Myers’ PSYCHOLOGY (6th Ed)

Myers’ PSYCHOLOGY (6th Ed)
Chapter 6 Perception James A. McCubbin, PhD Clemson University Worth Publishers

Selective Attention

Perception Selective Attention
focus of conscious awareness on a particular stimulus The appearance of the graphic on this slide allows for different perceptions. The blue circles can be organized into several different images, each of which are possible. Although you can see different interpretations of this graphic, you can see only one interpretation at a time. This ability to see only one image at a time indicates that our conscious attention is selective. Selective attention means that at any moment we focus our awareness only on a limited aspect of all that we are capable of experiencing. It is the focusing on one thing more than others.

Cocktail Party Effect The cocktail party effect is another example of selective attention. It is the ability to attend selectively to only one voice among many. The most well-known example of selective attention occurs when someone is concentrating on one particular conversation amidst a large amount of background noise, some of which may actually be louder than the conversation being attended to. Have you ever tried to talk to two people on two separate phones at the same time--a cell phone and a regular phone? When paying attention to what is being said on the regular phone by friend A, you won’t perceive what is being said to you on the cell phone by friend B. If you are later asked what friend B said to you on the cell phone, you may draw a blank.

Cocktail Party Effect well-known example of selective attention which occurs when someone is concentrating on one particular conversation amidst a large amount of background noise

Testing Selective Attention
Selective attention applies to all of the senses. Neisser and Becklen and Cervone demonstrated this dramatically. They showed people a one minute video tape in which the images of three men in black shirts tossing a basketball were superimposed over the images of three men in white shirts doing the same thing. They asked the viewers to press a key every time the black-shirted player passed the ball. Midway through the tape, a young woman carrying an umbrella sauntered across the screen. Most had focused their attention so completely on the black-shirted players that they failed to notice the woman. Neisser (1979); Becklen and Cervone (1983)

Selective Attention--Visual Stroop Effect
*Classic Stroop task (1935): slower to name color when word says a different color than to name the color of a colored square *Why does this happen? --reading is an automatic process --color naming is a controlled process --automatic process of reading interferes with our ability to selectively attend to ink color The Stroop Effect is normally demonstrated using color names. Two sets of color names (orange, red, blue, etc.) are written on cards. One set is written in the appropriate color for the word, while the other set is written in a different color (e,g, ‘orange” is written in green ink). On being asked to identify the colors in each list, research participants take longer to process the informaiton on the cards which contain the discrepant informaiton. Reading the color name occurs and an automatic cognitive sub-routine which interferes with the recognition of the color itsef.

For example, for the word, RED, you should say "Blue."
The famous "Stroop Effect" is named after J. Ridley Stroop who discovered this strange phenomenon in the 1930s. Here is your job: name the colors of the following words. Do NOT read the words...rather, say the color of the words. For example, for the word BLUE, you should say "RED". Say the colors as fast as you can. It is not as easy as you might think! WHY? The words themselves have a strong influence over your ability to say the color. The interference between the different information (what the words say and the color of the words) your brain receives causes a problem. There are two theories that may explain the Stroop effect: Speed of Processing Theory: the interference occurs because words are read faster than colors are named. Selective Attention Theory: the interference occurs because naming colors requires more attention than reading words. For example, for the word, RED, you should say "Blue."

Volunteer to Run the Stroop Test
Take the Stroop Test How did YOU do? MY Results: 1st Test: seconds 2nd Test: seconds That is more than double the time to read the “confusing “ words!! If you're like most people, your first inclination was to read the words, 'red, yellow, green...,' rather than the colors they're printed in, 'blue, green, red...' You've just experienced interference. When you look at one of the words, you see both its color and its meaning. If those two pieces of evidence are in conflict, you have to make a choice. Because experience has taught you that word meaning is more important than ink color, interference occurs when you try to pay attention only to the ink color. The interference effect suggests you're not always in complete control of what you pay attention to.

Perceptual Illusions

Perceptual Illusions Psychologists have always been fascinated with illusions. Illusions reveal the way we normally organize and interpret our sensations. Illusions occur when we perceive something inaccurately. In a way, they are misperceptions. Consider this illusion, the Muller-Lyer illusion. Does either line segment AB or BC appear longer? To most, the line segments appear to be the same length. Line AB is a full one-third longer than line BC. Our eyes are deceived because of a concept known as size-distance relationship.

Muller-Lyer Illusion Experiment
ACTIVITY Student volunteer needed to test your ability to click on the exact center of a horizontal line segment Go to Muller-Lyer Illusion Experiment This experiment is concerned with your judgment of where the midpoint of a horizontal line is. You will be presented with 20 arrows, one after another. For each you must try to click on the exact center of the horizontal line section. Try to imagine the arrowhead is not there and just click on the centre of the line. Afterwards you will be shown your results in a chart.

As you can clearly see from this animation, the arrows affect the perceived length of the line.

Size Distance Relationship Explanation
There are about 12 different explanations for the Muller-Lyer illusion. The most popular explanation of the Muller-Lyer illusion is that our brain makes mistakes about the relative depths of the two lines. We are used to seeing outside corners of buildings with lines sloping inward away from them. In these situations, the brain knows that the line running down the outside corner is the closest part of the image to us. The brain realizes that this line is really shorter than it appears when compared to the rest of the building. We are also used to seeing the inside corners of rooms with the lines of the roof and floor sloping outward away from them. In these situations, the brain knows that the corner is the furthest part of the image from us. The brain realizes that this line is really longer than it appears when compared to the rest of the room. When the brain compares lines from these two situations to each other, it reduces the size of the line with the inward sloping tails (the corner of the building) because it thinks this line is closer to us. It increases the size of the line with the outward sloping tails (the corner of the room) because it thinks this line is further away. This makes the line with the outward facing tails look longer. You often see this same depth trick used in paintings. By drawing lines that all slope up or down from corners, people get the impression of depth. The more distant line (i.e. inside corner) is perceived as longer.

Hermann Grid Illusion Stare at the middle of picture with black squares seconds. Are those really dots that appear at the corners of the squares? What happens if you focus on a dot? Now look at the middle of the picture with the white squares. Do you see dots again? What color are they? This figure is called the Hermann grid and the dark blobs can be explained by reference to receptive fields and lateral inhibition Your retina is partially composed of many small nerves, which function as receptors of light. These receptors are arranged in rows on the inside of your retina. A number of scientists have shown that it is possible to illuminate and record from a single receptor (A) without illuminating its neighboring receptors. It was discovered that if you illuminate a single receptor (A) you will get a large response; however, when you add illumination to A's neighbors, the response in A decreases. In other words, illumination of receptors "inhibits" of firing of neighboring receptors. This effect is called lateral inhibition because it is transmitted laterally, across the retina, in a structure called the lateral plexus. In the case of the Hermann grid, there is light coming from the four sides of the intersection, but from only two sides of a band going away from the intersection. The region viewing the intersection is more inhibited than the region of the band going away. Thus the intersection appears darker than the other section. You see dark spots at the intersections of the white bands, but not at the points away from the intersections. The effect is greater in your peripheral vision, where lateral inhibition acts over greater distances.

How Many Black Dots Can You Count?
Here’s another variation. On-off response of rods and cones to photons of light gets translated into conscious perception of visual images. The mechanistic basis for the Hermann grid illusion is believed to lie in the way retinal receptive fields respond to stimulation of their centers and lateral surrounds. In these grids, you can see small grey dots bouncing around in the intersections of the gridlines, except at the grid intersection which you are actually looking at. The dots appear to move because as you move your eyes, the one you try to look at disappears, whereas the one you were looking at reappears. The reason the dots disappear and reappear is that when you look directly at something, you point your most sensitive vision in that direction, so that you gather information with finer resolution. Everything in your peripheral vision is summed more coarsely, so that at the grid intersections, the surrounding colors differ to those along the grids.

Perceptual Illusions The distorted room seen above is named after the American ophthalmologist Adelbert Ames, Jr., who first constructed such a room in He based his design on a concept originally conceived by Hermann Helmholtz in the late 19th century. The first illusion is a result of looking through a special viewing point with one eye and a stationary head. Looking through this peephole removes any cues from stereopsis and makes the room appear normal and cubic although it's shape is actually trapezoidal, the floor is actually on an incline and the walls are slanted outward. The true shape of the room can be seen when not viewing the room through the peephole or when looking at it from a top view. The second illusion is that objects in the room appear to shrink or grow depending on where they move in the room. This special shape of the room removes all distance cues and does not allow for proper scaling of object size. A consequence of this is that we see people or objects as the same size as their retinal image. This room makes the transformation of objects that appear in it to seem impossible. The angle that at which an object appears impossible is called the Ames Transformation and in this example the Ames transformation point would be the peephole. We get a retinal image of a “normal room” despite its distorted shape.

Perceptual Illusions This ripple effect is created from a flat, two-dimensional drawing. Our brain does not allow us to perceive it as flat. The ripple illusion is in part an assumption about light sources.

Stare at the image below and slowly move your head toward and away from the screen.
Here’s another variation of the ripple effect. You should notice what appears to be 3D waves emerging from the flat surface.

