University of California, Berkeley
Department of Psychology

Psychology 1
Fall 2000

Midterm Examination 1
Feedback

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 biserial correlation coefficient) 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, we have established a cut off of r < .20.

To summarize, any items with a pass percent less than 50% and an item-to-total correlation less than .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: #41, #48, and #50.

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

Performance on the exam, as I said, was pretty good. 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) and RPP credits before determining letter grades. 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".

1. The doctrine of mentalism states that:

A. behavior, not mental life, is the true subject matter of psychology.
B. emotion and motivation are primitive mental processes.
C. a proper theory in psychology should be programmable on a high-speed computer.
D.* what people do is caused by what they think, feel, and want.

95% of the class got this item correct. The doctrine of mentalism states that mental (i.e., cognitive, emotional, or motivational states stand in relation to action as cause to effect. In other words, what we do is caused by what we know (or believe we know), feel, and desire. Mentalism is opposed to behaviorism, which in its radical form holds that mental states are irrelevant to behavior, and to some forms of biological reductionism which hold that behavior can be explained in terms of biological (i.e., neural and endocrine) principles, without invoking mental states at all.
2. Psychology is partly a biological science because:

A.* the brain is the physical basis of mind.
B. psychological principles are ultimately reducible to neurological principles.
C. only natural sciences like biology and physics are testable.
D. it is impossible to quantify social processes.

82% correct. Psychology is the science of mental life, but mind is what the brain does. Therefore, it's useful (though not strictly necessary) for psychologists to understand how the brain works. it's not at all clear that psychological principles are ultimately reducible to neurological principles. For example, the UCB philosopher John Searle (take his course!) argues vigorously that consciousness, for example, is an emergent property of the brain.
3. Anecdotal evidence should be viewed skeptically because it does NOT involve:

A. appropriate sample sizes.
B. credible eyewitnesses.
D.* systematic data collection.

58% correct. Anecdotal evidence is, almost by definition, based on only a single case, but it turns out that you can do perfectly good experiments with N = 1. The real problem is that anecdotal evidence is haphazard: somebody has an experience, or sees somebody else do something, and then draws general conclusions from it. But we have no idea how representative that case is, and whether the observations were valid and unbiased. For that we need the systematic data collection that really defines scientific activity.
4. Unlike the results of most experiments, correlational studies tend to have:

A. interrater reliability.
B. internal validity.
C. confounds.
D.* causal ambiguity.

49% correct, but an item-to-total r of .38; thus, the item was retained. The simple point is that correlation does not equal causation. Correlational studies are no more susceptible to confounds than experimental studies -- both can be poorly designed or executed or analyzed. But correlational studies are inherently ambiguous with respect to the direction of causality: we know only that X and Y are correlated; we do not know whether this is because X causes Y, Y causes X, or both are caused by yet a third variable, Z.
5. In a ______________ sample, subgroups are represented in proportions equal to their occurrence in a larger, naturally occurring, group of people.

A.* stratified
B. matched
C. random
D. planned

50% correct, item-to-total r= .38. This was a little technical, but it's an important concept. Random samples may vary (randomly) from the larger population: a sample of a population that is 12% African-American might, just by random, contain 12%, or 6%, 18%, or any other percent African Americans. But a sample stratified by ethnicity insures that there will be 12% African-Americans.
6. On a certain questionnaire the sex of a subject is indicated as 1 if female and 2 if male. These numbers are an example of a(n):

A.* nominal scale.
B. ordinal scale.
C. interval scale.
D. ratio scale.

62% correct. In a nominal scale, numbers stand for the names of things, not for quantities. We could just as easily assign females the number 0 and males the number 6. If you look at the way social and behavioral scientists code their data, you will probably find a tendency for male investigators to code females as 0 and males as 1, and a tendency for female investigators to code the reverse. This is interesting, if indeed it is true, but it doesn't matter to the analyses, because the digits just stand for names, not for quantities. The other scales are different: there, the numbers assigned have implications for the underlying quantities they represent. In an ordinal scale, 2 is greater than 1. In an interval scale, the distance between 0 and 1 is the same as that between 1 and 2. In a ratio scale, the ratio of 4/2 is the same as that of 2/1. In psychology, most scales are ordinal or interval in nature, though we often treat them, for sake of convenience, as if they were ratio scales, with little harm done most times.
7. In the distribution, 1 2 5 7 7 9 10 10 10 12, the mode is:

