CHAPTER 8: THE PSYCHOLOGY OF VISION QUICK GUIDE TO INSTRUCTOR S RESOURCES CHAPTER OBJECTIVES CHAPTER OBJECTIVES 8 1

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1 CHAPTER 8: THE PSYCHOLOGY OF VISION QUICK GUIDE TO INSTRUCTOR S RESOURCES CHAPTER OBJECTIVES 8 1 TEACHING SUGGESTIONS FROM PETER GRAY AND DAVID BJORKLUND 8 2 FOCUS QUESTIONS 8 2 CLASSROOM ACTIVITIES/DEMONSTRATIONS 8 3 ASSIGNMENTS 8 7 MEDIA RESOURCES 8 8 ONLINE DISCUSSION QUESTIONS 8 10 CHAPTER OBJECTIVES After completing Chapter 8, students should be able to: 1. Describe how the structures of the eye focus in order to form an image on the retina. 2. Describe how the receptors in the retina convert light energy into neural action potentials, and distinguish between rods and cones in terms of their distribution in the retina, sensitivity to different wavelengths, adaptation to light and dark, and acuity. 3. Explain the relationship of light wavelength to color perception. 4. Discuss the trichromatic and opponent-process theories of color vision, including evidence supporting these theories, and how together they explain color vision. 5. Explain how lateral inhibition provides a basis for the coding of contours. 6. Outline Treisman s feature-integration theory and the research that supports it. 7. Explain why we consciously perceive wholes before we perceive parts, and illustrate with reference to Gestalt principles of grouping. 8. Explain illusory contours and lightness illusions in terms of top-down and bottom-up processes. 9. Discuss perception in terms of the interaction of top-down and bottom-up processes. 10. List the brain pathways and functional abilities used to distinguish the what and where and how aspects of visual processing. 11. Outline Biederman s recognition-by-components theory and the research that supports it, and describe how context and patterns of movement also provide bases for object recognition. 12. Explain how unconscious inferences provide the basis for depth perception and give examples of binocular and monocular cues for depth. 13. Explain size illusions in terms of depth-processing theory and discuss some of the support for and objections to this theory. 14. Explain the booba/kiki effect and how it demonstrates multisensory processing. 15. Describe synesthesia and how the cross-activation theory explains this phenomenon. 1

2 TEACHING SUGGESTIONS FROM PETER GRAY AND DAVID BJORKLUND Perception involves an unconscious, unselective first stage followed by a conscious, selective second stage. One way to reduce this chapter s size for the shorter course is to assign just the first, second, and fifth sections (How the Eye Works; Seeing Colors; and Seeing in Three Dimensions). These sections give students a good understanding of the workings of the eye and the logic of studies of visual perception, and the cuts would reduce the chapter length by more than 40 percent. Any of the three Reflections and Connections (text p. 318) could provide a thesis for a lecture elaboration that would integrate many of the ideas and findings of the chapter. Another possible lecture thesis might be, Perception involves an unconscious, unselective first stage followed by a conscious, selective second stage. This lecture might begin with a review of Treisman s feature-integration theory and the evidence for it. The lecture might then describe how the same basic idea served as the foundation for Helmholtz s unconscious inference theory of perception and has been used to explain many visual illusions, such as the moon illusion. Few lecturers can resist the temptation to fill their perception lectures with dramatic visual illusions, and we see no reason to resist it. The trick, however, is to move beyond the wizardry to explain how perceptual psychologists use illusions in their effort to understand normal, nonillusory perception. A thesis for an illusion-filled lecture might be, The study of illusions has contributed to our understanding of the mechanisms of normal, accurate perception. You might begin by demonstrating a number of visual illusions and then ask: Why do we experience illusions in these cases and not in our normal, everyday visual experience? The answer is that our normal visual world provides rich, redundant information, but the conditions that produce illusions provide sparse, ambiguous information. Illusions are special cases, in which most of the cues present in normal vision are missing. Why, then, are perceptual psychologists interested in illusions? A general approach in science is to isolate relevant variables by removing other variables. By removing most of the usual cues for, say, size and distance judgments, researchers can determine which cues can produce accurate judgments by themselves and which cannot, and can begin to understand the mental steps involved in using those cues. To illustrate this, you might review the research described in the text indicating that size illusions originate in an unconscious misjudgment of the depth of one of the stimuli. This suggests that the processing involved in the initial judgment of depth including the use of such cues as linear perspective occurs in stage 1 (the automatic stage) of the two-stage perceptual system. FOCUS QUESTIONS 1. Through what steps might sophisticated eyes like ours have evolved from primitive beginnings? 