The conversion of energy from the environment into a pattern of responses by the nervous system is called ______, while making sense of that information is known as ______. acquisition ... attribution * sensation ... perception perception ... sensation assimilation ... accommodation Our sense organs are packed with specialized cells called _______ that convert environmental energies into signals for the nervous system. stimuli adaptors receivers * receptors For which sensory process does the brain need to make a copy of the outside world that physically resembles the stimulus? vision, but not smell smell, but not vision all sensory processes * no sensory process Which of our senses detects part of the electromagnetic spectrum? olfaction * vision hearing taste What makes the electromagnetic radiation from 400 nm to 700 nm visible? Those wavelengths match the frequency of action potentials produced in the optic nerve. * Our visual receptors are adapted to respond to those wavelengths. Those wavelengths have greater amplitude than other wavelengths. Those are the only wavelengths that can pass through the vitreous humor. The visual receptors (rods and cones) are located in the basilar membrane. A pupil. optic nerve. * retina. The adjustable opening in the eye, through which light passes, is the _______. retina iris fovea * pupil Which part of the eye changes its shape to enable us to focus first on a distant object and then on a nearby object? retina cornea B pupil * lens Why are some people nearsighted (myopic)? Their fovea is in the shadow of the pupil. Their lens has become stiff and inflexible. * Their eyeball is elongated; the distance from pupil to retina is long. Their eyeball is flattened; the distance from pupil to retina is short. Julie's eyeballs are elongated. Judy's are flattened. How will their vision differ? * Julie will be nearsighted; Judy will be farsighted. Julie will see moving objects better; Judy will see stationary objects better. Julie will see reds more clearly; Judy will see blues more clearly. Julie's vision will follow the Young-Helmholtz theory; Judy's will follow the opponent-process theory. For people to be able to focus both on nearby objects and on objects far away, they can see best if the shape of their eyeballs is _______. flattened elongated * spherical lopsided As people grow older, the lens of each eye becomes less flexible. How does that change their vision? They have more trouble adapting to dim light. * They have more trouble focusing on nearby objects. Objects toward the periphery of the visual field look smaller than before. Colors appear less bright than before. Why do many older people have difficulty focusing on nearby objects? The cornea shrinks and becomes flattened. Muscles controlling the pupil of the eye fatigue rapidly. * The lens becomes less flexible. Many axons in the optic nerve degenerate. Sometimes people with cataracts have the lens of the eye removed surgically. Which of the following is most likely to change in their vision? All wavelengths of light will appear the same color. They will no longer be able to see at all. They will be able to see infrared light, which they could not previously see. * They will see some colors, especially blues, more clearly than before. The rods in the retina are specialized for vision in the center of the retina. highly detailed vision. * vision in dim light. color vision. Which of the following is NOT true of the rods in the retina? * important for color vision more numerous in the periphery than in the fovea specialized for vision in dim light less sensitive to detail than the cones Compared to the rods, the cones in the retina are more sensitive to very dim light. A * more common toward the fovea. less sensitive to detail. less important for color vision. Which of the following is NOT true of the cones in the retina? more useful than rods in bright light but less useful in dim light responsible for color vision * located mostly in the peripheral areas of the retina more numerous in the pigeon retina than in the rat retina The proportion of cones is greatest in which part of the retina? the blind spot the cornea B * the fovea the periphery If you want to see something in detail you focus it on the _______. * fovea cornea periphery iris Animal species with good color vision (such as most birds) generally have a relatively elongated eyeball. a relatively flattened eyeball. * a high percentage of cones in the retina. a high percentage of rods in the retina. The proportion of rods is greatest in which part of the human retina? * the periphery the fovea the blind spot the cornea Why do you have better color vision in the fovea than in the periphery of the retina? More receptors pool their resources to excite the next cell near the fovea than in the periphery. * The fovea has a higher proportion of cones than the periphery does. The eyeball is more spherical near the fovea than in the periphery. The periphery is in the shadow of the pupil. How do the eyes of predatory birds (such as hawks and owls) differ from those of humans? The birds have no cones in their retinas. * The birds have a greater density of receptors on the top half of their retinas. The birds have more efficient lenses. The foveas of the birds have an equal number of rods and cones. Why are people generally