University of California, Berkeley

Department of Psychology

Psychology W1
Summer Session 2013

Midterm Examination 1

Scoring Key and Item Analysis

In the scoring key that follows, correct answers are marked with a double asterisk (**).

Some of you may have noticed that this exam was essentially identical to Midterm 1 for the Fall 2010 offering of the course.  All I did was to re-order most of the answers (thus changing the keying), and try to correct the items identified as "bad" by the statistical analysis of the 2010 exam.  This was deliberate, as we wanted to compare the online version of the course to the "on ground" version taught on campus.  I rarely repeat an exam -- in fact, I've only done it it when I moved from one university to another (and for much the same purpose), and I don't intend to do it again. 

The statistical analysis of this exam revealed no bad items, as defined in the Exam Information page.  All of the items with relatively low pass percents had respectable item-to-total correlations: by statistical definition, they were difficult but fair.  So no items had to be rescored.  This was expected, because I had corrected the few problematic items from the 2010 administration, but anything can happen!

Which, apparently, it did.  Exactly what happened isn't exactly clear, and we'll figure it out precisely before too long, but apparently some demon got into ANGEL and re-arranged the items on the exam.  That wouldn't have been so bad, except that this same demon apparently re-arranged the options within some items, such that -- to make up an example -- some students had to answer a question where option a was "All of the above", or option b read "B and C are correct".  Obviously, that doesn't make any sense.  This has never happened before.  The faulty items were #6, 10, 16, 24, 34, 39, 44, and 46 (these numbers refer to the "official" numbering below), and they were corrected by rescoring each of these items correct for all responses.  Rest assured that we have exorcised the demon, and this won't happen on Midterm 2.

Before rescoring, the mean score on the exam was 34 (68%), which is right in the middle of the usual range for my exams (again, see the Exam Information page).  The reliability of the exam was .90, which is excellent by psychometric standards.

After rescoring, the mean score rose to 38.00 (standard deviation = 7.56), or 76%, which was slightly better than the on-ground class did in Fall 2010 (73%).  The mean and median scores were also 38. 

In this feedback, I provide the percentage of the class that got each item correct and the item-to-total correlation (rpb) for each item, as well as 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.

1. Psychology shares with anthropology and political science an interest in:

a. the sharing of individual experience. 

b. the relation of the individual to the cosmos.

c. the relation of the individual to society. **

d. the relation of humans to other animals.

90% of the class got this correct; item-to-total rpb = ..25.  Psychology is the science of mental life, seeking to understand how the mind works. It is a behavioral science, as psychologists explain behavior in terms of the individual's mental states. It is a biological science, because the brain is the physical basis of mind. And it is a social science, because the individual's mental life and behavior takes place in a context of other individuals. Therefore, psychology, as a social science, seeks to understand the relation between the structures and processes of the individual mind to the structures and processes in society.

2. The difference between an experimental design and a quasi-experimental design is that _____.

a. only quasi-experimental designs use random assignment

b. quasi-experimental designs are specifically designed to investigate correlational effects; experimental designs are not

c. experimental design studies are specifically designed to investigate alcohol effects; quasi-experimental designs are not

d. only experimental designs use random assignment ** 

78% correct, rpb = .45.  All experiments seek to go beyond establishing mere correlations, to determining causal relations. True experimental designs involve random assignment of subjects to conditions. Quasi-experimental designs retain the essence of experimental control over independent variables, but depart from strictly random assignment. For example, a quasi-experiment might select different groups of subjects of low, average, and high IQ. This would necessarily yield more low- and high-IQ subjects than would be the case with truly random selection.

3. In a scientific experiment, the variable that is manipulated by the experimenter to determine its effect is called the _____.

a. dependent variable

   b. experimental group

c. independent variable ** 

d. sample

80%, .34.  Basic vocabulary: the independent variables are controlled (manipulated) by the experimenter, to see if they have a (causal) effect on the dependent variable, or the outcome of the experiment.

4. In a negative correlation, as one variable increases, the value of the other variable __________.

a. increases

b. decreases **

c. stays the same

d. randomly varies

100%. In a positive correlation, high scores on one variable are associated with high scores on the other -- like the hypothesized relationship between brain size and intelligence; in a negative correlation, high scores on one variable are associated with low scores on the other -- like the hypothesized relationship between intelligence and speed of problem-solving.

5. Scientists refer to the situation in which there exists a possibility that another factor, different from the dependent and independent variables, may cause changes in both variables as _____.

a. a correlation

b. bias

c. the third-variable problem ** 

d. confounding variable situation

68%, .26. The third-variable problem arises in correlational research, and it's the reason why we can't infer causation from mere correlation. That is, two variables may be correlated with each other, not because one causes the other, but because both are the effects of some third variable which is the cause of both. The confounding variable situation arises in both experimental research, where the researcher tries to infer causal relations from the effect of an independent variable A on a dependent variable Z. But if he or she hasn't controlled all the potentially confounding variables, the true cause of changes in Z may be some uncontrolled, confounding variable B.

