Department of Psychology
Midterm Examination 1
Final Scoring Key
In the scoring key that follows, correct answers are marked with an asterisk (*).
The statistical analysis identified five (5) bad items: #s 35, 40, 47, and 49. These items were rescored correct for all responses. Students who got any of these items wrong, in terms of the preliminary scoring key, should give themselves one (1) additional point for each such item (do not give yourself the additional point if you got a bad item "right").
The average score on the rescored exam was 38.33, standard deviation = 6.15), or approximately 77% correct. The median score was 39. This was excellent performance by the historical standards of Psych 1, in which my usual mean is somewhere between 65-70% correct.
In what follows, I provide the percentage of the class that got each item correct, as well as the item-to-total correlation for each item, followed by commentary on why the right answer is right, and the others wrong.
Choose the best answer to each of the following 50 questions. Questions are drawn from the text and lectures in roughly equal proportions, with the understanding that there is considerable overlap between the two sources. Usually, only one question is drawn from each major section of each chapter of the required readings; again, sometimes this question also draws on material discussed in class. Read the entire exam through before answering any questions: sometimes one question will help you answer another one.
Most questions can be correctly answered in one of two ways: (1) by fact-retrieval, meaning that you remember the answer from your reading of the text or listening to the lecture; or (2) inference, meaning that you can infer the answer from some general principle discussed in the text or lecture. If you cannot determine the correct answer by either of these methods, try to eliminate at least one option as clearly wrong: this maximizes the likelihood that you will get the correct answer by chance. Also, go with your intuitions: if you have actually done the assigned readings and attended the lectures, your "informed guesses" will likely be right more often than they are wrong.
Be sure you are using a red Scantron sheet.
Fill in the appropriate circles with a #2 pencil only.
Be sure you put your name on the front of the red Scantron sheet.
Be sure you put your Student ID# on both sides of the red Scantron sheet.
Indicate Exam 001 (use all three digits) on the reverse side of the red Scantron sheet.
Retain this exam, along with a record of your answers.
1. Let's say you want to assess the effect of subliminal suggestions on ratings of attractiveness. You ask 20 students to listen to subliminal tapes, then have them rate the attractiveness of 20 peers. You discover that all the peers were rated as highly attractive, with a mean of 8 out of a possible 10. Why is the above experimental design inadequate?
a. It lacks demand characteristics.
b. It lacks an independent variable.
c. It lacks a dependent variable.
d. It lacks a control group.*
91% correct, item-to-total rpb = .18. 8/10 compared to what? Without a control or comparison group, which doesn't receive the subliminal suggestion, we have no idea whether the suggestion has an effect. With a proper control group, the presence or absence of the subliminal suggestion would be the independent variable, while the attractiveness rating is the dependent variable. All experiments have demand characteristics, which are subtle cues contained in the experimental situation that communicate the purpose of the experiment to the subject.
2. Which of the following can be a significant problem for correlational studies?
a. It is nearly impossible to find an effect in most studies.
b. It can be hard to tell which factor is causing the other.*
c. Demand characteristics can be a significant problem.
d. Placebo effects can be a significant problem.
90%, rpb = .27. People commonly confuse correlation with causation. Two variables may be correlated because they are in a cause-and-effect relation. Or they may be correlated because they are both the effects of some third cause.
3. Which of the following is most relevant to a study�s external validity?
a. the degree to which the study�s participants reflect the greater population*
b. the degree to which the study is measuring what it claims to be measuring
c. the fact that the study is conducted outdoors
d. the degree to which the study�s participants are different from the greater population
95%, .31. External validity has to do with the degree to which experimental results can be generalized to the population as a whole. On some dimensions, college students -- who serve as subjects in the vast majority of psychological experiments -- may be quite different from most other people, which threatens the external validity of the research in question. Of course, on other dimensions, we are all pretty much alike, so relying on college students is not so much of a problem.
4. A psychological explanation of behavior is in terms of:
a. brain activity.
b. the individual�s state of mind*
c. objectively recorded data.
d. sociocultural factors that impinge on the individual.
76%, .30. Psychology is rooted in the doctrine of mentalism, which states that behavior is to be explained in terms of the individual's particular cognitive, emotional, and motivational states. The biological level of explanation depends on such things as genes, evolution, and brain processes. The sociocultural level depends on such things as organizational structure, dominance hierarchies, tradition, and the like.
5. The key idea in Darwin's theory of natural selection is as follows:
a. Evolution favors the better or more advanced organism.
b. Evolution favors the organism that is better suited to its current environment.
c. Variations in a species sometimes lead to reproductive advantage.
d. Both b and c are correct.*
78%, .21. For Darwin, some inter-individual variation occurs naturally in every species, because of the way that inheritance (meaning genetics). Occasionally, some variant enhances the organism's fitness for its environment, and this genetic advantage is passed to the offspring of the favored individual. But it's not that the favored individual is more advanced. Cockroaches fit better in some environments than people do, but that doesn't mean that cockroaches are more advanced creatures than humans.
