroboscopic vision.

27 Monocular Cues Linear Perspective: Parallel lines, such as railroad tracks, appear to converge in the distance. The more the lines converge, the greater their perceived distance. © The New Yorker Collection, 2002, Jack Ziegler from All rights reserved.

28 Monocular Cues Light and Shadow: Nearby objects reflect more light into our eyes than more distant objects. Given two identical objects, the dimmer one appears to be farther away. From “Perceiving Shape From Shading” by Vilayaur S. Ramachandran. © 1988 by Scientific American, Inc. All rights reserved.

29 Motion Perception Motion Perception: Objects traveling towards us grow in size and those moving away shrink in size. The same is true when the observer moves to or from an object. OBJECTIVE 8| State the basic assumption we make in our perceptions of motion, and explain how these perceptions can be deceiving.

30 Apparent Motion Phi Phenomenon: When lights flash at a 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.

31 Perceptual Constancy Perceiving objects as unchanging even as illumination and retinal images change. Shape constancy refers to the fact that although the image may slightly change on our retina (the door going from a rectangle to almost a trapezoidal form) we still perceive a constant shape . OBJECTIVE 9| Explain the importance of perceptual constancy. Shape Constancy

32 Stable size perception amid changing size of the stimuli.
Size Constancy Stable size perception amid changing size of the stimuli. OBJECTIVE 10| Describe the shape and size constancy, and explain how our expectations about perceived size and distance to some visual illusions. Size Constancy

33 Size-Distance Relationship
The distant monster (below, left) and the top red bar (below, right) appear bigger because of distance cues. Alan Choisnet/ The Image Bank From Shepard, 1990

34 Size-Distance Relationship
Both girls in the room are of similar height. However, we perceive them to be of different heights as they stand in the two corners of the room. Both photos from S. Schwartzenberg/ The Exploratorium

35 Ames Room The Ames room is designed with only a couple of right angles, to demonstrate the size-distance illusion.

36 Other Perceptual Illusions
Moon Illusion: The moon looks up to 50% larger on the horizon, than it does in the high night sky. Cues to objects distances on the horizon make the moon behind them seem larger. Ponzo Illusion: Experience tells us that a more distant object must be larger than a nearer one in order to cast the same size image on the retina. Muller-Lyer Illusion: Our experience with the corners of rooms or buildings prompts us to determine that the vertical line on the left appears shorter than the same length vertical line on the right.

37 Lightness Constancy Courtesy Edward Adelson OBJECTIVE 11| Discuss lightness constancy and its similarity to color constancy. We perceive an object as having a constant color regardless of the illumination. The color and brightness of square A and B are the same, as are the “shirts.”

38 Relative Luminance The amount of light that an object reflects relative to its surroundings

39 Perceptual Interpretation
How important is experience in shaping our perceptual interpretation? Immanuel Kant ( ) maintained that knowledge comes from our inborn ways of organizing sensory experiences. John Locke ( ) argued that we learn to perceive the world through our experiences.

40 Restored Vision After cataract surgery, blind adults were able to regain sight. These individuals could differentiate figure and ground relationships, yet they had difficulty distinguishing a circle and a triangle (Von Senden, 1932). They had never learned to tell the difference visually. OBJECTIVE 12| Describe the contribution of restored-vision and sensory deprivation research in our understanding of the nature-nurture interplay in our perceptions.

41 Facial Recognition After blind adults regained sight, they were able to recognize distinct features, but were unable to recognize faces. Normal observers also show difficulty in facial recognition when the lower half of the pictures are changed. Courtesy of Richard LeGrand

42 Sensory Deprivation Kittens raised without exposure to horizontal lines later had difficulty perceiving horizontal bars. This demonstrates the critical period for normal sensory and perceptual development. Blakemore & Cooper (1970)

43 Perceptual Adaptation
Visual perceptual adaptation is the ability to adjust to an artificially displaced visual field, e.g., prism glasses that displace the visual field by a set number of degrees. OBJECTIVE 13| Explain how the research on distorting goggles increases our understanding of the adaptability of perception. Courtesy of Hubert Dolezal

44 Perceptual Set A mental predisposition to perceive one thing and not another. What you see in the center picture is influenced by the flanking pictures. OBJECTIVE 14| Define perceptual set, and explain how it influences what we do or do not perceive. Right half the class should close their eyes and the left half of the class should see the saxophonist for about 20 seconds. Then the left half of the class should close the eyes and the right half should see the woman’s face. All of them should then write their responses while watching the middle picture. Responses are compared to show perceptual set. From Shepard, 1990.

45 Perceptual Set Other examples of perceptual set.
Frank Searle, photo Adams/ Corbis-Sygma Dick Ruhl (a) Loch ness monster or a tree trunk; (b) Flying saucers or clouds?

46 Schemas Schemas are concepts that organize and interpret unfamiliar information. Courtesy of Anna Elizabeth Voskuil All what we perceive not only comes from the environment but also from our minds. Schemas or concepts develop through experience. Children's schemas represent reality as well as their abilities to represent what they see.

47 Face schemas are accentuated by specific features on the face.
Features on a Face Face schemas are accentuated by specific features on the face. Kieran Lee/ FaceLab, Department of Psychology, University of Western Australia Students recognized a caricature of Arnold Schwarzenegger faster than his actual photo.

48 Eyes and mouth play a dominant role in face recognition.
Eye & Mouth Eyes and mouth play a dominant role in face recognition. Courtesy of Christopher Tyler Portrait artists understood the importance of this recognition and therefore centered an eye in their paintings.

49 Context Effects The context surrounding an object can radically alter our perception. OBJECTIVE 15| Explain why the same stimulus can evoke different perceptions in different contexts. The two center squares are both 60% grey

50 Context instilled by culture also alters perception.
Cultural Context Context instilled by culture also alters perception. To an East African, the woman sitting is balancing a metal box on her head, while the family is sitting under a tree.

51 Is perception innate or acquired?
Perception Revisited Is perception innate or acquired?

52 Perception & Human Factors
Human Factor Psychologists design machines that assist our natural perceptions. Photodisc/ Punchstock Courtesy of General Electric OBJECTIVE 16| Describe the role human factors psychologists play in creating user-friendly machines and work settings. The knobs for the stove burners on the right are easier to understand than those on the left.

53 Human Factors & Misperceptions
Understanding human factors enables us to design equipment to prevent disasters. Two-thirds of airline crashes caused by human error are largely due to errors of perception.

54 Human Factors in Space To combat conditions of monotony, stress, and weightlessness when traveling to Mars, NASA engages Human Factor Psychologists. Transit Habituation (Transhab), NASA

55 Is There Extrasensory Perception?
Perception without sensory input is called extrasensory perception (ESP). A large percentage of scientists do not believe in ESP. OBJECTIVE 17| Identify the three most testable forms of ESP, and explain why most research psychologists remain, skeptical of ESP.

56 Claims of ESP Parapsychologists investigate phenomena including astrological predictions, psychic healing, communication with the dead, and out-of-body experiences, but most relevant are telepathy, clairvoyance, and precognition.

57 Types of ESP Telepathy: Mind-to-mind communication. One person sending thoughts and the other receiving them. Clairvoyance: Perception of remote events, such as sensing a friend’s house on fire. Precognition: Perceiving future events, such as a political leader’s death. Psycho-Kinesis: Being able to manipulate objects with only your mind.

58 Putting ESP to Experimental Test
In an experiment with 28,000 individuals, Wiseman attempted to prove whether or not one can psychically influence or predict a coin toss. People were able to correctly influence or predict a coin toss 49.8% of the time.

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