A. 7.
B. 7.3.
C. 8.
D.* 10.

91% correct. I'll never ask you to memorize a formula, and I'll never ask you to do a calculation that you can't do with paper and pencil alone, but the mean, median, and mode are measures of central tendency that you should know something about. The mean is the arithmetic average -- in this case, 7.3. The median is the midpoint in the distribution -- in this case, 8. The mode is the most frequent observation -- in this case, 10. In a normal distribution, also known as the "bell curve", the mean, median, and mode are the same. To the extent that they're not the same, the distribution is skewed or biased in some way. In that respect, this test was "normal": on the preliminary scoring, the mean was 33.06, the median 34, and the mode 35. Pretty good, huh?
8. In golf the better one's ability, the lower are one's golf scores. Golfing ability and golf scores are:

A.* negatively correlated.
B. positively correlated.
C. related according to their square roots.
D. too variable to be correlated.

96% correct. A correlation expresses the strength and direction between two variables. If both variables increase or decrease together, the correlation is positive. If one variable increases while the other one decreases, the correlation is negative. The strength of a correlation can be estimated by examining the envelope around the scatterplot (see the exercise in the Interactive Psychology software). If the envelope is round, the correlation is near zero. If the envelope is more oblong, the correlation is stronger. If the envelope is essentially a straight line, the correlation is near + or -1.0.
9. If one obtains a critical ratio of 5, then:

A. one can be absolutely confident in rejecting the null hypothesis.
B. one should accept the null hypothesis.
C.* one should accept the alternative hypothesis.
D. the difference between means was less than the standard error.

27% correct, but item-to-total r = .27. The critical ratio is important in hypothesis testing, and is essentially the ratio of the difference between a population mean and the sample mean, divided by the standard deviation of the population. The basic principle involved is that, by convention, a critical ratio of 2 or greater is the threshold for determining that a difference is probably too great to have occurred by chance. A C.R. of 5 is a lot higher than a C.R. of 2, so one should reject the null hypothesis and accept the alternative.
10. The functionalist perspective in psychology, elaborated by James, Dewey and Angell, asserted that:

A. complex mental states are composed of elementary associations.
B. mental states are assembled from elementary sensations, images, and feelings.
C.* mind is the basis for the organism�s adaptive behavior.
D. psychology is the study of behavior, not the study of mind.

46% correct, item-to-total r = .25. The functionalists were influenced by Darwin and his theory of evolution, and assumed that form (in this case, mind) followed function (in Darwin's theory, adaptation). Mind is important because it enhances the organism's ability to adapt to its environment. In fact, in the human case at least, mind is important because it allows us to adapt the environment to us -- with the result that we are able to live in environments, such as outer space and the Antarctic, which would be impossible for our primate relatives or caveman ancestors.
11. A general characteristic of the primary motor areas is that:

A.* the amount of tissue devoted to a specific area is related to that area's function.
B. the primary motor area contains the sensory area that corresponds to the same area of the body.
C. they are localized in only two lobes of the cerebral hemispheres.
D. the location of a neuron in the primary motor area depends on the importance of the body area to which that neuron corresponds.

64% correct. the primary motor areas are in the frontal lobe. The distribution of the various parts of the body within the frontal cortex is represented by the motor homunculus, which is larger for those parts of the body that require fine motor control. A parallel somatosensory homunculus is in the parietal lobe.
12. In right-handed individuals, the __________ of the human brain has been shown to be important for recognizing faces, comprehending spatial relationships, and perception of music.

