University of California, Berkeley
Department of Psychology

Psychology 1
Fall 2001

Midterm Examination 1
Preliminary Scoring Key and Initial Feedback

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.

Correct answers are marked with an asterisk (*).

Exams are scored twice: once to identify "bad" items, the second time to correct for those bad items and generate a final score for each student.

In order to forestall quibbles about which items are "bad", bad items are identified according to two objective, statistical (or psychometric) criteria.

First, we look at the proportion of students who got the item right. In order to be rescored, a minority (< 50%) of the class must have gotten the item correct according to the provisional answer key. In psychometrics, this statistic is known as the pass percent.

But pass percent is not the only applicable criterion. Some questions are harder than others, and even a very difficult item might be "good", so long as it discriminates between students who do relatively well, and those who do relatively poorly, on the test as a whole. In psychometrics, this is known as the item-to-total correlation, and is measured by the correlation coefficient (strictly speaking, the point-biserial correlation coefficient, abbreviated rpb) between the item and the rest of the items on the test. With upwards of 500 subjects in the sample (i.e., the number of students enrolled in the course), even very small correlations are statistically significant. Accordingly, I have established a cut off of rpb < .20.

To summarize, any items with a pass percent < 50% and an item-to-total correlation < .20 are rescored correct for all responses. In other words, if you got one or more of the rescored items wrong according to the provisional scoring key, then you should give yourself one (1) additional point for each such item.

Our analysis revealed three "bad" items:

#10, #40, and #48.

These items, and only these items, will be rescored.

Performance on the exam, as I said, was pretty good. Psychometrically, a test with an average score of 50% provides the best discrimination among test-takers, but a mean that low can be pretty dispiriting for people -- think about your tests in calculus, physics, or chemistry! For a lower-level introductory course I shoot for a higher goal, an average of 65-70% correct.

This class hit that mark on the initial scoring: M = 33.35 (SD = 7.05), or 67% correct on average. Adding in the three rescored items raised this mean to 35.60 (SD = 6.92), or 71% correct on average. This is excellent performance.

In evaluating your own score, keep in mind that letter grades are assigned on the basis of total points, not points on individual exams. If you only scored in the 80s on this exam, you still have an opportunity to receive some kind of "A" in the course, because we add in section points (including credit for completing the Interactive Psychology software or writing the term paper) and RPP credits before determining letter grades. That's up to 100 points!

Most students in my section of Psych 1 end up with some kind of "A" or "B", and vanishingly few do worse than some kind of "C".

What follows is a report of the item analysis, plus a paragraph of commentary on each item. The commentaries are not yet complete, but I'm posting this now so you can get feedback on the "bad" items, and overall performance.

Individual grades will be posted to the course website sometime next week, after the rescoring has been completed and "bad" scantrons scored by hand.

1. Mental states include all but the following:

A. thoughts

B. feelings

C. desires

*D. actions

94% correct, rpb = .19. This is pretty much definitional. In Kant's view, the primary mental faculties are cognition, emotion, and motivation. According to the doctrine of mentalism, mental states cause actions to occur. So, behaviors, belong in a different category. In addition, there are some behaviors that aren't necessarily "mental" at all, such as reflexes that are mediated solely at the level of the spinal cord and instinctive behaviors in animals that don't have much by way of brains.

2. Psychology is a biological science because:

A. organisms cooperate and compete with each other in the ordinary course of everyday living.

*B. the brain is the physical basis of the mind.

C. it is primarily concerned with the flow of information through a physical system.

D. the immune system is the basis of information-processing in the brain.

95%, .22. Psychology studies the world at the level of the individual's mind and behavior, but because the brain is the physical basis of mind, psychologists also need to know something about biology. The idea that biological theories constrain psychological theories is probably overstated, but still it's hard to imagine someone studying vision, for example, without knowing anything about the optics of the eye or how the visual system of the brain works. The immune system may be of interest to psychologists, but the nervous system takes priority. The fact that individuals cooperate and compete with each other would make psychology a social science. There are non-biological physical systems, like computers, that process information.

3. Cerebral blood flow studies indicate:

*A. which areas of the brain are active.

B. that blood flow to certain areas of the brain produces auditory experiences such as hearing clicks.

C. that blood flow to certain areas of the brain produces involuntary movements.

D. that blood flow to certain areas of the brain produces visual experiences such as seeing lights.

91%, .26. There's no evidence that blood flow to various areas of the brain produces anything. However, blood flow is a correlate of various brain activities. In some brain-imaging techniques, we are essentially measuring the increases and decreases in blood flow that occur as various areas of the brain become more or less active. In this way, we can infer which parts of the brain are involved in various aspects of mental life.