6. The control group _____.

a. provides a basis for comparison, allowing the experimenter to assess the effects of the experimental manipulation

b. provides a means of reducing demand characteristics

c. must be matched to the experimental group in all respects except for the experimental manipulation 

d. both a and c are correct **

41%, .20.  Rescored. Experimental designs manipulate independent variables to determine their effects on dependent variables. But you can't see these effects unless there's some group (or condition) that doesn't get the manipulation. This is the control group. So, for example, if you want to determine the effect of sleep deprivation on task performance, you can't simply sleep-deprive all your subjects. Some of them have to get a normal night's sleep, and these constitute the control group.

7. The purpose of informed consent is to tell participants _____.

a. what the study will involve and what the relevant risks are, and to inform participants that they are free to leave the study if they wish ** 

b. what the expected outcome of the study is

c. what the actual outcome of the study was, after the study has been completed

d. whether they will be in the experimental or control group

95%, .18.  A psychological experiment (whether a true experiment or a correlational study) represents an agreement, a kind of contract, between subject and experimenter. Accordingly, subjects have to be informed in advance about the procedures and any risks attached to them. So, for example, in a clinical trial of a new medication, patients must be told before they enroll that they might get a placebo instead of an active drug.

8. If an individual changes his diet because it is discovered he has phenylketonuria (PKU), then one can conclude that although he had the _____ for PKU, it did not lead to the _____ of retardation.

a. phenotype; genotype

b. genotype; phenotype ** 

c. dominant gene; recessive trait

d. recessive gene; dominant trait

75%, .41.  PKU has a genetic basis, but it can be prevented by altering the person's diet. Altering the diet doesn't change the person's genetic makeup (his or her genotype), and this genetic anomaly can still be passed on to his or her offspring. But it does affect the actual expression of the gene, or the phenotype, which reflects the interaction between genetic inheritance and the environment.

9. Which of the following is NOT one of Darwin's three principles of evolution?

a. In all populations, only the best fit of individuals survives and reproduces. ** 

b. Certain of the variants must survive and reproduce at higher rates than others.

c. Traits associated with superior survival and reproduction must be passed from parents to offspring.

d. There must be variation among individuals within a population.

58%, .44.  The three core principles of Darwin's theory are variation, survival value, and inheritance. Some variants are more likely to survive than others, and these are more likely to be passed on to the individual's offspring. Darwin didn't know anything about genes, or the precise principles of heredity. But he knew that there was some innate variation, and that these innate variants must be passed from generation to generation somehow. It's not the case that only the fittest survive. Many less-well-fitted individuals survive as well, and also pass their traits on to their offspring. But over the long course of evolutionary time, individuals possessing those variants that have greater survival value will be more likely to -- well, survive and reproduce. As a result, traits associated with superior survival value will become more frequent.

10. Why does natural selection favor flexibility in behavior?

a. Animals should be able to behave randomly to keep predators guessing about their behavior.

b. Species evolve in highly changing environments.

c. Animals should behave in highly flexible ways so that they increase the chance of emitting the best behavior in the environmental situation.

d. Both a and b. **

34%, .34. Rescored. This was  a bad item before, and it's still not a great item.  The question concerns the imitations of evolutionary explanations of behavior, and the key was flexibility. Darwinian evolution by natural selection proposes a mechanism by which species adjust to environmental change, and the key to the success of Darwinian evolution is that environmental change is slow, and evolutionary change matches that slow pace. But natural selection provides no mechanism for adaptation to rapid environmental change, which is why the dinosaurs went extinct when the asteroid hit, ending the Cretaceous period. Moreover, Darwinian evolution operates on fixed traits. Sure, there's natural variation within a species, and some variants are more adaptive than others (see an earlier question), but whatever variant you've got, your behavior is fixed around it. If you're a finch, you've either got a blunt beak or a sharp beak, and there's nothing you can do to change that if you're a blunt-beaked finch and you find yourself on an island where s sharp beak would be better. Same thing goes with behavior. By virtue of innate variation, one individual may be disposed to behave in one way, another individual may be disposed to behave in another way, but there's no way for natural selection to change your behavior in response to rapidly changing conditions. So, there's got to be a mechanism by which individual species members can adapt to rapidly changing environments. We call that mechanism learning. While Darwinian evolution operates on congenital characteristics, learning operates on acquired characteristics. Now, some evolutionary psychologists argue that the capacity for learning is itself a product of evolution, and they're probably right about that. But the important point is that Darwinian evolution provides a mechanism by which species can change their characteristic behavior in response to slow environmental change, while learning provides a mechanism by which individuals can change their behavior in response to rapid environmental change. It's a different mechanism entirely -- and, frankly, more important as a basis for adaptive behavior.