A. occipital lobe
B.* right hemisphere
C. frontal lobe
D. left hemisphere

70% correct. Right-handed individuals, especially mature males, are more strongly lateralized than left-handed individuals. And in such individuals, spatial and pattern perception is best in the right cerebral hemisphere -- especially in the posterior association areas of the parietal and temporal lobe.
13. After the spinal cord is disconnected from the brain some spinal reflexes have lowered thresholds. This phenomenon best illustrates the concept of:

A. temporal summation.
B. apraxia.
C. reciprocal inhibition.
D.* disinhibition.

60% correct. Paraplegia impairs conscious sensation and voluntary motor control in areas covered by spinal nerves connecting to the spinal cord below the location of the injury. However, spinal reflexes mediated by these nerves are preserved. The reflexes in paraplegia are stronger than those in intact organisms, because the brain sends inhibitory signals down the spinal cord. These cannot reach spinal centers below the site of the cut, resulting in disinhibition. Temporal summation is a phenomenon of neural transmission, reciprocal inhibition is illustrated by the opponent-process theory of color vision, and apraxia is a neurological syndrome affecting controlled, voluntary movements, resulting from damage to the primary motor areas of the frontal cortex.
14. Which of the following cannot be used for signaling the intensity of a stimulus?

A. the type of neuron activated (e.g., low vs. high threshold neurons)
B. the number of neurons activated
C.* amplitude of action potentials
D. the frequency of firing along axons

54% correct. Neurons fire according to an all-or-none law, which means that a neuron will fire when stimulation exceeds some threshold; but the strength of the action potential remains constant, regardless of the amount of super-threshold stimulation. The neuron either fires or it does not. This raises the problem of how stimulus intensity is coded in the nervous system. It turns out that some neurons have higher thresholds than others. So, if a "low threshold" neuron fires but a "high threshold" neuron does not, that is one signal that the stimulus is not too strong; if a "high" threshold neuron fires, then the stimulus must be relatively strong. High-intensity stimulation also increases the rate at which a neuron will fire (the mechanism for temporal summation), and the number of neurons which fire simultaneously (spatial summation).
15. Drugs can act on neurons in a variety of ways. Which is a fairly uncommon way?

A.* blocking conduction down the axon
B. stimulating release of a neurotransmitter
C. blocking receptor sites, thus making neurotransmitters less effective
D. interfering with the recycling of neurotransmitters

84% correct. Drugs act on synaptic transmission, and there are three processes in synaptic transmission: secretion of neurotransmitter into the synaptic cleft by the presynaptic neuron (option B); uptake of neurotransmitter by the post-synaptic neuron (Option C); and reuptake of unused neurotransmitter by the pre-synaptic neuron (Option D).
16. In young children, recovery of speech and other brain functions following injury is more likely than it is for adults. Thus, we say that a child's brain has:

A. less specificity.
B. more specificity.
C. less plasticity.
D.* more plasticity.

88% correct. By plasticity we mean the ability of the brain to reorganize itself in response to various kinds of events. The immature brain is less rigidly organized than the less-mature brain, which has more plasticity with respect to functional specialization. Therefore, if a young child suffers damage to the usual speech centers, or whatever, it is more likely that other brain areas will take over the lost functions.
17. Which of the following best exemplifies the concept of positive feedback?

A. panting by a dog, which lowers body temperature on a hot day
B.* the start of an argument, where one person raises his voice, causing the other person to raise his voice, which in turn makes the first person shout
C. vasoconstriction when body temperature drops below a certain level
D. a person who walks two hundred miles through snow to get a beer but is so cold when she gets there she takes cocoa instead

63% correct. Positive feedback increases the event that produced it; negative feedback decreases that event. The positive geotaxis of a moth is an example of positive feedback: t flaps its wings more intensely, the closer it gets to the light. Hunger is a good example of negative feedback: we eat to restore depleted body sugars.
18. Vasoconstriction is a __________ of the blood's capillaries that occurs when your body is too __________.

A. widening; cold
B. widening; hot
C.* narrowing; cold
D. narrowing; hot

82% correct. Maybe a little technical, but most of you got it right anyway. You should have gotten the answer correct just by knowing what "constriction" means. Narrowing. And what do you want to do when the body's cold? Constrict the blood vessels, so that not too much blood is exposed to the cold surface of the skin, as opposed to the body's warm core.
19. Which of the following would not be a signal for an organism to drink?

A. a drop in blood pressure
B. an increase in salt concentration in the hypothalamus
C.* a drop in blood sugar level
D. a chemical messenger released by the kidney

58% correct. Again perhaps a little technical, but it is important to know the basic principles by which these homeostatic mechanisms work. In this case all you had to know was that thirst and drinking are responsive to levels of cell fluids (and salts), while hunger and eating are responsive to blood sugar levels.
20. Decreasing signs of emotion in Selye�s "general adaptation syndrome" are most likely due to:

A. activation of the sympathetic nervous system.
B.* activation of the parasympathetic nervous system.
C. activation of the peripheral nervous system.
D. activation of the somatic nervous system.

