17.6: Chapter Exercises

Chapter Exercises

1. Linda is thirty-two years old, outspoken, single, and very bright. She majored in philosophy. As a student, she was deeply concerned with issues of discrimination and social justice, and she has also participated in antinuclear demonstrations. Rank the probabilities of each of the following:
   1. Linda is a bank teller.
   2. Linda is either a bank teller or a leader in the feminist movement.
   3. Linda is a bank teller and a leader in the feminist movement.
   4. Linda is a bank teller, a leader in the feminist movement, and she plays the guitar.
2. Suppose that you don’t know anything about Sue except that she is a woman. Rank the following from most probable to least probable:
   1. Isabella is a student.
   2. Isabella is a student who wants someday to be the first astronaut from Rhode Island.
   3. Isabella is either a student or a professor of English.
   4. Isabella is either a student or she isn’t.
3. Couples often disagree, even argue, about who has been doing more than theirshare of the housework lately. Often, each person quite honestly and sincerely thinks that they have done more than the other. This could happen without any self-deception or wishful thinking on the part of either person. How might some of the things we have learned in this chapter help explain it?
4. It is sometimes said that when people give us estimates for repairing our car or our home they are likely to start out by giving us a high estimate, since many people just accept the recommendations. Assuming this is true, imagine a person you know gets a very high estimate of the cost of a new roof, but decides to spend less than recommendation but a good deal more than they had originally planned. Which heuristic may have been involved here, and how did it work?
5. In the pretest, you were asked which alternative seems more likely in the next ten years:
   1. An all-out nuclear war?
   2. An all-out nuclear war that accidently develops out of a confrontation in the Middle East involving Iraq or Iran and some of their neighbors and that then spreads out of the region to other countries? Which answer is right? Why? Which heuristic might aid and abet giving the wrong answer?
6. Do you think that there are more famous people from Oklahoma or from Kansas (a state of roughly the same size)? Don’t proceed until you have thought about this question. How do you think people from Kansas would answer this question? What heuristics might be involved here?
7. Wilbur wants to buy a new car. He goes to the bookstore to get a mochaccino and the latest issue of Consumer Reports, which contains their most recent safety survey of large-sized sedans. The Chevrolet Impala has the highest safety rating, and Wilbur notes this. His next stop is to see his hairstylist, Wilma. Hearing that Wilbur is interested in buying an Impala, Wilma shrieks, “Those cars are dangerous! Total death traps. My client Suzy totaled hers when she ran into a utility pole going fifteen miles per hour!” So, Wilbur buys a Honda instead. Why? What should Wilbur have done? What is the relevant heuristic or reasoning fallacy? How would you evaluate the credibility of his two sources of information?
8. We know the following about Wilma: She is 23 years old, athletic, and has taken various forms of dance for 18 years. Is she more likely to be a Dallas Cowboys cheerleader or a sales clerk for Dillard’s? Defend your answer and relate it explicitly to concepts and material studied in this chapter.
9. Which hand is more probable?
   1. Ace of spades, king of spades, queen of spades, jack of spades, ten of spades.
   2. Three of hearts, eight of diamonds, jack of spades, two of spades, nine of clubs. Many people judge the first more likely. How might overreliance on one or more inferential heuristics lead to this error?
10. Wilbur is very shy and withdrawn, helpful, but with little interest in people or in the world of reality. He has a need for order and structure, and a passion for detail. Which is more likely and why: that Wilbur is a farmer or that he is a librarian? If you require more information to answer this question, what information do you need? How could you get it?
11. Suppose that we polled people and found the following (this example is hypothetical). The people polled were asked to estimate the percentage of American adults who were unemployed. Those who were employed underestimated the number, and those were unemployed overestimated it.
12. In experiments, subjects consistently err in judging the relative frequency of two kinds of English words. They estimate that the number of words beginning with a certain letter (for example ‘R’ or ‘K’) is greater than the number of words with those letters appearing third, even in the case of letters where words with the letter in third position are far more numerous than words in which the letter comes first. Explain what might lead subjects to this conclusion.
13. Most automobile accidents occur close to home. Why do you suppose this is true? Should you feel safer as you drive further from home?
14. Airlines sometimes post “full” fares prices that are higher than the fares they typically charge, and automobile dealers often post suggested retail prices on the window sticker that are higher than they will really charge. What is going on here? How effective do you think it is? What would be some good ways to resist these tactics?
15. In December of 1989, Norman, Oklahoma residents were warned about house fires. “On the average, we have two to three house fires with the Christmas season,” said Fire Marshal Larry Gardner, “and we haven’t had one yet.” Gardner appeared to be arguing that since we hadn’t had a severe house fire yet, we were very likely to have one soon. Assuming this was his intention, what fallacy was he committing?
16. Earlier, we learned about illusory correlations. Explain what an illusory correlation is, and say how the availability heuristic might encourage us to believe in certain illusory correlations. Give an example to illustrate your points.

Answers to Selected Exercises

9. The two hands are equally probable, but overreliance on the representativeness heuristic may lead us to think that the second hand is more likely, because it more closely resembles our mental picture of a random hand of cards.

11. In our example we imagined that some people were polled and asked to estimate the percentage of American adults who were unemployed. Those who were employed underestimated the number, and those were unemployed overestimated it. Why? One reason is that unemployed people are more likely to live in areas and to go to places where there are other unemployed people, and of course their own situation is highly salient to them. By contrast, people who are employed tend to interact mostly with others who are employed too. Different samples were available to the people in the two groups.