http www psychologie tudresden dei 1kawdiverses20 Materialwww illusionworks

http: //www. psychologie. tu-dresden. de/i 1/kaw/diverses%20 Material/www. illusionworks. com/index. html Unit 4 Perception pt. 2 http: //www. eyetricks. com/scary_optical_illusion 2. htm

§Perception §a process of organizing and interpreting sensory information, enabling us to recognize meaningful objects and events https: //www. youtube. com/watch? v=ORo. TCBr. CKIQ Perceptual set: a mental predisposition to perceive one thing and not another.

Stare at the black dot in the middle. You should see the outer edges of the circle fade away! Troxler’s fading It occurs because even if our eyes move a little when we are fixating a point, away from that point, in the perception field, the movements aren’t large enough to observe other elements; in conclusion the neurons remain focused on the main object and our visual system doesn’t involve new ones for the other elements.

Big Idea • Although it seems the brain interacts directly with the outside world, it does not. • The brain senses the world indirectly because the sense organs convert stimulation into the language of the nervous system: neural messages. – In short, the brain never receives stimulation directly from the outside world.

http: //www. michaelbach. de/ot/ Chapter 8 Are the red lines parallel?

http: //www. thedesignwork. com/65 -amazing-optical-illusion-pictures/

http: //www. michaelbach. de/ot/col_lilac. Chaser/index. html

Afterimages following bright lights or adapting stimuli of excessively longer alternating patterns (contingent perceptual aftereffect, CAE), are the effects on the eyes or brain of excessive stimulation of a specific type - brightness, tilt, colour, movement, and so on. The theory is that stimuli have individual dedicated neural paths in the visual outer wall of an organism for the early stages of visual processing; repetitive stimulation of only a few channels misleads the visual system.

Our experiences shape how we perceive things: Let us try something out:

You are about to witness the perpetrator of a crime!

Describe what you saw. Keep in mind, that this is a police investigation and that your testimony can be used in a court of law.

Young lady or Old lady?

'lateral inhibition' - the term used to describe the complex way in which the cells on the back of the retina respond to areas of black and white. There is, however, little point in explaining theory. Why? Because a few years ago it was shown to be completely untrue, and thus the explanation for the illusion remains a mystery. . .

Context Effects Context effect is the influence that our environment plays on us intellectually, emotionally, and sometimes even physically. • For example, if a constant noise was made and it was disrupted by the phrase, “ill is on the duck” your brain would most likely make “ill”, “bill. ” All this change is meant to satisfy the perceptual set element of our brains. I myself have had stuff like this happen to me. Walking in on conversation or being distracted usually ends up with me hearing something different. "Context" is close in meaning to "environment, "

• Brain Games 1 http: //www. youtube. com/watch? v=PN 1 NAi. M 55 h. U&feature=related

Auditory Illusions If the sounds do not work click here for link.

Amazingly the "blue" spirals actually have the same color as the green. In other words no blue exists in the illusion; it only exists in your mind.

Perceptual Interpretation § Perceptual Adaptation § (vision) ability to adjust to an artificially displaced visual field § prism glasses § Perceptual Set § a mental predisposition to perceive one thing and not another

Perceptual Set: Schemas § What you see in the center is influenced by perceptual set

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. 28

Perceptual Organization Gestalt Laws of Grouping • Proximity – Seeing 3 pair of lines in A • Similarity – Seeing columns of orange and red dots in B • Continuity – Seeing lines that connect 1 to 2 and 3 to 4 in C • Closure – Seeing a horse in D Psychology, 4/e by Saul Kassin © 2004 Prentice Hall

Continuity • Continuation – Leads the eye along a path. The principles of continuation is used to lead the viewers attention to a certain area or to connect an object to a specific action

• Closure – The eyes fill in the missing gaps to make the image/object whole.