unable to distinguish color in their extreme peripheral vision? * Receptors in the periphery are mostly rods. Receptors in the periphery are too close to the blind spot. Yellow pigments in the periphery filter out many wavelengths. Colored light is diffracted by the eyeball like a rainbow so it does not reach the periphery. It is hard to perceive color when the light is dim, because vision in dim light depends on the _______. * rods basilar membrane fovea cones How does vision in the periphery differ from vision in the fovea? Vision in the periphery is more sensitive to detail. * Vision in the periphery is more likely to be color-blind. Vision in the periphery is more likely to be nearsighted. Vision in the periphery is more likely to be farsighted. We are better able to detect weak, faint lights in the periphery of our vision than in the central area because receptors are packed more densely in the periphery than in A the center of the retina. * large numbers of receptors in the periphery pool their messages to excite the next cell in the visual system. the periphery of the retina includes mostly cones instead of rods. the cornea and lens are the thickest in their central region and thinner toward the periphery. If you are trying to see an extremely faint star, what would be a good way to make it easier to see? Blink your eyes as often as possible. Focus the light on the fovea of the eye. Look back and forth between the sky and a bright light on the earth. * Look slightly to the side of the star. Where do changes take place in the retina to make dark adaptation possible? * in both the cones and rods, but the rods adapt over a longer period of time in both the cones and rods, but the cones adapt over a longer period of time B only in the rods only in the cones Dark adaptation occurs over a longer period of time in _____ than in _____. * rods ... cones cones ... rods red light ... blue light blue light ... red light What, if anything, can lower a person's threshold for detecting a visual stimulus? Damage in the parietal cortex of the brain. Paralysis of the muscles attached to the eyes. * Spending half an hour in a very dark room. It is impossible to lower this threshold. After you have thoroughly adapted to extremely dim light, you can see objects more easily in the * periphery of the retina. fovea of the retina. left half of each retina. upper half of each retina. Is it true that cats can see in the dark? If so, how? Yes. But no one knows how they do it. Yes. Their eyes can detect objects without any transmission of energy from the object. Yes. Their eyes send out sight rays that strike objects in the dark. * No. Vision in the dark is impossible. The route of visual information from the visual receptors (rods and cones) to the brain is receptors -- optic nerve -- bipolar cells -- ganglion cells -- brain receptors -- optic nerve -- ganglion cells -- bipolar cells -- brain receptors -- ganglion cells -- optic nerve -- bipolar cells -- brain * receptors -- bipolar cells -- ganglion cells -- optic nerve -- brain The optic nerve is composed of axons from rods. both cones and rods. cones. * ganglion cells. The "blind spot" of the retina is the center of the retina. * point where the optic nerve leaves the retina. part of the retina that is in the shadow of the pupil. border between the cone area and the rod area of the retina. Suppose there were a species of mammal in which the visual receptors sent their impulses directly back to the brain, instead of sending them to bipolar cells inside the eyeball. This change in anatomy would ELIMINATE which feature of vision? * the blind spot dark adaptation the phi effect the sensory threshold In the human brain, most of the axons from the optic nerve go to the hypothalamus A * thalamus corpus callosum cerebellum The primary area of the cortex for visual processing is on the _____ lobe. frontal temporal parietal * occipital About what percentage of humans are born with a "blind spot" in their retinas? * 100% about 50% of males and 25% of females B 10-20% less than 5% Physically, lights of different colors differ in their _______. direction polarization intensity * wavelength According to the trichromatic theory (or Young-Helmholtz theory) of color vision, how do we perceive the difference between one color and another? by the velocity of action potentials produced by any given cone by the total amount of activity by cones in a particular area of the retina * by the relative amount of excitation of three types of cones by the ratio between the activity of the cones and the activity of the rods According to the trichromatic (or Young-Helmholtz) theory, we perceive color by * the relative levels of activity by three types of cones. different velocities of impulses by each receptor in the retina. different frequencies of impulses by each receptor in the retina. a red-green system and a yellow-blue system. According to the trichromatic (or Young-Helmholtz) theory, we perceive white when * all three types of cones are equally active. both the red-green and the yellow-blue systems are at their neutral point. a cone produces impulses at a high, steady rate. cones fire impulses at the same rate as rods. Which of the following observations most strongly supports the trichromatic (or Young-Helmholtz) theory of color vision? If a