4. During dreaming, the EEG most resembles that:

*A. of when you are attentively listening to a fascinating introductory psychology lecture.

B. of when you are awake, but relaxed and have your eyes closed.

C. of the deepest stages of slow-wave sleep.

D. of when you are close to death in a coma.

42%, .36. People are much more likely to report dreaming when they are awakened from Stage REM, where there are rapid eye movements, than from Stage NREM, where there are not. And during Stage REM, the EEG is characterized by low-voltage, high-frequency activity similar to that seen in waking. In Stage NREM, the EEG is characterized by high-voltage, low-frequency activity (slow waves). Eyes-closed relaxation is more likely to be characterized by an EEG of moderate frequency. In coma, there is little activity in the brain at all.

5. The limbic system:

A. is involved in the control of sensory functions.

B. is involved in the control of the skeletal musculature.

C. is involved in the control of such higher mental processes as thinking and language.

*D. is involved in the control of emotional and motivational activities.

63%, .42. The limbic system, including the hypothalamus, amygdala, and the anterior cingulate cortex, is involved in emotional states (such as fear) and motivational states (such as hunger and thirst). Sensory functions are controlled in the somatosensory projection area of the parietal lobe, the auditory projection area of the temporal lobe, the visual projection area of the occipital lobe, and other similar areas (like the olfactory bulb). Control of the skeletal musculature is centered in the "motor area" of the frontal lobe. The control of "higher" mental processes is given over to the "association areas" of the brain, especially the prefrontal cortex.

6. During brain surgery, a portion of the patient's primary motor projection area is stimulated and the patient's left leg moves. The site of stimulation is probably the __________ side of the __________ lobe.

A. left, frontal

*B. right, frontal

C. left, parietal

D. right, parietal

58%, .34 Remember the principle of contralateral projection: the left hemisphere receives stimulation from the right side of the body (and the right visual field of each eye), and controls motor activities on the right side of the body. The motor area is in the frontal lobe. Therefore, the patient is most likely being stimulated in the right frontal lobe.

7. A man fixates on the exact center of the screen just as the word Springtime is flashed for a quarter of a second. With his left hand, he selects a picture of a metal spring to indicate what he saw. Which of the following is most likely to be true about this man?

A. He is a normal right-hander.

B. He is blind in his left eye.

C. He is blind in his right eye.

*D. He has a severed corpus callosum .

59%, .30. Remember that the right visual half-field of each eye projects to the left hemisphere, and vice-versa; that the right hemisphere controls motor activities of the left arm and leg; and that language is localized in the left hemisphere. when the corpus callosum has been severed, information initially processed by one hemisphere cannot be shared with the other hemisphere. This being the case, the word Spring, being on the left side of the fixation point, will project to the right hemisphere, so the patient will identify a spring with his left hand.

8. In the normal frog, a pinprick on the toe produces a small, reflexive withdrawal of the hindleg. After decapitation, the same pinprick produces a much larger reaction. This strongly suggests that:

*A. the brain has an inhibitory effect on spinal reflexes.

B. the brain has an excitatory effect on spinal reflexes.

C. the spinal cord has an inhibitory effect on cerebral reflexes.

D. the spinal cord has an excitatory effect on cerebral reflexes.

78%, .38. Remember the characteristics of spinal reflexes in paraplegia: they are more intense than in normals, because the spinal centers processing the reflex cannot receive inhibitory messages that are usually sent down the spinal cord by the brain.

9. In the hierarchical organization of the nervous system, the brain most closely resembles a:

A. cell.

B. tissue.

C. synapse.

*D. organ.

89%, .21. Cells are the smallest independent units of any biological system. Neurons are the cells of the nervous system, and they are separated from each other by synapses. Tissues are groups of related cells, and organs are groups of related tissues. The brain consists of the neocortex as well as subcortical structures such as the hippocampus and the amygdala. We know from Brodmann's studies, among others, that the each of these structures is composed of "parts" made up of different kinds of neurons. Therefore, the brain most closely resembles an organ, consisting of several different kinds of tissue.

10. Recovery from brain damage:

A. is usually complete, but it takes more than a decade.

*B. is common, but is only pronounced during the first year after the trauma.

