Science B44 Vision and Brain Fall 2006 Final Page 1 Science B44 FINAL EXAM FALL 2006 The exam has a total of 122 points. Multiple choice questions are worth 1 point each and short answer questions, 4 points each. The debate question is worth 10 points. The questions must be answered in 5 separate blue books, one for each of the 5 sections. FIRST BOOK Put your name and student ID on a new blue book, number the book #1 and begin. You should take no more than 36 minutes to finish the multiple choice and short answer questions for this section. BOOK 1 MULTIPLE CHOICE QUESTIONS Choose the one best answer for each and write the question number and the answer letter in your blue book, one answer per line. For example 1. c 2. b 3. b and so on 1. The major part of light refraction in the human eye happens in: a. Cornea b. Pupil c. Lens d. Retina 2. Which of the following is false in very dim illumination a. The fovea is blind. b. Vision is only black and white. c. Motion perception is not possible. d. Depth perception is preserved.
Science B44 Vision and Brain Fall 2006 Final Page 2 3. The following figure is an OFF-center receptive field of a ganglion cell, where light is projected on its receptive field in different conditions. Which condition causes the largest activity of the cell? a. Condition a b. Condition b c. Condition c d. Condition d 4. A simple cell has a. Orientation and position selectivity. b. Motion and position selectivity. c. Orientation but not position selectivity d. Orientation and direction selectivity. 5. Retinotopy means a. Points that are adjacent in the world are adjacent on the retina. b. Points that are adjacent in the world are adjacent on the visual cortex. c. Points that are adjacent on the retina are adjacent on the cortex. d. All of the above. 6. Which of the following cells does NOT have separate excitatory and inhibitory regions in its receptive field: a. Retinal ganglion cell. b. LGN cell. c. Simple cell. d. Complex cell.
Science B44 Vision and Brain Fall 2006 Final Page 3 7. The fact that these parallel horizontal lines look tilted, shows that orientation in the visual system is represented in what manner? a. adaptive b. competitive c. sampled d. ordered 8. Which is true: a. Any image can be decomposed to sine wave patterns. b. High spatial frequencies convey large scale information about the image. c. Cells in visual cortex do not care about spatial frequency of image. d. Detailed image information is lost when an image is decomposed into its spatial frequency components. 9. The visual system measures brightness only at edges (transitions from light to dark). If this is true, then the brightness of homogeneous regions (where there are no edges) can t be measured directly, and instead must be filled in from measurements at the edges. Which illusion supports this claim? a. The Craik Cornsweet Illusion b. The Brightness Aftereffect c. The Ames Room d. The Ponzo Illusion 10. If someone turns off the lights in the exam room now, what will happen to the light coming to your eyes from exam papers and words: a. The average luminance increases. b. The average contrast remains constant. c. The luminance of words (black) and the paper (white) decrease equally. d. The average contrast of the page decreases, making it harder for you to read.
Science B44 Vision and Brain Fall 2006 Final Page 4 11. What is the main difference of observation and correlation methods: a. Observation shows the causal relationship but correlation doesn t show it. b. Correlation shows the causal relationship but observation doesn t show it. c. Correlation can reveal hidden third variables but observation cannot. d. Correlation is less prone to the observer bias. 12. Which statement is NOT true: a. Evolution theory comes mainly from observation. b. Observations are sometimes the only choice for investigating natural phenomena. c. Experiments per se cannot establish cause and effect relationships. d. Experiments can be affected by observer bias.