11. A heritability ratio is a statistic that _____.

a. summarizes how much of the variance in a population can be attributed to genetic differences across species

b. summarizes how much of the variance in a population can be attributed to genetic differences across individuals ** 

c. averages the variance in inheritance of a characteristic across a sample of individuals

d. averages the variance in a genetic difference within an individual

57%, .47. Heritability has to do with the extent of genetic influence on a particular trait within a particular population -- that is, how much variance within a population can be attributed to the genes, and how much to the environment. We'll talk more about this in the lectures on "Psychological Development", and again in the lectures on "Psychopathology and Psychotherapy". Some of you went for A, but heritability doesn't talk about population variance across species -- heritability only makes sense within a species, because genetic transmission can only occur within a single species. It can't occur across species.

12. 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 _____.

a. the soul ** 

b. the ego

c. intelligence

d. language

74%, .52. Descartes, a loyal son of the Church, held that the soul was the key to consciousness and free will, which separated humankind from the animals, and left open the possibility for sin. What Descartes called soul, we now call mind. Although philosophers were interested in the mind before Descartes, he really focused attention on problems of knowledge, thus laying the philosophical foundations for psychology as the scientific study of mind. Later, during what is known as the "behaviorist revolution", a group of psychologists decided to abandon the study of mind, and to focus on behavior instead (this led to things like the Stimulus-Response Theory of Learning). Hence the little verse by R.S. Woodworth: "First psychology lost its soul, then it lost its mind, then it lost consciousness; it still has behavior, of a kind" -- implying that the kind of behavior that is not caused by mind, like reflexes, taxes, and instincts, is not very interesting to psychologists.

13. You are looking at a neuron under a microscope and find the part that sends signals to other neurons. You have identified the _____.

a. dendrites 

b. axon **

c. cell body or soma

d. glia

71%, .36. This is just vocabulary. Neurotransmitters taken up by the dendrites cause depolarization at the cell body, which sends a neural impulse down the axon to the terminal fibers. The function of glia cells is not yet completely understood, but at the very least they provide structural support for neurons.

14. In the lock-and-key model of synaptic transmission, the "key" gets to the "lock" by _____.

a. diffusion across the synaptic gap ** 

b. rapid conduction down to the axon

c. weak attractive forces of the lock

d. removal of synaptic vesicles

88%, .47.  Neurons don't connect directly to each other. They're separated by a small gap called the synapse. Molecules called neurotransmitters (the "keys") are secreted into the synapse by the terminal fibers of the presynaptic neuron, and fit into receptacles (the "locks") on the dendrites of the post-synaptic neuron. The lock-and-key model helps explain how certain psychoactive drugs work -- either by promoting (agonists) or inhibiting (antagonists) synaptic transmission.

15. A fundamental difference between the endocrine and nervous systems is the _____.

a. types of chemicals used as transmitters

b. distance the chemicals must travel to have an effect ** 

c. means by which messages travel from one cell to another (chemical vs. electrical)

d. presence vs. absence of target organs

36%, .59.  I don't intentionally repeat items from past exams, but I do take some test items from a file supplied by the textbook publisher, and this one was repeated from a previous edition; and I liked it so much I chose it twice. It turns out that many neurotransmitters are also active in the endocrine system, where they're called hormones. An example of epinephrine, which is also the hormone adrenalin (and norepinephrine corresponds to noradrenalin). But whereas neurotransmitters only cross the synaptic gap from one neuron to another (and neurons are cells, not organs), which is a relatively short distance, hormones circulate throughout the body, over much longer distances, through the bloodstream, in order to reach their target organs.

16. One important limitation of both CT and MRI scans is that _____.

a. they are notoriously unreliable

b. they can't tell us which parts of the brain are active at any point in time **

c.  they do not show brain anatomy

d. all of the above are correct

83%, .42. Rescored. Computerized tomography (which is, essentially, a kind of X-ray) and magnetic resonance imaging both reveal anatomical structure -- they can identify cancers, and they can identify lesions. But they can't track moment-to-moment changes in function. They can show what parts of the brain are damaged or diseased, but they can't show parts of the brain in action. For that, you need positron emission tomography (PET) or a variant on MRI known as functional magnetic resonance imaging (fMRI).

17. The sympathetic nervous system is likely responsible for controlling which behavior?

a. raising your arm to answer a question

b. feeling sleepy after dinner

c. increases in heart rate as you get ready to give a speech ** 

d. walking quickly when you are late

80%, .41.  The sympathetic nervous system activates various bodily organs to help the organism respond to stressful situations (like giving an after-dinner speech). It depletes bodily resources, which are restored by the parasympathetic nervous system (which controls digestion through the secretion of hormones that make you sleepy after you've eaten the dinner). Raising your arm or walking (slowly or quickly) would be a function of the skeletal or somatic nervous system, which controls the muscles and tendons.

18. Let's say person X suffers a stroke and, as a result, is unable to recognize faces. Chances are good that the damage is located _____.

a. in the right hemisphere ** 

b. in the amygdala

c. in the corpus callosum

d. in the left hemisphere

49%, .29. The "fusiform face area", apparently responsible for recognizing familiar faces (though it does much more than that), is in the underside of the temporal lobe -- the fusiform area -- in the right hemisphere (which, remember, is generally better at pattern recognition than the left hemisphere).