person stares at something bright green and then looks away, he or she sees a red afterimage. It is easier to distinguish colors in bright light than in dim light. Even when people wear tinted glasses, they can still recognize all the different colors. * People can match any color of light by mixing three colors in various amounts. If you look at tiny dots of various colors from a distance, the blue dots are more likely to look black than the other dots are. Why? Blue light that travels a great distance becomes too weak to stimulate the receptors. * The cones that are sensitive to blue light are less numerous than cones that respond to red or green light. Other colors of light stimulate rods as well as cones, but blue light does not. Blue light is filtered out by the pupil of the eye. According to the trichromatic (or Young-Helmholtz) theory of color vision, how do we tell the difference between bright yellow light and dim yellow light? The bright light produces a different ratio of firing by the three types of cones than the dim light does. * The bright light produces a greater total amount of activity by the cones than the dim light does. The dim light produces negative afterimages, but the bright light does not. The bright light excites rods as well as cones, while the dim light excites only cones. According to the opponent-process theory of color vision, we perceive color by different frequencies of impulses by each receptor in the retina. varying levels of activity by three types of cones. * a red-green system and a yellow-blue system. a comparison by the cortex of light patterns in different parts of the retina. When a given bipolar cell increases its activity over its spontaneous rate, you see green. According to the opponent-process theory of color vision, when that cell decreases its activity below its spontaneous rate, you will see _______. * red A light green white blue One advantage of the opponent-process theory of color vision, in contrast to the trichromatic theory, is that the opponent-process theory can more easily account for the differences between rods and cones. * the phenomenon of negative afterimages. species differences in color vision. the fact that the retina contains three types of cones. Which of the following would cause someone to experience negative afterimages? pressure on the optic nerve at the point where it exits the retina adapting to complete darkness and then looking at a dimly lit scene B failing to include enough vitamin A in the diet * staring at a red object and then looking at a whitesurface The opponent-process theory of color vision accounts for the observation that * after staring at something of one bright color for a while, we can look away and see a different color. the most common kind of colorblindness is much more common in men than it is in women. we have better color vision in the fovea than we do in the periphery of the eyes. it is easier to see small red spots from a distance than it is to see equally small blue spots from the same distance. If you stare at a brightly lit picture for a minute and then look away, you see a negative afterimage. Sometimes that afterimage seems to move. What makes it move? fluctuations in the opening of the pupil fatigue of axons composing the optic nerve drift of fluids across the cornea * voluntary movements of the eyes The term "color constancy" refers to the fact that you see mostly red and green in the fovea, mostly yellow and blue in the periphery. after you stare at a brightly colored object and then look away, you see a different color. you continue to see color briefly after the lights are turned off. * a green apple still looks green even when you wear red glasses. According to the retinex theory we perceive color through the combined contributions of the rods and cones. * cortex and retina. left hemisphere and right hemisphere. bipolar cells and ganglion cells. Which of these observations gave rise to the retinex theory of color vision? Color vision is well developed in the fovea but not in the periphery. * The apparent color of an object depends on the color of nearby objects. Most people who have trouble seeing red have trouble seeing green as well. It is possible to match any color by mixing three other colors. Which of the following hypothetical observations (IF it were true) would cast the greatest doubt on the retinex theory of color vision? Certain colors cannot be matched by any combination of other colors. Some animal species have only two kinds of cones instead of three. * People who wear tinted glasses have great trouble identifying colors. People who stare at a bright color and then look away continue to see the same color. Which of the following aspects of color vision depends most strongly on the cerebral cortex -- and can be lost after damage to the cerebral cortex that does not impair other aspects of color vision? * color constancy perception of blue light negative afterimages color brightness Which of the three theories of color vision is correct? trichromatic theory, but not the other two opponent-process theory, but not the other two retinex theory, but not the other two * All three theories are correct in explaining some aspects of color vision. Which is the most common form of color blindness? inability to distinguish bright colors from