75% correct. The initial emotional arousal reflects sympathetic activation; the subsequent decrease in emotional arousal reflects parasympathetic activation, which comes in later and acts as an antagonist to the sympathetic nervous system.
21. Predatory attacks and attacks in self-defense:

A. are behaviorally indistinguishable.
B.* are controlled by different areas of the brain.
C. both entail rage.
D. all of the above

70% correct. The principle at stake here is that different forms of behavior are controlled by different brain "modules". You don't even have to know which modules. Predatory attack on another species (for food), "angry" counterattack against another species in self-defense, and aggression against conspecifics are very different motives, controlled by very different centers in the limbic system.
22. In order for the cerebral cortex to govern its own level of arousal it seems essential to have neural connections from:

A. one hemisphere to the other hemisphere via the corpus callosum.
B. the cortex to the autonomic nervous system.
C. the hypothalamus to the cortex.
D.* the cortex to subcortical systems in the mid- and hindbrain.

26% correct, item-to-total r = .24. Levels of cortical arousal are controlled by the reticular activating system (which is how it got its name) in the midbrain. Now, the nervous system could have been wired in such a way that the cortex is a passive recipient of signals from the RAS. In this case, cortical arousal would be controlled by the RAS, but it would not be controlling its own level of arousal. The only way the cortex can control its own level of arousal is by sending signals down a pathway running from the cortex to subcortical centers.
23. A patient loses the ability to speak, but retains the ability to understand what is said to her. She probably has suffered damage in the:

A. frontal lobe, near the cerebral commissure.
B.* frontal lobe, near the lateral fissure.
C. parietal lobe, near the central fissure.
D. temporal lobe, near the lateral fissure.

47% correct, item-to-total r = .27. Remember that language function is controlled by at least two centers: Wernicke's area, which is damaged in Wernicke's (or receptive) aphasia, and Broca's area, which is damaged in Broca's (or expressive) aphasia. In this case, the patient's expressive functions are impaired, but receptive functions are spared, so you would expect to find damage in Broca's area -- in the frontal lobe, near the lateral fissure close to that portion of the motor strip that controls voluntary movements of the throat, tongue, lips, and larynx (which is near the central fissure, too, but that wasn't one of the options).
24. When we compare the brains of humans to those of non-mammalian species, we observe that:

A. proportionally more brain tissue is devoted to cerebral cortex, especially in the occipital lobe.
B. proportionally more brain tissue is devoted to hindbrain structures.
C. proportionally more brain tissue is devoted to midbrain structures.
D.* proportionally more brain tissue is devoted to the frontal lobes.

60% correct. The big difference is in the relative size of the cerebral cortex, compared to the rest of brain tissue: it's much bigger in humans and other primates, than in those of non-mammals, like birds, reptiles, and fish. But within the cerebral cortex, the biggest difference is in the frontal lobes, and especially the pre-frontal cortex. We think that prefrontal cortex is the locus of most of those functions that make for "intelligence", so the results of the comparison make sense.
25. Natural selection refers to the process or principle:

A. whereby organisms can identify mates of their own species.
B. whereby animals avoid potentially harmful foods.
C. that explains how environmental factors limit natural resources.
D.* that explains why organisms with certain hereditary attributes will eventually outnumber organisms who lack these attributes.

95% correct. I don't think that any comment is needed on this one, except to reinforce that nature selects certain hereditary attributes because they confer an adaptive advantage, and the genes for these attributes pass to the offspring who inherit them.
26. Fixed-action patterns (instincts) are normally elicited by genetically pre-programmed:

A. pair-bonding.
B. sexually arousing photographs.
C.* releasing stimuli.
D. aggressive behavior.

84% correct. Some instincts are associated with aggression and pair-bonding, but there are others -- for example, those involved in parenting behavior. What these behaviors all have in common is that they are genetically programmed, built into the nervous system by evolution, and that they are released by the appearance of certain stimuli in the environment. For example, the herring-gull chick pecks for food, but only if the parent's beak has a contrasting spot; the parent regurgitates food into the chick's mouth, ut only if the check pecks its beak. The importance of specific releasing stimuli distinguish instincts from reflexes and taxes, which do not make fine discriminations among eliciting stimuli. Reflexes and taxes are, in a word, indiscriminate responses to stimulation.
27. Most truly aggressive encounters take place between:

A.* males of the same species.
B. predator and prey.
C. males and females of the same species.
D. members of different species competing for food.