6. What does homeostasis produce?
a. a predictable increase in the number of action potentials
b. a predictable increase in one�s basal metabolic rate
c. a stable internal equilibrium*
d. a cue for positive feedback
97%, .34. Homeostasis is the process by which organisms maintain their internal environments as stable levels: we eat when blood sugars drop below a certain level, and stop eating when optimal levels of blood sugar have been restored.
7. The autonomic nervous system has two branches: the sympathetic and the parasympathetic. What does each do?
a. The sympathetic revs up bodily activities, the parasympathetic restores the body�s activities to normal.*
b. The sympathetic sends messages to the glands, the parasympathetic to the smooth muscles.
c. The sympathetic provides positive feedback, the parasympathetic negative feedback.
d. The sympathetic restores homeostasis, the parasympathetic revs the body up.
96%, .24. Think of it this way: sympathy is a feeling, and the sympathetic nervous system mediates, among other things, emotional arousal. Paramedics help restore health, and the parasympathetic nervous system acts to restored, or slow the depletion of, bodily resources depleted by sympathetic activity. In this way, the sympathetic and parasympathetic branches are antagonistic to each other, going in opposite directions.
8. What can be said about external cues, such as the sight of food?
a. They act independently of internal cues such as feelings of satiety.
b. They are more likely to lead to eating in the context of hunger than satiety.*
c. They are more likely to lead to eating in the context of satiety than hunger.
d. They have no effect on the hypothalamus.
73%, .37. External cues like the presence of food tend to elicit eating behavior under any circumstances, which is why people eat when food is available, even though they're not hungry. But the effect of external cues is much greater when people are actually hungry. This is what we would call an interaction between external cues (presence of food) and internal cues (hunger pangs), about which more later in the course.
9. One form of violence that organisms engage in is called predation. Such predatory attacks seem to be an outgrowth of
a. dominance hierarchies.
b. hormonal imbalance.
c. intense arousal.
d. the hunger motive.*
76%, .40. Predation is behavior in which an organism of one species attacks an organism of another species, and is closely related to hunger. Aggression is different, because in this case the attack is by one species member against a conspecific organism.
10. How do humans and animals differ in their sexual response?
a. Human females are under strict hormonal control, but female animals are not.
b. Female animals are under strict hormonal control, but human females are not.*
c. Human males are reliant on testosterone for sexual arousal, while male animals are reliant on progesterone for sexual arousal.
d. Human males are reliant on progesterone for sexual arousal, while male animals are reliant on testosterone for sexual arousal.
81%, .48. Mating in nonhuman animals is strictly for purposes of reproduction, and thus is tightly controlled by hormones (particularly female hormones). It's instinctual. But human mating serves both reproductive and "recreational" purposes. Which is why humans, but not nonhuman animals, will mate at times, and in ways, that can't lead to procreation.
11. Many processes in the brain functioned essentially mechanically, according to Descartes, but what truly governed our behavior, what made humans different from animals, what made reason and choice possible, was
b. the ego.
d. the soul.*
64%, .38.Psyche is Greek for "soul", a concept that has been secularized so that psychology means the science of the mind, not the science of the soul. For Descartes, soul and mind went together, and only humans had either one.Language may distinguish humans from other animals, but that wasn't Descartes' view. And the discussion of learning shows that even nonhuman animals can be intelligent.
12. The various new neuroimaging techniques are powerful, but at the same time
a. they do not, on their own, tell us whether a particular brain activity is a cause or a consequence of a given psychological process.*
b. they tend to yield extremely inconsistent data.
c. none of them can show changes in the brain�s minute-by-minute functioning.
d. they can cause brain damage in certain individuals.
90%, .34. Neuroimaging techniques allow us to see the brain at work, but in order to understand the meaning of the brain activity we have to have a correct understanding of the experimental task at the psychological level of analysis. Neuroscience thus depends on psychology.
13. __________ are bundles of neurons that conduct excitation toward the brain or spinal cord.
c. Efferent nerves
d. Afferent nerves*
85%, .42. Think of it this way: affects are feelings, and afferent neurons, bundled into afferent nerves, carry sensory impulses from the sensory receptors to the central nervous system so that they can be "felt". Effects are actions, so to speak, and efferent neurons, bundled into efferent nerves, carry messages to stimulate the activity of effectors such as the muscles and internal organs.