dim colors A inability to see any color at all inability to distinguish yellow from blue * inability to distinguish red from green Investigators believe that most cases of color blindness are due to an abnormality in the _____. rods * cones bipolar cells occipital cortex Someone who has been red-green color-blind in both eyes throughout his or her lifetime would describe a red rose as looking blue green B yellow * red How can psychologists determine what the world looks like to a red-green color-blind person? Ask a person with red-green color blindness to describe what he or she sees. * Ask someone who is red-green color blind in one eye to describe what he or she sees. Study the pattern of light that reflects off the retina of the color-blind person. Record the brain waves from an area of the scalp over the occipital lobe. Why would it be impossible for people who traveled to a different planet to see different colors from the ones they see on earth? * Color perception is a property of the eyes and brain, not of the light. All stars emit the same distribution of various wavelengths of light. After the eye gets used to the types of light we see on earth, it loses its ability to see other types of light. The cornea filters out all but three wavelengths of light. The pitch of a sound (such as high C or B-flat) depends on the _______ of the sound waves. velocity amplitude location * frequency The loudness of a sound depends on which physical aspect of sound waves? velocity * amplitude location frequency The receptor cells along the basilar membrane, which give rise to hearing, are known as _____. rods pheromones * hair cells cones Sound waves are carried through the ear by three tiny bones to a fluid-filled, snail-shaped structure called the _____. * cochlea incus escargot semicircular canal The route of auditory information from some external sound source to the auditory cortex in the brain is * eardrum -- hammer, anvil, and stirrup -- cochlea -- hair cells -- auditory nerve hammer, anvil, and stirrup -- eardrum -- cochlea -auditory nerve -- hair cells auditory nerve -- eardrum -- hammer, anvil, and stirrup -- hair cells -- cochlea eardrum -- hammer, anvil, and stirrup -- auditory nerve -- hair cells -- cochlea Conductive deafness is caused by damage to the cochlea. * bones connected to the eardrum. auditory nerve. hair cells along the basilar membrane. Which of the following is true of people with conductive deafness? Nothing can be done to improve their hearing. A They can hear pitch but they cannot localize the source of the sound. Their hearing loss is generally caused by prolonged exposure to loud noises. * They can hear their own voice. Under what conditions (if any) would a person be MOST likely to hear a tone in the 18,000-20,000 Hz range? * when young after reaching old age immediately after a loud noise under no conditions: humans are incapable of hearing frequencies above 10,000 Hz By what means do we perceive the pitch of a low-frequency sound, such as 30 Hz? Sound waves of a particular frequency excite hair cells at a particular location along the basilar membrane. A sound wave of a particular frequency (such as 30 Hz) excites exactly that number of hair cells (30). B Each sound wave excites a group, or "volley," of hair cells. * Each hair cell sends one impulse for each sound wave. By what means do we perceive the pitch of an intermediate-frequency sound (such as 1000 Hz)? A sound wave of 1000 Hz excites 1,000 hair cells to respond. A sound wave of a particular frequency excites hair cells at a particular location along the basilar membrane. Each hair cell sends one impulse for each sound wave. * Each sound wave excites a group, or "volley," of hair cells. Suppose someone has damage to the hair cells just at the stirrup end of the basilar membrane. That person will have most difficulty hearing which frequency of sounds? those of intermediate frequency -- for example, 800 Hz all frequencies to the same degree those of low frequency -- for example, 30 Hz * those of high frequency -- for example, 10,000 Hz Our ability to distinguish one high-frequency sound from another -- for example, 8000 Hz from 9000 Hz -- depends on * which part of the basilar membrane has hair cells with the greatest activity. the frequency of action potentials produced by each axon in the auditory nerve. differences in response between cells in the left ear and cells in the right ear. differences in the velocity of individual action potentials of the auditory nerve. In the human ear, the ability to perceive intermediate frequencies (about 100 - 5000 Hz) depends on neurons working according to the _____ principle. place gate * volley frequency In the human ear, the ability to perceive high frequencies (above 5000 Hz) depends on neurons working according to the _____ principle. * place serve volley frequency When hair cells at a particular point along your basilar membrane produce 50 impulses per second, you hear a tone at 6000 Hz. What will you hear when those same cells produce 100 impulses per second? 