2. How do the cornea, iris, and lens help to form images on the retina? 3. How are cones and rods distributed on the retina, and how do they respond to light? 4. How do cone vision and rod vision differ? 5. What is the chemical basis for dark adaptation and light adaptation? Why do we see mostly with cones in bright light and with rods in dim light? 6. How does the trichromatic theory explain the three-primaries law? How was the theory validated by the discovery of three cone types? 7. Why does vision in some people obey a two-primaries law rather than the three-primaries law, and why are these people not good at picking cherries? How does the color vision of most nonprimate mammals, and that of most birds, differ from that of most humans? 8. How does the opponent-process theory explain (a) the law of complementarity in color mixing and (b) the complementarity of afterimages? 2

3 9. How has the opponent-process theory been validated in studies of the activity of neurons that receive input from cones? 10. How can we tell what an infant sees? What methods can be used to determine visual acuity in young babies? 11. What are experience-expectant processes, and how do they relate to the development of vision? 12. What kinds of stimulus features influence the activity of neurons in the primary visual cortex? 13. What is the difference between parallel processing and serial processing? What role does each play in Treisman s feature-integration theory of perception? 14. How do pop-out phenomena and mistakes in joining features provide evidence for Treisman s theory? 15. What are some principles of grouping proposed by Gestalt psychologists, and how does each help explain our ability to see whole objects? 16. How do reversible figures illustrate the visual system s strong tendency to separate figure and ground, even in the absence of sufficient cues for deciding which is which? 17. How do illusory contours illustrate the idea that the whole influences the perception of parts? How are illusory contours explained in terms of unconscious inference? 18. How is unconscious inference described as top-down control within the brain? What is the difference between top-down and bottom-up control? 19. What problem was Biederman s recognition-by-components theory designed to explain? What is the theory, and how is it supported by experiments on object recognition? 20. How is the recognition-by-components theory supported by the existence of two types of visual deficits caused by brain damage? 21. What are the anatomical and functional distinctions between two different visual pathways in the cerebral cortex? 22. What abilities are preserved in people with damage to the what pathway but lost in people with damage to the where-and-how pathway? 23. In sum, what are the distinct functions of the what and where-and-how visual pathways? 24. How did Helmholtz describe perception as a problem-solving process? 25. How does binocular disparity serve as a cue for depth? 26. How do stereoscopes provide an illusion of depth? 27. How does motion parallax serve as a cue for depth, and how is it similar to binocular disparity? 28. What are some cues for depth that exist in pictures as well as in the actual, three-dimensional world? 29. Why does size perception depend on distance perception? 30. How might the unconscious assessment of depth provide a basis for the Ponzo, Müller-Lyer, and moon illusions? 31. What is the McGurk effect, and how does it demonstrate visual dominance? 32. What are the defining features of synesthesia? Might synesthesia have any adaptive value? CLASSROOM ACTIVITIES/DEMONSTRATIONS Using a Polaroid Pinhole Camera to Demonstrate the Anatomy of the Eye This demonstration will cost you about $30 and take about a couple hours of outside class prep time. The improvement to your students comprehension of eye anatomy will be notable, though (see Prull & Banks, 2005). Plus, if you are artsy, you will find other uses for your pinhole camera! The materials are based on the construction instructions below, but you may use different materials (i.e., shoebox) just make sure to recalculate the exposure time (see Duchamp, 2007 reference). You probably should try the cameras at home first, too. Materials: 1 pack Polaroid 600 film; three 35 mm-deep aluminum foil baking tins with cardboard 3

4 lids; black paint and paintbrush or black spray paint; pins/nails of two different diameters (0.6 mm, 0.9 mm); ruler; acrylic brayer; tape; marker. Construction: Paint the inside of the tins and cardboard cover completely black this might take 2 3 coats of paint. In the center of one lid, poke a 0.6 mm hole, in the center of the other two a 0.9 mm hole. Cover the holes with two layers of tape. Now go into a completely dark room (such as the bathroom with the door edges taped), open the film cartridge and tape one photo to the bottom of each tray. Note which way is down (the side with more border) and when you put the cardboard lid on (make sure black side faces inside!), draw an arrow pointing up with the black marker so you know which side of the camera to stand up. Close the tins and tape carefully all the way around the edges. Demonstration 1: In the class prior to the one in which you introduce the visual system, have students observe as you take pictures with the pinhole cameras. You will need to photograph