65% correct. Predation occurs between species, aggression occurs between members of the same species. And, they're controlled by different brain centers.
28. In most animal species the final choice of a mate is made by:

A. the male, who usually initiates courtship.
B.* the female, who bears the major costs of reproduction.
C. both male and female equally, during courtship.
D. the arbitrary mechanisms of chance.

89% correct. Whoever bears the major costs of reproduction is the more selective in mating -- this is usually, but now always, the female (in the stickleback fish, it's the male). This is an important point, because it serves as a corrective to the traditional view of the female as passive in mating.
29. One disadvantage of innate stimulus-response tendencies such as instincts is that:

A.* they do not permit rapid adaptation to new environments.
B. they show that evolutionary processes can affect body parts, but not behaviors..
C. they do not support complex behavioral activities.
D. they mediate nonsocial behaviors, but not social interactions.

79% correct. Evolution can affect behavior as well as body morphology, and the behaviors (mostly social, involving things like courtship, mating, and parenting) which evolve can be very complicated -- consider, for example, the mating ritual of the stickleback fish. But innate S-R connections, being built in over the course of evolutionary time, take a long time to get in place and a correspondingly long time to change when the environment changes.
30. On the face of it, altruism seems to go against evolutionary principles. Why?

A.* because there is little or no apparent personal gain for the altruist
B. because altruistic animals are usually less "fit"
C. because altruism is unrelated to genetic inheritance
D. because it is rare and most animals engage in it to about the same degree

87% correct. Altruism is such a topic for debate among evolutionists because we usually think of evolution as selecting for adaptive behaviors, and adaptive behaviors are usually construed as those that permit the organism to survive long enough to breed breed and thus pass along its genes. Because evolution acts on genetically based characteristics (whether body morphology or social behavior), any behavior which increases the likelihood of the organism being killed before it can breed would seem to be a bad candidate for natural selection.
31. An animal is conditioned to salivate to a tone of 400 cycles per second (cps, or Hertz). On further trials, we reinforce a new tone of 350 cps with food, while another new tone of 450 cps is not reinforced. We find that:

A. initially, the animal responds to neither of the new stimuli.
B. it responds more to the tone of 450 cps than to the 350 cps tone.
C. it responds more to a tone of 350 cps than to one of 450 cps.
D.* eventually, the animal will respond to the 350 cps tone but not the 450 cps tone.

71% correct. This is about stimulus generalization and discrimination in conditioning. The two new tones are equally distant (50 cps up or down) from the original CS, so by virtue of the generalization gradient we would expect them initially to elicit similar responses; however, by virtue of reinforcement, we would expect that the CS to the new tone paired with the US would strengthen with trials, and the CS to the new tone unpaired with the US would weaken.
32. In a classical conditioning experiment, the magnitude of the response to the __________ varies with the number of CS-US pairings.

A.* CS
B. US
C. orienting reflex
D. unconditioned reflex

82% correct. The magnitude of the US doesn't vary, because it's a reflexive response to the US (and if it does vary, it diminishes due to habituation, independent of the number of pairings of CS with US); what varies with the number of reinforced presentations of the CS is the magnitude of response to the CS, or the conditioned response (CR). The orienting reflex (OR) is a response to the CS; it habituates with unreinforced presentations of the CS, but not as a function of the number of CS-US pairings.
33. Stimulus generalization is said to have occurred when:

A.* a number of stimuli produce the same response.
B. one stimulus produces several responses.
C. the US produces the CR.
D. the CS produces the UR.

80% correct. In classical conditioning, there is just one CS paired with the US. But when we test for generalization, we find that a number of stimuli, not just the CS, elicit the same CR; and the magnitude of CR elicited by these test stimuli varies with the similarity of the new stimuli to the original CS -- the generalization gradient.
34. In Thorndike's law of effect, what determines whether the response will be strengthened or weakened?