12,000 Hz * 6000 Hz but louder than before 6000 Hz at the same loudness as before 9000 Hz Absolute pitch refers to a baseball thrown in the exact center of the strike zone. the conversation you have with a car salesman when he gives you his rock-bottom offer. a perfect tone without any distortion. * the ability to listen to and correctly identify notes played on musical instruments. Absolute pitch seems to be the result of a dominant gene on the X chromosome. an unusual structure of the cochlea. * years of musical training that began before age six and continued into adulthood. two or more years of musical training, regardless of when the person began. A person is completely deaf in the left ear but has normal hearing in the right ear. Which aspect of hearing is most likely to be impaired in this person? ability to distinguish pitches of high-frequency sounds A ability to distinguish pitches of low-frequency sounds * ability to localize the source of a sound ability to hear changes in loudness We can determine whether a sound is coming from a source close to us or a source far away by attending to the difference between * sounds heard immediately and reflected sounds heard later. the response in the left ear and the response in the right ear. the responses by the hair cells close to the stirrup and the responses by hair cells farther away along the basilar membrane. the loudness at the beginning of the sound and the loudness one second later. When listening to two sounds you will judge sound A to be closer than sound B if sound A has more echoes. sound A is louder in one ear than the other, but sound B is equally loud in both ears. B * sound A includes more high-frequency tones. sound A uses the volley principle and sound B uses the place principle. Why is it difficult to tell whether a sound is coming from straight ahead of you or straight behind? Sounds directly behind you are subject to the effect of visual capture. * Sounds from either ahead or behind stimulate the left ear the same as the right ear. The auditory system is well prepared to localize the distance of a sound source, but not its direction. Most people have not had much practice at localizing sounds behind them. The vestibular system is responsible for which kind of sensation? pain and temperature * position of the head internal changes such as hunger and thirst pressure on the skin Which system enables you to keep your eyes focused on a given target even while your head is moving up and down and back and forth? * vestibular system gustatory system olfactory system somatosensory system Leo has suffered damage to his vestibular system. He is likely to have trouble tasting and smelling foods. identifying objects by feeling them without looking at them. * keeping his eyes focused on a target while his head moves. localizing the direction of the source of a sound. Three semicircular canals and two otolith organs make up the _______. olfactory system gustatory system * vestibular system somatosensory system A person with damage to his or her otolith organs would experience difficulty feeling deep pressure on the skin. distinguishing between two foods based solely on taste. distinguishing between two foods based solely on smell. * knowing which way is "up." Our brains use information from both the _____ and the _____ in order to help us maintain balance. cochlea ... basilar membrane cutaneous system ... olfactory system * visual system ... vestibular system vestibular system ... olfactory system Which sensory system is most impaired in astronauts who are experiencing weightlessness in space? * vestibular sensation vision olfaction somatosensory sensation The sensations of pressure, pain, warmth, cold, vibration, and stretch of the skin are collectively known as the ______ senses. gustatory A * cutaneous vestibular olfactory Why do people have more sensitive touch on the lips than on the back? * Receptors are more tightly packed on the lips. The hair on the back inhibits touch sensation. Information from the touch receptors on the back is not relayed to the brain. The lips are closer to the brain. When people are given the task of identifying raised- line drawings by touch alone, the best performance is usually seen in adults who have been blind since birth. adults with normal vision. B * blind adults who lost their sight later in life. children with normal vision. According to the gate theory of pain, each successive experience of pain is more intense than the last one. * messages from the brain to the spinal cord can decrease the sensation of pain. the experience of pain depends on stimulation of hair cells. a given neuron can send a signal of pain at one time, touch at another, and olfaction at still another. Pain sensations increase due to the release in the nervous system of a neurotransmitter called ______. endorphin * substance P serotonin dopamine Endorphins are neurotransmitters that inhibit the sensation of _____. taste audition olfaction * pain Closing the pain "gates" would be most expected following an increase in which of the substances below? substance P capsaicin * endorphin naloxone Capsaicin, the chemical that makes jalapeno peppers taste hot, can help a person sober up after drinking alcohol. * cause the release of a neurotransmitter associated with pain. increase the rate of protein synthesis in the corpus callosum. increase a person's ability to detect small changes in lights and sounds. Why do jalapeno peppers taste hot? * They contain a chemical that releases a neurotransmitter associated with pain. They contain sharp particles that cut the