14. The large brain structure that controls key life functions such as breathing, level of attentiveness, and the timing of sleep and dreaming is called the
59%, .35. The hindbrain (like the pons and the medulla) mediates vegetative functions, which is why people can live, even if they're comatose, following damage to midbrain structures like the reticular formation. The forebrain consists of the cerebral cortex, as well as subcortical structures like the hippocampus and amygdala.
15. Which of the following statements best describes the current scientific view regarding the functioning of our left and right hemispheres?
a. The hemispheres constantly compete for dominance over our daily activities.
b. The left hemisphere is our major hemisphere, while the right hemisphere plays only a minor role in daily activities.
c. The left hemisphere tends to be analytic, while the right hemisphere tends to be artistic.
d. Together, the left and right hemispheres contribute their specialized abilities to every task.*
71%, .24. The two hemispheres aren't quite identical, and they're not precisely redundant: there's hemispheric specialization, just like there's functional specialization within each hemisphere. For example, for most people language functions are localized in the left hemisphere, while the right hemisphere is particularly good at pattern perception. It's not a matter of analytic versus artistic: the right hemisphere is good at analyzing patterns, while poets and composers use their left hemispheres quiet a bit. But, just as with functional specialization, most mental and behavioral tasks require the integrated and coordinated activity of numerous brain "centers". The hemispheres are no exception. For example, in order to play the piano you have to be able to coordinate your left hemisphere (which controls your right hand and foot) with your right hemisphere (which controls your left hand and foot). That what the corpus callosum is for: to permit to two hemispheres to communicate with each other.
16. The brain seems to consist of a large number of separate and specialized modules. There is, in other words, a localization of brain function. At the same time, research also has shown that
a. which module performs which task varies from person to person.
b. there are no links from one module to another.
c. multiple brain areas are activated for any task we do.*
d. All of the above are correct answers.
92%, .41. What goes for the two hemispheres goes for the modules within the hemispheres.
17. In which lobe would you expect neurons to be most reliably activated by the stimulation of a nerve receiving sensory information from the skin of the knee?
79%, .31. The somatosensory area is located in the parietal lobe, adjacent to the central fissure. The primary motor cortex is located in the frontal lobe, adjacent to the central fissure. The primary auditory area is located in the temporal lobe, adjacent to the lateral fissure. And the primary visual area is located in the pole of the occipital lobe.
18. Bob is hit on the head and �sees stars. � The region of the brain that was most likely affected is the __________.
b. frontal cortex
c. occipital lobe*
d. limbic system
85%, .25. And the primary visual area is located in the pole of the occipital lobe. The somatosensory area is located in the parietal lobe, adjacent to the central fissure. The primary motor cortex is located in the frontal lobe, adjacent to the central fissure. The primary auditory area is located in the temporal lobe, adjacent to the lateral fissure. The cerebellum coordinates sensory and motor functions. The limbic system is involved in emotional reactions.
19. From what you know about the position of the various brain areas, which of the following seems most probable?
a. Damage to Wernicke�s area is more likely to be accompanied by paralysis than is damage to Broca�s area.
b. Damage to Wernicke�s area is more likely to be accompanied by deafness in the left ear than in the right ear.
c. Damage to Broca�s area is more likely to be accompanied by paralysis of the left arm than by paralysis of the right arm.
d. Damage to Broca�s area is more likely to be accompanied by paralysis than is damage to Wernicke�s area.*
64%, .41. Broca's area is located in the frontal lobe, adjacent to the primary motor cortex. Therefore, extensive damage could knock out both speech functions, leading to expressive aphasia, and voluntary motor functions, leading to paralysis of some motor functions (including, if the damage is really extensive, hemiplegia). Some of you went for Option A, but Wernicke's area is in not in the frontal lobe. Some of you went for Option B, but Wernicke's area is in the left hemisphere, and damage to the adjacent auditory cortex would produce deafness in the right (contralateral) ear.
20. In the lock-and-key model of synaptic transmission, the �key� gets to the �lock� by
a. removal of synaptic vesicles.
b. rapid conduction down to the axon.
c. weak attractive forces of the lock.
d. diffusion across the synaptic gap.*
90%, .42. Neurotransmitters secreted by the synaptic vesicles of the pre-synaptic neuron flow into the synaptic cleft, where they are picked up by the dendrites of the postsynaptic neuron; those that are not are cleaned away or returned to the presynaptic neuron through synaptic reuptake. But uptake by the postsynaptic neuron only happens if the neurotransmitter molecule is of the right shape to fit into the receptors of the postsynaptic neuron. Thus, neurotransmitters aren't interchangeable: there are specific neurotransmitters whose moleculer "keys" fit into postsynaptic "locks". Some psychoactive drugs modulate neural activity by affecting the lock-and-key mechanism.