A. latency of the response
B. goal of the animal
C.* consequences of the response
D. animal's noticing the connection between act and consequence

65% correct. Thorndike's Law of Effect states that S-R associations are formed based on the consequences (effect) of the response in question. If a particular behavior is rewarded in the presence of a stimulus, it will tend to occur in response to that stimulus; if it is not rewarded, or punished, it will tend not to occur in response to that stimulus.
35. In backward conditioning:

A.* the CS is uninformative about the onset of the US.
B. the CR is presented shortly after the UR.
C. there is a fairly high ratio of unreinforced trials.
D. all of the above

66% correct. In the standard conditioning paradigm, delay conditioning, and trace conditioning, the CS occurs before the US -- it serves as a signal that the onset of the US will occur shortly. But in backwards conditioning, the CS occurs after the US. So it is uninformative about the onset of the US, although it may be informative about the offset of the US. In retrospect, frankly, this question might have been worded a little better, but options B and C are clearly wrong, and so option D must have been wrong as well; that leaves only A as a viable option.
36. What general principle of learning was most seriously challenged by the results of learned taste aversion studies?

A. the contingency principle
B. the principle of preparedness
C. the assumption of the passive organism
D.* the equipotentiality (arbitrariness) principle

50% correct, item-to-total r = .42. There are four principles of traditional S-R theories of learning at stake: association by contiguity, arbitrariness (equipotentiality), the empty organism, and the passive organism. The taste-aversion studies do challenge association by contiguity, but they don't challenge any principle about contingency. They say nothing about the passive organism -- it's the studies of contiguity vs. contingency that reveal the behaving organism actively striving for predictability and controllability. By illustrating the principle of preparedness, they challenge the principle of arbitrariness or equipotentiality.
37. In order to demonstrate that an organism is responding on the basis of a learned concept rather than on the basis of a specific stimulus, one must demonstrate that:

A.* learning transfers to a situation with perceptually different stimuli.
B. learning persists over many trials on many consecutive days.
C. the animal can use symbols to correctly select its response.
D. all of the above

54% correct. Concepts are abstract mental representations of things, and are not closely tied to perceptual stimuli. The important thing in concept learning is that the organism can respond to a stimulus that it has never encountered before, so long as it belongs to the same conceptual category as stimuli it has encountered before. Conceptual learning is independent of the perceptual vagaries of particular stimuli. Animals that can learn concepts may or may not be able to manipulate abstract symbolic representations of those concepts: this ability is pretty much confined to humans, with our capacity for language. Arguably some of our primate relatives have some symbolic capacity, but pigeons who can respond to trees, fish, or faces that they haven't seen before, just because they belong in the same category as other trees, fish, or faces that they have seen before, doesn't mean that they have an abstract symbol (like a word) for trees, fish, or faces.
38. In classical conditioning, organisms are learning to _____ their environment; in instrumental conditioning, they are learning to _____ it.

A. habituate to; avoid
B. generalize from; sensitize to
C.* predict; control
D. deduce; induce.

93% correct. Again, no comment needed from here, except to restate that in classical conditioning, the organism learns to predict the US on the basis of the CS; in instrumental conditioning, the organism learns that it's CR is effective in controlling the environment.
39. Transduction refers to:

A. the point at which a proximal sensory stimulus impinges upon the organism.
B.* the conversion of a proximal stimulus into a receptor process, giving rise to a neural impulse.
C. the psychological sensation associated with a stimulus.
D. the electrical activity in the cerebral cortex associated with by the perception of a stimulus.

83% correct. Transduction is the first step in sensation, the process by which the proximal stimulus (the pattern of physical energy radiating from the distal stimulus, and falling on the organism's sensory surfaces) is transformed into a neural impulse for processing by the nervous system. A proximal stimulus impinge on an organism without being transduced, as when a beam of light falls on the back of my head instead of on the retina of my eye. Transduction enables psychological sensation, but it is not the sensation itself; this requires electrical activity in the cerebral cortex, far from the receptor organs that accomplish transduction.
40. Suppose you can just tell the difference between lifting 100 grams and 102 grams. According to Weber's law, you would need to add __________ grams to tell the new weight from a standard weight of 1000 grams.

