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Perception Chapter 6 Slide 2 Perception Selective Attention Perceptual Illusions Perceptual Organization Form Perception Motion Perception Perceptual Constancy Slide 3 Perception Perceptual Interpretation Sensory Deprivation and Restored Vision Perceptual Adaptation Perceptual Set Perception and Human Factor Slide 4 Perception Is there Extrasensory Perception? Claims of ESP Premonitions or Pretensions Putting ESP to Experimental Test Slide 5 THE STROOP EFFECT Slide 6 BLUE, RED, GREEN, ORANGE, BROWN, RED, GREEN, BLUE, ORANGE, BLUE, RED, ORANGE, GREEN, BROWN, RED, BLUE, BROWN, GREEN, ORANGE, RED, BLUE Slide 7 BLUE, RED, GREEN, ORANGE, BROWN, RED, GREEN, BLUE, ORANGE, BLUE, RED, ORANGE, GREEN, BROWN, RED, BLUE, BROWN, GREEN, ORANGE, RED, BLUE Slide 8 Perception The process of selecting, organizing, and interpreting sensory information, which enables us to recognize meaningful objects and events. Slide 9 Selective Attention Perceptions about objects change from moment to moment. We can perceive different forms of the Necker cube; however, we can only pay attention to one aspect of the object at a time. Necker Cube Slide 10 Selective Attention The focus on ones consciousness on a particular stimulus Important for self-regulation Ex: driving, cocktail party effect -must focus on road rather than hunger or feelings about argument. Slide 11 x Slide 12 Video The Office Halloween Costume Contest Slide 13 Awareness Test Slide 14 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 Slide 15 Change Blindness Change blindness is a form of inattentional blindness in which two-thirds of individuals giving directions failed to notice a change in the individual asking for directions. 1998 Psychonomic Society Inc. Image provided courtesy of Daniel J. Simmons. Slide 16 Slide 17 Perceptual Illusions Illusions provide good examples in understanding how perception is organized. Studying faulty perception is as important as studying other perceptual phenomena. Line AB is longer than line BC. Slide 18 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 Slide 19 Illusion of a Worm 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. 1981, by permission of Christoph Redies and Lothar Spillmann and Pion Limited, London Slide 20 3-D Illusion It takes a great deal of effort to perceive this figure in two dimensions. Reprinted with kind permission of Elsevier Science-NL. Adapted from Hoffman, D. & Richards, W. Parts of recognition. Cognition, 63, 29-78 Slide 21 Perceptual Organization When vision competes with our other senses, vision usually wins a phenomena 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. The whole is greater than the sum of its parts Slide 22 Mcgurk Effect Video Slide 23 Organization of the visual field into objects (figures) that stand out from their surroundings (ground). Form Perception Time Savings Suggestion, 2003 Roger Sheperd. Slide 24 Grouping After distinguishing the figure from the ground, our perception needs to organize the figure into a meaningful form using grouping rules. Slide 25 Slide 26 Depth Perception Visual Cliff Depth perception enables us to judge distances. Gibson and Walk (1960) suggested that human infants (crawling age) have depth perception. Even newborn animals show depth perception. Innervisions Slide 27 Binocular Cues Stimuli suggestive of depth that involve simultaneous perception by both eyes Ex: close one eye and bring fingertips together Ex: roll up paper and you will see a hole in your hand Slide 28 Binocular Cues Retinal disparity: Images from the two eyes differ. 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. Slide 29 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. Slide 30 Depth Perception Monocular cues:cues that can be perceived by one eye, to create an illusion of depth Perspective:a monocular cue for depth based on the convergence (coming together) of parallel lines as they recede into the distance Slide 31 Monocular Cues Relative Size: If two objects are similar in size, we perceive the one that casts a smaller retinal image to be farther away. Slide 32 Monocular Cues Interposition: Objects that occlude (block) other objects tend to be perceived as closer. Slide 33 Monocular Cues Relative Clarity: Because light from distant objects passes through more light than closer objects, we perceive hazy objects to be farther away than those objects that appear sharp and clear. Slide 34 Monocular Cues Texture Gradient: Indistinct (fine) texture signals an increasing distance. Closer objects appear to have rougher (more detailed) surfaces Eric Lessing/ Art Resource, NY Slide 35 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 Slide 36 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. Slide 37 Motion Parallax A monocular cue for depth based on the perception that nearby objects appear to move more rapidly in relation to our own motion Mountains-move with us (greater distances) Trees, roadside markers-move rapidly Slide 38 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 cartoonbank.com. All rights reserved. Slide 39 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. Slide 40 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. Slide 41 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. -a row of lights is switched on, then off, then the next row -the on-off process is perceived as movement (Ex: electronic scoreboard baseball) Two lights flashing one after the other. One light jumping from one point to another: Illusion of motion. Slide 42 Perception of Movement 1)Autokinetic effect-the tendency to perceive a stationary point of light in a dark room as moving 2) Stroboscopic motion-a visual illusion in which the perception of motion is generated by a series of stationary images presented in rapid