Science B44 Vision and Brain Fall 2006 Final Page 5 BOOK 1 SHORT ANSWER QUESTIONS In your first book, write the answers to each of these questions. 13. You are hurtling down a black diamond ski run at Nashoba (!) and are unfortunately headed toward a tree. Miraculously, you are able to angle your head at the last moment so that you avoid certain death. Nevertheless, you are going to lose the visual functions of one lobe of your cortex -- either the occipital, parietal or temporal lobe -- well actually two -- the same one from both left and right hemispheres, as in both left and right parietal lobes. Unusually, you get to choose which one. Pick the lobe (left and right) you are willing to sacrifice, describe functions what you will lose and why you prefer this loss to what you would lose with the other two. Any choice is fine if justified with a description of the visual losses (see below for answer key if you based your answer on all losses that result from damaged lobe) and a rationale for the particular choice of loss. (1) Occipital: total blindness (blindsight is not really functional vision) (1) Parietal: Balint syndrome, loss of attention to more than one item but residual object identification and much restricted conscious vision. (1) Temporal: Lose object identity, conscious vision, retain where pathway to guide actions. (1) If you answered based on all functions of each lobe (we added the restriction visual functions after the exam had started), the grading is similar but for parietal you would need to add touch and for temporal auditory. 14. Using a diagram, explain how the receptive field of simple cells in V1 is made from those in LGN and show the stimulus that generates the best response from this receptive field. Diagram showing alignment of LGN receptive fields of same type (1 point) and convergence on a simple cell in V1 (1 point) and the optimal stimulus (1 point). Description, 1 points: Connect the output of center-surround cells with same preference (eg ON center) and with adjacent receptive fields that fall along a line. If a line brighter than the background (if the cells were ON center) is aligned with the centers, it will lead to maximum activity of the simple cell receiving input from these LGN cells. In other words, the preferred stimulus for this cell would be a bright bar oriented along the ON areas of those LGN cells. (doesn t have to be this detailed as long as all is correct on the diagram, if diagram and text disagree, score is based on diagram for conflicting points)
Science B44 Vision and Brain Fall 2006 Final Page 6 Best stimulus: white bar aligned with ON centers 15. Compare grand mother cell coding vs. distributed coding. Mention at least two advantages of distributed coding comparing to grand mother cell coding. In grand mother cell coding, one cell represents each face or object (1) whereas in distributed coding the pattern of activity across a population of cells represents each face or object (1). This makes distributed code more tolerant to noise and damage (in grandmother cell coding, if that cell dies, you can no longer recognize the target of that cell) (1). Second advantage: (1 point for any of), unknown targets will be still be similar (pattern of activation related to) to known ones rather than having no representation at all; distributed coding increases the capacity (like our 3 cones can represent by their pattern of activity, many more than 3 colors).
Science B44 Vision and Brain Fall 2006 Final Page 7 SECOND BOOK Put your name and student ID on a new blue book, number the book #2 and begin. You should take no more than 36 minutes to finish the multiple choice and short answer questions for this section. BOOK 2 MULTIPLE CHOICE QUESTIONS 16. Which is true: a. Human visual system cannot recover the exact wavelength distribution of colored stimuli. b. Color blind people with red cone deficiency cannot detect a red stimulus in a blue background. c. Human color vision has four dimensions: red, green, yellow and blue. d. The peak of sensitivity of rods in terms of wavelength, falls between that of the Green cones and the Red cones 17. Cortical color blindness results from damage to area a. V1 b. V2 c. V4 d. V8 18. Which of the following is not true? a. Binocular cells have receptive field in each eye. b. Zero disparity means that an image falls on corresponding retinal points c. Crossed disparity means an object is closer than the point you are fixating d. Perceived depth decrease with increasing disparity. 19. The amount of binocular disparity of an object is proportional to: a. The distance of the object from the fixation point. b. The distance of the object from eyes. c. The absolute location of the object in the space. d. The position of the object relative to the optic disk.
Science B44 Vision and Brain Fall 2006 Final Page 8 20. If people are asked to judge the size of a traffic light their estimate is very bad. What does this tell us about size perception? a. Size constancy does not exist for all objects, and thus it is not a useful cue. b. The size of an object on our retina is the most reliable cue for computing the size of an object. c. Perceived size cannot be a reliable cue if we do not have a good estimate of the distance. d. We make more size judgment errors with objects that are above the ground compared to those that are on the ground. 21. An afterimage appears larger when it is viewed against a distant surface because a. it changes its visual angle with viewing distance. b. it moves with the eyes. c. it fades with elapsed time. d. perceived size is roughly proportional to perceived distance. 22. The fact that, in the images below, the left face is recognized better than the right face is evidence for: a. modal completion b. amodal completion c. gestalt grouping d. top-down filling in
Science B44 Vision and Brain Fall 2006 Final Page 9 23. In the ambiguous image to the right, the border between the white and black surfaces is always owned by a. the figure b. the angel c. the surface seen in front d. the black surface 24. The fruit man perceived in this picture is an example of shape recognition based on: a. Distinctive features. b. Components. c. Structure. d. Shape templates. 25. If you can read the rest of this sentence it is because it deosn t mttaer in waht oredr the ltteers in a wrod are, the olny iprmoetnt tihng is taht the frist and lsat ltteer be at the rghit pclae. Which model of recognition did you use to do it? a. Shape templates. b. Geons. c. Object knowledge. d. Structure.