something that stays still for 20 seconds (0.9 mm camera) and 40 seconds (0.6 mm camera), so perhaps have students stack up their books on a table, using another table to place your cameras. As the exposure takes place, introduce the ideas of the cameras as you expose the pinhole, light is entering, which allows an image to be recorded on the film taped inside. At the end of the exposure time, tape the holes with two layers of tape (new tape). Exposing the Film: In your completely dark room, open one camera at a time (this is important so that you can keep the photo with the correct camera). You will need to roll over the image back and forth, and hard, with the acrylic brayer (such as on the counter or on a toilet cover). After you ve done this with each picture, leave the black room and write the aperture diameter on each photo and whether or not a lens was used. Demonstration 2: In the following class, bring in your cameras and the developed pictures. Pass the two pictures taken without the lens and have students note the differences between the three. For example, the picture taken with the smaller opening is dimmer but the focus is better than the picture taken with the larger opening. Thus, you can discuss the tradeoffs between the two images. Then pass the picture taken with the lens and have students note that the image is brighter and more detailed than the other two. After, introduce the anatomy of the eye, noting the function of the pinhole (e.g., pupil), the inverted image on the film mimicking that of the retinal image, and so on. Sources: Duchamp (2007). Let s make a pinhole Polaroid camera! Retrieved March 6, 2014, from Prull, M. W., & Banks, W. P. (2005). Seeing the light: A classroom-sized pinhole camera demonstration for teaching vision. Teaching of Psychology, 32(2), [This article explains how to use a projection screen and light from a window for a real-time demonstration.] Color Perception Demonstrations With these demonstrations, you can illustrate both the trichromatic theory and opponent-processes theory of color vision, as well as the importance of contours in feature detection. 1. Chromatic Adaptation: Color a 15 x 15 cm red square on a transparency, going over it two times to make the color vivid. Put a small black dot in the center. Turn out the lights, and have students first stare at the dot and note the even coloring, then cover half of the square and have them stare at the exposed half for 60 seconds. When you uncover the square, students should note that the side they stared at (adapting stimulus) is much duller than the side you just exposed (novel stimulus). Have students discuss how this can be explained using the trichromatic theory (the adapting stimulus selectively bleaches the photopigments of the long wavelength receptors). 2. Afterimage Using a Red Adapting Stimulus: Have students stare at the red square for 60 seconds, 4

5 after which you replace the transparency with a clear transparency with a black X in the center. Have students stare at the X to get the blue/green afterimage. Have students discuss why the afterimage appears. Note that one explanation is the selective bleaching from the above demonstration. 3. Afterimage Using a Green Adapting Stimulus: Make the same square as in the first demonstration, but with a green square. Have students stare at the center for 60 seconds. Replace the transparency with the clear transparency as in the second demonstration. Students should see a red afterimage. Since with selective bleaching you would expect a blue-violet afterimage, have students discuss what accounts for the red image. Opponent-process theory explains this better than the trichromatic theory. 4. Disappearance of the Adapting Stimulus: Create a red square as in the first demonstration, but only colored once so that the color is less saturated. Have students stare at the center for 90 seconds. If their eyes are steady, portions of the square will disappear and reappear, or the entire stimulus will fade. Discuss the importance of contours, highlighting that when we do not view contours moving, form perception ceases. Source: Horner, D. T. (1997). Demonstrations of color perception and the importance of contours. Teaching of Psychology, 24(4), Decreased Visual Perception During Saccadic Eye Movements James Kalat (1999) proposes the following activity to highlight a paradoxical inhibition of visual sensation. We all have two kinds of eye movements: pursuit eye movements, in which our eyes follow a moving object, and saccadic (suh-kah-dik) eye movements, in which the eyes alternate between fixations (periods of stationary focus) and saccades (ballistic jumps from one fixation point to another). Visual perception is greatly, though not entirely, suppressed during saccades. This suppression serves a useful function, as vision during a saccade would be blurry. People are not ordinarily aware of this suppression, any more than they are aware of the blind spot in each eye. Nevertheless, a simple procedure can demonstrate the great decrease in visual sensitivity that occurs during saccades. Procedure: Ask students to bring small handheld mirrors to class. You probably should bring additional mirrors for students who do not bring their own. Students can share mirrors, although a ratio of more than four to six students per