21. In young children, recovery of speech and other brain functions following injury is more likely than it is for adults. Thus, we say that a child�s brain has __________ than an adult�s.
a. less transduction
b. more transduction
c. less plasticity
d. more plasticity*
96%, .32. Transduction has to do with the conversion of a proximal stimulus (see below) into a neural impulse. Plasticity has to do with the brain's ability to alter its structure and function in response to changing circumstances. As a rule, children's brains are more plastic than adults', so that recovery of function due to damage to some portion of the brain is more likely to occur in children than in adults. It may be that some brain modules are specialized for various functions, but if these modules are damaged the immature brain may have enough plasticity -- enough flexibility -- to permit some other module, not initially dedicated to that function, to take over. But even mature brains show some degree of plasticity -- otherwise, we'd never learn anything.
22. More than anything else, when the early Empiricist philosophers sought to offer an account of learning, they focused on:
b. the creation of belief systems.
c. how learning leads to the creation of new skills.
d. the creation of elaborate belief systems.
65%, .27. Empiricism is the philosophical contrast to nativism: Nativists believed that knowledge was innate, while empiricists believed that knowledge was acquired through experience -- that is, through the creation of associations through learning. A lot of you went for C, which doesn't have anything to do with the debate between Nativists and Empiricists.
23. An obvious benefit of habituation is this:
a. It narrows the range of stimuli that elicit alarm.
b. It guarantees that we will respond to novel inputs.
c. It leads to enduring brain changes in the hippocampus.
d. Both a and b*
55%, .16. In habituation, response to a stimulus declines with repeated presentation of that stimulus. By virtue of habituation, organisms don't respond (with alarm or arousal) to every stimulus that occurs in their environment. Rather, response is reserved for novel stimuli. some students may have been misled by the word "guarantees" in Option b, on the ground that, in taking multiple-choice tests, you should avoid extreme statements. "Guarantees" might not have been the best choice of word here, but here's where the statistical analysis cuts objectively cuts through subjective impressions. The item proved to be "good" in statistical terms, and if I rescored the item based solely on subjective impressions, I risk lapsing into solipsism -- there's no point in doing the statistical analysis if you're not going to use the information to evaluate items.
24. Unconditioned responses by definition occur
a. independent of any learning.*
b. only in lower organisms.
c. only in conditions of deprivation.
d. only in response to secondary reinforcers.
95%, .35. URs are reflexive responses to stimulation, and reflexes are, by definition, innate stimulus-response associations, hard-wired into the nervous system. Reflexes are also automatic, in that they occur regardless of the circumstances in which they are elicited.
25. The speed of relearning confirms which of the following facts?
a. You can�t teach an old dog new tricks.
b. We learn better when under pressure.
c. Extinction does not erase initial learning.*
d. The effects of initial learning always outstrip subsequent learning.
93%, .41. Savings in relearning after extinction, like spontaneous recovery, indicates that the extinguished CR is not lost, but rather inhibited.
26. When does stimulus generalization occur?
a. when an organism responds to a range of stimuli that are similar to the original CS*
b. when an organism produces several slightly different responses to the same CS
c. when an organism responds only to a particular CS
d. when an organism responds to second-order conditioning
93%, .40. Stimulus generalization occurs when an organism responds to stimuli other than the one to which it has been conditioned. Generalization follows a gradient, meaning that response is greatest to new stimuli that most closely resemble the original conditioned stimulus.
27. Which of the following statements is false?
a. Initially, discrimination training results in generalization.
b. In discrimination learning, the CS+ takes on significance opposite of the CS�.
c. The CS� takes on the role of the inhibitor.
d. While the CS+ predicts the occurrence of the US, the CS� conveys little or no information.*
58%, .37. In the early phases of discrimination training the organism's responses are indiscriminate -- that is, it generalizes the CR to the CS- as well as the CS+. However, it eventually learns that the CS+ predicts the US, while the CS- predicts the absence of the US. At this point, the CS- inhibits the CR, while the CS+ elicits the CR. So, both the CS- and the CS+ convey information to the organism: the CS+ about the presence of the US, the CS- about its absence. Some of you went for Option A, but the initial response to a CS- is, in fact, a generalized CR.
28. What will happen in a classical conditioning experiment if the likelihood of the US following the CS is 30 percent and the likelihood of the US being presented alone is also 30 percent?
a. There will be no conditioning, no matter how contiguous the CS and US.*
b. There will be strong conditioning if the US arrives about half a second after the CS.
c. There will be no obvious effect at first, but after a rest period the CR will appear when the CS is presented.
d. The animal will show surprise reactions when the CS is presented.