Science B44 Vision and Brain Fall 2006 Final Page 10 26. When you tilt a picture folded like the one shown the picture seems to distort. This does not happen when a flat picture is tilted. What does this demonstrate about our visual system? a. Tilting the folding picture creates inconsistent light sources in the image which cause distortion at different angles. b. We correct for viewing angle when looking at flat pictures c. The folds in the picture cause distortions when the picture is tilted. d. Our internal representation of space is not fully 3D. 27. As we carefully look at some paintings, we realize some inconsistencies that break the rules of physics in the paintings. What do these inconsistencies tell us? a. Our visual system does not check the consistency of all the image properties. b. Painters knew nothing about vision science. c. The visual system sometimes does not have enough information to check the consistency of image properties. d. Our visual system is fooled from time to time in real world, just as it is in the paintings. Since it is infrequent, it is not a problem.
Science B44 Vision and Brain Fall 2006 Final Page 11 BOOK 2 SHORT ANSWER QUESTIONS In your second book, write the answers to each of these questions. 28. Describe retinal and cortical color blindness and mention two differences between their symptoms: Retinal color blindness is the result of the partial or total loss of one class of retinal cones (1). Cortical color blindness results from damage to area V8 the cortical locus of color processing (1). In cortical color blindness, patient lose the subjective experience of color and the world looks black and white which is not the case in retinal color blindness where a reduced set of colors are still seen (1). In cortical color blindness the patient can perform shape and motion from color detection but not in the retinal color blindness (1). 29. Explain what Bela Julesz s experiment with random dot stereograms (showing 2 similar random patches of black and white presented to each eye) tells us about depth processing. It tells us that depth processing can precede shape analysis (2). In the RDS, there is no shape (1). However, because of the existing disparity, the disparity-defined shape can be perceived (1). 30. In class we mentioned that visual search results for the target cube with an odd orientation (see picture) showed no increase in reaction time when more distractor cubes were added to the display. How does this demonstrate that preattentive identification is not limited to properties extracted by individual cells in striate cortex (V1)?
Science B44 Vision and Brain Fall 2006 Final Page 12 First part: items that require attention for identification show an increase in reaction time with the number of distractors present as each item is identified one at a time, serially. If there is no increase in reaction time, the orientation of each cube must be identified preattentively, in parallel, all at once (1). Second part: Cells in striate cortex measure properties like the orientation of an edge, color, motion, disparity (1). Third part: The orientation of the cubes cannot be captured by any individual cell (1). Fourth part: Analysis beyond that available in individual cells of V1 must identify cube orientation in the absence of attention (1). The logic of these 4 parts can be presented in any order. The second and third part can be made in one statement if the wording of second part is measures only simple properties like..
Science B44 Vision and Brain Fall 2006 Final Page 13 THIRD BOOK Put your name and student ID on a new blue book, number the book #3 and begin. You should take no more than 36 minutes to finish the multiple choice and short answer questions for this section. BOOK 3 MULTIPLE CHOICE QUESTIONS 31. Which object feature is NOT capable of solving the aperture problem? a. corners b. line endings c. dotted textures d. edges 32. Which is NOT true: a. Motion is inferred solely from position change of objects. b. Motion can help visual system recover shape information. c. Motion can help visual system recover depth information. d. Motion direction of a line cannot be recovered through a small aperture. 33. A toddler stands in a room and the walls suddenly move forward. The optic flow would appear as though the wall in front of the child was moving her, and consequently the child would correct her posture and fall. a. away from; forward b. away from; backward c. toward; forward d. toward; backward 34. A bar is moving downward on a computer monitor. At a particular point in time, two small dots are flashed at either end of the bar, and then disappear immediately. Which one of the following is TRUE about the perceived location of the bar and the dots, at the time the dots flashes are perceived? a. The bar is perceived to lie below the dots. b. The bar and the dots are seen aligned, as they actually are. c. The bar is perceived above the dots. d. It is not possible to attend to the dots and the bar at the same time so no judgment can be made.