Proximity • Continuation – Leads the eye along a path. The principles of continuation is used to lead the viewers attention to a certain area or to connect an object to a specific action

Depth Perception is the ability to judge the distances of objects, which also allows us to see them in three dimensions Innervisions Later research has demonstrated, however, that children as young as three-months are able to perceive the visual cliff. Depth perception enables us to judge distances. Visual Cliff: E. J. Gibson and R. D. Walk This tool was originally developed to determine if infants had developed depth perception. A visual cliff is created by connecting a transparent glass surface to an opaque patterned surface. The floor below has the same pattern as the opaque surface. This apparatus creates the visual illusion of a cliff, while protecting the subject from injury. Visual Cliff 36

• How do we see depth? MONOCULAR CUE—HOW IT WORKS Aerial Perspective Height in Plane Objects that are near seem crisper and clearer; far away objects appear fuzzier. MONOCULAR CUE—HOW IT WORKS Aerial Perspective Objects that are near seem crisper and clearer; far away objects appear fuzzier. Height in Plane Objects that are farther away appear higher in the visual scene. Interposition Objects that are nearer block objects that are farther away. Linear Perspective Lines that are parallel (e. g. , railroad tracks) look like they come to a point in the distance. The farther the lines, the closer they are. Motion Parallax When you are moving and you fixate on a spot, objects closer to you than that spot appear to move in the direction opposite to your motion; objects farther than that spot appear to move in the same direction as you are moving. Relative Size If two objects are of the same size, the closer one is bigger. Interposition Linear Perspective Motion Parallax Relative Size Objects that are farther away appear higher in the visual scene. Objects that are nearer block objects that are farther away. Lines that are parallel (e. g. , railroad tracks) look like they come to a point in the distance. The farther the lines, the closer they are. When you are moving and you fixate on a spot, objects closer to you than that spot appear to move in the direction opposite to your motion; objects farther than that spot appear to move in the same direction as you are moving. If two objects are of the same size, the closer one is bigger.

Binocular Cues: Depth cues such as retinal disparity that depends on the use of two eyes. 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. 39

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. 40

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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. 42

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. 43

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. 44

Monocular Cues Texture Gradient: Indistinct (fine) texture signals an increasing distance. © Eric Lessing/ Art Resource, NY 45

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 46

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. 47

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. 48

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. 49

Motion perception • Phi Phenomenon: with a succession of lights that creates the impression of, say, a moving arrow.

Perceptual Constancy Perceiving objects as unchanging even as illumination and retinal images change. Perceptual constancies include constancies of shape and size. Shape Constancy 52

Size-Distance Relationship Size Constancy: From Shepard, 1990 Alan Choisnet/ The Image Bank The distant monster (below, left) and the top red bar (below, right) appear bigger because of distance cues. 53

Perceptual Constancies Size Constancy: Alan Choisnet/ The Image Bank From Shepard, 1990 54

Perceptual Constancies Shape Constancy Have you ever noticed, for example, when you approach the dinner table that the shapes of the plates do not change? When you look at them from some distance away from the table, the shapes of the round plates are elliptical on your retina. The only time that the image of a round plate is approximately round on your retina is when you look at it straight on. If you are not sure what I mean, look at the dinner plate demo. Psychology, 4/e by Saul Kassin © 2004 Prentice Hall

Perceptual Adaptation Courtesy of Hubert Dolezal Visual ability to adjust to an artificially displaced visual field, e. g. , prism glasses. 56

Features on a Face schemas are accentuated by specific features on the face. Kieran Lee/ Face. Lab, Department of Psychology, University of Western Australia Students recognized a caricature of Arnold Schwarzenegger faster than his actual photo. 57

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. 58

Cultural 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. 59

Is There Extrasensory Perception? § Extrasensory Perception § controversial claim that perception can occur apart from sensory input § telepathy § clairvoyance § precognition § Parapsychology § the study of paranormal phenomena § ESP § psychokinesis

Claims of ESP 1. Telepathy: Mind-to-mind communication. One person sending thoughts and the other receiving them. 2. Clairvoyance: Perception of remote events, such as sensing a friend’s house on fire. 3. Precognition: Perceiving future events, such as a political leader’s death. 61

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. 62

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. 63

Subliminal Stimulation • Below one’s absolute threshold for conscious awareness. • Show clip Does this work? Yes and No • Slide studies showed some emotional reactivi (called priming a response). • The effects are subtle and fleeting.