Unit 4 Sensation Perception Statement of Inquiry Students

Unit 4: Sensation & Perception Statement of Inquiry: Students will understand the power of perception to shape human understanding and cognition through an inquiry into how the brain receives processes sensory stimuli. Factual Question How do we process the information we receive from our environments? Conceptual Question How does our interpretation of the information we receive from the environment influence our behaviors and mental processes? Debatable Question To what extent does our perception shape our reality? LESSON 4: Visual Processing ESSENTIAL QUESTION: How does visual processing help us understand the world while leaving us susceptible to illusions? LEARNING GOALS: I can… • Explain the difference between monocular and binocular cues • Describe the significance of perceptual constancy • I can hypothesize on the role of top down processing in causing us to perceive visual illusions Today’s Warm Up: 1. What’s the difference between rods and cones? 2. Explain inattention or change blindness & give an example. Today’s Lesson Plan: • Warm up & review • Lecture • Application modules: online learning • Mid-Unit quiz • Open Note Practice FRQ See Unit Overview for key vocab & homework.

Synesthsia

Perception in Brain Our perceptions are a combination of sensory (bottom-up) and cognitive (top-down) processes. Sometimes, top down processing leaves us susceptible to visual illusions. 3

Top Down vs. Bottom Up Processing • Bottom up processing requires more attention to detail and is key to BUILDING schemas in the first place • Top down processing relies on our use of existing knowledge to perceive and interpret new information

Perceptual Constancy • Perceiving objects as unchanging even as illumination and retinal images change. – Perceptual constancies include constancies of shape and size. Shape Constancy 5

Size Constancy • Even if the size of the stimuli APPEARS bigger in the image to the left, we perceive the two cars are the same size because one is closer than the other Size Constancy 6

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 7

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 8

Perceptual Adaptation • Visual ability to adjust to an artificially displaced visual field, e. g. , prism glasses. Courtesy of Hubert Dolezal 9

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. Two lights after the Illusion other. of motion. One light jumping from flashing one pointone to another: 10

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. 11

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

Psych. Sim 5 Module • Google: Psych. Sim 5 – Select: Visual Illusions

Sensation / Perception Book • Plan your Sensation books – What story can you adapt? – What information about the eye or ear will you want to include? – What elements of perception do you intend to cover?

Visual Cues Monocular Cues Binocular Cues • Provide deep information about visual processing; can be perceived with one eye only • Provide deep information about visual processing; requires use of both yes

Binocular Cues: Retinal disparity: Ø Images from the two eyes differ b/c each eye is capturing light at a different angle Ø 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. 18

Binocular cues: Depth Perception Innervisions 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. • We have depth perception because our eyes are in different locations, allowing light to reach eye at different times Visual Cliff Experiment 19

Binocular Cues Ø Convergence: facilitates depth perception. Ø basically helps the observer perceive how close or far an object is. Ø This involves the physiological angles that either eyes need to rotate to focus on the object. 20

Monocular Cues Relative Size: Ø If two objects are similar in size, we perceive the one that casts a smaller retinal image to be farther away. 21

Monocular Cues: Interposition Ø 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. 22

Monocular Cues Ø 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. 23

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

Monocular Cue: Relative Height Ø 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 25

Monocular Cue: Relative Motion / Motion Parallax Ø Objects closer to a fixation point appear to move faster and in opposing direction to those objects that are farther away. 26

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

Monocular Cue: Light & Shadow Ø 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. 28

Color Constancy Color of an object remains the same under different illuminations. However, when context changes the color of an object may look different. R. Beau Lotto at University College, London 29

Co ur tes y Ed wa rd A de lso n Lightness Constancy The color and brightness of square A and B are the same. 30

Pre-Quiz Review – https: //www. youtube. com/watch? v=un. Wn. Zv. XJH 2 o – Watch the video as a review of the Sensation / Perception content we have learned so far. Make sure you can apply these terms: • • • Top down & bottom up processing Signal detection theory Absolute threshold Sensory Adaptation Difference threshold & Weber’s law Prosopagnosia Rods & Cones Fovea Bipolar & ganglion cells Feature detectors Parallel Processing

Time to Practice Master Your Vocabulary!!! • Do exit pass in classroom. • Practice Quizlet Sets ON YOUR OWN: – 4. 1 – Sensation: I’m making this soon – 4. 2 – Perception: https: //quizlet. com/_7 e 50 am – 4. 3 – The Eye: https: //quizlet. com/_7 e 8 igp

Sensation / Perception Book • Plan your Sensation books – What story can you adapt? – What information about the eye or ear will you want to include? – What elements of perception do you intend to cover?