C. is more complete in older people than in infants.

D. is rare unless special therapies are employed.

19%, .04. A BAD ITEM, but not because of content. It just doesn't "work" psychometrically, so we dropped it. A lot of people went for D. Recovery from brain damage, when it occurs, may be aided by physical and other therapies, but it also occurs spontaneously. Recovery may be complete, but is more typically partial, because -- as a general rule -- central nervous system tissue does not regenerate after it is damaged. Most recovery takes place in the first year of the trauma. The longer the patient goes, as for example in the case of coma, the less likely recovery is. Recovery of function is more likely in infants than in older individuals, because the infant nervous system has more equipotentiality -- it is less firmly, less rigidly specialized.

11. Studies of neurological patients with brain lesions indicate that the _____ plays an important role in memory.

A. thalamus

B. hypothalamus

*C. hippocampus

D. amygdala

86%, .25. The thalamus is a sensory relay center. The hypothalamus is important for homeostatic regulation, underlying biological motives such as hunger and thirst. The hippocampus is important for memory, as in the case of H.M. The amygdala is important for fear and other emotions.

12. Patient XZ has difficulty speaking and writing, but can read adequately and understand others' speech. She most likely suffers from a lesion in:

A. Brodmann's Area.

B. the temporal lobe.

*C. the frontal lobe.

D. Penfield's area.

61%, .38. So we're talking about aphasia here, and expressive aphasia at that. Expressive aphasia is also known as Broca's aphasia, and it has been tied to Broca's area, which is in the frontal cortex near the motor strip. Wernicke's area is in the temporoparietal region, and it produces receptive aphasia, where speech comprehension is impaired as well as production. Brodmann's areas aren't defined by function, but rather by cytoarchitecture -- the structure of the constituent cells. There isn't a Penfield's area.

13. Lashley's "Search for the Engram" discovered that specific pieces of knowledge are represented by:

A. discrete clusters of neurons in the hippocampus.

B. individual cells in the reticular formation.

C. small groups of cells in the cerebral cortex.

*D. large groups of neurons distributed throughout the whole cortex.

64%, .34. Lashley taught cats a simple task, and then destroyed various amounts of their cortical tissue (the hippocampus is in the subcortex) to see how much damage, and where, resulted in the loss of function. He never found any particular area that represented the cat's knowledge of the task. Therefore he concluded that the neural representation of learning was not in discrete locations in cerebral cortex, much less in individual cells (which, logically, can't represent anything), but rather that each piece of knowledge was distributed widely over the cortex as a whole. This is Lashley's Law of Mass Action. It follows that, so long as some critical mass of neurons remain intact, learning will remain intact as well.

14. A rat is fed a diet that contains 5 calories per gram. On this diet, the rat's daily intake is 60 grams. The diet is now concentrated to contain 10 calories per gram. The rat will now ingest approximately:

*A. 30 grams per day.

B. 60 grams per day.

C. 15 grams per day.

D. an unknown amount per day, since its daily intake cannot be determined from the information provided.

61%, .37. From a biological point of view, animals eat to get calories, not to get any particular bulk of food. So, the rat's initial intake is 300 (5x60) calories. When the diet is concentrated, the rat will eat less food: 300/10 or 30 grams a day.

15. The adrenal medulla __________ arousal by releasing __________ into the bloodstream.

A. decreases; norepinephrine

B. decreases; dopamine

C. increases; serotonin

*D. increases; epinephrine

53%, .26. The adrenal glands are enervated by the autonomic nervous system, which instigates emotional arousal, in response to an environmental stressor, by releasing both epinephrine (adrenalin) and norepinephrine (noradrenalin) into the bloodstream. The epinephrine generates emotional arousal, while the norepinephrine releases stored sugar, but they both increase during arousal.

16. Administration of X grams of amphetamine to a person who uses the drug for the first time leads to a fourfold increase in heart rate. Administration of an identical dose to an experienced user elicits only a twofold increase in heart rate. This discrepancy is an example of:

A. a withdrawal symptom.

*B. tolerance.

C. stimulation seeking.

D. drive reduction.

96%, .16. Tolerance is the name given to the fact that, with repeated usage, of a psychoactive drug such as amphetamine, an increased dose is required to achieve a constant effect (such as heartrate acceleration). You need more drug to get high, and that's where the addictive cycle starts.

17. Which of the following motives is the most difficult to explain in terms of principles of negative feedback?

A. temperature regulation

*B. sex

C. thirst

D. hunger

75%, .39. In negative feedback, the activity of the system decreases the condition that instigated the activity. In positive feedback, the activity of the system increases the condition that instigated it. Most biological motives, being based on homeostatic regulation, are based on negative feedback -- the system is trying to return the organism to a prior state (of body temperature, cell fluids, blood sugars, etc.). Sex, however, isn't like that, because it has more to do with seeking pleasure than avoiding unpleasures such as heat and cold, hunger, and thirst.