Ripple Stare at the image for a while and you will begin to notice bumpy ridges appearing within the image.

Pinna-Brelstaff Illusion
Focus on the star in the center of Figure A. Slowly move your head toward the page, then away from it. The rotation you perceive is called the Pinna-Brelstaff illusion. Vision researchers Baingio Pinna and Gavin Brelstaff theorize that illusory rotation arises from the brain's strategy of making certain neurons responsible for detecting both the orientation and the direction of movement of visual lines and curves Neurons in the visual cortex of the brain are organized into subgroups, each of which responds best to lines oriented at a specific angle. (Remember the Hubel & Wiesel feature detectors cat experiment?) Neurons that "prefer" the particular angle of an object viewed at any given moment are more active than those preferring other orientations. A subgroup of visual neurons gets most excited when a line with a preferred orientation is in motion and the direction of that motion is at a right angle to the line's orientation Just as the brain determines the orientation of objects by "looking" at which groups of orientation-selective neurons are active, it also assesses the direction of motion of objects by the activity of those same nerve cells. This doubling up of orientation and motion detection works great if a line is moving at right angles to its orientation, but if the line is moving in any other direction, the brain gets confused When you move your head toward Figure A, both circles appear to expand. Each bar slides outward across your retina, stimulating cells tuned to that bar's particular tilt. Because those cells are doing double duty, the stimulation convinces them that the bars are moving in a perpendicular direction as well. The two motions, added together, create an illusion of circular motion. Figure A's inner circle appears to move clockwise. The reverse tilt of the bars in the outer circle of Figure A makes it appear to move counterclockwise. When you move your head away from the page, both motions reverse direction, reversing the direction of the illusion.

Ebbinghaus Illusion The central circles have the same size. You wouldn't say so because your perception is being influenced by the surrounding circles. This is called the Ebbinghaus illusion or the Titchener illusion and is only one of many examples where the physical size does not correspond to the perceived size.

In the middle are some red lines
In the middle are some red lines. If black lines are added to them then you see, in addition to the red lines, a glowing red disk. (It looks like a light red spinning disc that is in the center.) A photometer (a device which measures light) would not detect the red disk that you see. That red disk is entirely created by your visual system.

Visual Illusions--Attention
Count the number of F's in the text below: FINISHED FILES ARE THE RE- SULT OF YEARS OF SCIENTIF- IC COMBINED WITH THE EXPERIENCE OF YEARS.

How many F's did you count? Three? WRONG ANSWER !
There are six F's in the text. Take a look: FINISHED FILES ARE THE RE- SULT OF YEARS OF SCIENTIF- IC COMBINED WITH THE EXPERIENCE OF YEARS. The explanation is: The human brain pays little attention to words that are not very important for understanding the sentence, like the word 'OF'. Moreover, the fact that the sentence is written in capital letters makes it harder to distinguish the F's. If you counted the correct number of F's you are very special. (It is also possible that you stared at your screen for a very long time.)

Impossible Figures

What’s wrong with this picture?
This is another example of an impossible figure. Recall we looked at a picture of the devil’s fork in our unit on human development. We perceive this figure as a whole though impossible figure. This is the Gestalt principle of grouping at work. But this figure doesn’t necessarily have to be a whole, as we’ll see from the Discovering Psychology video segment on Sensations & Perceptions. There is a good example in the video of an impossible figure. Show: Discovering Psychology—Sensation & Perception.

Here’s a good example of the grouping principle at work
Here’s a good example of the grouping principle at work. This picture is in your text on page Take a look at figure Then turn over to page 225 for the explanation.

What’s wrong with this picture?

Count the elephant’s legs

Impossible Dinosaur

Impossible Dog Here’s an impossible dog for the impossible dog house.

Variation of Devil’s Fork

This is an impossible construction
This is an impossible construction. Look closely at the lowest fist : it's a mother with a child in her arms ! It’s titled, “Violence and Softness.”

There are two ways to see a line drawing of a cube
There are two ways to see a line drawing of a cube. Sometimes one face of the cube looks like it is at the front, and then the same face appears to be at the back. This is called a reversal. Notice how the cube reverses each time a block goes through it. This is because the block has depth cues which force a particular depth view to emerge.

Relativity by Escher

Try to count all impossible figures in this magazine cover

Ambiguous Images

Slave Market With the Disappearing Bust of Voltaire
Salvadore Dali, the famous surrealist is well known for painting bizarre landscapes with 'rubber' clocks dripping from tree branches. Dali, the artist, also experimented with ambiguous forms. Here he uses several design elements to form an ambiguous cameo of the French philosopher François Voltaire.

Artist: Canu (1815) Violets With Hidden Profiles
This picture contains the profiles of Napoleon, his wife Josephine and their son. Can you find all three? The print shown is from an engraving by Canu in Copies were circulated among the supporters of the exiled Emperor. They would toast, "Corporal Violet." Artist: Canu (1815)

Which direction is the window facing?

Perceptual Organization:
Form Perception Depth Perception

Perceptual Organization- Gestalt
Visual Capture tendency for vision to dominate the other senses Gestalt- an organized whole tendency to integrate pieces of information into meaningful wholes Vision is our most dominant sense. When vision conflicts with other sensations, vision usually prevails—a phenomenon called visual capture. We are more likely to believe with our eyes than our other senses when there is a conflict. If you recall our study of perspectives in psychology, you may remember that Gestalt psychology had its most lasting impact in the area of perception. Gestaltists were intrigued with how the mind organizes sensations and perceptions. It is the brain’s tendency to perceive the whole from its parts. “The sum of the whole is more than its parts.” When we are given incomplete perceptual information, we tend to organize it so that it makes sense. We interpret things the way they should be, not the way they really are.

Perceptual Organization- Illusory Contours

The illusory square appears to move from one position to the other
The illusory square appears to move from one position to the other. Below are the two image frames used to create the illusion of motion. The motion is induced by swapping quickly between the two frames. The squares themselves are also an illusion, as they have no real boundaries, but are mentally constructed from interpolating between aligned boundaries.

Form Perception

Perceptual Organization- Gestalt
Grouping the perceptual tendency to organize stimuli into coherent groups Grouping Principles proximity- group nearby figures together similarity- group figures that are similar continuity- perceive continuous patterns closure- fill in gaps connectedness- spots, lines and areas are seen as unit when connected Gestaltists identified principles by which we organize our sensations into perceptions. They found that we use certain perceptual cues to make sense of things. One such cue is similarity, in which we group like things together. We’ll look at visual examples of each of these principles in a minute. For example, organization might be based on similarity of color. Using the perceptual cue of proximity, we group things together that are near one another. It means that objects can be perceptually organized according to their spacing. Another process is called closure. Here, we fill in or close the details that aren’t there to complete the picture. Using edges and other cues, we fill in what’s missing. With continuity, we perceive smooth, continuous lines rather than discontinuous ones.

Perceptual Organization- Grouping Principles
If you look at the area of the slide labeled continuity, our tendency is to perceive the object as a wavy and a straight line rather than as a series of alternating half-circles. With proximity, because certain lines are closer to each other than others, we consider them a set or grouped together. With similarity, we perceive this image as columns of triangles and circles rather than as rows containing two triangles and one circle. With connectedness, where objects are uniform in size and linked, we perceive spots and lines as a single unit.

Form Perception: Figure and Ground
The terms figure and ground explain how we use elements of the scene which are similar in appearance and shape and group them together as a whole. We first try to separate any object, called the figure, from its surroundings, called the ground. Similar elements (figure) are contrasted with dissimilar elements (ground) to give the impression of a whole. Do you see the white horses and riders? Now look for the black horses and riders!

Perceptual Organization
Figure and Ground organization of the visual field into objects (figures) that stand out from their surroundings (ground) The figure-ground relationship continually reverse—but we always organize the stimulus into a figure against the ground. Is this graphic a vase, or profiles of a younger Prince Philip and Queen Elizabeth? With a reversible figure illusion like this one, the brain is doing the best it can with an ambiguous figure, wanting to make sure it doesn’t miss something important.

Two Color Tools Two-Color Tool Set
There is a neatly engineered ambiguity between foreground and background in this figure. The tools are both dark and light colored, and they are all neatly packed together. How many tools are there in all, both light and dark? 20. Can you find them all?

Camouflage: Breakdown of Figure-Ground Relationship
A breakdown of figure and ground occurs with camouflage, where the objective is to make the figure so much like the ground that it disappears from view. Notice the painting of the bird below. Only with great difficulty can you separate the bird from the log it is perched on. Figure and ground have merged together.

M. C. Escher Do you see white birds or black birds? This is another drawing by M.C. Escher. He did the black knights/white nights drawing we saw a few slides back.

Law of Common Fate Another principle, the law of common fate , states that when objects move in the same direction, we tend to see them as a unit. When dots 1, 3, and 5 move up and dots 2, 4, and 6, move down at the same time, the dots moving in the same direction are perceived as a group.