19. Following a stroke, a patient shows grossly diminished sensitivity to touch and other stimulation in the right hand and arm. The probable site of the lesion is the _____.

a. right frontal lobe

b. right parietal area

c. left parietal lobe ** 

d. left frontal lobe

76%, .54.  Remember the principle of contralateral projection -- to make a long story short, the right hemisphere controls the left side of the body, and vice-versa; and sensations from the right side of the body (or the right visual half-field) project to the left hemisphere, and vice-versa. And the parietal lobe contains the primary somatosensory area. So damage to the left parietal lobe would impair tactile sensation in the right side of the body.

20. After a stroke involving Wernicke's area, a person would have the most trouble _____.

a. making hand gestures

b. listening to a radio talk show ** 

c. pronouncing words

d. understanding traffic signs

61%, .59.  Broca's aphasia, or expressive aphasia, occurs following damage to Broca's area in the left frontal lobe. Wernicke's aphasia, or receptive aphasia, occurs following damage to Wernicke's area in the left temporal lobe (near the border with the parietal lobe). Broca's aphasics have trouble speaking, but they can understand speech perfectly well. Wernicke's aphasics have difficulty understanding speech, but traffic signs and hand gestures are not linguistic in nature (a red octagonal sign means "stop", regardless of whether you can read the word), so these functions would be generally unimpaired. Because there is no damage to Broca's area, Wernicke's aphasics would have no trouble pronouncing words -- which is why their speech is often characterized as fluent but meaningless.

21. Samantha is a highly trained pianist. How would you expect her brain to differ from those not highly trained in music?

a. She should have a much larger occipital cortex.

b. She should show more cortical area devoted to the representation of finger movements. ** 

c. She should have a larger sensation area, particularly for hearing.

d. There should be no differences between her brain and nonmusician brains.

63%, .50.  Experience shapes the brain. Pianists, who use their fingers a lot, have more cortical tissue devoted to the "finger" area of the motor cortex in the frontal lobe than do non-pianists. French horn players, who manipulate valves with their left hand, would be expected to have more tissue in the "finger" area of the right hemisphere; trumpet players, who manipulate valves with their right hand, would be expected to have more tissue in the "finger" area of the right hemisphere. Note, however, that the absolute number of neurons doesn't necessarily change. It's the connections between neurons. Also, by virtue of exercise, the "finger" area may capture some adjacent tissue in the motor homunculus that would ordinarily be devoted to the wrist or the face.

22. Compared to the parasympathetic nervous system, the sympathetic nervous system:

a. acts discretely, on one internal organ at a time.

b. mobilizes the body to meet emergencies. ** 

c. has a slow rate of onset but a rapid rate of offset.

d. conserves bodily resources like oxygen and sugars in the blood.

93%, .31.  The sympathetic nervous system acts quickly as a unit, to get the body aroused for flight or fight, to tend or befriend. The antagonistic parasympathetic nervous system acts more slowly and discretely, on whatever organ needs "attention" as bodily resources are depleted and must be conserved or restored.

23. The amygdala plays an important role in:

a. mediating some emotional responses. **

b. encoding new memories.

c. understanding written, but not spoken, language.

d. regulating the diurnal sleep-wake cycle.

88%, .26.  Just as the hippocampus plays an important role in memory, so the amygdala plays an important role in emotion -- especially negative emotions, and especially fear. Remember Patient S.M., whose amygdala was destroyed by a calcification process, and who no longer could experience, or for that matter recognize, fear and other negative emotions.

24. An obvious benefit of habituation is that _____.

a. it narrows the range of stimuli that elicit alarm

b. it leads to enduring brain changes in the hippocampus

c. it guarantees that we will respond to novel inputs 

d. both a and c **

30%, .32. Rescored.  Organisms alert to new, surprising, and unfamiliar stimuli. But with repeated presentation, the new becomes old, the unfamiliar familiar, and the surprising becomes expected. That's habituation -- the one form of learning that occurs in every organism that has a nervous system, and which lays the foundation for classical conditioning.

25. What learned contingency is most important in classical conditioning?

a. if US, then UR and if not US, then not UR

b. if CS, then CR and if not CS, then not CR

c. if CS, then US and if not CS, then not US ** 

d. if US, then CS and if not US, then not CS

55%, .46.  Remember that association by contiguity is wrong, and association by contingency is right, as the governing principle of classical and instrumental conditioning. It's not enough that the CS and US occur close together in space and time (which is he "if CS, then US") part. It's critical that the CS actually predict, provide information about, the US. It doesn't do that unless the organism can also keep track of the number of times that the CS is not followed by the US. Conditioning occurs when the probability of the US, given the prior presentation of the CS, is greater than the probability of the US, given the absence of the CS.

26. In classical conditioning, the animal must learn about the relationship between _____; in instrumental conditioning, it must learn about the relationship between _____.

a. CR and US; stimulus and response

b. CS and US; response and reinforcement ** 

c. CR and UR; response and reinforcement

d. CS and UR; stimulus and response

74%, .34.  Classical conditioning is about prediction -- the organism is learning to predict the occurrence of an event, the US, on the basis of another event, the CS. Instrumental conditioning is about control -- the organism is learning what behaviors (responses) are effective in producing particular outcomes (reinforcements).

