CRITICAL THINKING LESSON 8B:
Cognitive Heuristics and Fallacious Reasoning

The mistake made by the customers buying turquoise jewelry in Critical Thinking Lesson 8A was not caused simply by a lapse of attention or by a lack of motivation. In fact, most of the customers probably gave some thought to whether or not they were spending their money wisely. The problem was that they didn't have much knowledge about turquoise jewelry, so they had to rely on their intuition about the relationship between the price of an item and its quality. This intuitive processing of information caused them to experience a "cognitive illusion." A cognitive illusion is an error of reasoning caused by an intuitive judgement that seems, on its surface, to be very convincing. Because our intuitions often seem so compelling, we typically do not attempt to test their accuracy. Thus, we continue making the same mistake indefinitely, all the while thinking that we are acting appropriately. Cognitive illusions often are caused by the use of "cognitive heuristics."

A cognitive heuristic is a mental shortcut used to solve a complex problem. The customers who bought the turquoise jewelry were using the following heuristic: expensive items are of better quality than inexpensive items. There are many other such examples in your everyday life. For instance, when you are trying to find the most inexpensive items at the grocery store, you tend to use mental shortcuts to quickly identify them. Thus, if you see a sign under a product at the store that says something like "low everyday savings," you are more likely to buy that product than if there had been no sign. Why? The store owners are hoping that you will use your sale-sign heuristic to infer that the item is on sale, even when it isn't. Let's look at two of the more common cognitive heuristics that can lead to cognitive illusions.

The Availability Heuristic. Answer the following question: do more people die each year in the United States from being hit by falling airplane parts or from being attacked by sharks? Most of you probably immediately answered "shark attacks." But this answer is wrong: "in an average year in the United States 30 times more people are killed by falling airplane parts than by shark attacks" (Ruscio, 2002, p.111). In this example, we see the influence of a common cognitive heuristic--the availability heuristic, which is a mental shortcut in which one judges a phenomenon to be more frequent or more likely to occur when memories of it are easily retrieved. Because shark attacks, when they occur, are publicized widely on television news and have been immortalized in very popular movies, it is very easy for most people to bring instances of them to mind. But, because you probably have never heard of or seen anyone being hit by a falling airplane part, memories of deaths caused by this event are not mentally available to you.

The discussion in Chapter 7 about memory suggests that four factors are important for making an event memorable and, therefore, easy to bring to mind. First, events that are easily perceived by the senses (that are concrete) are more memorable than events that are not. For example, it probably is easier to form a memory of a particular chair than it is to form a memory of the meaning of the concept of determinism. A chair is a highly concrete object that can easily be imagined whereas determinism is not something that can be perceived by the senses and, hence, cannot be imagined. Second, events that have personal relevance are more memorable than events that are not. As you learned in Chapter 7, self-referent encoding (making information personally meaningful) improves retrieval of the information later on. Third, events that are associated with emotion are more memorable than events that are not. As mentioned in Critical Thinking Lesson 7A, "strong emotions, especially ones involving happiness and fear, tend to lead to the development of enduring memories." Fourth, events that occur repeatedly are more memorable than events that do not. This is something that your everyday experience probably has demonstrated to you countless times. For example, if you read a textbook chapter several times, you will tend to remember it much better than if you read it only once.

One important way in which the availability heuristic leads us into error involves the fact that the occurrence of an event typically is more salient to us (and, hence, more memorable and available) than is its nonoccurrence. For example, in Critical Thinking Lesson 1, we discussed the common belief that washing one's car causes it to rain. Most people readily notice occasions on which it rains soon after they have washed their car. This makes it more likely that they will form memories of these occasions and that they will easily recall them in the future. On the other hand, most people probably don't notice occasions on which it does not rain soon after they have washed their car; or occasions on which it rains when they have not washed their car. Such nonoccurrences are not remembered. In general, we have stronger and more enduring memories for occasions on which something happened, which causes us to overestimate their frequency.

The Representativeness Heuristic. Read the following description carefully and then answer the question that follows it:

Robert is a white male, who works as an executive in an insurance company. He has been married for twenty-five years and has two children: a son, who is in medical school studying to become a doctor, and a daughter, who has just been accepted to an ivy-league university. Robert makes an annual salary that is well above the national average ($150,000). He was brought up in a working-class neighborhood on the south side of Chicago but now lives in an upper-middle-class suburb near the south side of the city. He likes politicians who are tough on crime and against abortion rights. He also would like to see welfare abolished because he thinks that most welfare recipients are simply too lazy to work. Robert likes to have a glass of expensive wine with his dinner. Is Robert more likely to be a Democrat or a Republican?