tongue. They alter the shape of the taste buds sensitive to bitter and sour substances. They contain a chemical that prevents the release of endorphins in the brain. People sometimes feel a pleasant excitement from listening to music. How could you determine whether the music produces pleasure by releasing endorphins? * Test whether naloxone (a drug that blocks endorphin synapses) decreases the pleasure produced by the music. Test whether injections of endorphins lead to increased activity in the brain areas sensitive to sounds. Test whether people who take drugs that resemble endorphins like to listen to music more than most other people do. Test whether people who listen to music frequently have a higher than normal level of capsaicin in their blood. In adult humans, taste buds are located * almost exclusively along the outside edge of the tongue. almost exclusively in the center of the tongue. almost exclusively on the roof of the mouth. evenly spread across the surface of the tongue. Cooling the tongue decreases a person's sensitivity to sweet tastes without affecting sensitivity to other tastes. What conclusion can we draw from this observation? * The tongue has receptors for sweet tastes that are different A from the receptors for other tastes. People can detect sweet substances in lower concentrations than they can detect other substances. At least some of the taste buds are similar to the receptors that detect changes in temperature. Taste receptors signal differences in taste quality by increasing or decreasing their frequency of action potentials. Right after you brush your teeth, orange juice tastes bad. Why? The acids in the orange juice attack the exposed enamel of the teeth. The taste of the orange juice seems bad by comparison to the taste of the toothpaste. The fluoride in the toothpaste reacts with the sugar in the orange juice to produce a toxic chemical. * The toothpaste contains a chemical that changes the properties of certain taste receptors. What basic research strategy do investigators use to determine how many types of taste receptors people have? They compare the EEGs of people who have just tasted different substances. They compare the weights of different taste buds. B * They try to find methods that will strengthen or impair one taste without affecting others. They ask people to eat combinations of different foods and then to describe the taste. Olfaction refers to the sense of ______. balance touch limb position * smell We perceive color by relying on ______ kinds of cones; we detect odors by relying on ______ kinds of olfactory receptors.= three ... seven two ... five five ... two * three ... more than 100 An odorous chemical released by an animal that changes the way other members of its species respond to it socially is known as a _______. photopigment steroid testosterone * pheromone Which of the following behaviors is probably controlled in part by pheromones? Men begin to grow hair on their faces after puberty. People who eat meat tend to smell different from people who eat only vegetables. * Female roommates tend to synchronize their menstrual cycles. People tend to awaken earlier in the summer months than they do in the winter months. A sensory threshold is the stimulus a person likes best. * intensity at which a person can detect a stimulus 50% of the time. most intense stimulus that a person can perceive. negative afterimage of a stimulus. Is it possible for people to detect a stimulus that is weaker than the sensory threshold? If so, why or how? Yes, the sensory threshold has nothing to do with people's ability to detect a stimulus. * Yes, by definition people can detect a stimulus slightly weaker than the threshold almost 50% of the time. No, it is by definition impossible to detect a stimulus that is weaker than the sensory threshold. Yes, some people can respond to the nonsensory aspects of the stimulus. A stimulus so weak that a person can detect its presence only 50% of the time is a stimulus at the * sensory threshold. subliminal level. apex. Gestalt level. Because of sensory adaptation, the sensory threshold for vision remains constant in a variety of lighting conditions. increases as a person stays in a dimly lit room. changes in an unpredictable way from one time to another. * decreases as a person stays in a dimly lit room. After prolonged exposure to bright lights, your sensory threshold for light increases. This change is referred to as motion parallax. A * sensory adaptation. the phi effect. induced movement. The absolute threshold refers to the amount of stimulation needed to cause a receptor to fire at its maximum rate. a sensory threshold that is the same across all species of mammals. * the sensory threshold at the time of maximum sensory adaptation. the minimum intensity at which a given individual can detect a stimulus 100% of the time. When people try to judge whether a stimulus is present or absent, they make correct judgments, misses, and false alarms. The study of their answers is known as * signal-detection theory. Gestalt psychology. B opponent-process theory. the psychophysical function. According to signal-detection theory, the probability that a person will report seeing a dim light depends on the ability of the receptors to respond to the light AND on the influence of subliminal perception. * rewards