mirror would delay the demonstration considerably. First instruct students, Look at yourself in a mirror and focus on your left eye. Then shift your focus to your right eye. Did you see your eyes move? They will agree that they did not. Many will explain this as the result of the eye movement being too slight or too fast to be visible. You can discredit that hypothesis easily. Look at your neighbor s eyes. Focus on his or her left eye, then move your focus to the right eye. Have your neighbor focus on your left eye and then move the focus to your right eye. Did each of you see the other person s eyes move? Students consistently report that they did see the other person s eyes move. Therefore, the inability to see one s eye movement in the mirror is not simply a consequence of the high speed or short distance of the movement; rather, it demonstrates decreased vision during the movement itself. Visual perception is largely suppressed during saccades by at least two mechanisms. First, certain areas in the parietal cortex monitor impending eye movements and send a message to the primary visual cortex to inhibit movement during saccades. Even if someone is in total darkness, the moment of a saccade is associated with decreased neural activity and blood flow, especially in the magnocellular pathway, which is the primary pathway for movement detection (Burr et al., 1994; Paus et al., 1995). Second, what one perceives at the end of a saccade produces backward masking that interferes with what one saw during the saccade. For example, if a stimulus, such as an illuminated vertical line, is flashed so that it both starts and stops during a horizontal saccade, a viewer does perceive a blurry light, with its 5

6 width proportional to the distance the eyes moved while the stimulus was present. If, however, the stimulus persists after the saccade has ended, the viewer clearly perceives the stimulus during the fixation; the preceding blur, if perceived at all, is only a weak image (Matin et al., 1972). The longer the stimulus remains on during the fixation, the weaker the perception of the blur during the preceding saccade. One consequence of the decreased vision during saccades is that we can read only during fixations, not during the saccades between them. Because we are limited to seeing about 11 characters during each fixation (Just & Carpenter, 1987), the maximum number of words we can read (not counting those that we skip over and infer) is limited by the number of fixations per second. An average college student with a text of average difficulty averages about four fixations per second, with occasional backtracks and pauses, yielding an overall reading speed of about 200 words per minute. Very skilled readers decrease the duration of their fixations, thereby increasing the number of fixations per second and doubling or tripling their reading speed while maintaining good comprehension, at least for reading material with simple vocabulary (Just & Carpenter, 1987). (Speed-reading a chemistry textbook is not a good idea.) However, saccades themselves last 25 to 50 ms (milliseconds), setting a theoretical limit to reading speed. Even with the unrealistic assumptions that someone keeps all saccades to the minimum of 25 ms, has minimum fixation durations, and reads material limited to short words, the maximum reading speed would be 4,800 words per minute. When graduates of speed-reading courses claim to read 5,000 to 10,000 words per minute, we may safely infer that they are skipping over a fair percentage of the words. In addition to its relevance for reading, this demonstration of detecting eye movements illustrates a basic point about perception and consciousness: There are moments in time when stimuli strike our sense organs but never reach awareness. Sources: Burr, D. C., Morrone, M. C., & Ross, R. (1994). Selective suppression of the magnocellular visual pathway during saccadic eye movements. Nature, 371, Just, M. A., & Carpenter, P. A. (1987). The Psychology of Reading and Language Comprehension. Boston: Allyn & Bacon. Kalat, J. W. (1999). Decreased visual perception during saccadic eye movements. In L. T. Benjamin, B. F. Nodine, R. M. Ernst, & C. B. Broeker (Eds.), Activities Handbook for the Teaching of Psychology (pp ). Washington, DC: American Psychological Association. Matin, E., Clymer, A. B., & Matin, L. (1972). Metacontrast and saccadic suppression. Science, 178, Paus, T., Marrett, S., Worsley, K. T., & Evans, A. C. (1995). Extraretinal modulation of cerebral blood flow in the human visual cortex: Implications for saccadic suppression. Journal of Neurophysiology, 74, Gestalt Principles of Grouping Demonstration Taking the principles of grouping to the real world, this demonstration has students see how our visual systems group objects from advertisements, catalogs, and artwork. Find one example that illustrates one principle best. After showing the standard principles with the pictures from the text, introduce your examples first in original form, and then with either a new PowerPoint slide or a transparency, do an overlay that shows the principles in action. For example, you could use a piece to illustrate symmetry, closure, or proximity. Source: Kozub, F. J. (1991). Oh say, can you see? Teaching of Psychology, 18(3), Perceived Distance and Size Many students have trouble understanding Kaufman and Rock s explanation for the moon illusion (see text pp ). A demonstration of some other size-distance illusions can help make their explanation easier to understand. 6