18. When we talk about the evolutionary "fitness" of an organism we are referring to characteristics that:

A. contribute to the organism's health and survival.

B. enhance the organism's longevity, regardless of its health.

*C. contribute to the organism's reproductive success.

D. make the organism larger and stronger than other members of its species.

67%, .33. In evolutionary terms, an organism is successful if it reproduces itself. It doesn't matter how long you live, how healthy or strong you are, or how much money you make. All that matters, for evolution, is whether you pass on your genes.

19. Neurological evidence concerning the relationship between predation

and aggression indicates that, in cats:

A. both behaviors are elicited by stimulation of the same hypothalamic area.

*B. each behavior is elicited by stimulation of a different area of the hypothalamus.

C. both behaviors are elicited by stimulating an area of the hypothalamus that controls eating.

D. both a and c

77%, .48. Predation and aggression are behaviorally different: predation is against individuals of other species (the cat eating a mouse, for example), while aggression is against individuals of the same species (two cats fighting, for example). And, it turns out, that they are regulated by different areas of the hypothalamus: predation, by the area that controls eating; aggression, by the area that controls response to threat.

20. Someone says "Display systems in both humans and animals are just like a human language that has a very small vocabulary." Why is this statement false?

A. because some animals have a large number of displays, and some human languages have a rather small vocabulary

*B. because display systems lack rules for putting individual displays together to form new messages

C. because displays are completely unaffected by the context in which the display is made

D. all of the above

52%, .41. The most important difference between nonhuman social displays and human language is that human language is flexibly creative: humans can string words together in entirely novel ways to represent new ideas and communicate them to others. However, nonhuman social displays are rigidly programmed.

21. The major problem with "instincts" or fixed action patterns is that:

A. they can be disrupted by damaged to the spinal cord.

B. they involve the organism's entire skeletal musculature.

C. they evolved to serve adaptation to environments that have changed greatly over the past millions of years.

*D. they do not permit individual organisms to respond quickly to environmental changes.

79%, .44. Same point, in another way. Instincts evolved through natural selection to aid the adaptation of entire species to a particular environmental niche. And all individual species members share these behaviors in common. But natural selection affords no means by which an individual can "reprogram" itself to respond to changed environmental circumstances -- for the simple reason that evolutionary time is much longer than the lifespan of any individual species member. That's what we have learning for: to permit individual organisms to change their own behaviors in response to changed circumstances. But unlike instincts, what an individual has learned cannot be passed to the next generation through genetic transmission: there is no inheritance of acquired characteristics, and that applies to behavior as well as to body morphology.

22. The adaptive significance of habituation is that it:

A. greatly attenuates the effects of sensitization.

*B. allows animals to ignore familiar but harmless stimuli.

C. paves the way for associative conditioning.

D. keeps neurons active that otherwise might degenerate.

86%, .40. You want a mechanism for responding to changed circumstances (i.e., surprising events) in the environment. That's what the orienting response is. The orienting response paves the way for associative conditioning, because the organism can then search the environment for predictors of this new, surprising event: A CS for the US. But you don't want to have to continue to respond to them unless they're really important. That's what habituation does. Habituation, in that sense, is something like extinction, except that the orienting response is an unconditioned response, not a conditioned one. USs habituate; CSs extinguish.

23. The presentation of an air puff to the eye leads reflexively to closure of the eyelid. The air puff is an example of a(n):

A. conditioned response.

B. unconditioned response.

C. conditioned stimulus.

*D. unconditioned stimulus.

78%, .43. The conditioned eyeblink response is a very popular paradigm for studying classical conditioning in humans. the airpuff reflexively elicits an eyeblink response. Therefore, the air puff is an unconditioned stimulus. The eyeblink is the unconditioned response, and may be elicited as a conditioned response if the airpuff is preceded by a conditioned stimulus like a tone.

24. After extinction takes place:

A. conditioning can no longer occur to the old CS.

B. reacquisition can occur, but at a slower rate than before.

*C. reacquisition can occur, and at a faster rate than before.

D. whether reacquisition can occur depends on whether extinction has gone below zero.

88%, .42. Extinction is the loss of a conditioned response when reinforcement has been terminated -- that is, when the CS no longer predicts the US. But the CR is not lost. It returns to some degree after a rest interval (what is known as spontaneous recovery).