51%, .26. Conditioning occurs when the probability of the US occurring in the presence of the CS is greater than the probability of the US occurring in its absence. In this case, the two probabilities are equal. Therefore, no conditioning will occur. A lot of you went for Option C, but that has to do with spontaneous recovery.
29. A phenomenon called the �blocking effect� demonstrates the key role played by __________ in conditioning.
52%, .33. In Kamin's blocking experiment, the animal is conditioned to CS1, and then to a compound of CS1 and CS2. Because the US and the CS-US relationship, haven't changed, the CS2 is redundant with CS1. Because CS2 provides no new information to the organism, no conditioning will occur to CS2. Conditioning occurs only when the US surprises the organism. In the blocking experiment, no surprise occurs because the organism already has a good predictor of the US -- namely, CS1. Some of you went for Option A, presumably on the ground that Kamin's experiment shows that learning is intelligent, and not just a matter of conditioning, but choosing that option didn't correlate with overall test performance: in fact, the correlation was negative (-.11).
30. According to Thorndike�s �law of effect,�
a. punishment has little effect on behavior.
b. rewarded responses are strengthened.*
c. learning usually results from sudden insights or sudden solutions to problems, not gradually.
d. punished responses are paradoxically strengthened.
96%, .26. Thorndike's Law of Effect says that conditioned responses are gradually strengthened by reward and gradually weakened by nonreward, but it says nothing about punishment. And it says nothing about insight.
31. During training, in classical conditioning, the US is presented __________, while in operant conditioning the reward is presented __________.
a. during every test trial; only on a variable interval schedule
b. immediately after the response; immediately before a response
c. regardless of behavior; contingent on behavior*
d. contingent on behavior; regardless of behavior
88%, .44. In classical conditioning, reinforcement (the US) is presented contingent only on the CS, regardless of what the organism does. For Pavlov, bell is followed by food no matter what the dog does. In Kamin's blocking experiment, noise is followed by shock regardless of what the rat does. By contrast, in instrumental conditioning reinforcement (the reward) is contingent on the organism making the conditioned response. For Thorndike, the cat gets out of the cage only if it presses the paddle. And for Skinner, the pigeon gets a food pellet only if it pecks the key.
32. Gamblers often persist at gambling even when they very rarely receive a payoff. How can one explain this persistence?
a. There is a gradual increase in performance with successive approximations.
b. There is a strong resistance to extinction when performance has been maintained with a variable schedule of reinforcement.*
c. Typically, the gambler will pause for a brief rest after each case of reinforcement, thereby increasing stamina.
d. The gambler experiences learned helplessness and is unable to stop.
86%, .35. This is about schedules of reinforcement in instrumental (operant) conditioning. You can think of pulling the lever of a slot machine as a conditioned response. In slots, reward is presented on a variable-ratio schedule, with a very low ratio setting, meaning that the gambler has to make lots of conditioned responses (lever pulls) before it gets any reward. Under these circumstances, the organism -- the gambler -- will emit a large number of conditioned responses -- lever pulls - -even though individual responses are rarely rewarded. The gambler is essentially on an extinction schedule, because lever pulls rarely deliver reward. But still, lever-pulling persists -- indicates strong resistance to extinction. Successive approximations (Option A) are characteristic of shaping. Pauses in responding (Option C) are characteristic of fixed-interval schedules of reinforcement, because reinforcement will not be delivered again for a period of time, regardless of what the organism does. In learned helplessness (Option D), the organism has learned not to make the CR: the problem is starting to respond, not stopping.
33. What does latent learning show?
a. Learning can occur without behavioral change.*
b. Learning can occur suddenly, in a single trial.
c. Learning will not occur if blocking is present.
d. Learning requires a certain amount of response control.
67%, .40. This is about Tolman's experiment (Tolman, after whom Berkeley's Tolman Hall was named; Gleitman, your textbook author, was Tolman's PhD student), in which one group of rats was simply allowed to explore a maze, without receiving any reward. Nevertheless, when reward was introduced, they quickly found their way to the goal box -- showing that they had learned the "map" of the maze during the exploration trials. So, learning can occur in the absence of reinforcement. And learning can occur in the absence of behavioral change -- behavior changes when there is an incentive, such as the introduction of food into the goal box, for the animal to use (display) what it has learned. Behavior changed suddenly when the incentives were changed. But the learning had occurred gradually, on the earlier exploration trials.
34. Rats A and B receive shocks in a Skinner box. Rat A can terminate the shock by pressing a bar. For rat B, there is no response that leads to shock termination. The experimenter then tries to teach both rats another similar shock-avoidance task. What result would one expect?
a. Rat A will learn the avoidance task more quickly than rat B.*
b. Rat B will learn the avoidance task more quickly than rat A.
c. The rats will learn the avoidance task at equal rates.
d. Neither rat A nor rat B will be able to learn the avoidance task.