7 The size of a visual afterimage appears to change as it is projected to surfaces at different distances; however, it does not change. This is often referred to as Emmert s law, and it is an easy and effective way to demonstrate how perceived distance can affect perceived size. Begin the demonstration by having students fix their eyes on a dark spot on an overhead (simply lay a coin on the projector to produce a dark spot on the screen). Have them stare at the center of the spot for about one minute. Then have them stare at a white piece of paper on their desks. They should see a light afterimage of the dark spot. Have them note its size. Then have them project the afterimage on a light-colored wall or projection screen at least a few feet away from their desks. The afterimage will appear much larger than it was on the paper. Have them switch back to the paper to verify that the spot has not really grown. Why does the afterimage appear larger when projected on a distant surface? Because its retinal size remains the same but it seems farther away, unconscious processes tell us that it must be larger. The hole-in-palm illusion described by Tsai (1987) illustrates the same relationship between perceived size and distance. Using a long tube with a diameter of about 1 inch (such as the kind that comes with gift-wrapping paper) or a rolled-up sheet of paper to produce a paper tube about 11 inches long and 1 inch in diameter, have students hold the tube up to their right eye with their right hand. Then, have them put their left hand (with the palm facing them) next to the tube. Now, with both eyes open they should have the illusion of a hole in the palm of their hand (sometimes it helps to focus on the objects seen through the tube, and let the palm go out of focus). If they move their palm along the paper tube quickly, the size of the hole appears to change; it grows as the palm moves away, and it shrinks as the palm comes closer. Because the retinal size of the hole remains the same while the retinal size of the palm is actually shrinking as it moves away, size constancy helps us perceive that the size of the palm remains the same even though the hole appears to grow. These examples will help students see the relationship between perceived distance and size, and will help them understand the depth-processing explanation of the moon illusion. Source: Tsai, L. S. (1987). An enlarging hole on the palm illusion and a theory of the moon on the horizon. Perceptual and Motor Skills, 65, ASSIGNMENTS What Does Color Vision Tell Us about the Different Functions of Primate Eyes? Humans are the only primates that have three types of cones; the others have two. Students should provide a summary of the function of the different types of cones and an overview of how this changes what humans can see versus what other primates can see when looking at the same image. Finally, using the text as a model of the function of different abilities, they should provide a scientifically grounded speculation of what was important in human ancient environments and primate ancient environments to result in this difference. Environment includes social interactions. Comparing Camera and Eye One way to encourage students to think about the physiology of the eye is to have them compare a typical 35 mm camera to the visual system. They should note the similarities and differences. For example, both eye and camera have a lens that focuses an inverted image on a light-sensitive surface. In a camera, the f-stop adjusts the amount of light entering; in the eye, the pupil varies in size to allow more or less light to enter. Camera and eye differ in how they focus light onto the light-sensitive surface. In the eye, the lens changes shape (becoming more or less flat to focus on nearer or more distant objects). The lens in a camera moves closer to or farther away from the film. When your students begin to compare camera film to the retina, they will see that both can be sensitive to color or not (trichromatic or monochromatic; color or black-and-white film). However, while film is uniformly sensitive to light, the distribution of rods and cones varies across the retina. Also, the light-sensitive surface (the retina) is 7

8 actually the farthest away from the light, almost as if the film in a camera had been put in backward. Another possibility is to compare the eye to a video camera. In this case, you have both systems sending information to another place. Whatever comparisons are made, the students will have to consider eye physiology in detail, a process that will promote understanding. Gestalt Principles of Grouping In addition to the demonstration above, have students locate their own print examples of the Gestalt principles of grouping. Have them select one piece per principle that you wish to highlight, and include with tracing paper an overlay illustrating the principle more concretely. Source: Kozub, F. J. (1991). Oh say, can you see? Teaching of Psychology, 18(3), Bottom-Up and Top-Down Processing in Everyday Perception Ask students to select some specific event that might occur during an interesting