Proximity The principle of proximity or nearness enables us to group what we see according to their closeness. Visual stimuli that are close together are grouped together. In a figure below, the circles are seen as arranged in pairs.

Perceptual Organization- Grouping Principles
Gestalt grouping principles are at work here. We’ll come back to this image later when we talk about impossible figures.

Depth Perception

3D Vision—A Function of Depth Perception
Depth perception is difficult because we have access to 2-D images Cue—stimulus characteristics that influence our perceptions One of the major questions perception researchers have tried to answer is: how do we perceive the three-dimensional properties of the world when the images on our retinas are only two-dimensional? Depth perception is difficult because we have access to 2-D images. We are able to see in 3-D because the visual system can utilize depth cues that appear in the retinal images. We are able to see in 3-D because the visual system can utilize depth cues that appear in the retinal images.

Perceptual Organization-Depth Perception
ability to see objects in three dimensions allows us to judge distance Binocular cues retinal disparity images from the two eyes differ closer the object, the larger the disparity convergence neuromuscular cue two eyes move inward for near objects Depth cues are usually divided into two kinds: binocular (meaning using two eyes) and monocular (meaning using one eye). Whenever we are not focusing on an object, the image of that object falls on two different points of the two retinas. The amount of disparity (difference) between the two retinal images can be used as a cue for distance. Because the two eyes converge on an object when we are viewing it, the brain can use the angle of convergence as a cue to how far away that object is. For example: The larger the angle, the nearer the object.

You might recall the Gibson & Walk (1960) experiment that we talked about in our unit on human development. They placed 6- to 14-month old children on the edge of a visual cliff. Their mothers then coaxed them to crawl out onto the glass. Most refused to do so, indicating that they could perceive depth. Perhaps by crawling age the infants had learned to perceive depth. Yet newborn animals with virtually no visual experience—including young kittens, a day old goat, a newly hatched chicks, respond similarly. Each species, by the time it is mobile, has the perceptual abilities it needs. Visual Cliff

Development of Depth Perception
*Walk and Gibson (1961) found that all of the 6- to -14 month-old infants tested refused to crawl over the deep side to their mothers. --When their mothers stood on the shallow side, the babies did crawl to them. --Thus, 6 months old perceive depth *Infants younger than 6 months cannot crawl so they were placed on one side or the other and heart rate was monitored --Those on the deep side had a slowing HR (typical reaction when orienting self to new situation) --Babies didn’t know how to react, but they did know that something was different on the deep side Thus, biological maturation predisposes our warness of heights. Experience amplifies it.

Binocular Cues Monocular depth cues, as we’ll see in a minute, allow us to see in 3-D with the view of only one eye, but our best depth perception occurs if we look through both eyes. This is because our right and left eyes see a slightly different view of the world. This difference between the image in the two eyes is known as binocular retinal disparity.

One binocular depth cue is retinal disparity
One binocular depth cue is retinal disparity. The relative position of objects on the two retinas depends on their distance from us. Nearby objects have much more different relative positions than do distant objects, and that gives us a clue to their relative distances from us. This is because our eyes see objects at different angles. The images received by the two eyes, located at slightly different points in space, are disparate. The degree of disparity provides a basis for the judgment of distance. Did you ever have a Viewmaster when you were little? Children's Viewmasters produce a three-dimensional image that has depth because of a slightly different picture that is delivered to each eye. Binocular stereopsis is the perception of depth based on retinal disparity.

Stereograms—3D Images Bring the image up close to your face without attempting to focus. Slowly move away from the image and keep your eyes relaxed. Before you reach arms length, a picture should jump out at you. Hold the image about arms length in front of you but focus on something behind it. Shift your field of vision to the image without shifting focus. The image should be apparent if your focus is correct. Several of our pictures have 2 black dots near the bottom. If you stare at them and relax your eyes, you should see 4 dots. If you can bring the 2 middle dots together so you see 3 dots, the image will be in focus. Put reflective glass in front of the image and focus on your reflection. At the proper distance, this should allow you to see the 3d object. Some people see the 3d picture very quickly, others may need to spend awhile practicing before seeing their first stereogram. Still others never see the image. If you are having difficulties, remember to be patient. If you know of someone who can see the images, ask for advice. There are a lot of different tricks people use to see the images. Seeing the 3d object for the first time can be surprising. You don't expect to see something stand out from the page. Good luck! Explain that these directions apply to the stereogram on the next page. There is also one for students to try on page 217 of their text. I could never see the 3D image in any of these!

After several minutes, click mouse.
Pink man graphic will appear. This is supposed to be what student see in 3D on the stereogram.

Try this one. Click. Students are supposed to see the helicopter.

Monocular Cues Monocular cues are cues that allow us to see depth with one eye only. That is why a person who has sight in only one eye can still see depth.

Monocular Cues relative size smaller image is more distant interposition closer object blocks distant object relative clarity hazy object seen as more distant texture coarse --> close fine --> distant We’ll look at visual examples of each of these monocular cues in just a moment. Common monocular cues are relative size which means that a larger object is perceived as closer and a smaller object as further away. With interposition, an object seems closer if it partially blocks the view of another object. With relative clarity, we perceive hazy objects as further away and clearer objects as closer. With texture gradients, a change from a distinct texture to an indistinct texture indicates increasing distance of the object. Other monocular cues include relative height or height in field, where an object that is higher in a two-dimensional plane is seen as farther away; and shading or shadowing, where an object gains depth if it’s appropriately shaded around the edges. The Ames Room that we talked about earlier is an example of the use of a monocular cue. It is designed so that monocular cues give the illusion that two people are equally far away.

Relative size is the first of our monocular depth cues. If two objects are similar in size, we perceive the one that casts the smaller retinal image as farther away. Relative Size

Here’s another example of relative size
Here’s another example of relative size. When similar objects cast different sized images on the retina, we are generally correct in assuming that the ones casting the smaller images are more distant than those casting the larger images.

All soldiers are the same size. This is a distortion of perspective.

Interposition Interposition (or partial occlusion) happens when objects are overlapping. The object that is partially covered by another one appears to be in the back. For example, the blue star is in front of the pink bar, while the yellow moon is not. We know that because the yellow moon is partially covered by the pick bar and the pink bar is partially covered by the blue star.

Thus, if one object partially blocks our view of another object, we perceive it as closer. Here, the smaller deer is closer than the larger deer.

This is also an impossible figure but our text uses it to illustrate interposition. This painting purposely confuses figure and ground relationship by interposition of the trees. Artist: Rene Magritte

Perceptual Organization—Depth Perception
Texture gradients also show depth. Close objects are farther apart and have larger grains. Far objects are closer together and have small grains. Objects further away appear smaller and are more densely packed. Texture

This is a really good example of texture as a monocular depth cue
This is a really good example of texture as a monocular depth cue. When we look at any textured surface, the elements comprising the texture appear smaller and denser as the distance increases. Texture gradients, together with linear perspective, are used a lot in artwork. Textural changes give us such a strong cue about what we see.

Monocular Cues (cont.) relative height higher objects seen as more distant relative motion (motion parallax) closer objects seem to move faster linear perspective parallel lines converge with distance relative brightness closer objects appear brighter These are additional monocular depth cues that we’ll look at examples of in a moment.

Relative Height The vertical position of an object in the image, or height-in-field, is another cue which we use to determine depth. Objects placed higher in a picture appear to be farther away. Our normal visual field extends from the ground just ahead of us to the sky above and ahead of us. The horizon is about midway in the field, and objects move towards the bottom of the field as they become closer. Thus far-away objects are higher in our visual field than closer objects. We extend this to pictures, and thus get the height-in-field effect. Take a look at this animation. It starts with six objects at the same level of the illustration and they look to be at the same distance. Then they move; three go above the horizon line and three below the horizon line. At the end the two star-like objects are nearest to the horizon line and look the farthest away. The two circles are farthest from the horizon line and appear nearest.

The relative height cue can lead to a powerful sense of depth as seen in this landscape by Eugene Boudin called "The Coast of Protrieux". The coast near is at the bottom of the slide and as it recedes in distance it gets ever higher. As there are not any objects, nor any interposition, nor any real strong texture, the primary cues to depth being used in this picture is relative height. When the object is in the sky, like the clouds in "The Coast of Portrieux" above, then the effects of relative height are reversed. Here lower indicates farther away. The general rule is that the closer to the level of the horizon, usually near the middle, the farther away the object appears.

This painting is an example of linear perspective. Parallel lines, such as railroad tracks, appear to converge in the distance. The more the lines converge, the greater their perceived distance. This painting makes effective use of several distance cues, such as texture gradient, interposition, linear perspective, relative size, and relative height. Perspective Techniques

Linear perspective (often referred to only as perspective) is one of the most often used in two-dimensional artworks to give the perception of three dimensions. According to linear perspective, far objects are systematically smaller in size than nearer objects. Thus, for example , the road appears to converge at a point called the vanish point.