93%, .24. This is about learned helplessness. Rat A has learned that there is something it can do to escape shock. Rat B has learned that shock occurs regardless of what it does. Therefore, A will learn the new shock-avoidance task more readily than B. B already "knows" that shock is uncontrollable, and that it is helpless in such situations.
35. Which of the following is an aspect of neural plasticity that allows learning to occur?
a. the formation of synapses
b. changes in neuronal sensitivity to stimulation*
c. changes in synaptic function
d. all of the above
15%, .06. A bad item. The neural basis of learning appears to be long-term potentiation (LTP), by which we mean a change in the sensitivity of post-synaptic neurons to stimulation by presynaptic neurons. Think of the reflex arc: with learning, the efferent neuron (mediating response) is more likely to be excited by stimulation from the afferent neuron (mediating the stimulus), passed through the interneuron (mediating the association between them). New synapses aren't formed during learning, but by virtue of LTP, transmission across some synapses is facilitated. Most of you went for Option D, but the plasticity that allows learning doesn't extend to the formation of synapses, which rules out Option A, and thus Option D as well. What changes in learning is the ease of synaptic transmission, not the structure of the synapse as well. Now, that might mean that Option C is correct, which might also push people toward Option D. And after all, Option C refers to changes in synaptic function, which is one way of thinking abut changes in neuronal sensitivity to stimulation.
36. A man is looking at a tree. What is the proximal stimulus?
a. the tree
b. the light waves reflected by the tree
c. the image cast by the tree on the man�s retina*
d. the pattern of nerve impulses triggered by the retinal image and conducted by the optic nerve to the brain
37%, .25. A hard item, but a fair one, especially since I think I've asked a question like this on every exam covering sensation and perception. The distal stimulus refers to an object in the environment -- in this case, a tree. The tree reflects light, which may be why so many went for Option B. But the proximal stimulus refers to the light waves that fall on the man's retina, creating an image of the distal stimulus. By virtue of transduction by the rods and cones in the retina, the proximal stimulus is converted into a pattern of neural impulses carried over the optic nerve to the visual cortex in the occipital lobe of the brain.
37. The smaller the Weber fraction,
a. the less sensitive the sense modality.
b. the higher the response criterion.
c. the more sensitive the sense modality.*
d. the shorter the duration of response to any sensory impression.
67%, .38. In psychophysics, the Weber fraction is the ratio that must be added to a stimulus to produce a just-noticeable difference in the intensity of that stimulus. It is, effectively, a constant across wide ranges of stimulation. So, if it takes 1 unit to produce a change in a stimulus of 100 units (Weber fraction = 1/100), it will take 2 units to produce a change in a stimulus of 200 units (Weber fraction = 2/200 = 1/100). Low ratios mean that very little intensity must be added to produce a noticeable change -- which means, in turn, that the sensory modality is very sensitive to change, responding even to very small amounts of change.
38. What is a major advantage of signal-detection methods over traditional ways of measuring thresholds?
a. Signal-detection methods allow the investigator to distinguish between sensitivity effects and tendencies to respond too conservatively or too liberally.*
b. Signal-detection methods allow the investigator to separate hits and misses from correct negatives and false alarms.
c. Signal-detection methods allow the investigator to introduce occasional �catch� trials to eliminate response biases.
d. Signal-detection methods allow the investigator to multiply the effects of sensitivity by the magnitude of the response bias.
39%, .39. Traditional psychophysics views the observer as passive: detection is simply a matter of their being enough intensity in the proximal stimulus. But signal detection assumes that the observer is active -- has expectations about whether the stimulus will be presented, and motives to detect the stimulus or not. By varying the number of catch trials, and by varying the consequences for being right or making a mistake, signal detection methods attempt to take account of these cognitive and motivational factors. A lot of you went for Option B, but the whole point of separating hits and misses is to take account of expectations and motives.
39. According to the doctrine of specific nerve energies, why do we experience differences in the sensory quality of the taste of iced tea, the sound of birds singing, and the sight of a fireworks display?
a. because of our past experiences with these particular stimuli
b. because different sensations excite different nervous structures*
c. because there are physiological differences in the conduction speed of the neurons that are associated with different sense organs
d. all of the above
52%, .47. The doctrine of specific nerve energies says that each modality is defined by a particular neural pathway, not by a particular proximal stimulus. Thus, what makes vision different from audition is not the difference between electromagnetic radiation and mechanical vibration; it's the difference between the rods and cones and the basilar membrane; between the optic nerve and the auditory nerve; and, especially, between the auditory and visual projection areas.A lot of you went for Option D, but Option A is clearly wrong, and the problem with Option C is that it's not conduction speed, but conduction pathways that define the specific nerve energies.