25. Instrumental conditioning differs from classical conditioning in which of the following ways?

*A. Reinforcement is contingent upon a response in instrumental conditioning, but not in classical conditioning.

B. Instrumental conditioning requires "insight," but classical conditioning does not.

C. Classical, but not instrumental, conditioning is impossible with autonomic responses.

D. Instrumental conditioning involves S-S associations, while conditioning involves S-R associations.

75%, .33.In classical conditioning, reinforcement, in the form of the unconditioned stimulus, is delivered following the conditioned stimulus no matter what the subject does. But in instrumental conditioning, reinforcement is only delivered if the subject makes a particular response -- the conditioned response. Put another way, in classical conditioning the response to be conditioned is elicited by the stimulus. In instrumental conditioning, however, the conditioned response is freely emitted by the organism. While classical conditioning of autonomic responses is quite common, It used to be thought that instrumental conditioning could only be applied to skeletal (motor) responses. However, the discovery that autonomic responses could also be brought under instrumental control laid the foundation for clinical applications of "biofeedback".

26. The most effective conditioning occurs when:

A. the CS follows the US by about 0.5 seconds.

*B. the CS precedes the US by about 0.5 seconds.

C. the CS and US the occur simultaneously.

D. the CS and US the occur on alternate trials.

78%, .47.Conditioning occurs only when the CS provides information about the US. When the CS and the US occur simultaneously, or occur on alternate trials, there is no such information. When the CS follows the US, you get inhibition of conditioning, because the CS provides information about the absence of the US..

27. A strong argument that contiguity is not absolutely essential for classical conditioning comes from studies of:

A. spontaneous recovery.

B. generalization gradients.

C. extinction of conditioned avoidance.

*D. learned taste aversions.

59%, .36.Learned taste aversions, like the association between sweet water and nausea studied by Garcia in his "bait shyness" experiments, occur quickly even though a delay of several hours is interposed between the taste and the nausea. Spontaneous recovery provides evidence that the CR is not lost during extinction, but that fact doesn't bear on contiguity or contingency.

28. Learning in the form of __________ involves postsynaptic mechanisms in which receiving neurons become increasingly sensitive with repeated stimulation.

A. instrumental conditioning

B. negative reinforcement

C. stimulus generalization

*D. long-term potentiation

62%, .49. There was a big hint here, which is that of the four alternatives, only one was a biological construct. In any event, in order for organisms to learn, there has to be some way for the nervous system to change. Long-term potentiation, in which changes occur in the sensitivity of a post-synaptic neuron to depolarization by a pre-synaptic neuron, is likely to be the cellular mechanism for all forms of learning.

29. Pigeons in operant chambers would be said to have successfully learned the concept of sameness if they learned to peck green keylights when shown green lights, red keylights when shown red lights, and then could demonstrate transfer of training by:

A. selecting yellow keylights when shown yellow lights.

*B. selecting keylights with triangles when shown triangles.

C. generalizing to other green and red stimuli.

D. avoiding pecking keylights with unfamiliar colors.

28%, .24. A difficult item, but still a good one, and the concept is important. The concept the pigeon is trying to learn is sameness. After training on green and red, transfer to yellow would show that the pigeon has learned the concept of same color. But the only way to demonstrate that the pigeon has learned the broader concept of sameness, in general, is to test transfer to an entirely different stimulus category -- from color to shape, for example.

30. According to Thorndike's Law of Effect:

A. associations are formed between stimuli and responses that co-occur in space and time.

B. motivational states arouse sequences of responses.

*C. responses that lead to reward are strengthened.

D. connections between stimuli and responses are weakened through disuse.

83%, .32.Alternative "A" is the principle of association by contiguity, now replaced by the principle of association by contingency. "B" is Thorndike's Law of Readiness. "D" is Thorndike's Law of Practice.

31. Learned helplessness occurs:

A. the animal is paralyzed by conditioned fear because:

B. the animal is in the "exhaustion" phase of the general adaptation syndrome.

*C. the animal has negative expectations of control over shock.

D. extinction has been put on a partial reinforcement schedule.

63%, .38. Sorry for the typo in "A", but it shouldn't have made any difference. Mowrer's two-process learning theory held that avoidance learning was motivated by fear, but we now know that avoidance learning is motivated by (positive) expectations of control over the shock. Learned helplessness occurs because, by virtue of the prior classical fear conditioning, the animal has acquired negative expectations of control -- that is, it doesn't expect that it's behavior will control shock. Avoidance is about expectancies, not about fear. All instrumental learning is about expectancies -- expectancies of control -- just like all classical conditioning is about expectancies -- expectancies of prediction.

