Thinking About Psychology: The Science of Mind and Behavior Charles T. Blair-Broeker Randal M. Ernst

Perception Module 10

Perception The process of organizing and interpreting sensory information Top Down Processing

Organizational Principles Module 10: Perception

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. (Other examples: dichotic listening) OBJECTIVE 1| Describe the interplay between attention and perception. Necker Cube

SELECTIVE ATTENTION Our brain can only focus on 1 thing at a time Stress narrows attention OTHER EXAMPLES: Cell phones in car ?

Count the number of times the ball is passed: http://www.youtube.com/watch?v=vJG698U2Mvo

Change Blindness http://www.youtube.com/watch?v=-HVw9kWkPX0

Gestalt The “whole,” or the organizational patterns that we tend to perceive Gestalt psychologists stressed that the whole is greater than the sum of its parts. By breaking experiences into their basic parts, something important is lost. Ex. Butter, eggs, flour, sugar, salt, brown sugar, baking soda, vanilla, chocolate chips

Organizational Principles: Figure-Ground Relationships Module 10: Perception

Figure-Ground The perceptual tendency to organize stimuli into objects (the figures) that stand out from their surrounding (the ground) - doesn’t have to be visual The figure is the object(s) that stands out or draws one’s attention. The ground is the background. Right now, what is the “figure”?

What’s the “figure” now?

Organizational Principles: Grouping Principles Module 10: Perception

Grouping The perceptual tendency to organize stimuli into understandable groups Several principles of grouping include: Similarity Proximity Closure Continuity

Grouping - Similarity The tendency to place items that look similar into a group

Draw what you just saw.

Grouping - Proximity The tendency to place objects that are physically close to each other in a group

Draw what you just saw

Grouping – Closure The tendency to look at the whole by filling in gaps in a perceptual field

Draw what you just saw

Grouping – Continuity The tendency to perceive that movement of an object continues once it appears to move in a particular direction

Draw what you just saw

Depth Perception Module 10: Perception

Depth Perception The ability to see in three dimensions and judge distances How does this happen? Inverted, 2 dimensional image projected on retina

Visual Cliff A laboratory device for testing depth perception in infants and young animals Infants are reluctant to crawl past the “edge” of the visual cliff Other animals had similar results. Suggests that depth perception, to some extend, is inborn

Visual Cliff

Depth Perception: Binocular Depth Cues Module 10: Perception

Binocular Cues Depth cues that require the use of both eyes – allows us to see 3 dimensions

Retinal Disparity A binocular depth cue resulting from slightly different images produced by the separation of the retinas in the left and right eye Is most effective when the item is quite close to the person

Binocular Depth Cues: Finger Sausage

Convergence A binocular depth cue related to the tension in the eye muscles when the eyes track inward to focus on objects close to the viewer The more tension in the eye muscle, the closer the object is Works best at close distances

Depth Perception: Monocular Depth Cues Module 10: Perception

Monocular Cues Depth cues that require the use of only one eye Monocular depth cues include: relative size, relative motion, interposition, relative height, texture gradient, relative clarity, and linear perspective.

Monocular Depth Cues – Relative Size Using the perceived size of a familiar object to determine depth The larger the object appears, the closer the object is to the viewer

Relative Size: Which Pencil is farther away? Monocular Cues Relative Size: Which Pencil is farther away? OBJECTIVE 7| Explain how monocular cues differ from binocular cues, and describe several monocular cues for perceiving depth.

Monocular Depth Cues – Relative Motion A person who is moving can determine depth by focusing on a distant object. Objects further away than the object of focus will appear to move in the same direction as the subject is moving. Objects closer than the object of focus will appear to move in the opposite direction.

Relative Motion

Monocular Depth Cues – Interposition Method of determining depth by noting that closer objects partially obstruct the more distant objects Also called “overlap”

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.