27. Working as a car mechanic for a taxi company, Jay receives a paycheck every two weeks. Which type of reinforcement schedule is Jay on?

a. Fixed Interval ** 

b. Variable Interval

c. Fixed Ratio

d. Variable Ratio

95%, .19.  In ratio schedules, reinforcement is delivered after the organism has made some number of responses since the last reinforcement. In interval schedules, reinforcement is delivered after a particular period of time has elapsed since the last reinforcement. In fixed schedules, this ratio or interval is -- well , fixed at a particular number. In variable schedules, the ratio or interval varies around some mean. Jay is paid every two weeks without fail, so he's on a fixed interval (FI) schedule. If he was paid on the 1st and the 15th of the month, except when that day falls on a weekend, in which case he is paid on the business day closest to the 1st or the 15th, that would be a variable interval.

28. Which of the following occurs in a learned helplessness situation?

a. Punishment is administered at predictable intervals.

b. The organism lacks control over its environment. ** 

c. There exists a contingent relationship between some response and punishment.

d. There exists a very slight chance of escape learning.

71%, .48.  Just as classical conditioning is about predicting events, instrumental conditioning is about controlling events -- including, as in the case of escape and avoidance learning, whether the animal is going to get shocked, and how much. In helplessness, the pretreatment of inescapable shock leads the animal to acquire a negative expectation of control -- that it lacks control over its environment -- that generalizes to the avoidance situation. It's not that there exists a "very slight chance" of escape learning. In the pretreatment, there's no chance at all -- the shock is simply inescapable. In the test of avoidance learning, there is every chance of escape and avoidance -- but the animal doesn't take it, because of the negative expectation acquired from the pretreatment.

29. The normal defense reaction of species XYZ involves wing flapping in the face of danger. For these birds, according to the principle of belongingness, which of the following responses would be easiest to learn?

a. flapping its wings to produce water

b. flapping its wings to produce food

c. flapping its wings to avoid shock ** 

d. all of the above would be equally easy to learn

87%, .30.  Evolution prepares organisms to learn certain stimulus-response connections readily: learning is fastest when what the organism has to learn capitalizes on its innate response tendencies. Birds tend to peck at their food, and they tend to fly away from danger. So, it's easy for birds to learn to peck a key to get food, but hard for them to learn to peck a key to avoid shock. And it's easy for them to learn to flap their wings to avoid shock, but hard for them to learn to flap their wings to get food. This result, of course, violates the arbitrariness assumption of traditional stimulus-response (S-R) theories of learning.

30. What is the main effect of long-term potentiation (LTP)?

a. LTP decreases sensitivity of the postsynaptic neuron in response to repeated stimulation.

b. LTP stimulates sympathetic activation.

c. LTP increases sensitivity of the postsynaptic neuron in response to repeated stimulation. **

d. LTP stimulates parasympathetic activation.

88%, .28.  LTP is, apparently, the biochemical basis of learning, and Eric Kandel of Columbia University, a psychiatrist assisted by a whole bunch of psychologists, got the Nobel Prize for discovering it. When two neurons fire in close succession on repeated occasions, (as when a pre-synaptic neuron releases neurotransmitter in sufficient quantities to depolarize a post-synaptic neuron), chemical changes in the post-synaptic neuron increase its sensitivity to the activity of the pre-synaptic neuron. In short, it's threshold for depolarization changes. In this sense, the nervous system can be thought of as "learning": the "behavior" of the pre-synaptic neuron undergoes a relatively permanent change as a result of "experience". Note, that it could have gone differently. For example, the change could occur in the presynaptic neuron, such that it releases more neurotransmitter into the synapse. But that's not what happens. The change occurs in the sensitivity of the post-synaptic neuron.

31. Why are reflexes, instincts, and other innate behaviors inadequate as mechanisms for behavioral adaptation?

a. There must be a mechanism that allows individuals to change their behavior in response to changing stimuli. ** 

b. While reflexes are found only in vertebrate organisms, instincts are found only in invertebrates and primitive vertebrates.

c. Instincts generalize uncontrollably beyond the specific stimuli to which they have been conditioned by natural selection.

d. They only involve single muscle systems.

78%, .36.  Reflexes (which involve single muscle systems), taxes (which involve the organism's entire skeletal musculature), and instincts (which are highly discriminative responses to stimulation), are important elements of an organism's innate behavioral equipment. But they're not enough. Organisms have to be able to acquire new responses to old stimuli, and they also have to be able to respond to new stimuli, and they have to be able to respond to -- to anticipate -- stimuli that are not physically present in the environment. All of these things are accomplished by learning.

32. Which assumption of traditional stimulus-response theory is not contradicted by research on taste-aversion learning?

a. Association by contiguity.

b. Arbitrariness.

c. The passive organism. ** 

d. The empty organism.