32. A man sees a tree. What is the distal stimulus?

*A. the tree

B. the light waves reflected by the tree

C. the image on the man's retina cast by the tree

D. the pattern of nerve impulses triggered by the retinal image and conducted by the optic nerve to the brain

60%, .43. The distal stimulus is the object in the environment. The proximal stimulus is the pattern of physical energies (in this case, electromagnetic radiation in the visible spectrum) emitted by by the distal stimulus and falling on the receptor organs (in this case, the rods and cones on the retina of the eye) of the observer. The receptor organs than transduce this physical energy into neural impulses, which are carried by the optic nerve to the visual projection area in the occipital lobe of the brain.

33. Why does sugar taste sweet and vinegar taste sour? According to specificity theory:

*A. they activate different fibers that carry the information to the brain.

B. the threshold for sour is lower than the threshold for sweet tastes.

C. the size of the JNDs for sugar are smaller than those for vinegar.

D. they trigger different patterns of nerve impulses, generating a type of taste code, analogous to the bar codes on consumer products.

43%, .24.Specificity theory is, essentially, Helmholtz's extension of Muller's Doctrine of Specific Nerve Energies (as discussed in the Lecture Supplements). According to specificity theory, various qualities of sensation correspond to specific stimulus energies, which are picked up by specific receptor organs that are specifically sensitive to them. A lot of you went for D, which is the pattern theory, not the specificity theory.

34. According to opponent-process theory, a visual stimulus that results in a perfect balance of both red-green and yellow-blue systems would be perceived as:

A. mixed colors.

B. blankness.

C. vividly colorful.

*D. achromatic.

55%, .31.The opponent-process theory of color version is another variant on specificity theory. If there is a perfect balance between the red-green and yellow-blue systems, with red and green opposing each other and yellow and blue opposing each other, then there is no color vision. Vision is achromatic, consisting entirely of blacks and whites and greys.

35. When a sound stimulus is transmitted to the cochlea:

A. for low-frequency sound, only one place on the basilar membrane vibrates.

*B. for high-frequency sound, the whole basilar membrane moves, but one place moves maximally.

C. the frequency of vibration of the basilar membrane always equals the frequency of the sound wave.

D. the frequency of vibration of the basilar membrane never equals the frequency of the sound wave.

34%, .32. Auditory pitch is represented by a two-process system. For low pitches, up to about 1,000 cycles per second, the basilar membrane vibrates as a whole, at about the frequency with which it is stimulated. But the "frequency" mechanism can't work for high-frequency stimulation, because of the refractory periods of the nerves involved. Accordingly, for high pitches, over about 1,000 cps, the basilar membrane continues to vibrates as a whole, but one portion of it vibrates more strongly than the others. This "place" mechanism allows us to hear relatively high-frequency pitches.

36. When looking down a rocky beach you see individual stones nearby, but

farther away you can see only a rough-looking terrain. This best example shows us judging distance from:

*A. texture gradients.

B. interposition.

C. shape constancy.

D. linear perspective.

89%, .35. Shape constancy isn't a cue for distance. It's a result of distance perception, when the visual system takes account of distance cues such as texture gradients, interposition, and linear perspective.

37. What would happen if you suddenly had an involuntary twitch of one of your eye muscles, a twitch analogous to the jerks one sometimes has prior to going to sleep?

*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 both motion parallax and optic flow.

57%, .40.This is analogous to the demonstration in which you focus one eye on a distant object, and then gently poke it to shift the image from one part of the retina to the other. Movement of the retinal image is a cue for motion, especially when this movement is not produced by the "egomotion" of the eyes and the head. In this case, the muscles in question aren't active, so there's no information about egomotion, so the object is perceived as moving instead of still.

38. According to Gibson's ecological view of perception:

A. people perceive distal stimuli directly.

*B. all the information needed for perception is provided by the proximal stimulus.

C. the perception of motion, depth, and rigidity must be learned through trial-and-error contingencies.

D. monocular cues are sufficient for the perception of motion.

69%, .24. Gibson's ecological view of perception is, in some ways, similar to the stimulus-response theory of learning, because Gibson assumes that all you need to understand perception is in the world outside the organism. All the information needed for perception is provided by the proximal stimulus.

