4Perception Perceptual Interpretation Sensory Deprivation and Restored VisionPerceptual AdaptationPerceptual SetPerception and Human Factor
5Perception Is there Extrasensory Perception? Claims of ESP Premonitions or PretensionsPutting ESP to Experimental Test
6PerceptionThe process of selecting, organizing, and interpreting sensory information, which enables us to recognize meaningful objects and events.
7Selective AttentionThe 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
8Inattentional 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
10Perceptual IllusionsIllusions 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.
11Tall ArchIn this picture, the vertical dimension of the arch looks longer than the horizontal dimension. However, both are equal.Rick Friedman/ Black Star
133-D IllusionReprinted with kind permission of Elsevier Science-NL. Adapted fromHoffman, D. & Richards, W. Parts of recognition. Cognition, 63, 29-78It takes a great deal of effort to perceive this figure in two dimensions.
14Perceptual 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.
18Depth PerceptionDepth 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.InnervisionsVisual Cliff
19Binocular CuesBinocular 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.
20Binocular CuesConvergence: 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.
21Monocular CuesMonocular 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.
22Monocular CuesInterposition: 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 ofMr. and Mrs. Paul Mellon. Photo by Richard Carafelli.
23Monocular CuesRelative 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.
25Monocular CuesRelative 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
26Monocular CuesRelative 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.
29Motion PerceptionMotion 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.
30Apparent MotionPhi 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.
31Perceptual ConstancyPerceiving 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
32Stable size perception amid changing size of the stimuli. Size ConstancyStable 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
33Size-Distance Relationship The distant monster (below, left) and the top red bar (below, right) appear bigger because of distance cues.Alan Choisnet/ The Image BankFrom Shepard, 1990
34Size-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
35Ames RoomThe Ames room is designed with only a couple of right angles, to demonstrate the size-distance illusion.
36Other 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.
37Lightness ConstancyCourtesy Edward AdelsonOBJECTIVE 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.”
38Relative LuminanceThe amount of light that an object reflects relative to its surroundings
39Perceptual Interpretation How important is experience in shaping ourperceptual 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.
40Restored VisionAfter 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.
41Facial RecognitionAfter 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
42Sensory DeprivationKittens 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)
43Perceptual 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
44Perceptual SetA 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.
45Perceptual Set Other examples of perceptual set. Frank Searle, photo Adams/ Corbis-SygmaDick Ruhl(a) Loch ness monster or a tree trunk; (b) Flying saucers or clouds?
46SchemasSchemas are concepts that organize and interpret unfamiliar information.Courtesy of Anna Elizabeth VoskuilAll 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.
47Face schemas are accentuated by specific features on the face. Features on a FaceFace schemas are accentuated by specific features on the face.Kieran Lee/ FaceLab, Department of Psychology,University of Western AustraliaStudents recognized a caricature of Arnold Schwarzenegger faster than his actual photo.
48Eyes and mouth play a dominant role in face recognition. Eye & MouthEyes and mouth play a dominant role in face recognition.Courtesy of Christopher TylerPortrait artists understood the importance of this recognition and therefore centered an eye in their paintings.
49Context EffectsThe 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
50Context instilled by culture also alters perception. Cultural ContextContext 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.
51Is perception innate or acquired? Perception RevisitedIs perception innate or acquired?
52Perception & Human Factors Human Factor Psychologists design machines that assist our natural perceptions.Photodisc/ PunchstockCourtesy of General ElectricOBJECTIVE 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.
53Human 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.
54Human Factors in SpaceTo combat conditions of monotony, stress, and weightlessness when traveling to Mars, NASA engages Human Factor Psychologists.Transit Habituation (Transhab), NASA
55Is 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.
56Claims of ESPParapsychologists investigate phenomena including astrological predictions, psychic healing, communication with the dead, and out-of-body experiences, but most relevant are telepathy, clairvoyance, and precognition.
57Types of ESPTelepathy: 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.
58Putting 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.