Monocular Depth Cues—Light and Shadow
The use of shading produces a sense of depth consistent with an assumed light source. Gaussian blurring provides the illusion of depth in the figures above. The first, nonblurred figure appears flat while the others show some depth. Look at the images with both eyes and then with each eye. Does blurring provide a monocular or binocular cue to depth? (Monocular) Also, nearby objects reflect more light to our eyes. Thus, given two identical objects, the dimmer one seems farther away. Compare the figures on the various backgrounds. Does the illusion of depth appear equal for all figures or is it enhanced by some backgrounds?

Motion Perception

Motion Parallax Cue to distance in visual perception, which depends upon the fact that when the perceiver is in motion, objects which are at a greater distance appear to move more slowly than objects that are more nearby. Motion parallax is another monocular depth cue. Motion parallax is the apparent relative movement of objects in the visual field, which occurs when the person doing the perceiving moves around. Objects in the foreground seem to move more than objects in the background, so that when a perceiver moves, such objects appear to change their relative position in the visual field. Most of you have experienced this phenomenon. For example, if your sitting on a plane at the gate and your plane is backing out and you fix your gaze on some object, say another part of the airport terminal, object between you and the terminal also appear to move.

Two objects that move the same distance...
have different apparent motions. As this animation demonstrates, our field of view widens at a distance. Apparent motion is the ratio of movement distance to field of view: The greater the distance, the wider the field of view, and the smaller the apparent movement. In this figure, we see the angle of distance is greater for the green spot than the blue spot, even though their motion is the same. Everyone would agree that the green dot is closer to us. You saw it moves in a wider angle that did the blue dot, assuming both were moving at the same speed. As we move, objects that are closer to us move farther across our field of view than do objects that are in the distance. Thus, the nearer the object, the faster it seems to move. Although our animated graphic shows the points in motion, it works out just the same if the observer moves and the points are fixed. As Einstein pointed out, its all relative.

The perceived direction of a moving object in your field of view is dependent on its proximity to you. For example, if you fixate on an object, and you turn your head, any thing in front of your fixation point will appear to move in the opposite direction that your head is turning. Anything beyond your point of fixation appears to move in the same direction as your head. Motion Parallax

Hey. Try this: 1) Give a thumbs-up. 2) Close one eye - any eye will do
Hey! Try this: 1) Give a thumbs-up. 2) Close one eye - any eye will do! 3) Fixate on your thumb while turning your head to the left. You will notice that your thumb and anything in front it appears to move to the right, while anything behind your thumb moves to the left.

Stroboscopic Movement
The illusion of movement created by a rapid succession of stationary images Example: an animated cartoon (series of cells flashed)

Phi Phenomenon An illusion of movement created when two or more stationary lights separated by a short distance blink on and off at short intervals Example: marquees and holiday lights

Perpetual Constancies

Perceptual Constancy Perceptual Constancy
perceiving objects as unchanging despite changes in retinal image color shape size Perceptual constancy enables us to perceive an object as unchanging even though the stimuli we receive from it change. Thus, we can identify objects regardless of the angle, distance, or illumination by which we view them. There are many forms of perceptual constancy, of which the most studied have been size constancy, shape constancy, color constancy, and location constancy. Here, the door is recognizable as a door despite its orientation. The door is still a rectangle despite the increasing trapezoidal image it creates on our retinas.

Perceptual Organization
Although the monsters in figure A cast the same retinal images (they are the same size), the linear perspective tells our brain that the monster in pursuit is farther away. Because something further away should be seen as smaller, the fact that this monster is bigger tells us it is meant to be perceived as a bigger monster. The image to the right is an example of the “Ponzo Illusion.” The distant red line appears larger than the closer red line.

Ponzo Illusion In these images, the lines appear to be different lengths through being presented with conflicting information about depth. The converging lines indicate that the top line is farther away than the bottom line. This is another example of the Ponzo illusion.

This animation shows you better that the two lines are in fact the same size.

Perceptual Organization-Muller-Lyer Illusion
Richard L. Gregory (1968) suggested that the corners in our rectangularly carpentered world teach us to interpret outward or inward pointing arrowheads at the ends of a line as a cue to the line’s distance from us and so its length. The red line at the ticket booth appears shorter to us than the red line in the corner of the room but if we measure them we find they are the same length. If we replace the arrowheads with circles, we still get much the same effect. This illusion is apparently cultural because it’s not present in cultures that live in round houses, for example, the Zulu of Africa.

Perceptual Organization-Brightness Contrast
Although the interior rectangles are in fact identical, we perceive the right one as lighter because of the contrast with its darker background.

You can see the brightness contrast effect better here.
Contextual effect In the figure on the left you see two alternating frames. Note that the central rectangle within the dark surround looks brighter than the rectangle within the bright surround. But in both frames the central rectangles have exactly the same intensity. In this example the perceived brightness does not simply correspond to the physical intensity and is influenced by the context. Let’s try the same effect but with colors on the next slide.

The two blue panels above are the same blue (according to a spectral photometer). However they are not the same blue to you. This is an example of how you construct the colors that you see. Color is not simply surface reflectance, or surface reflectance as filtered through your three cone systems. Color is a complex construction of your visual intelligence that is not yet well understood.

The red is the same color in each stripe.

Perceptual Interpretation

Mental Blindness: Sensory Deprivation and Restored Vision
When animals or infants are deprived of sensation at critical stages of development, they may never develop normal abilities. For example, some people born with cataracts (clouded corneas), never learn to use their vision once they receive corneal transplants. There have been a number of clinical studies of adults who have had cataracts removed and their vision restored. Although blind at birth, they later regained their sight. After the surgery, the patients could distinguish figure from ground and could sense colors—suggesting these aspects of perception are innate. But the formerly blind patients often could not recognize by sight objects that were familiar by touch. Researchers have conducted experiments on sensory deprivation on kittens and monkeys. In one experiment, they outfitted them with goggles through which the animals could only see diffused light, unpatterned light. After infancy, their goggles were removed and the animals showed perceptual limitation much like adults born with cataracts. The results of visual experiments with cats, monkeys, and humans suggests that there is a critical period for normal sensory and perceptual development. Lacking visual stimulation, the cortical cells had not developed normal connections. Although their eyes still functioned normally and their retinas were able to relay signals to their visual cortex, they nonetheless remained functionally blind to shape. Nurture shapes what nature has endowed.

Sensory Restriction- Blakemore & Cooper, 1970
Kittens raised without exposure to horizontal lines later had difficulty perceiving horizontal bars.

Development of Perception
Experiments with kittens have demonstrated that the kinds of visual stimulation received during infancy can affect visual functioning. Blakemore and Cooper (1970) One group of 2 week old kittens put in cages covered with vertical black and white stripes. One group of 2 week old kittens put in cages covered with horizontal stripes After 5 months, both groups of kittens showed permanent visual defects, including clumsy movements and the inability to perceive objects properly.

Kittens raised in horizontally striped cages ignored vertically oriented objects
Kittens raised in vertically striped cages ignored horizontally oriented objects CONCLUSION: The brain’s visual cortex may adjust permanently to the kind of visual stimulation it receives during maturation.

“To See or Not”

Read article: “Sight Unseen”
Show video: At Far Sight At First Sight is a romance adapted by writer Steve Levitt based upon the story To See and Not See from noted writer Dr. Oliver Sacks' collection, An Anthropologist on Mars. Dr. Sacks' work is also the basis for the Penny Marshall film Awakenings, starring Robert De Niro and Robin Williams and the opera The Man Who Mistook His Wife For a Hat by Michael Morris with music by Michael Nyman. In his original story, Dr. Sacks tells of receiving a call in October 1991 from a retired minister in the Midwest. His daughter was about to marry a fifty-year old man, Virgil, who had been blind since early childhood. He had thick cataracts and been diagnosed with retinitis pigmentosa, a disease which slowly eats away the retinas. As he could still make the distinction between light and dark, it was found he was misdiagnosed and simple cataract extraction could possibly restore his sight. While surgery was a success, Virgil, like his cinematic counterpart, found he would have to learn to use his vision much like an infant would, even though he was adept at relating to the world through touch. In his A New Theory of Vision, written in 1709, George Berkeley concluded there was no necessary connection between a tactile world and a sight world; a connection between them could be established only on the basis of experience. This same story was also adapted into the play Molly Sweeney by Brian Friel.

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 adaptation in vision is the ability to adjust to an artificially displaced or even inverted field of vision. Humans adapt to distorting lenses quickly. Take them off and they readapt to normal vision. George Stratton (1896) was the pioneer in the study of inverted vision. He invented and wore optical headgear for 8 days that flipped his world upside down, making him the first person to experience a right-side-up retinal image while standing upright. At first, he was disoriented but by the 8th day he could comfortably reach for something in the right direction and walk without bumping into things. When he finally removed the headgear, he readapted quickly. People have been able to ride a bike, ski, and fly an airplane with inverted vision. It is not because the brain reinverts the retinal image to an upside down image. Rather, by actively interacting with their environment, they adapt to the context and learn to coordinate their movements. Perceptual set is a state of readiness or preparedness to perceive certain kinds of information rather than other kinds. Perceptual set is a powerful phenomenon which links closely with selective attention and which can be affected by a range of circumstances, such as prior experience, emotion, motivation, culture and habit.