39. Some artists create paintings where the figure and the background relations are deliberately reversible and ambiguous. Such ambiguity illustrates the important general point about human perception that:

A. adaptation to steady or repeated stimulation happens in almost all of the senses.

B. different proximal stimuli can be parsed in the same way.

C. only a few basic perceptual abilities are inborn.

*D. the same proximal stimuli can be parsed in more than one way.

90%, .28. Dali is one such artist. So is Jasper Johns, whose paintings are full of things like Ruben's vase and Jastrow's duck-rabbit. But the whole point of the reversible, or ambiguous, or bistable figures is that perception changes even though stimulation remains constant. In other words, the same proximal stimuli can be parsed, or analzed, or understood, in more than one way.

40. In impossible figures:

A. primitive features do not connect with each other in logical ways.

B. bottom-up processing cannot occur.

*C. individual parts of the figure make sense.

D. we process the entire array simultaneously, and in parallel, which results in a top-down overload.

25%, .17. A BAD ITEM. A lot of you went for A, which isn't a bad choice, but it's not a matter of what's logical. It's a matter of whether the features connect with each other in ways that are appropriate for an object that exists in three dimensions. The individual parts of the figure make sense, but they don't connect up into a sensible whole.

41. One of perception's major characteristics, __________, is illustrated by the cocktail-party effect.

A. ambiguity

B. constancy

C. adaptation

*D. selectivity

63%, .36.Perception is selective, by virtue of attention. We pay attention to one object, ignoring others; and sometimes our attention is drawn to a new object by its salience. There's a lot more information in the stimulus field than we could possibly process, and attention helps us filter out irrelevant stimuli.

42. Size constancy refers to the phenomenon of seeing objects:

A. as the same size even if they are really different sizes.

B. as different in size even though they are really the same size.

*C. as the same size even if they move to a different distance.

D. as the same size even when they get smaller, as when a balloon loses air.

66%, .45.This is pretty much definitional. There are lots of different constancies, but size constancy allows us to perceive an object as remaining constant in size even though it moves to a different distance, thus changing the size of the image it casts on the retina.

43. Visual illusions such as the Muller-Lyer (arrows-and-feathers) illusion are:

A. predicted by the theory of direct perception.

B. produced by the application of binocular cues to distance.

C. more frequent in illiterate than literate cultures .

*D. produced by unconscious inferences.

51%, .34. Direct perception can't predict illusions, because it's a theory of realism: it attempts to explain how people see the world as it really is, but in illusions we see the world the way it isn't. In any event, the Muller-Lyer illusion is produced by unconscious inference from linear perspective cues to distance, and linear perspective is a monocular cue.

44. Cultural differences in perception indicate that:

*A. perception is not simply a product of innate mechanisms.

B. different cultures evolved different perceptual mechanisms to serve in different environments.

C. perception is a bottom-up process, unaffected by beliefs and expectations.

D. perception is not influenced by "Gestalt" principles such as closure and good continuation.

77%, .42. We're all biologically the same. To the extent that our perceptual mechanisms evolved, they evolved to serve the "Environment of Early Adaptation", roughly the East African Savannah during the Pleistoscene Era. Then hominids migrated out of East Africa to the rest of the world, but there hasn't been enough time for natural selection to evolve any new psychological mechanisms since then. So, were all stuck with the same set of innate perceptual mechanisms, despite differences in "race" or ethnicity or culture, literacy, or social class. People of different "races" or ethnicities aren't different species or subspecies, and so we all evolved the same package of innate mechanisms. Therefore, if there are cultural differences in perception, they can't be a product of innate cultural differences, because there aren't any. Culture is a human construction, passed on by social learning.

45. ____________________ evidence tends to be dismissed by psychological scientists because it involves information that is acquired through informal or unsystematic methods.

A. Correlational

*B. Anecdotal

C. Experimental

D. none of the above

85%, .42. Anecdotal evidence is informal evidence, causally gathered and impressionistically analyzed. Correlational and experimental methods are formal, quantitative scientific methods.

46. Charlene conducted a correlational study and discovered that there was a strong relationship between the frequency with which students conversed with other students in class and the frequency that students attended weekend parties. Charlene is cautious about interpreting her findings. Why?

A. Correlational studies can have directionality problems, so Charlene does not know whether students had more conversations because they met other students at parties or if students were invited to more parties because they took part in more classroom conversations.

B. Correlational studies can have third-variable problems, so Charlene does not know if some other variable, such as sociability, directly affected whether students engaged in more classroom conversations and whether they attended more parties.