37%, .58. Taste-aversion learning contradicts the assumption of association by contiguity, because rats can learn a connection between the taste of water and nausea, even though these two events are separated by a long temporal interval. It contradicts the arbitrariness assumption, because rats can form associations between taste and nausea but not between taste and shock, and they can form associations between sight and sound and shock but not sight and sound and taste. It contradicts the assumption of the empty organism because, in order to understand what rats can learn and what they cannot learn, we have to understand how their internal workings have been shapes by evolution. As I said in lecture, that's pretty good for one experiment -- which is why it's so famous. But, alas, taste-aversion learning doesn't tell us anything about the assumption of the passive organism. That assumption is contradicted by research such as Kamin's blocking experiment, which shows that rats are surprised by unexpected events, actively search the environment for predictors of those events -- and, when they identify such a predictor, actively focus their attention on that predictor and actively ignore everything else. the Kamin experiment, for its part, also contradicts three of the four assumptions. Blocking contradicts the assumption of association by contiguity, because the redundant CS is as contiguous with the US as the original CS. It contradicts the assumption of the empty organism, because in order to understand what the organism learns we have to understand its internal mental states of surprise, expectancy, and attention. And it contradicts the assumption of the passive organism, because it portrays the animal as actively searching for, and attending to, reliable predictors of environmental events. That's why the blocking experiment is so famous.

33. Sounds in the environment enter the ear and cause a membrane in the inner ear to vibrate. In the case of audition, what does vibration of the inner ear membrane represent?

a. the distal stimulus

b. the proximal stimulus ** 

c. a measure of adaptation

d. a neural basis for the tabula rasa

88%, .35. The distal stimulus is some object or event in the environment. The proximal stimulus is the pattern of physical energy -- light waves, sound waves, pressure, chemical molecules, whatever -- that emanates from the distal stimulus and falls on the organism's sensory surfaces -- the rods and cones in the retina of the eye, the vibration of the basilar membrane against hair cells in the inner ear, tactile receptors in the skin, chemo-receptors in the nose or on the tongue, whatever.

34. In a signal-detection experiment, Frank, the participant, has a very casual attitude and tends to say, "Yes, I hear the tone" most of the time, even when he is in doubt. What will this lead to?

a. the researcher's disregard of Frank's data 

b. an increase in the number of false alarms

c. an increase in the number of hits

d. both b and c **

37%, .35. Rescored. Unlike classical psychophysics, for which detection is simply a function of stimulus intensity and the sensitivity of the sensory modality, signal detection theory also takes the expectancies and motives of the observer into account. By varying the base rates of "signal on", it can vary the observer's expectancies. By varying the payoffs for hits and false alarms, it can vary the observers motives. More important, it can actually calculate what the observer's expectancies and motives are. Frank doesn't care much about this task, he says "yes, the signal's on" on virtually every trial, and so while he'll score a lot of hits, he'll also score a lot of false alarms.

35. Most psychologists believe that there are at least _____ different skin sensations. They are _____.

a. three; pressure, temperature, and pain

b. three; pressure, warmth, and cold

c. four; pressure, warmth, cold, and pain ** 

d. four; pressure, itch, temperature, and pain

78%, .30.  Aristotle said there was just one skin sense, the tactile sense of touch. But Sherrington argued that there were at least three skin senses -- touch, temperature, and pain. But, as the text makes clear, we now know that there are two quite different temperature senses -- one for warmth, the other for cold (hot stimuli activate both senses). This is all in flux: there might be additional skin senses, like itching, and there might be two different pain senses, one for "fast" and the other for "slow" pain. But there are definitely two temperature senses, warmth and cold, which makes the correct answer C not D.

36. Which of the following best describes the function of taste receptors?

a. Taste receptors can respond to any tastant indiscriminately.

b. Taste receptors respond to only one kind of tastant.

c. Taste receptors are especially sensitive to one particular tastant, but can respond to any of the basic tastes. ** 

d. Taste receptors respond to both tastants and odorants.

75%, .54.  This is about specificity vs. pattern theory. There are several different qualities of taste and odor, and it's possible that there are separate taste and odor receptors sensitive to each one. But that doesn't seem to be the case. There are different receptors, and each responds to any of the stimuli, but it is particularly responsive to one stimulus versus the others. So, it's the pattern of neural impulses that's important. The same principle holds for color vision: each of the cones responds to the entire spectrum of wavelengths, but different cones are maximally responsive to short, medium, and long wavelengths.

37. Which finding is inconsistent with the place theory of pitch?

a. For low-frequency sounds, the basilar membrane is deformed almost equally along its entire length. ** 

b. For high-frequency tones, the site of peak deformation along the basilar membrane does not correspond to stimulus characteristics.

c. Normal adults can discriminate between the frequencies of tones considerably higher than 500 hertz.

d. High-frequency tones cause peak deformations close to the oval window, while low-frequency tones have their peaks farther away from this structure.

53%, .45.  The place theory says that the point at which the basilar membrane vibrates maximally varies from high to low pitches. The frequency theory says that the basilar membrane vibrates as a whole, and that it's frequency of vibration matches the frequency of the stimulus. At low pitches, the basilar membrane vibrates as a whole, supporting the frequency theory and contradicting the place theory. But at high pitches, the basilar membrane vibrates maximally at different locations, supporting the place theory and contradicting the frequency theory.