Perceptual Set- Schemas
What you see in the center is influenced by perceptual set Our experiences, assumptions, and expectations affect what we perceive. For example, in looking at this three graphics, we see a series of 3 woman’s faces. However, if we look at the top one by itself, without reference to the other two images, we may see a man playing the saxophone rather than a woman’s face. Our looking at the two other unambiguous versions of the face likely influence our initial interpretation of the first version as a woman’s face rather than saxophone player. Click mouse now. Perceptual set can also influence what we hear as well as what we see. For example, people listening to rock music or a Bill Clinton speech can often perceive an evil message if told what to listen for. Our schemas influence our perceptual sets. Our schemas for faces, for example, prime us to see faces in the moon (“the man in the moon”). One researcher discovered that our face recognition is especially tuned to the eyes and mouth. Examples of Perceptual Sets: When you do not recognize a friend in the hallway if he gets a new hair style, new hair color, change of clothing style, getting contacts, etc. Your perceptual set is for your friend’s old look. Also, a more important social one would be police using criminal profiling. They may miss the real criminals or accuse the innocent if they fit the perceptual set of the criminal being sought.

Mystery Woman So attuned are we to eyes that we have trouble imaging what Mona Lisa’s inverted eyes and mouth will look like when we turn her face right side up. Now let’s look at both Monas right-side-up on the next slide.

Turn them right-side-up and one looks normal, the other grotesque
Turn them right-side-up and one looks normal, the other grotesque. Why the surprising difference? Since an upside-down face is not a familiar point of view, you may not have noticed that one of these pictures has been altered. In the right-hand photo, Mona's eyes and mouth have been turned around. It's only when the photos are turned right-side-up, and the view is more familiar, that you notice the real distortion.

Face Schemas Let’s take a look at another example:
The Thatcher Illusion Yes, it’s Maggie Thatcher, former Prime Minister of the U.K. This illusion was first described by Thompson in It seems to get at something fundamental about the way we perceive faces and expressions. It has been the subject of several subsequent papers. Checkout the illusion of Madonna on page 230 of our book. This one is really good. It got me. Slowly rotate your book so that the graphic is now upside down. As you do so you will reach a point where you suddenly cannot assimilate her mouth and eyes into a schema for faces.

This one is just for humor.

Is it a frog? Click mouse. No, it’s a horse.

A man with a red hat getting out of the water?
Click mouse. Or a drowning man screaming for help?

Perception without Sensation?
Extrasensory Perception controversial claim that perception can occur apart from sensory input telepathy clairvoyance precognition Parapsychology the study of paranormal phenomena ESP psychokinesis Five British universities now have parapsychology units staffed by Ph.D. graduates of Edinburgh University's parapsychology program (Morris, 2000). But other research psychologists and scientists—including 96 percent of the scientists in the National Academy of Sciences—have been skeptical (McConnell, 1991). Claims of paranormal phenomena include astrological predictions, psychic healing, communication with the dead, and out-of-body experiences. Of these, the most testable and (for a perception chapter) most relevant claims are for three varieties of ESP: Telepathy, or mind-to-mind communication—one person sending thoughts to another or perceiving another's thoughts. Clairvoyance, or perceiving remote events, such as sensing that a friend's house is on fire. Precognition, or perceiving future events, such as a political leader's death or a sporting event's outcome. Closely linked with these are claims of psychokinesis, or "mind over matter," such as levitating a table or influencing the roll of a die.

Main criticisms of parapsychology:
ESP effects have not been consistently reproducible. Parapsychology has suffered from a number of frauds and hoaxes. The tendency of people to recall only event that confirm their expectations accounts for much of the belief in ESP. After thousands of experiments, a reproducible ESP phenomenon has never been discovered, nor has anyone produced any individual who can convincingly demonstrate psychic ability. Magician James Randi offered $1 million to anyone who can demonstrate any paranormal ability before a group of competent experts. No one has been able to demonstrate a single, reproducible instance of ESP. Stage psychics

ESP Most research psychologists are skeptical of the claims of defenders of ESP There have been no reliable demonstrations of ESP

The predictions of leading psychics are: --often ambiguous prophecies the later interpreted to match actual events. --no more accurate than guesses made by others. --nearly always inaccurate . The tallied predictions of leading psychics reveal very poor accuracy. Between 1978 and 1985, the National Enquirer’s favorite psychic yielded 2 accurate predictions out of 486. Analyses of psychic visions offered to police departments reveal that these, too, are no more accurate than guesses made by others. Psychics working with police generate hundreds of predictions (which increases the odds of an occasional correct guess), which psychics then report to the media. Vague predictions can later be interpreted to match events that provide a perceptual set for interpreting them.

Ganzfeld Procedure But some are newly intrigued by findings recently published by social psychologist Daryl Bem and parapsychologist Charles Honorton (1994) using the "ganzfeld procedure." The procedure places the subject in a reclining chair, plays hissing white noise through headphones, and shines diffuse red light through translucent ping-pong ball halves taped over the eyes. Ostensibly, this reduction of external distractions enables subjects better to hear still small voices within. Building on earlier studies using this procedure, Bem and Honorton isolated a "sender" and "receiver" in separate, shielded chambers and had the sender concentrate on a randomly selected visual images. The “receivers” were then asked which of the images best matched the images they experienced during the session. In 11 studies, the receivers beat chance (25% actually matched) by a bigger than usual margin (32% accurately matched). However, follow up studies using the ganzfeld procedure found no effect.

Student volunteer needed to test your ESP
Zener Cards for ESP Student volunteer needed to test your ESP Zener Card Test After card activity: Stop—Show video: Secrets of the Psychics (Nova)—50 min. Randi James “debunks” psychics including Uri Geller and explains how they work. The Zener cards were used in forced choice experiments - ones in which the participant chose the target from a set of known possible targets. Originally used by Rhine and his colleagues, they consist of five simple symbols: star, circle. square, cross and wavy lines. The cards were shuffled, originally by hand but later by machine, and the participant then attempted to determine the order of the cards through the use of psi. In a telepathy protocol, the cards were viewed by a remote person (the sender) who attempted to 'transmit' the information to the participant. In a clairvoyance (also called general ESP, or GESP) protocol, the cards were not viewed by anyone prior to the participant's psi attempt. In this experiment, the protocol is a clairvoyant one. When you are ready, the computer will select 25 cards at random, each of which will show one of the five Zener symbols. There are no limits to how often each symbol can be selected (i.e. the pack of cards from which the computer makes its selection is limitless!). Your task is to use psi to determine which cards have been selected. On the next screen, you will see 25 sets of 5 Zener cards. You should choose one from each set. Do this by clicking on each desired card. When you have chosen from each of the 25 sets, click on the button at the bottom of the page and you will be given your results.

Try Your Hand at Sensation/Perception Online Jeopardy
Try Your Hand at Sensation/Perception Online Jeopardy! Sensation/Perception Jeopardy

Review Jeopardy

The historical movement associated with the statement, “The whole may exceed the sum of its parts” is: a. parapsychology. b. behavioral psychology. c. functional psychology. d. Gestalt psychology.

Answer: d--Gestalt psychology
Gestalt psychology, which developed in Germany at the turn of the 20th century, was interested in how clusters of sensations are organized into whole perceptions. Page 213 Answer A: Parapsychology is the study of ESP and other paranormal phenomena. Answers B. & C:. Behavioral and functional psychology developed later in the United States.

a. connectedness. b. similarity. c. continuity. d. proximity.
Figures tend to be perceived as whole, complete objects, even if spaces or gaps exist in the presentation, thus demonstrating the principle of: a. connectedness. b. similarity. c. continuity. d. proximity. e. closure.

Answer: e--closure Page 215
Answer A: Connectedness refers to the tendency to see uniform and linked itmes as a unit. Answer B: Similarity refers to the tendency to group similar items. Answer C: Continuity refers to the tendency to group stimuli into smooth continuous patterns. Answer D: Proximity refers to the tendency to group the items that are close to each other .

The figure-ground relationship has demonstrated that:
a. perception is largely innate. b. perception is simply a point-for-point representation of sensation. c. the same stimulus can trigger more than one perception. d. different people see different things when viewing a scene.

Answer: C--the same stimulus can trigger more than one perception
Although we always differentiate a stimulus into figure and ground, those elements of the stimulus we perceive as figure and those as ground may change. In this way, the same stimulus can trigger more than one perception. Page 214 Answer A: The idea of a figure-ground relationship has no bearing on the issue of whether perception is innate. Answer B: Perception cannot be simply a point for point representation of sensation since, in the figure ground relationships a single stimulus can trigger more than one perception. Answer D: Figure-ground relationships demonstrate the existence of general rather than individual principles of perceptual organization. Significantly, even the same person can see different figure-ground relationships when viewing a scene.

When we stare at an object, each eye receives a slightly different image, providing a depth cue known as: a. convergence. b. linear perspective. c. relative motion. d. retinal disparity.