40. Which theory explains why we hear tones below 500 hertz?
a. the theory of cochlear vibration
b. pitch theory
c. frequency theory*
d. place theory
46%, .09.A bad item, even though I often ask a question like this. Pitch is related to the frequency with which the proximal stimulus vibrates. Perhaps the easiest way to produce the sensation of auditory pitch would be to translate the frequency with which the proximal stimulus vibrates into the frequency of vibration of the basilar membrane, and thereafter into the frequency of the neural impulse carried through the auditory nerve. Unfortunately for this proposal, we can hear frequencies up to 20,000 cps, and neurons can't fire that fast. According to the duplex theory of pitch, low pitches (associated with low frequencies, up to about 5,000 cps) are represented by the frequency with which the basilar membrane vibrates; but high pitches (associated with high frequencies, about 1,000 cps and above) are represented by the place at which the basilar membrane vibrates maximally. These two principles account for auditory pitch: frequency for low pitches, place for high pitches
41. What does the duplex theory of vision propose?
a. We have two eyes, each with a slightly different view of the world.
b. There are two separate receptor systems, one for color vision and one for monochromatic vision.*
c. Ganglion cells are activated when the lights go on and bipolar cells are activated when the lights go off.
d. Our visual system is made up of two types of stimuli, the proximal stimulus and the distal stimulus.
45%, .38. Two-process theories abound in psychology, and here's another one. The retina holds two kinds of cells sensitive to light: rods, which are very sensitive even to low intensities of light, but not to color -- thus producing monochromatic vision of dark, light, and gray; and the cones, which are sensitive to color -- red and green, yellow and blue, and everything else -- but not to low intensities of light. Bipolar cells receive neural impulses from the rods and cones, and then pass them on to ganglion cells. But what's really important at the level of the introductory course is the different characteristics of rod and cone vision. A lot of you went for Option A, which has to do with binocular convergence, not the fact that there are two separate receptor systems, rods for monochromatic vision and cones for color vision.
42. What negative afterimage would you see if you were presented with a blue-colored square?
a. a red-colored square
b. a black-colored square
c. a yellow-colored square*
d. a green-colored square
79%, .45. This is the kind of evidence that led to formulation of the opponent-process theory of color vision, which holds that color vision is a product of two opponent-process systems, one for red and green, the other for yellow and blue (there's also a third opponent-process system for light and dark). These opponent processes are organized in an antagonistic relation to each other (antagonism is another common principle in psychology, as with the sympathetic and parasympathetic nervous systems), such that stimulation of one element suppresses or inhibits the other. Thus, stimulation of the blue element in the yellow-blue pair activates the blue process, but inhibits the opponent yellow process. When the blue stimulus is terminated, the blue process goes off and the yellow process springs back -- thus producing the negative afterimage of yellow.
43. A person with only one eye could perceive depth by using which cue(s)?
a. linear perspective
b. texture gradients
c. relative size
d. all of the above*
89%, .33. Cues to depth come in four basic categories: ocular, depending on feedback from the eye itself; and optical or pictorial, such as you would find in a pictorial representation of three dimensions on a two-dimensional canvas. Moreover, binocular cues depend on information from both eyes, while monocular cues work even with information from only one eye. Most optical or pictorial cues are monocular in nature; the only exception is retinal disparity, which obviously involves two eyes, two retinas, and the disparity between their images.
44. What would happen if you suddenly experienced an involuntary twitch of one of your eye muscles?
a. The world would seem to move.*
b. The world would remain stationary.
c. There would be a momentary �blank� time in your perceptual experience.
d. You would experience motion parallax and optic flow.
48%, .41. A hard item, but fair. One of the cues to motion is the movement of an image across the retina. But when you move your eye voluntarily, you don't perceive the object as moving: the world appears stationary even though the images move on the retina. This is because the visual system automatically compensates or the voluntary movement of the eye. But when your eye twitches, the eye moves involuntarily, and the information that would ordinarily come from the voluntary movement isn't available. So, all the visual system "knows" is that the image is moving, and so the object is perceived as moving.
45. Which general law(s) tie(s) the Gestalt grouping factors together?
a. the laws of feature detection
b. the law of perceptual constancy
c. the law of serial processing
d. the laws of perceptual organization*
60%, .34. Gestalt is German for "form", and all the Gestalt principles are about how the perceiver organizes the entire pattern of stimulation into the best form possible. So, we tend to perceive similar figures as belonging together, and closer figures as belonging together, and we group line segments together so as to produce smooth contours. These elements of form are not necessarily in the stimulus -- they are products of the organizational activity of the perceptual system.