A. 1
B. 2
C. 10
D.* 20

85% correct. According to Weber's Law, the amount of change required to produce a just-noticeable difference in sensation is a constant ratio of the original stimulus. So, if you need 102 grams to detect a difference from 100 grams, the change needed is 2% (2/100). And 2% of 1000 grams is 20 grams.
41. Gibson�s "direct " or "ecological" view of perception would be considered to involve:

A. nativism and top-down processing
B. empiricism and top-down processing.
C.* nativism and bottom-up processing.
D. empiricism and bottom-up processing.

A BAD ITEM: 28% correct, item-to-total r = .10. Some of the discussion of nativism and empiricism may have misled people about this one. Gibson's ecological view of perception is clearly an instance of bottom-up processing, because it holds that all the information needed for perception is provided by the stimulus, and the perceptual apparatus analyzes this information without recourse to "unconscious inferences" and the other "higher" mental processes implied by the notion of top-down processing. But Gibson's theory also counts as nativism, because he holds that these perceptual mechanisms are innate, a product of our evolutionary heritage. They're not learned through experience, as an empiricist would want.
42. Most feature-detection processes are _____ while at least some pattern-recognition processes are _____.

A.* innate; culturally bound
B. associated with visual processing; associated with auditory processing
C. processed in the occipital lobe; processed in the prefrontal cortex
D. found in "lower" animals such as frogs and cats; generally confined to "higher" animals such as primates and humans.

39% correct, item-to-total r = .31. Feature detectors are largely, perhaps exclusively, innate: Hubel and Wiesel won the Nobel prize for discovering the neural centers in the frog visual system that are hard-wired to respond to things like points, shadows, and edges. Feature-detectors in vision might well be found in the occipital lobe, but there are feature detectors for other sensory modalities, as well as for vision, and will be found elsewhere in the nervous system. But most pattern-recognition processes are learned, as the organism gains experience with its environment. A particularly powerful example of pattern recognition is entailed by the decoding of spoken and written language, which is definitely culture-bound: if you are not part of a particular language culture, certain patterns of sound and sight simply have no meaning to you.
43. Compare two tones of 1,000 hertz and 500 hertz. What can we say about the movement of the basilar membrane in response to these tones?

A.* The peak of the vibratory wave will be closer to the oval window for the 1,000-hertz tone than for the 500-hertz tone.
B. The peak of the vibratory wave will be closer to the oval window for the 500-hertz tone than for the 1,000-hertz tone.
C. There will be a peak in the vibratory wave for the 500-hertz tone; but there will be no such peak for the 1,000-hertz tone, which affects the entire membrane equally.
D. There will be a peak in the vibratory wave for the 1,000-hertz tone; but there will be no such peak for the 500-hertz tone, which affects the entire membrane equally.

54% correct. In retrospect, this item was a little too picky, but it proved to be an acceptable item statistically, and so we retained it. The intent of the question was to test your knowledge of the place vs. frequency theories of auditory pitch: that low pitches are coded by frequency, and high pitches are coded by place. Exactly where the places are on the basilar membrane corresponding to relatively high and relatively low pitches is something you have to memorize in classes on auditory sensation, but you shouldn't have to know it at this level of the course.
44. Light of any wavelength will stimulate:

A. all four color receptors, but will do so unequally.
B.* all three color receptors, but will do so unequally.
C. only one or two of the four color receptors.
D. only one or two of the three color receptors.

66% correct. But this one was not too picky: There are three types of color receptors (cones), which is why we refer to the trichromatic theory of color vision. Each receptor is maximally responsive to a particular wavelength of stimulation, but they all respond to light of any wavelength. Output from these cone elements is then processed, a little further on in the visual system (roughly in the lateral geniculate nucleus), by red-green and blue-yellow opponent processes. So there are 3 color receptors, but 4 color processes, the latter arranged into 2 pairs.
45. Devices that make photographs appear three-dimensional do so by:

A.* presenting slightly different images to each eye.
B. presenting slightly different images, one right after the other.
C. slowly moving the photograph toward the viewer.
D. quickly moving the photograph toward the viewer.