Answer: D--retinal disparity
The greater the retinal disparity, or difference between the images, the less the distance. Page 216 Answer A: Convergence is the extent to which the eyes move inward when looking at an object. Answer B: Linear perspective is the monocular distance cue in which parallel lines appear to converge in the distance. Answer C: Relative motion is the monocular distance cue in which objects at different distances change their relative positions in our visual image, with the of those closest moving most.

a. perceptual constancy.
As we move, viewed objects cast changing shapes on our retinas, although we do not perceive the objects as changing. This is part of the phenomenon of: a. perceptual constancy. b. relative motion. c. linear perspective. d. continuity.

Answer: A--perceptual constancy
Perception of constant shape, like perception of constant size, is part of the phenomenon of perceptual constancy. Page 221 Answer B: Relative motion is a monocular distance cue in which objects at different distances appear to move at different rates. Answer C: Linear perspective is the monocular distance cue in which lines we know to be parallel converge in the distance, thus indicating depth. Answer D: Continuity is the perceptual tendency to group items into continuous patterns.

Which of the following illustrates the principle of visual capture?
a. We tend to form first impressions of other people on the basis of appearance. b. Because visual processing is automatic, we can pay attention to a visual image and any other sensation at the same time. c. We cannot simultaneously attend to a visual image and another sensation. d. When there is a conflict between visual information and that from another sense, vision tends to dominate.

Answer: D--When there is a conflict between visual information and that from another sense, vision tends to dominate. Page 234 Answers A, B, & C: Visual capture has nothing to do with forming impressions of people or whether we can attend to more than one stimulus at a time.

A person claiming to be able to read another’s mind is claiming to have the ESP ability of:
a. psychokinesis. b. precognition. c. clairvoyance. d. telepathy.

Answer: d--telepathy Page 234
Answer A: Psychokinesis refers to the claimed ability to perform acts of “mind over matter.” Answer B: Precognition refers to the claimed ability to perceive future events. Answer C: Clairvoyance refers to the claimed ability to perceive remote events.

Which philosopher maintained that knowledge comes from inborn ways of organizing our sensory experiences? a. Locke b. Kant c. Gibson d. Walk e. Neisser

Answer: b--Kant Page 226 Answer A: LOCKE argued that knowledge is not inborn but comes through learning. Answers C & D: Gibson and Walk studied depth perception using the visual cliffs; they made no claims about the source of knowledge. Answer E: NEISSER studied selective attention .

Which of the following was not mentioned in the text as a criticism of parapsychology?
a. ESP effects have not been consistently reproducible. b. Parapsychology has suffered from a number of frauds and hoaxes. c. The tendency of people to recall only event that confirm their expectations accounts for much of the belief in ESP. d. There have been no laboratory-controlled studies of ESP.

Answer: D--There have been no laboratory-controlled studies of ESP.
As discussed in the text, parapsychologists have conducted numerous experiments with both psychic and normal subjects. Page 236 – 238 Answers A, B, and C: These are all valid criticisms of parapsychology mentioned in the text .

Which of the following depth cues creates the impression of a visual cliff?
a. interposition. b. relative height c. linear perspective d. texture gradient e. relative clarity

Answer: D--texture gradient
There is, of course, no actual drop off. The texture gradient of the checkerboard pattern beneath the glass table imparts the impression of depth. The other cues mentioned would not be relevant to the situation in this experiment. Page 215, 218

Kittens reared seeing only horizontal lines:
a. later had difficulty perceiving both horizontal and vertical lines. b. later had difficulty perceiving vertical lines, but eventually regained normal sensitivity. c. later had difficulty perceiving vertical lines, and never regained normal sensitivity. d. showed no impairment in perception, indicating that neural feature detectors develop even in the absence of normal sensory experiences.

Answer: C--later had difficulty perceiving vertical lines, and never regained normal sensitivity
Page 227 Answers A & B: The kittens had difficulty only with lines they had never experienced and never regain normal sensitivity. Answer C: Both perceptual and feature-detector impairment resulted from visual deprivation.

Adults who are born blind but later have their vision restored:
a. are almost immediately able to recognize familiar objects. b. typically fail to recognize familiar objects. c. are unable to follow moving objects with their eyes. d. have excellent eye-hand coordination.

Answer: B--typically fail to recognize familiar objects
Because they have not had early visual experiences, these adults typically have difficulty learning to perceive objects. Page 226 Answer A: Such patients typically could not usually recognize objects with which they were familiar by touch, and in some cases this inability persisted. Answer C: Being able to perceive figure-ground relationships, patients are able to follow moving objects with their eyes. Answer D: This answer is incorrect because I hand coordination is an acquired skill and requires much practice .

________ processing refers to how the physical characteristics of stimuli influence their interpretation. a. Top-down b. Bottom-up c. Parapsychological d. Human factors

Answer: B--bottom-up Page 214
Answer A: Top-down processing refers to how our knowledge and expectations influence perception. Answer C: Parapsychology is the study of perception outside normal sensory input. Answer D: Human factors psychology is concerned with how best to design machines and works settings to take into account human perception.

Which of the following is not a monocular depth cue?
a. texture gradient. b. relative height. c. retinal disparity d. interposition. e. light and shadow.

Answer: C--retinal disparity
Retinal disparity is a binocular cue; all other cues mentioned are monocular. Page 216 – 218

The moon illusion occurs in part because distance cues at the horizon make the moon seem:
a. farther away and therefore larger. b. closer and therefore larger. c. farther away and therefore smaller. d. closer and therefore smaller.

Answer: A--farther away and therefore larger
The moon appears larger at the horizon than overhead in the sky because objects at the horizon provide distance cues that make the moon seem farther away and therefore larger. In the open sky, of course, there are no such cues. Page 222

Figure is to ground as _____ is to ____.
a. night; day b. top; bottom c. cloud; sky d. sensation; perception

Answer: C--cloud; sky We see a cloud as a figure against the background of sky. Page 214 Answers A, B, & D: The figure-ground relationship refers to the organization of the visual field into objects (figures) that stand out from their surroundings (ground).

The study of perception is primarily concerned with how we:
a. detect sights, sounds and other stimuli. b. sense environmental stimuli. c. develop sensitivity to illusions. d. interpret sensory stimuli.

Answer: D--interpret sensory stimuli
Page 209 Answers A & B: The study of sensation is concerned with these processes. Answer C: Although studying illusions has helped psychologists understand ordinary perceptual mechanisms, it is not the primary focus of the field of perception.

Which of the following influences perception?
a. biological maturation b. the context in which stimuli are perceived c. expectations d. All of the above.

Answer: D--All of the above.
Page 228 – 230

Jack claims that he often has dreams that predict future events
Jack claims that he often has dreams that predict future events. He claims to have the power of: a. telepathy. b. clairvoyance. c. precognition. d. psychokinesis.

Answer: C--precognition
Page 234 Answer A: This answer would be correct had Jack claimed to be able to read someone else’s mind. Answer B: This answer would be correct had Jack claimed to be able to sense remote events, such as a friend in distress. Answer D: This answer would be correct had Jack claimed to be able to levitate objects or bend spoons without applying any physical force.

Using the ganzfeld procedure to investigate telepathy, researchers have found that:
a. when external distractions are reduced, both the “sender” and receiver become much more accurate in demonstrating ESP. b. only “senders” become much more accurate. c. only “receivers” become much more accurate. d. over many studies, none of the above can occur.

Answer: D--Over many studies, none of the above can occur
Page 237 Answer A: The experiment involved written numerals, not thoughts. Answer C: The experiment did not require students to “see the future.” Answer D: The experiment had nothing to do with the mental manipulation of the matter.

The tendency to organize stimuli into smooth, uninterrupted patterns is called:
a. closure. b. continuity. c. similarity. d. proximity. e. connectedness.

Answer: B--continuity
Page 215 Answer A: Closure refers to the tendency to perceptually fill in gaps in recognizable objects in the visual field. Answer C: Similarity refers to the tendency to group items that are similar. Answer D: Proximity refers to the tendency to group items that are near one another. Answer E: Connectedness refers to the tendency to group uniform and linked items.

Which of the following is a monocular depth cue?
a. light and shadow b. convergence. c. retinal disparity. d. All of the above.

Answer: A--light and shadow
Page 217 Answers B & C: Convergence and retinal disparity are both binocular cues that depend on information from both eyes.

a. Perception develops largely through learning.
Which of the following statements is consistent with the Gestalt theory of perception? a. Perception develops largely through learning. b. Perception is the product of heredity. c. The mind organizes sensations into meaningful perceptions. d. Perception results directly from sensation.

Answer: C--The mind organizes sensations into meaningful perceptions.
Page 213 Answers A & B: Gestalt psychologists did not deal with the origins of perception; they were more concerned with its form. Answer D: In fact, they argued just the opposite: Perception is more than mere sensory experience.

Experiments with distorted visual environments demonstrate that:
a. adaptation rarely takes place. b. animals adapt readily, but humans do not. c. humans adapt readily, while lower animals typically do not. d. adaptation is possible during a critical period in infancy but not thereafter.