and penalties for correct judgments and errors. distance the light had to travel before reaching the receptors. shape of the person's psychophysical function. An experimenter presents a faint sound. Matt says he hears it; Nick says he does not. Before we can decide for sure whether Matt has a lower sensory threshold than Nick, what additional information do we need to know? the shape of the psychophysical function for each man whether either man has recently been exposed to loud sounds or to anything else that might permanently damage his hearing the average sensory threshold for a large number of normal people * how often each man says he hears something when the experimenter presents no sound A person's "threshold" for detecting the presence of a visual stimulus is a constant, determined by a combination of genetic and environmental influences. a biological constant, which varies among people depending entirely on differences in their genes. a constant, which is the same for all people. * a variable which can change quickly under the influence of new instructions. In an experiment where subjects are asked to try to read words flashed on the screen for a split second, subjects typically respond at the same speed to all words, as long as they are shown above the absolute threshold. * do most poorly identifying emotionally loaded words. do most poorly identifying ordinary (non-emotionally loaded) words. do most poorly identifying their own name. "Subliminal perception" means perceiving * stimuli weaker than the sensory threshold. by a combination of attentive and preattentive processes. information without the use of any sense organ. stimuli that might affect your behavior. One of the main problems researchers face when attempting to study subliminal perception is there is no such thing as a subliminal stimulus. the unconscious mind actively suppresses subliminally perceived stimuli. * you must rely on the person's self-report of whether or not he or she detected the stimulus. people remember almost all of the stimuli that are presented to them, whether above or below threshold. Investigations of supposed "backward messages" on rock records indicate that such messages are perceived consciously and they exert strong and lasting effects on behavior. people resist such messages and generally do exactly the opposite of what the messages tell them to do. * if such messages are present, they have little or no effect on our behavior. such messages are perceived unconsciously and they exert strong and lasting effects on behavior. Some people have claimed that messages recorded backward on rock music are perverting the minds of American youth. Which of the following is the best-supported evidence AGAINST that claim? Because backward messages are heard subliminally, they affect only people's unconscious behavior. It is illegal to put backward messages on recordings. The minds of American youth are already perverted. * People cannot understand backward speech and do not respond to it. Some people claim that certain rock bands include messages recorded backwards on some of their songs. Psychological researchers have concluded that no rock bands have recorded backwards messages. A backwards messages have unconscious influences on behavior, but almost all people successfully resist such influences. most people hear such messages and consciously translate them into forward messages. * backwards messages have no detectable influences on behavior. Subjects in an experiment of subliminal perception watch a screen. The word PENCIL is flashed so briefly that none of them are consciously aware of it. How will it affect their behavior, if at all? * They can recognize related words, such as WRITE, faster than usual. They will be more likely than usual to buy pencils. It will have no effect on their behavior. They will be less likely than usual to buy pencils. Research on subliminal perception has demonstrated that subliminal persuasion is an effective means of influencing people. backward messages in music can be understood by most listeners, but are unlikely to influence their behavior. B subliminal stimuli have no effect whatsoever. * the effects of subliminal stimuli, when present, are generally either weak or short-lived. What is a "feature detector" in the visual system? a muscle that controls eye movements * a neuron that increases its activity when a certain pattern is shown to the retina a structure in the cornea that changes shape in the presence of bright light A cell that carries information back and forth between rods and cones A "feature detector" neuron in the visual cortex of the brain responds to bright light anywhere on the retina. any light that shines on the neuron itself. * light in a particular shape or pattern in one part of the retina. light from an object at a particular distance away from the individual. A neuron in the visual cortex becomes excited whenever light of a particular shape (such as a line) falls on a particular part of the retina. That neuron is said to be a visual constancy. * feature detector. ganglion cell. basilar membrane. Experimenters Hubel and Wiesel found that cells in the visual cortex of monkeys respond vigorously only when light falls on their retina in a particular shape and in a particular location. Therefore those cells