Science B44 Vision and Brain Fall 2006 Final Page 14 35. You need to find your car in the parking lot. For personal reasons that you do not want to share, you have a fuchsia-colored car. All the other cars in the lot are silver. To find your car you rely on which of the following types of attention? a. Orienting reflex b. Location based selection c. Attentional gaze d. Feature based selection 36. You are looking at a display where you can clearly see a set of bars but you can t count them. What could cause this problem? a. Insufficient visual resolution b. Insufficient attentional resolution c. Attentional bottleneck (capacity limited to 3 or 4 items) d. Feature integration 37. Which is NOT true about split brain patients: a. They can name objects presented to their left visual field. b. Split brain is the result of cutting corpus callosum. c. They have independent visual perception in left and right visual fields. d. They are faster than normal subjects in some full field visual search tasks. 38. Where in the brain does the lesion responsible for blind sight lie? a. Occipital cortex b. Temporal cortex c. Frontal cortex d. Parietal cortex 39. Which of the following is evidence that short-term memory is for identities, not raw shape information? a. The number of colors we can remember is about 4. b. More shapes can be stored in memory if they are familiar. c. Memory has a short duration unless information is rehearsed. d. Large changes to a scene can go undetected (change blindness).
Science B44 Vision and Brain Fall 2006 Final Page 15 40. Short-term visual memory has a capacity of about whereas long-term memory has a capacity of about. a. 4 items; 100 pictures b. 4 items; 1 million pictures c. 10 items; 100 pictures d. 10 items; 1 million pictures 41. Patient ST had a severe car accident and subsequent head trauma last year. His wife mentions a few points about his memory: When he asks the price of tomatoes from the grocer, he keeps on forgetting it a few seconds later and asks again. He has no problem remembering the events on their 20 th wedding anniversary. Where would the most likely damaged area(s) in ST be? a. Hippocampus b. Frontal lobe c. Occipital and temporal lobes d. Amygdala 42. Where are visual long term memories stored? a. Frontal lobes b. Occipital and temporal lobes c. Amygdala d. Hippocampus
Science B44 Vision and Brain Fall 2006 Final Page 16 BOOK 3 SHORT ANSWER QUESTIONS In your third book, write the answers to each of these questions. 43. Describe how the inattentional blindness experiment demonstrates priming without conscious visual awareness. Subjects focus their attention on a task to the left or right of fixation, like judging whether the horizontal or vertical bar of a cross is longer (1). When the cross appears, a word is presented at fixation the same time (1). Many subjects report seeing only the cross and not the word. This is inattentional blindness (1). Of those who did not see the word, an unusually high proportion will complete a word stem with the unseen word, indicating some processing of the word without awareness (1).) 44. Explain what visible persistence is, how long it typically lasts, and how the two images below could be used to determine the duration of visible persistence? Visible persistence: the persisting image of a stimulus after the stimulus has been turned off (1). It typically lasts 100-250 ms (1). These two images can be presented in succession with a blank screen in between that lasts for a variable amount of time (1). When the blank is shorter than the duration of persistence, the persisting image of a overlaps with and is integrated with image b, revealing the location of the missing dot. (1)
Science B44 Vision and Brain Fall 2006 Final Page 17 45. First, explain why there needs to be a language of vision. Second, describe 3 components of vision descriptions that are language-like (give a specific example of each). Vision can t send pictures or movies to the rest of the mind because then each part of the brain would have to have its own visual system. (1). Visual language has nouns (e.g., objects) (1), verbs (e.g., familiar actions) (1) and prepositions (e.g., in/out) (1). [also, could mention any of orthography, syntax, or phrase structure for 1 point each]
Science B44 Vision and Brain Fall 2006 Final Page 18 FOURTH BOOK Put your name and student ID on a new blue book, number the book #4 and begin. You should take no more than 36 minutes to finish the multiple choice and short answer questions for this section. BOOK 4 MULTIPLE CHOICE QUESTIONS 46. There are separate low-level and high-level motion systems. Which of the following is not evidence for a separate high-level motion system? a. Reverse motion, where two directions could be seen in one stimulus. b. Apparent motion over ranges too long to fall within one receptive field. c. We can perceive a walker in a simple point-light display. d. We can see motion even when the moving object is too fast to track. 47. Regarding McGurk effect, which is NOT true: a. It tells us that speech perception is affected by visual input b. When we hear a syllable, the mouth motion can affect what we perceive c. It shows that auditory and visual modalities are independent. d. It is an example of an action model overcoming contradictory information. 48. We are presented with a visual search task. The stimuli are point-light walkers, all but one is moving to the right. Regarding the stimulus, which one is correct? a. The slope for detecting the odd walker is dependent on the number of walkers. (bad wording, RT is dependent, slope is > 0) b. The target present line has a steeper slope compared to the target absent line. c. Since this task is very difficult, the data cannot verify whether identifying a walker requires attention. d. Detecting the odd walker is accomplished preattentively.