Answer: C--humans adapt readily, while lower animals typically do not.
Humans and certain animals, such as monkeys, are able to adjust to upside- down worlds and other visual distortions, figuring out the relationship between the perceived and the actual reality; lower animals, such as chickens and fish, are typically unable to adapt. Page to 227 – 228 Answer A: Humans and certain animals are able to adapt quite well to distorted visual environments (and then to readapt). Answer B: This answer is incorrect because humans are the most adaptable of creatures. Answer D: Humans are able to adapt at any age to distorted visual environments.

The phenomenon that refers to the ways in which an individual’s expectations influence perception is called: a. perceptual set. b. retinal disparity. c. convergence. d. visual capture.

Answer: A--perceptual set
Page 228 Answer B: Retinal disparity is binocular depth cue based on the fact that each eye receives a slightly different view of the world. Answer C: Convergence is a binocular depth cue based on the fact that the eyes swing inward to focus on near objects. Answer D: Visual capture refers to the tendency of vision to dominate the other senses.

b. human factors psychologists.
Psychologists who study the importance of considering perceptual phenomena in the design of machines and work settings are called: a. parapsychologists. b. human factors psychologists. c. psychokineticists. d. Gestalt psychologists.

Answer: B--human factors psychologists
Page 233 Answer A: Parapsychologists study claims of ESP. Answer B: Psychokineticists are people who claim ESP has the power of “mind over matter.” Answer D. Gestalt psychologists emphasize the organization of sensation into meaningful perceptions.

According to the philosopher _____, we learn to perceive the world.
a. Locke. b. Kant. c. Gibson. d. Walk. e. Neisser.

Answer: A--Locke Page 226 Answer B: Kanat claimed that knowledge is inborn. Answers C and D: Gibson and Walk made no claims about the origins of perception. Answer E: Neisser studied selected attention.

a. linear perspective; binocular
The tendency to perceive hazy objects as being at a distance is known as _________. This is a _____ depth cue. a. linear perspective; binocular b. linear perspective; monocular c. relative clarity; binocular d. relative clarity; monocular

Answer: D--relative clarity; monocular
Page 217 Answers A & B: Linear perspective, which is a monocular cue, refers to the tendency of parallel lines to converge in the distance. Answer C: Relative clarity requires only one eye and is therefore a monocular cue.

a. size; shape b. size; distance c. size; brightness
The phenomenon of size constancy is based upon the close connection between an object’s perceived _____ and its perceived ______. a. size; shape b. size; distance c. size; brightness d. shape; distance e. shape; brightness

Answer: B--size; distance
Page 221

Which of the following statements best describe the effects of sensory restriction?
a. It produces functional blindness when experienced for any length of time at any age. b. It has greater effects on humans than on animals. c. It has more damaging effects when experienced during infancy. d. It has greater effects on adults than on children.

Answer: C-- It has more damaging effects when experienced during infancy
There appears to be a critical period for perceptual development, in that sensory restriction has severe, even permanently, disruptive effects when it occurs in infancy but not when it occurs later in life. Page 226 Answers A & D: Sensory restriction does not have the same effect at all ages, and it is more damaging to children than to adults. This is because there is a critical period for perceptual development; whether functional blindness will result depends in part on the nature of the sensory restriction. Answer B: Research studies have not indicated that sensory restriction is more damaging to humans than to animals.

Psychologists who study ESP are called:
a. clairvoyants. b. telepaths. c. parapsychologists. d. levitators.

Answer: C-- parapsychologists
Page 234 Answers A, B, & D: These psychics claim to exhibit the phenomena studied by parapsychologists.

The depth cue that occurs when we watch stable objects at different distances as we are moving is:
a. convergence. b. interposition. c. relative clarity. d. relative motion.

Answer: D-- relative motion
When we move, stable objects we see also appear to move, and the distance and speed of the apparent motion cue us to the objects’ relative distance. Page 218 Answers A, B, & C: These depth cues are unrelated to movement and thus work even when we are stationary.

Which of the following statements concerning ESP is true?
a. Most ESP researchers are quacks. b. There have been a large number of reliable demonstrations of ESP. c. Most research psychologists are skeptical of the claims of defenders of ESP. d. There have been reliable laboratory demonstrations of ESP, but the results are no different from those that would occur by chance.

Answer: C-- Most research psychologists are skeptical of the claims of defenders of ESP
Page 234 Answer A: Many ESP researchers are sincere, reputable researchers. Answer B & D: There have been no reliable demonstrations of ESP.

c. perceptual constancy.
Each time you see your car, it projects a different image on the retinas of your eyes, yet you do not perceive it as changing. This is because of: a. perceptual set. b. retinal disparity. c. perceptual constancy. d. convergence.

Answer: C-- perceptual constancy
Because of perceptual constancy, we see the car’s shape and size as always the same. Page 221 Answer A: Perceptual set is a mental predisposition to perceive one thing and not the other. Answer B: Retinal disparity means that our right and left eyes each receive slightly different images. Answer D: Convergence is a form of neuromuscular feedback in which the eyes swing in, or out, as we view objects at different distances.

The term gestalt means:
a. grouping. b. sensation. c. perception. d. whole. e. visual capture.

Answer: D--whole Gestalt means a “form” or “organized whole.” Page 213

People asked to judge the distances of white disks under either clear or foggy conditions:
a. estimated the disks to be more distant when viewed under clear conditions. b. estimated the disks to be nearer when viewed under clear condition. c. took atmospheric conditions into consideration and judged the disks to be equally distant under the two viewing conditions. d. were much less accurate under foggy conditions.

Answer: B-- estimated the disks to be nearer when viewed under clear condition
We perceive hazy objects as farther away than sharp, clear objects: this cue to depth is relative clarity. Page 212, 217 Answer A & C: The disks were estimated to be nearer when viewed under clear conditions. Answer D: As shown on the chart on page 212, foggy conditions increase the perceived distance but by no means necessarily reduce accuracy.

Studies of the visual cliff have provided evidence that much of depth perception is
a. innate. b. learned. c. innate in lower animals, learned in humans. d. innate in humans, learned in lower animals.

Answer: A-- innate Most infants refused to crawl out over the “cliff” even when coaxed, suggesting that much of depth perception is innate. Studies with the young of “lower” animals show the same thing. Page 215

All of the following are laws of perceptual organization except :
a. proximity. b. closure. c. continuity. d. connectedness. e. simplicity.

Answer: E-- simplicity
Page

You probably perceive the diagram above as three separate objects due to the principle of :
a. proximity. b. continuity. c. closure. d. connectedness.

Answer: D-- connectedness
Page 215 Answer A: Proximity is the tendency to group objects near to one another. The diagram is perceived as three distinct units, even though the points are evenly spaced. Answer B: Continuity is the tendency to group stimuli into smooth, uninterrupted patterns. There is no such continuity in this diagram. Answer C: Closure is the perceptual tendency to fill in gaps in a form. In the diagram, three disconnected units are perceived as a unit rather than a single whole.

_____ processing refers to how our knowledge and expectations influence perception.
a. top-down b. bottom-up c. parapsychological d. human factors

Answer: A-- top-down Page 214
Answer B: Bottom-up processing refers to the physical characteristics of stimuli rather than their perceptual interpretation. Answer C: Parapsychology is the study of perception outside of normal sensory input. Answer D: Human factors psychology is concerned with how best to design machines and work settings to take into account human perception.

a. linear perspective. b. shape constancy. c. retinal disparity.
Although carpenter Smith perceived a briefly viewed object as a screwdriver, police officer Wesson perceived the same object as a knife. This illustrates that perception is guided by: a. linear perspective. b. shape constancy. c. retinal disparity. d. perceptual set. e. convergence.

Answer: D--perceptual set
The two people interpreted a briefly perceived object in terms of their perceptual sets, or mental predispositions, in this case conditioned by their work experiences. Page 228 Answer A: Both Smith and Wesson had the same sensory experience of the object, so linear perspective cues would not cause their differing perceptions. Answer B: Shape constancy refers to the perception that objects remain constant in shape even when our retinal images of them change. Answer C & E: Retinal disparity and convergence are binocular depth cues; they have nothing to do with individual differences in perception.

a. relative size b. interposition c. retinal disparity
Because the flowers in the foreground appeared coarse and grainy, the photographer decided that the picture was taken too near the subject. This conclusion was based on which depth cue?. a. relative size b. interposition c. retinal disparity d. texture gradient.

Answer: D--texture gradient
When the texture of an object is coarse and grainy, we perceive the object as nearer than when its texture is finer and less distinct. Page 218 Answers A & B: Relative size and interposition are sued to judge the relative distances of two or more objects; because only one photograph was involved, these cues are irrelevant. Answer C: Retinal disparity refers to the different images our eyes receive; whether the photograph’s texture was coarse or fine, the retinal disparity would be the same.

The fact that a white object under dim illumination appears lighter than a gray object on under bright illumination is called : a. relative luminance. b. perceptual adaptation. c. color contrast. d. lightness constancy.