*C. both a and b

D. none of the above

90%, .13. A correlation coefficient expresses the magnitude and direction of the relationship between two variables. If conversations go up when party invitations go up, then there is a positive correlation between them. But we don't know whether A is correlated with B because A causes B, B causes A, or both A and B are caused by a third variable, C.

47. Laboratory studies sometimes lack external validity because participants are tested under artificial conditions. Which of the following research topics is most likely to have high external validity when studied in a laboratory environment?

A. courtship activities in humans

B. maternal behavior in chimpanzees

*C. visual perception in rodents

D. cheating behavior in students

72%, .41.Laboratory studies are inherently artificial, in that they attempt to model some isolated aspect of the real world outside the laboratory. Human courtship and cheating behavior is highly likely to be altered by the laboratory environment. Also, we know that mating and parenting behaviors are different in the lab than they are in animals' natural environments. But there's little or no reason to think that basic aspects of visual function in nonhuman animals are any different in the laboratory than they are in the real world.

48. The least useful measure of central tendency is the:

A. mean.

*B. mode.

C. median.

D. All of the above are equally useful.

30%, .17. A BAD ITEM, with a lot of you going for D. The mean is the arithmetic average of a set of observations. The median is the point which divides the distribution of observations in half. The median is the most frequent observation. In a truly normal distribution, the mean, the median, and the mode are the same. But most distributions are quasinormal, at best. When there is a discrepancy between the mean, the median, and the mode, it is the mode that is most likely to be thrown off by random variation or error. Therefore, it is the least useful measure of central tendency. For example, in the original scoring of this midterm, the mean was 33.35, the median 34.00, and the mode 38. Not too far from normality, huh? But if just two students changed their scores from 38 to, say, 36 and 40, respectively, the mode would have changed to 34, but the mean wouldn't have changed very at all, and the mode wouldn't have changed at all. The mean and the median are preferable to the mode because they are least likely to be affected by minor random variation. As for these two, if your distribution departs radically from normal, the median is less likely to be affected by minor random variation than the mean. So, for example, in statistics about incomes or housing costs, economists refer the median, because people like Bill Gates and Larry Ellison distort the mean. The median less susceptible to distortion by "outliers".

49. If two variables are correlated perfectly in a negative way, then:

A. all the data points in a scatter plot will lie on the line of best fit.

B. the line of best fit will slope downward.

C. the scatter plot will reveal points scattered about the line of best fit but the general trend will be a downward slope.

*D. a and b

77%, .31.A correlation coefficient expresses the magnitude and direction of the relationship between two variables. Therefore, if you inspect a scatterplot of the two variables, with the axes crossing at zero (like they should), the higher the correlation, the closer the individual points are to the line of best fit. A positive correlation will be indicated by a line of best fit that slopes upward from left to right. A negative correlation will be indicated by a line of best fit that slopes downward from left to right.

50. A teacher grades an examination and finds 1 test paper with an extremely low score. That score is so low that the teacher wonders whether the paper really belonged to one of his own students or whether it somehow accidentally slipped in from another class. As a first check, the teacher looks at the class mean and the class standard deviation which are 100 and 5 respectively. Using the standard critical ratio, what is the highest score that probably came from another class?

A. 105

B. 50

C. 95

*D. 90

39%, .26. I worried a lot about this item, and good for those of you who got it.And it wasn't the hardest item on the exam, either! (#29 and #35 were harder.) The question is whether this score is likely to have occurred by chance. We know that, with a mean of 100 and a standard deviation of 5, that 95% of scores will lie between 90 (2 standard deviations below the mean) and 110 (2 standard deviations above). This "2" is the critical ratio for the the 95% confidence interval. Scores of 95 and 105 are well within the 95% confidence interval, 90 is right on the edge, and 50 is well below. Therefore, by this standard, 90 is the highest score that we can say probably came from the other class. Remember the rule of 67, 95, and 99: in a normal distribution, 67% of the scores will fall within 1 standard deviation of the mean, 95% within 2 standard deviations, and 99% within 3 standard deviations. If a score is more than 2 standard deviations from the mean, we can be reasonably confident that it doesn't come from this distribution. We can't be certain, because of course there is that pesky 5% of scores that lie outside the 95% confidence interval, 2.5% above and 2.5% below. If two means differ by more than 2 standard deviations, we can be 95% confident that the difference is statistically significant, and not just a product of random variation.

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.

Be sure that you have created an account on the course website.

This is how we will be able to give you notice of your grade.

The revised answer key, and comments on the exam items, will be posted

on the course website when grades are posted.