Science B44 Vision and Brain Fall 2006 Final Page 19 49. Which is NOT true about an action model: a. Action models can fill in the missing bits of actions. b. Action models can be fitted to both simple and complex movements. c. Action models are available for both familiar and novel movements. d. Action models can serve as verbs in the language of vision. 50. Mirror neurons in our motor cortex respond: a. when we execute actions and when we see others execute them. b. when we see others execute actions, but not when we execute them. c. when we execute actions, but not when we see others execute them. d. only when we execute actions at the same time we see another executing the same action. 51. The emotional valence of a scene can be determined: a. faster than identity b. equal to identity c. slower than identity d. after about 1 second of viewing 52. What is the most plausible neural mechanism underlying Capgras syndrome? a. Damage to the amygdala b. Damage of face recognition area c. Damage to connections between face area and amygdala d. Damage to the connections between long-term memory areas and amygdala 53. Which is NOT true about eye gaze: a. Human visual system has extraordinary sensitivity to other s gaze direction. b. White visible sclera helps humans in perceiving each others gaze direction. c. Eye contact is a strong signal of dominance in primates. d. Sensitivity to direction of gaze does not develop until after 1 year.
Science B44 Vision and Brain Fall 2006 Final Page 20 54. Which of the following statements about the change of the visual system during the first year after birth is FALSE? a. The eyeball and lens grow and change shape. b. Receptors mature. c. Axons sprout and connect the eye to the brain. d. Many new neurons are added to the visual system. 55. At 20 months old, infants will use cues, but they will not use cues when remembering the location of a hidden object. a. geometric; pattern/landmark b. pattern/landmark; geometric c. pattern/landmark; depth d. depth; geometric 56. You adapt 2 mo. old infants to stimulus (a) below. Then remove the occluder and show infants (b) or (c). Which of the following is most likely true? a. Infants will spend the same amount of time looking at b & c b. Infants will look longer at c because they expect the object to continue behind the occluder c. Infants will look longer at b because they are surprised that two disconnected objects are present d. Infants have cannot tell the difference between a, b and c a b c
Science B44 Vision and Brain Fall 2006 Final Page 21 57. A researcher is testing a 4 mo. old baby s visual development. The researcher presents a green truck to the infant until it looks away and records the time the infant looked. She repeats the experiment for 2 other times, and on the 4 th presentation, she shows a red version of the same truck and records the looking time until the baby looks away. The baby s looking time is as follows: 13 sec, 10 sec, 7 sec, 7 sec. which statement is correct about the name of this technique and what does the experiment tell us? a. Looking time, color vision has developed by the age of 4 months b. Habituation, color vision has developed by the age of 4 months c. Looking time, color vision has NOT developed by the age of 4 months d. Habituation, color vision has NOT developed by the age of 4 months
Science B44 Vision and Brain Fall 2006 Final Page 22 BOOK 4 SHORT ANSWER QUESTIONS In your fourth book, write the answers to each of these questions. 58. Explain why the average face is perceived more attractive? (Hint: what does attractiveness mean in evolutionary terms) The theory is that those faces are perceived most attractive are those that predict reproductive success (1). The most successful is the most frequent. The average face is closest to representing the average value of all the most common (frequent, successful) traits (1). The one face that is closest to the average of all faces in the population has a good chance of having all the most successful genes (to the extent they are represented in the face) and so is the best bet for successful offspring (2). 59. Infants develop an understanding of how objects move at a very young age. Describe the tubes experiment and how it provides evidence that infants inappropriately apply their model of gravity up to the age of 2½. The tubes apparatus has several holes at the top and bottom and a tube that connects one of the top holes to any cup at the bottom including ones that are not directly below (1). When a ball is dropped in a hole at the top, infants expect the ball to land in the cup directly below (1) showing that toddlers at 2 1/2 years of age have a model of gravity (1) but that it is overapplied because they do not take into account the fact that the tube must take the ball to another cup (1). 60. These two figures represent the range of orientation preferences of individual cells recorded from the cortex of kittens raised in striped environments. (a) Identify which pattern (left or right) is found after the kitten is reared in a horizontally striped environment. (b) What can you conclude from this experiment?