everyday task and write about the roles of top-down and bottom-up processing in the pattern perception and object recognition involved in that task. Tasks that lend themselves to analysis include driving a car, hitting a baseball, listening to music, or understanding the speech of a person with a foreign accent. It is important for students to consider a brief, specific event. For example, a student might analyze the perceptual process involved in braking a car when a child chases a ball into the street, focusing on the recognition that a child has entered the car s path. This might involve a consideration of the perception of motion, shapes, and depth. Encourage students to think about the stimulus features involved (bottom-up) and then the knowledge that allows one to combine the features, anticipating what might happen in the situation (topdown). Students should see how top-down and bottom-up processes work together, and that sometimes a process cannot be easily labeled as one or the other. How Do 3-D Glasses Work? Have students research how 3-D glasses make a two-dimensional movie appear more lifelike. Along with their research, they should connect how the glasses help us see 2-D in 3-D to what they have learned about how we see in three dimensions. MEDIA RESOURCES Videos Vision: How We See, Scientific American Introductory Psychology Videos (8 minutes, 40 seconds) What humans see is only a small part of what exists out in the world, says Richard Masland. As complex as the human visual system is, we are only designed to see a small part of the electromagnetic spectrum the same part that is required for photosynthesis. Does this tell us something about the evolutionary history of the visual system? This program provides an overview of the human visual system, including the basic structures and functions of the eye and nervous system that are involved in visual processing. What is color blindness and where does it originate? What parts of the electromagnetic spectrum are unavailable to the human visual system? What are rods and cones and how do they work? A Variety of Visual Illusions, Clips A-H, Worth Video Anthology for Introductory Psychology (6 minutes, 16 seconds) 8

9 The clips in this series are from Michael Bach s Visual Illusions Web site. These visual illusions, which often seem like malfunctions of the visual system, are actually the result of adaptations of our visual pathways to efficiently process typical, everyday visual stimuli. Each illusion not only provides insight into visual processing in humans, but also lends insight into the features of our environments that are most common and most important to human life, leading to the evolutionary development of these visual heuristics. What areas of the brain and/or visual sensory system result in each of these illusions? In other words, what do these apparent malfunctions in visual perception tell us about how our visual system operates? How might the processes that lead to these illusions be adaptive in everyday situations? Visual Information Processing: Elementary Concepts, Worth Video Anthology for Introductory Psychology (9 minutes, 11 seconds) This video illustrates how visual information moves along visual pathways from the eye to the visual cortex and features the Nobel Prize-winning work of David Hubel and Torsten Wiesel. It also introduces Russell DeValois s findings about spatial frequencies. How are visual images interpreted by the brain? How did Drs. Hubel and Wiesel discover feature detectors in the cat s brain? How do Drs. DeValois s, Hubel s, and Wiesel s interpretations of how the brain interprets orientation, edge, and spatial frequencies of visual stimuli compare? Interactive Presentation Slides 6.2 Vision and Hearing The first part of this PowerPoint presentation covers the visual system including the structure of the eye, the visual pathway and color vision. Student Activities/Simulations (Web Portal) PsychSim 5 Colorful World Reviews the principles of color sensation; includes a comparison of the trichromatic and opponentprocess theories of color vision. Visual Illusions This activity offers students the opportunity to test their susceptibility to four famous visual illusions. In the Müller-Lyer, Ponzo, horizontal-vertical, and Poggendorff illusions, students will be asked to adjust the length or position of one part of the stimulus to match the apparent length or position of another part. Concepts in Action Structure of the Eye Demonstrates the structure of the human eye. The Visual Pathway Discusses the pathway light travels through to the brain. PsychInvestigator Psychology of Vision Discusses vision and asks students to find their blind spot. 9

10 ONLINE DISCUSSION QUESTIONS Optical Illusions Our vision can be easily tricked. Go online and find two visual illusions. Post the links to these illusions and describe why you think our vision might be fooled by these illusions. What do the illusions tell us about the ways our vision normally operates, when not being tricked? Your Favorite Image What is your favorite professional photograph or painting? Using what you now know about how we perceive images, interpret the image. For example, how is it that we perceive features and contours of the image to create a whole? Select two theories from the book to interpret your image. 10