38. What does the Young-Helmholtz theory fail to explain?

a. the Young-Helmholtz theory is remarkably comprehensive; with regard to its scope, no questions remain unanswered

b. how we discriminate between lights of different wavelengths

c. why yellow looks like a primary color but is not considered to be one **

d. how many color receptors humans have 

67%, .51.  The Young-Helmholtz theory says that color vision is the product of three color receptors, each sensitive to "red", "green", and "blue" light, and that all the other colors are produced by a process similar to the additive mixture of these three primary colors -- much like your TV or computer screen works. Thus, Y-H says that yellow is produced by the mixture of red and green, just as purple is produced by the additive mixture of red and blue, and orange by the mixture of red and yellow. When people look at purple, they do, in fact, see red and blue. But when people look at yellow, they don't see a mix of red and green, or any other mix. They see yellow. So yellow is a primary color, and so it ought to have its own cone. But it doesn't. There is only a single mid-wavelength cone for "green". So there has to be some other mechanism for color vision besides the relatively simple one implied by the trichromatic theory.

39. Feature detectors in human visual systems are tuned to respond to specific stimuli such as lines and edges with different orientations. How do we organize all these specific pieces of information so that we can perceive organized wholes?

a. by using our previous experience

b. by recognizing lines and edges and combining this recognition with the assistance of other, more complex feature detectors 

c. by using an opponent-process-type function that exerts itself on the visual cortex

d. both a and b **

46%, .41. Rescored.  Innate feature-detection consists of two components -- detecting the presence of elementary features in the stimulus, and detecting the presence of certain combinations of features. Then, feature detection is followed by learned pattern-recognition. After the stimulus has been analyzed into its constituent features, higher-order pattern-recognition processes identify patterns of features that are familiar, or have meaning, for the perceiver.

40. Sensation is typically understood as the detection of simple stimulus attributes. How would perception usually be defined?

a. how we organize and integrate simple sensory elements ** 

b. how we come to understand people

c. how we form attitudes about the world we see

d. a lower-order brain process, primarily executed by the hindbrain

80%, .28.  Sensation has to do with detecting the presence of a stimulus in the environment, or a change in that stimulus. Perception has to do with forming an internal mental representation of that stimulus -- at the very least, identifying its shape, its location, and its activity. Some theorists identify sensation (and perception as well) as a low-level process, but it isn't: perception involves problem-solving activity, and even signal detection is influenced by higher-order expectations and motives. And besides, perception isn't performed by the hindbrain, which is the most primitive part of the brain. Perception is a product of the activity of the cerebral cortex.

41. Most of us see the following figure as rows instead of columns. Which gestalt grouping factor of perceptual organization is represented here?

Test question

a. closure

b. similarity ** 

c. transposition of form

d. figure and ground separation

88%, .38. This is about the Gestalt principles of perceptual organization. According to the principle of similarity, we perceive similar objects as somehow belonging together. Therefore, perceivers will tend to group the 0s together, and also the Ss, so that the stimulus is perceived as four horizontal columns, not five vertical ones.

42. What do reversible figures demonstrate?

a. Perceptual parsing is inherent in the stimulus.

b. Perceptual parsing is not inherent in the stimulus. ** 

c. Figure-ground relationships are inherent in the stimulus.

d. Figure-ground relationships are stable.

47%, .56. In reversible figures, such as Ruben's vase or Jastrow's duck-rabbit, the percept changes even though the stimulus remains constant. This strongly indicates that all the information required for perception is not provided by the stimulus, and automatically extracted by the perceptual apparatus; rather, some of the necessary information must be supplied by the perceiver, in the course of active perceptual problem-solving.

43. To which of the following are expectancies and context effects especially important?

a. top-down processing ** 

b. feature detection

c. bottom-up processing

d. gestalt principles of separation

55%, .54.  Perception is the product of both bottom-up and top-down processes. Bottom-up processing is exemplified by feature-detection -- it involves unpacking the stimulus. Top-down processing is exemplified by signal-detection and especially pattern-recognition. It involves matching the features of the stimulus to knowledge stored in memory -- a process that is heavily influenced by expectancies and context.

44. Which area(s) of the cortex is (are) directly involved in processing visual information?

a. occipital

b. parietal

c. temporal

d. all of the above areas of the cortex **

34%, .50. Rescored. A hard item, but a good one. This has to do with the limits on modularity or functional specialization. We generally think of visual processing as localized in the occipital lobe, which after all is the location of the primary visual cortex. But the brain isn't just a "mental toolkit" of independent modules. The brain acts as an integrated system. Connections between the occipital and parietal lobes form the "where" pathway for identifying the location of an object in space, and connections between the occipital and temporal lobes form the "what" pathway for identifying what an object is.