act as photopigments. * feature detectors. opponent processes. ganglion cells. After someone watches a waterfall, he or she perceives an illusion of objects moving upward. Psychologists study such illusions to try to learn about * the properties of feature-detector neurons in the visual cortex. how genetic differences among people affect their vision. how individuals' visual experiences differ across cultures. the relationship between movements of the eye muscles and vision. Which of the following phenomena demonstrates the effects of fatiguing one set of cells in the brain, followed by a rebound of activity by another set? the Mller-Lyer illusion reversible figures, such as the old woman/young woman drawing the disappearance of an object when it enters the blind spot of the retina * the effects of staring at a color, a waterfall, or a set of lines People stare at a pattern of narrow black-and-white lines for a minute and then look at some wider lines. The second set of lines appears even wider than usual to them. Why? Staring at the first set of lines led to the phenomenon of induced motion. Staring at the first set of lines produced sensory adaptation. * Staring at the first set of lines fatigued certain feature detectors. Staring at the first set of lines changed these people's psychophysical function. After you stare at a pattern of narrow lines long enough to fatigue certain feature detectors, you now stare at slightly wider lines. How will your perception of those lines differ from your usual perception of them? They will appear to be curved. They will appear to be narrower than usual. * They will appear to be wider than usual. They will appear to be slanted. Which of the following is actual evidence AGAINST the idea that pattern perception is based solely on feature detection? The visual cortex of humans is organized in a manner very A similar to that of cats and monkeys. * The context of a scene influences our perception of the patterns within the scene. People who have stared at narrow lines for a minute see other lines as wider than they usually appear to be. Most cells in the visual cortex respond more vigorously to one stimulus than to others. The term "Gestalt" (as in Gestalt psychology) came from a Danish word meaning division into parts. * a German word meaning pattern or configuration. the name of the founder, B. F. Gestalt. the initials of seven psychologists. Gestalt psychologists REJECTED the belief that the ability to perceive sensory information depends on both heredity and environment. the whole is more than the sum of its parts. B * visual perception involves the passive adding up of lines and dots. different parts of the brain serve different functions in behavior. The slogan of Gestalt psychology is the hole is more than the sum of its parts. the whole is more than some of its parts. * the whole is more than the sum of its parts. the hole is more than some of its parts. Which of the following would a Gestalt psychologist be LEAST likely to study? optical illusions * feature detectors in the visual cortex the principles of similarity, proximity, and continuation reversible figures Gestalt psychologists specialized in studying the physiological role of feature detectors in vision. * how we organize a visual perception as a whole. the elementary components of experience. interactions between visual and auditory experiences. One reversible figure can be seen either as a vase or as two profiles looking toward each other. This example illustrates the Gestalt principle of * figure and ground. good figure. proximity. continuation. Which of the following is NOT one of the Gestalt principles of perception? proximity similarity closure * sensory adaptation The tendency to perceive objects that are close together as belonging to the same group is called _____. similarity closure continuation * proximity What is meant by the term "top-down processing" in vision? The brain begins by identifying lines and points; it later combines those into an overall perception. People first attend to the top of the object and then turn their attention to the lower parts. The light from the top of the visual field strikes the bottom of the retina. * The brain first identifies overall visual patterns and then fills in the parts. The Gestalt approach to perception describes how visual perception develops from the _______; the feature-detector approach describes how vision develops from the _______. * top down ... bottom up bottom up ... top down top down ... top down bottom up ... bottom up Our feature detectors probably contribute most strongly to which aspect of vision? top-down processing A attentive processes * preattentive processes the Gestalt principles Which of the following observations illustrates the contribution of preattentive processes to vision? If an object passes behind a barrier and later emerges on the other side, people do not always recognize it as the same object. If one pentagon points down and others point up, people take longer to find the different one if there are many pentagons than if there are just a few. With practice, people can recognize that one complex object could be rotated to look like another complex object. * People can find one vertical line among a group of circles equally fast regardless of how many circles are present.