Answer: D--lightness constancy
Although the amount of light reflected from a white object is less in dim light than in bright light—and may be less than the amount of light reflected from a brightly lit gray object—the brightness of the white object is perceived as remaining constant. Because a white object reflects a higher percentage of the light falling on it than does a gray object, and the brightness of objects is perceived as constant despite variations in illumination, white is perceived as brighter than gray even under dim illumination. Page 224 Answer A: Relative luminance refers to the relative intensity of light falling on surfaces that are close in proximity. Lightness constancy is perceived despite variations in illumination. Answer B: Perceptual adaptation refers to the ability to adjust to an artificially modified perceptual environment, such as an inverted visual field. Answer C: Color contrast is not discussed in this text.

When two familiar objects of equal size cast unequal retinal images, the object that cast the smaller retinal image will be perceived as being: a. closer than the other object. b. more distant than the other object. c. larger than the other object. d. smaller than the other object.

Answer: B--more distant than the other object
The phenomenon described is the basis for the monocular depth cue of relative size. Page 217 Answer A: The object casting the LARGER retinal image would be perceived as closer. Answers C & D: Because of size constancy, the perceived size of familiar objects remains constant, despite changes in their retinal image size.

a. retinal disparity b. interposition c. continuity d. proximity
If you slowly bring your finger toward your face until it eventually touches your nose, eye-muscle cues called ______ convey depth information to your brain a. retinal disparity b. interposition c. continuity d. proximity e. convergence

Answer: E-- convergence
As an object comes closer in our field of vision, the eyes swing inward (converge) and provide muscular cues as to the object’s distance. Page 217 Answer A: Retinal disparity refers to the slightly different images of an object received by the two eyes due to their different angles of viewing. Answer B: Interposition is a monocular cue to distance in which an object that partially blocks another is seen as closer. Answers C & D: Continuity and proximity are Gestalt grouping principles, rather than distance cues.

Concluding her presentation on sensation and perception Kelly notes that:
a. sensation is bottom-up processing. b. perception is top-down processing c. A and B are both true. sensation and perception blend into one continuous process.

Answer: D--sensation and perception blend into one continuous process
Page 214

a. increases; decreases
As her friend Milo walks toward her, Noriko perceives his size as remaining constant because his perceived distance _____ at the same time that her retinal image of him ________. a. increases; decreases b. increases; increases c. decreases; decreases d. decreases; increases

Answer: D-- decreases; increases
Page 221

In the absence of perceptual constancy :
objects would appear to change size as their distance from us changed. depth perception would be based exclusively on monocular cues. c. depth perception would be based exclusively on binocular cues. d. depth perception would be impossible.

Answer: A--objects would appear to change size as their distance from us changed
Because we perceive the size of a familiar object as constant even as its retinal image grows smaller, we perceive the objects as being farther away. Page 221 Answers B & C: Perceptual constancy is a cognitive, rather than sensory, phenomenon. Therefore, the absence of perceptual constancy would not alter sensitivity to monocular or binocular cues. Answer D: Although the absence of perceptual constancy would impair depth perception based on the size-distance relationship, other cues to depth, such as texture gradient could still be used.

a. relative size b. interposition c. relative height
The illusion that the St. Louis Gateway arch appears taller than it is wide (even though its height and width are equal) is based on our sensitivity to which monocular depth cue? a. relative size b. interposition c. relative height d. retinal disparity

Answer: C--relative height
We perceive objects higher in our field of vision as farther away. Thus, the brain perceives a vertical line the same length as a horizontal line to be more distant and mentally adjusts its apparent length to make it seem longer. Page Please note that this explanation also explains the horizontal-vertical illusion on our PsychSim: Visual Illusions lab. Answers A & B: These monocular cues are irrelevant in this particular illusion. Answer D: Retinal disparity is a binocular cue to depth.

How do we perceive a pole that partially covers a bush?
a. as farther away b. as nearer c. as larger There is not enough information to determine the object’s size or distance .

Answer: B--as nearer This is an example of the principle of interposition in depth perception. Page 217 Answer A: The partially obscured object is perceived as farther away. Answer C: The perceived size of an object is not altered when that objects overlaps another.

An artist paints a tree orchard so that the parallel rows of the trees converge at the top of the canvas. Which cue has the artist used to convey distance? a. interposition b. relative clarity c. linear perspective d. texture gradient

Answer: C--linear perspective
Page 218 Answer A: Interposition is a monocular depth cue in which an object that partially covers another is perceived as closer. Answer B: Had the artist painted the trees so that the images of some were sharp and others hazy, the artist would have been using relative clarity. Answer D: Had the artist painted the trees so that there was a gradual change from a coarse, distinct to a fine, indistinct texture, texture gradient would have been used to convey depth.

Objects higher in our field of vision are perceived as ______ due to the principle of _________:
a. nearer; relative height b. nearer; linear perspective c. farther away; relative height d. farther away; linear perspective

Answer: C--farther away; relative height
Page 218 Answers B & D: Linear perspective is the apparent convergence of parallel lines as a cue to distance.

According to the principle of light and shadow, if one of two identical objects reflects more light to your eyes it will be perceived as: a. larger. b. smaller. c. farther away. d. nearer.

Answer: D--nearer Nearby objects reflect more light to the eyes. Thus, given two identical objects, the brighter one seems nearer. Page 218 Answers A & B: Because of the principle of size constancy, an object’s perceived size is unaffected by its distance, angle of viewing, or illumination.

Your friend tosses you a frisbee
Your friend tosses you a frisbee. You know that it is getting closer instead of larger because of : a. shape constancy. b. relative motion. c. size constancy. d. All of the above.

Answer: C--size constancy
This is an illustration of the size-distance relationship in depth perception. Page 221 Answer A: Although the frisbee’s shape is perceived as constant (even as the shape of its retinal image changes), this is not a cue to its distance. Answer B: Relative motion is the perception that when we move, stationary objects at different distances change their relative positions in our visual image, with those moving closest moving most. In this example, only the frisbee is moving.

Which explanation of the Muller-Lyer illusion is offered by the text?
The corners in our carpentered world teaches us to interpret outward- or inward-pointing arrowheads at the end of a line as a cue to the line’s distance from us and so to its length. The drawing’s violation of linear perspective makes one line seem longer. Top down processing of the illusion is prevented because of the stimuli’s ambiguity. d. All of the above were offered as explanations.

Answer: A-- The corners in our carpentered world teaches us to interpret outward- or inward-pointing arrowheads at the end of a line as a cue to the line’s distance from us and so to its length Page

a. relative motion continuity c. visual capture d. proximity
When the traffic light changed from red to green, the drivers on both sides of Leon’s vehicle pulled quickly forward, giving Leon the disorienting feel that his car was rolling backward. Which principle explains Leon’s misperception? a. relative motion continuity c. visual capture d. proximity

Answer: C--visual capture
Although Leon’s other senses would have told him his car was not moving, the visual images of the other cars moving forward “captured” his awareness and created the perception that he was rolling backward. Page 213 Answer A: Relative motion is a distance cue that occurs when stationary objects appear to move as we move. Just the opposite is happening to Leon. Answers B & D: Continuity and proximity are Gestalt principles of grouping, rather than cues to distance.

Regina claims that she can bend spoons, levitate furniture and perform many other “mind over matter” feats. Regina apparently believes she has the power of : a. telepathy b. clairvoyance c. precognition d. psychokinesis

Answer: D--psychokinesis
Page 234 Answer A: Telepathy is the claimed ability to “read” minds. Answer B: Clairvoyance refers to the claimed ability to perceive remote events. Answer C: Precognition refers to the claimed ability to perceive future events.

The predictions of leading psychics are:
often ambiguous prophecies the later interpreted to match actual events. b. no more accurate than guesses made by others. c. nearly always inaccurate. d. all of the above

Answer: D—all of the above
Page 235

a. closure. b. similarity c. continuity d. proximity e. connectedness.
Studying the roadmap before her trip, Colleen had no trouble following the route of the highway she planned to travel. Colleen’s ability illustrates the principle of : a. closure. b. similarity c. continuity d. proximity e. connectedness.

Answer: C--continuity
She perceives the line for the road as continuous, even though it is interrupted by lines indicating other roads. Page 215 Answer A: Closure refers to the perceptual filling in of gaps in a stimulus to create a complete, whole object. Answer B: Similarity is the tendency to perceive similar objects as belonging together. On a road map, all the lines representing roads appear similar. Thus, this cue could not be the basis for Colleen’s ability to trace the route of a particular road. Answer D: Proximity is the tendency to group objects near to one another as a single unit. Answer E: Connectedness is the tendency to group linked items. In this case, the roads often are not clearly linked.

The insensitivity of many rural Africans to the Muller-Lyer illusion proves that perception:
a. is largely a “bottom-up” phenomenon b. is unpredictable. c. is influenced by cultural experience. d. is characterized by all of the above.

Answer: C-- is influenced by cultural experience
Page Answer A: If perception were entirely based on the physical characteristics of a stimulus (“bottom-up”), lack of experience with a carpentered environment would not reduce sensitivity to the illusion. Answer B: Principles of grouping, depth perception, and sensitivity to illusions all demonstrate that perception often IS predictable.

Myers’ PSYCHOLOGY (6th Ed)

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