succession (flip book, motion pictures) Slide 43 Slide 44 Perceptual Constancy Perceiving objects as unchanging even as illumination and retinal images change. Perceptual constancies include constancies of shape and size. Shape Constancy Slide 45 Size Constancy Stable size perception amid changing size of the stimuli. Size Constancy Slide 46 Size-Distance Relationship The distant monster (below, left) and the top red bar (below, right) appear bigger because of distance cues. Ponzo effect From Shepard, 1990 Alan Choisnet/ The Image Bank Slide 47 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 Slide 48 Ames Room The Ames room is designed to demonstrate the size- distance illusion. Slide 49 Lightness Constancy The color and brightness of square A and B are the same. Courtesy Edward Adelson Slide 50 Perceiving familiar objects as having consistent color even when changing illumination filters the light reflected by the object. Color Constancy Slide 51 Monocular Cues (pg.254) Relative size (smaller is more distant) Interposition (an object that blocks another is closer than the blocked object) Relative clarity (hazy object is farther away than an object seen clearly) Texture gradient (coarse distinct objects are closer) Relative height (objects higher in our visual field are farther away) Relative Motion or Motion Parallax (when you are moving, objects closer than a fixation point appear to move backwards and closer the object, the faster it moves. Objects beyond the fixation point appear to move with you ) Linear perspective (the more two parallel lines converge, the farther away they are) Light and shadow (nearby objects reflect more light than faraway objects) Slide 52 Day 3 Slide 53 Perceptual Interpretation Immanuel Kant (1724-1804) maintained that knowledge comes from our inborn ways of organizing sensory experiences. John Locke (1632-1704) argued that we learn to perceive the world through our experiences. How important is experience in shaping our perceptual interpretation? Slide 54 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). Slide 55 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. Critical Period Courtesy of Richard LeGrand Slide 56 Kittens raised without exposure to horizontal lines later had difficulty perceiving horizontal bars. Blakemore & Cooper (1970) Sensory Deprivation Slide 57 The Ganzfeld Contours are important Little sensory change can lead to: Dizziness Fatigue snow blindness Slide 58 Vision and Balance Exercise: stand on one foot, then close your eyes, then try after you spin around a few times Maintaining balance depends on visual cues to some extent Slide 59 Perceptual Adaptation Visual ability to adjust to an artificially displaced visual field, e.g., prism glasses. Courtesy of Hubert Dolezal Slide 60 Perceptual Set A mental predisposition (bias or readiness) to perceive one thing and not another. What you see in the center picture is influenced by flanking pictures. Similar to priming or stereotyping Influenced by expectations or context Slide 61 Perceptual Set Slide 62 From Shepard, 1990. Slide 63 Perceptual Set From Shepard, 1990. Slide 64 (a) Loch ness monster or a tree trunk; (b) Flying saucers or clouds? Perceptual Set Other examples of perceptual set. Frank Searle, photo Adams/ Corbis-Sygma Dick Ruhl Slide 65 Girl or Boy or Same Kid? Slide 66 Shout out the answers What do these letters spell? FOLK Slide 67 How about these? CROAK Slide 68 And what do these letters spell? SOAK Slide 69 What do we call the white of an egg? Slide 70 Children's schemas represent reality as well as their abilities to represent what they see. Schemas Schemas are concepts that organize and interpret unfamiliar information. Courtesy of Anna Elizabeth Voskuil Slide 71 Students recognized a caricature of Arnold Schwarzenegger faster than his actual photo. Features on a Face Face schemas are accentuated by specific features on the face. Kieran Lee/ FaceLab, Department of Psychology, University of Western Australia Slide 72 Eye & Mouth Eyes and mouth play a dominant role in face recognition. Courtesy of Christopher Tyler Slide 73 Slide 74 Slide 75 Is the magician cabinet on the floor or hanging from the ceiling? Context Effects Context can radically alter perception. Slide 76 To an East African, the woman sitting is balancing a metal box on her head, while the family is sitting under a tree. Cultural Context Context instilled by culture also alters perception. Slide 77 Perception Revisited Is perception innate or acquired? Slide 78 Perception & Human Factors http://www.baddesigns.com/ Human Factor Psychologists design machines that assist our natural perceptions. natural mapping The knobs for the stove burners on the right are easier to understand than those on the left. Photodisc/ Punchstock Courtesy of General Electric Slide 79 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. Slide 80 Is There Extrasensory Perception? Perception without sensory input is called extrasensory perception (ESP). A large percentage of scientists do not believe in ESP. Slide 81 Claims of ESP Paranormal phenomena include astrological predictions, psychic healing, communication with the dead, and out-of-body experiences, but most relevant are telepathy, clairvoyance, and precognition. Slide 82 Claims 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 friends house on fire. Precognition: Perceiving future events, such as a political leaders death. Slide 83 Premonitions or Pretensions? Can psychics see the future? Can psychics aid police in identifying locations of dead bodies? What about psychic predictions of the famous Nostradamus? The answers to these questions are NO! Nostradamus predictions are retrofitted to events that took place after his predictions. Slide 84 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.