46. What do reversible figures demonstrate?
a. Perceptual parsing is not inherent in the stimulus.*
b. Perceptual parsing is inherent in the stimulus.
c. Figure-ground relationships are inherent in the stimulus.
d. Figure-ground relationships are stable.
56%, .38. Parsing is something the subject does (we'll encounter this term again in Gleitman's chapter on language). Far from being something that's inherent in the stimulus, it's something the perceiver does to make sense of stimulus information. In reversible figures, we can see the same stimulus as two quite different objects, depending on "how we look at it" - -for example, the vase-face figure or the "wife/mother-in-law". The importance of the reversible figures is that they show that not all the information needed for perception is given by the stimulus; there is also a cognitive contribution from the knowledge and expectations of the perceiver.
47. Which of the following best describes the phenomenon of perceptual constancy?
a. Our perception of an object changes when the proximal stimuli changes.
b. Our perception of an object remains the same in spite of changes in the proximal stimuli.*
c. Our perception of an object changes when the distal stimuli changes.
d. Our perception of an object remains the same in spite of changes in the distal stimuli.
8%, -.11, a really bad item, because the preliminary scoring key had the right answer as A, which is clearly wrong, instead of B, which is clearly right. This is just a typo on my part, when creating the scoring key. Mea maxima culpa. We could have simply rekeyed this item, but in my absence my instructions to the GSIs were simply to rescore bad items correct for all responses. Because students who chose the right answer, B, got credit, no harm has been done. Anyway, the perceptual constancies make the same point as the reversible figures, but in the opposite way. Here, perception of an object remains constant despite quite substantial changes in the pattern of proximal stimulation. It's as if the visual system compensates for certain stimulus changes, so that the percept remains stable. If the percept remains stable despite changes in the stimulus, then all the information for perception isn't provided by the stimulus; some of the information must be provided by the perceiver.
48. Being able to identify an ambiguous stimulus illustrates which major point about perception?
a. Perceptual systems depend mainly on top-down processing.
b. Perceptual systems have great difficulty adapting to ambiguous stimuli.
c. Perception is an active process.*
d. We make a large number of perceptual errors on a regular basis.
70%, .29. Unpacking the information contained in a stimulus is a matter of bottom-up processing. Adding information to a stimulus is a matter of top-down processing. So it's the same point again -- are you getting the idea that this is the most important point of the lectures (and readings) on sensation and perception. Ambiguous stimuli are ambiguous precisely because they don't contain enough information for the perceiver to disambiguate them. Rather, the perceiver has to rely on his or her knowledge, expectations, and beliefs to, in Bruner's phrase, "go beyond the information given" by the stimulus.
49. Which area(s) of the cortex is (are) directly involved in processing visual information?
d. All of the above areas of the cortex are involved.*
19%, .08, a bad item, maybe because it was a little tricky, but it was only a little tricky, and the point at stake is important. The occipital lobe contains the primary visual cortex, which is probably what 77%of you had in mind when you chose Option A -- though, interestingly, the item-to-total correlation for A was a measly 0.03. But there's more to visual perception than that. Even though there are modules in the occipital lobe that process various aspects of vision, the limits on localization of function apply to vision, just as they do to language. That is to say, visual processing, like language processing and everything else, depends on the integrated and coordinated activity of a number of different brain modules. So, for example, there are areas in the temporal cortex and the parietal cortex that are also involved in vision -- a "what" system in temporal cortex that identifies the object, and a "where" system in parietal cortex that locates objects in space. As another example, prosopagnosia, an inability to recognize faces and other objects at a subordinate level of categorization (more on levels of categorization later), results from brain damage at the junction of the temporal and parietal lobes.
50. Which aspect of perceptual attention is best illustrated by the cocktail-party effect?
72%, .41. At a cocktail party or similar gathering, we tend to focus on the person we're talking to, and "tune out" other voices and conversations. We don't process every bit of auditory stimulation that falls on our ears, and every bit of visual stimulation that falls on our eyes. Rather, we can actively select what aspects of the stimulus environment we're going to attend to, and which we're going to ignore. This isn't a matter of habituation, or adaptation to some level of stimulation. The person we're talking to can be talking very softly, while everyone else in the room is talking loudly. It's a matter of selective attention.
Retain this exam, along with a record of your answers.
A provisional answer key will be posted to the course website by 3:00 PM today.
The exam will be provisionally scored to identify and eliminate bad items.
The exam will then be rescored with bad items keyed correct for all responses.
Grades will be posted to the course website.
A final, revised, answer key, and analyses of the exam items, will be posted on the course website when grades are posted.
Requests for rescoring must be received within one (1) week of the posting of grades