77% correct. The paradox of depth perception is that the three-dimensional world casts two-dimensional images on the retina. How, then, do we see things in depth (three dimensions)? One mechanism is retinal disparity: each eye gets a slightly different 2D image of the world, and when these are fused, a 3D image results. It's this principle that underlies Viewmasters and the "Magic Eye" books.
46. Why does the world seem to move when you push your eyeball through the side of your eyelid?

A. Because the retinal receptors have been stimulated both by what you are looking at and the gentle mechanical force of the finger pressing against your lid.
B.* Because your eye has moved without a corresponding signal that a message has been sent out from the brain to the eye muscles.
C. Because your eye has moved without any corresponding signals that some part of your body is causing your eye to move.
D. Because you have moved some part of your body voluntarily rather than involuntarily.

49% correct, item-to-total r = .35. Remember that there are several different cues to motion: the image-retina system tracks the movement of an image across the retina of the eye, while the eye-head system tracks the movement of the eye and head as the person keeps the image in a fixed location on the retina. The visual system automatically corrects input from one system according to input from the other system. But when you push on your eyeball, you displace the retinal image without voluntarily moving your eye or head. This discrepancy leads to the illusory perception of motion.
47. Reversible figures demonstrate that:

A.* perceptual parsing is not inherent in the stimulus.
B. perceptual parsing is inherent in the stimulus.
C. figure-ground relationships are inherent in the stimulus.
D. figure-ground relationships are stable.

40% correct, item-to-total r = .55. The constancies show that perception can remain stable while stimulation changes; the reversible figures, such as Ruben's vase and the Necker cube, show that perception can change while stimulation remains constant. In other words, perception requires more than stimulation; put another way, perceptual parsing (organization) is not inherent in the stimulus, but requires a contribution from the visual system.
48. The perceptual constancies demonstrate that:

A. perceptual organization is determined by "Gestalt" principles such as proximity and good continuation.
B.* perceptual organization is determined by beliefs and expectations, as well as by the proximal stimulus.
C. we have immediate knowledge of the sensory world, by virtue of unconscious inferences.
D. illusions are created by misapplication of motion cues.

A BAD ITEM: 47% correct, item-to-total r = .12. Remember that the reversible figures, like Rubens' vase, the Necker cube, and the duck-rabbit (not to mention the Arizona Whale-Kangaroo!) were offered in partial refutation of Gibson's ecological view of perception (as were the Gestalt laws and the perceptual constancies). In the reversible figures, the stimulus remains constant, but the perception changes. Put another way, perceptual parsing is not inherent in the stimulus, but requires a cognitive contribution from the mind of the perceiver.
49. According to the perceptual problem-solving hypothesis, a viewer:

A. waits to form a hypothesis until the primitive features have been adequately analyzed.
B. examines features for fit, or failure to fit, an expectation.
C. uses both bottom-up and top-down processing.
D.* b and c

78% correct. Problem-solving or hypothesis-testing runs throughout the time course of perception. Even before features are completely analyzed, preliminary (bottom-up) output from the feature-detectors is being fit (in a top-down fashion) with the perceiver's expectations, beliefs, and other world-knowledge.
50. The Muller-Lyer (arrows and feathers) illusion and the moon illusion are both created by:

A.* misapplication of linear perspective and elevation cues.
B. unconscious magnifications of the retinal image.
C. misapplication of convergence and accommodation cues.
D. an increased ratio between the retinal size of the object and the retinal size of its background.

A BAD ITEM: 50% correct, item-to-total r = .13. This one could have gone either way, given that 50% of the class actually got it right, but the low item-to-total r led us to drop it. See? We're flexible! Anyway, in retrospect, it may have been too much to expect you to remember what the Muller-Lyer illusion looked like, though it's a famous illusion and you'll encounter it again if you take further courses in psychology. According to the most widely accepted explanation, both illusions are created by the unconscious misapplication of monocular optical cues to distance, like linear perspective and elevation from the horizon. Most who got this wrong went for options C or D, both of which are clearly wrong. Convergence and accommodation only provide information about depth if two objects are really at different distances from the observer, which isn't the case for an illusion printed on a piece of paper or presented on a screen. Nor do the retinal sizes of the stimuli change. What happens is that the perceiver perceives one object as further away than the other, unconsciously compensates for this distance information, and draws incorrect inferences from the retinal size of the object's image concerning the size of the object itself.