45. Which is an example of a higher-order invariant in size constancy?

a. the size of an object's retinal image

b. the actual size of the image out in the world

c. the ratio between the retinal size of the object and the retinal size of a stimulus in the background ** 

d. the apparent size of the object as the subject perceives it

41%, .41.  This was about Gibson's answer, from the ecological view of perception, to the problem of perceptual constancies. Constancies are, in a sense, the opposite of the reversible figures: in perceptual constancy, the percept remains stable despite changes in the stimulus. Therefore, it would seem at first glance that all the information needed for perception is not provided by the stimulus. But Gibson has an answer, which is that we're defining "the stimulus" improperly. For Gibson, "the stimulus" includes both the object and its background. So, the perception of size and distance isn't merely given by the size of the retinal image of the object. It's also given by the size of the retinal image of the object's background, and in particular the ratio of these retinal images. As the lion comes closer, its retinal size increases, but the ratio of its retinal size to that of the trees in the background remains constant. So, stimulation is invariant after all, and that's why perception is constant. So Gibson has a way out of the problem of perceptual constancy. But other problems, like the reversible figures and perceptual illusions, are -- well, they're more problematic for him.

46. A person with only one eye could perceive depth by using which cue(s)?

a. relative size 

b. texture gradients

c. linear perspective

d. all of the above **

84%, .42. Rescored.  A wide variety of cues provide information for the perception of depth or distance. some of these are ocular cues, in which the information comes from the eyes themselves; others are optical cues, in which the information comes from the retinal image, Some are binocular, in that they require two functioning eyes; others are monocular, or cyclopean, in that they are available to individuals who have only a single eye. All the "pictorial" cues for depth perception, including relative size, linear perspective, and texture gradients, are monocular optical cues. The motion cues for depth, including optic flow and motion parallax, also classify as monocular optical cues.

47. Why does the world seem to move when you push on your eyeball through the side of your eyelid?

a. The retinal receptors have been stimulated both by what you are looking at and by your finger pressing against your lid.

b. Your eye has been moved without the corresponding blinking that usually occurs when you put your finger very near your eye.

c. Your eye has moved without being signaled by the brain to do so. ** 

d. You have moved a part of your body voluntarily rather than involuntarily.

61%, .58.  This is another illustration of the complexity of the Gibsonian ecological view of perception, in which the entire array of available stimulation provides all the information needed for perception -- in this case, the perception of motion. An important cue for motion is the movement of the image across the retina. When you move your eyes, the retinal image of a stationary object also moves. Taken all by itself, that should give rise to the perception that the object is moving. But there's also feedback from the ocular muscles that tells the visual system that your eyes moved, and this allows it to compensate for, to correct for, the movement of the retinal image. So, the image is perceived as stationary despite the fact that the retinal image moves. But when you push on your eyeball, there's no such feedback from the ocular musculature. So, the retinal image moves from one part of the retina to another, but there's no correction based on muscle movements. Because there's no correction, the object appears to move, even though it's actually stationary.

48. The binding problem refers to _____.

a. identifying conjunctive stimuli

b. determining which elements of a stimulus show interposition

c. determining which elements in the stimulus information belong together ** 

d. looking for multiple stimulus elements in an array

83%, .15.  When we analyze an object into its constituent features, we confront the problem of piecing those features back together to form a coherent, accurate perceptual representation of the object. The binding problem is the problem of figuring out which features go together. The fact that the binding problem is truly a problem is demonstrated by illusory conjunctions that sometimes occur when we attempt to identify objects in a stimulus array. Sometimes the visual system binds the wrong features together, resulting in a perceptual representation that does not, actually represent the object.

49. The ecological view of perception states that:

a. because perception depends on unconscious inferences, we experience it as direct and unmediated.

b. perception is a problem-solving process that requires the perceiver to draw on knowledge of the environment stored in memory.

c. all the information needed for perception is provided by the stimulus field. ** 

d. transduction of the distal stimulus into the proximal stimulus is carried out by modular feature-detector mechanisms located in the brain.

70%, .60.  The ecological view of perception gets its name from its fundamental assumption, which is that all the information needed for perception is provided by the stimulus environment. For that reason, it asserts, there is no need for any "higher-order", "top-down" contribution from the perceiver.

50. Which phenomenon poses the least trouble for the ecological view of perception.

a. Top-down processing.

b. Ambiguous figures.

c. Visual illusions.

d. Perceptual constancies. ** 

62%, .55.  In the perceptual constancies, perception remains constant despite changes in stimulation. That would suggest, contrary to the ecological view, that perception requires more than extracting information from stimulation. But Gibson's reply is that higher-order stimulus features, such as the ratio of an object to its background, do, in fact, remain invariant despite changes in lower-order stimulus features, like the size of the retinal image of the object (ignoring its background). So, the reason that perception is invariant is that these higher-order features of stimulation are also invariant. It's not so easy for Gibson to escape the implications of the other phenomena: ambiguous figures, where perception changes while stimulation remains constant; visual illusions, where unconscious inferences lead us to perceive the world inaccurately; and expectation and cultural effects on perception, which are instances of top-down processing. But because Gibson has a workaround, the perceptual constancies give him the least trouble.