Monocular Depth Cues – Relative Height Method of determining depth by noting that distant objects appear higher in your field of vision than do closer objects

Relative height

In this picture, is the arch taller or wider? Tall Arch In this picture, is the arch taller or wider? Rick Friedman/ Black Star

Monocular Depth Cues – Texture Gradient Method of determining depth by noting that distant objects have a smoother texture than nearby objects

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

Texture Gradient

Monocular Depth Cues – Relative Clarity Method of determining depth by noting that distant objects are less clear than nearby objects Tends to work outdoors

Monocular Cues Relative Clarity: We perceive hazy objects to be farther away than those objects that appear sharp and clear.

Monocular Depth Cues–Linear Perspective Method of determining depth by noting that parallel lines appear to converge in the distance The lines appears to eventually merge on the horizon.

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.

Motion Perception Module 10: Perception

Stroboscopic Motion The illusion of motion by the rapid projection of slightly changing images The concept a motion picture uses

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.

Perceptual Constancy Module 10: Perception

Perceptual Constancy Perceiving the size, shape, and lightness of an object as unchanging, even as the retinal image of the object changes The understanding that objects usually remain the same

Perceptual Constancy: Size Constancy Module 10: Perception

Size Constancy A person’s understanding that as an object moves further or closer to them its actual size stays the same As an object appears to become larger we realize it is getting closer, not bigger. As an object appears to become smaller we realize it is moving farther away, not getting smaller.

Size Distance Relationship

Size Distance Relationship

Size Distance Relationship

Perceptual Constancy: Shape Constancy Module 10: Perception

Shape Constancy The understanding that an object’s shape remains the same even though the angle of view makes the shape appear changed

Shape Constancy

Perceptual Constancy: Lightness Constancy Module 10: Perception

Light Constancy The ability to see an object as having a constant level of lightness no matter how the lighting conditions change http://www.bing.com/videos/search?q=light+constancy+video&view=detail&mid=0BD2B35C7FA8A95B8BA10BD2B35C7FA8A95B8BA1&first=0&qpvt=light+constancy+video&adlt=strict

Illusion of the Camera Play “Lights, Camera, Magic!” (12:53) Segment #10 from Scientific American Frontiers: Video Collection for Introductory Psychology (2nd edition). http://vsx.onstreammedia.com/vsx/pbssaf/search/PBSPlayer?assetId=-1&ccstart=2600066&pt=0&vid=pbssaf301&entire=No

Perceptual Set Module 10: Perception

Perceptual Set A mental predisposition to perceive one thing and not another. What you see in the center picture is influenced by 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.

Perceptual Set A mental predisposition to perceive something one way and not another Example of top-down processing Influence of the “power of suggestion” (subliminal perception) Guided by schemas: concepts or mental frameworks that organize and interpret information

What do these letters spell? f o l k

What do these letters spell? c r o a k

What do these letters spell? s o a k

What do we call the white of an egg?

Subliminal Perception Play “Studying the Effects of Subliminal Stimulation on the Mind” (4:46) Segment #9 from The Mind: Psychology Teaching Modules (2nd edition). http://www.youtube.com/watch?v=cGpQgkCpM9c

Context Module 10: Perception

Context The setting or environment in which we interpret sensory stimuli EX. – If sad music is playing and you read homophones to people, they will write “mourning” and “die”. If they hear happy music, they will write “morning” and “dye”.

Illusions Module 10: Perception

Illusions Misinterpreting sensory stimuli Help researchers understand how sensation and perception normally works

Müller-Lyer Illusion

Müller-Lyer Illusion Most people think segment AB equals BC. In reality AB is much longer than BC.

Müller-Lyer Illusion

Müller-Lyer Illusion

Müller-Lyer Illusion

Müller-Lyer Illusion Insert “Müller-Lyer Illusion” Video #4 from Worth’s Digital Media Archive for Psychology. Instructions for importing the video file can be found in the ‘Readme’ file on the CD-ROM.

Ames Room Illusion: Secret Revealed

The End