Science B44 Vision and Brain Fall 2006 Final Page 23 (a) the left hand pattern of orientation preferences will be found after a kitten has been raised in an environment with only horizontal stripes. (2) (b) The experiment supports the conclusion that the visual system develops to respond to the environment it experiences. (2)
Science B44 Vision and Brain Fall 2006 Final Page 24 FIFTH BOOK Put your name and student ID on a new blue book, number the book #5 and begin. You should take no more than 36 minutes to finish the multiple choice and short answer questions for this section. BOOK 5 MULTIPLE CHOICE QUESTIONS 61. occurs when the focal point falls beyond the retina. a. Myopia b. Hyperopia. c. Cataracts. d. Macular Degeneration. 62. Which of the following is not true? a. For amblyopia, patching the weaker eye will restore binocular cortical cells b. The visual cortex of blind individuals can be recruited for tactile perception c. Reading in dim light can cause myopia in young children d. Blindness is a term legally applied for 20/200 vision. 63. Which of the following is not an optical problem: a. Macular degeneration. b. Cataract. c. Scarred cornea. d. Hyperopia. 64. What is true about patients with restored sight: a. surgery after age 15 produces best outcome. b. good motion perception. c. good depth perception. d. no color perception.
Science B44 Vision and Brain Fall 2006 Final Page 25 65. Visual agnosia results from damage to, resulting in an inability to. a. the ventral pathway; recognize objects b. the ventral pathway; perceive objects c. the dorsal pathway; control hand movements d. the dorsal pathway; report object orientation 66. Which of the following is true. a. Balint s Syndrome patients can only attend to one object in each visual field. b. Visual Agnosia results from damage to the temporal lobe. c. Neglect patients cannot attend to objects on the same side of visual space as their lesion. d. Prosopagnosia can result from damage to the temporal lobe. 67. Following is a drawing of a clock by a patient. Where would you localize the lesion? a. Dorsal stream, left side b. Ventral stream, left side c. Dorsal stream, right side d. Ventral stream, right side 68. Which of the following patients would most likely have damage restricted to parietal lobe? a. Visual agnosia b. Contralateral neglect c. Prosopagnosia d. Blindsight
Science B44 Vision and Brain Fall 2006 Final Page 26 BOOK 5 SHORT ANSWER QUESTIONS In your fifth book, write the answers to each of these questions. 69. Why is it interesting that line drawings can portray objects and scenes so convincingly? Is the effectiveness of line drawings a consequence of our culture or our physiology? Why do they work? Interesting because there are no lines around objects in the real world but line drawings still work (1). They work for babies, all cultures, and some non-human animals, so it is physiology not culture (1). They work because lines carry the key information for shape and layout (1). They work because the receptive fields that respond to the edges of real objects also respond to lines (1). 70. A vision researcher claims that faces are a particular kind of objects and thus face processing is not different from object recognition. Using patient evidence, falsify his claim. The evidence against this claim is a double dissociation between face processing and object recognition. Patient CK has agnosia without prosopagnosia and can recognize faces but not objects (2), whereas patients with prosopagnosia have no problem in object recognition but cannot recognize faces (2). 71. Choose one of the three debate questions below. Present arguments for both sides that were discussed during our last lecture and explain which side you favor. a. Vision develops only because of experience with the visual environment vs Much of vision is innate b. Receptive fields can explain everything vs Some aspects of vision, like amodal completion, cannot be explained by receptive fields c. Conscious vision is merely a witness of our behavior not the agent. vs Visual attention and awareness guide our decisions. Full marks for an answer that listed three reasonable points in favor of each side and made a choice of one side or the other.