How did you go about answering this question? One way would be to find out how frequently people with Robert's background are Democrats or Republicans. For instance, you might have known that most people brought up on the south side of Chicago are members of the Democratic party, and decided that Robert probably is a Democrat. It is more likely, however, that you examined Robert's attitudes and beliefs, compared them to stereotypes (oversimplified and rigidly held sets of beliefs) you have of Democrats and Republicans, and made a decision based on how closely Robert met one or the other stereotype. In this case, you made use of the "representativeness heuristic."

The representativeness heuristic is a mental shortcut in which one judges an event to be an instance of a particular category when the event has some characteristics that are consistent with that category. In other words, we conclude that an event is an instance of a particular category because it seems to be representative of other instances of that category. The representativeness heuristic typically relies upon the use of stereotypes to make decisions about which category an object, event, or person belongs in. For example, you will learn in Chapter 14 (p. 564) about a study by David Rosenhan in which eight normal people went to various mental hospitals and complained that they were hearing a voice that said, "empty," "hollow," or "thud." Other than this one (apparent) hallucination, they reported no other symptoms and acted normally. All were admitted with a diagnosis of schizophrenia. Because the stereotype of schizophrenia includes the symptom of hearing voices, the admitting physicians probably made use of the representativeness heuristic to make their diagnoses. A better way to diagnose these people would have involved the consideration of other information. The most important information would be the following: the number of people (both those who are normal as well as those who are suffering from other mental and physical disorders) who hear voices at least occasionally. In addition to this information, the clinicians should have considered whether or not these people showed other common symptoms of schizophrenia. But instead, they simply used the representativeness heuristic to quickly diagnose them with schizophrenia.

Fallacious Reasoning and Mindlessness

Words are very powerful influences on our behaviors, thoughts, and emotions. In fact, it may be apparent to you that we often react mindlessly to the words people use. For example, when someone is attempting to convince others of the sheer evil inherent in a person, it is not unheard of to compare the person to Adolph Hitler. The use of that name typically arouses an immediate emotional reaction in most people and they may respond mindlessly by developing a dislike of the person being so compared.

In the Critical Thinking Application at the end of Chapter 8, you learned about some ways in which people who wish to influence the beliefs and actions of others use words intended to get them to respond mindlessly. These attempts often involve the use of fallacious reasoning. A fallacy is an error in reasoning. Two of the more common fallacies are described here.

The Fallacy of Personal Attack. This is a fallacy in which, in order to undermine a claim, one attacks the person making the claim rather than the reasons supporting it. (This fallacy is known more formally as argumentum ad hominem.) For example, after learning about the psychoanalytic approach developed by Sigmund Freud, students sometimes will ask, "isn't it true that Freud used cocaine?" The implication of the question is that there must be something wrong with the psychoanalytic approach if the person who developed it had, at some point in his life, taken a drug known to affect thinking. Whether or not Freud ever used a psychotropic drug, however, is irrelevant to the evaluation of his theories. In order to determine if his theories are good ones, we must examine the evidence for and against them.

The fallacy of personal attack is a strategy that attempts to appeal to our hearts rather than to our heads. The fallacy suggests that the claim a person is making cannot be trusted if the person cannot be trusted. In this way, one hopes to sidestep a careful evaluation of the reasoning used to support the claim.

The Fallacy of Appeal to the Masses. This is a fallacy in which one points to what most people believe or do as evidence for or against a claim. (This fallacy is known more formally as argumentum ad populum.) Advertisers often use appeals to the masses. For example, "[Product Y] is the best-selling toothpaste in America"; or, "more people drive [Product Z] than any other automobile in its class." In general, the fact that many people do something or believe something is not good evidence for or against a claim. One cannot establish what is true by taking a vote.

As with the fallacy of personal attack, the fallacy of appeal to the masses is a strategy that attempts to appeal to our hearts rather than to our heads. The fallacy involves the attempt to manipulate people by tapping into their motivation to be part of the crowd rather than to encourage them to carefully evaluate the reasoning used to support a claim.

CRITICAL THINKING QUESTIONS FOR LESSON 8B

Question 8B-1
In Critical Thinking Lesson 4, it was stated that "many people believe that the full moon affects human behavior in various unusual ways," such as by increasing murder rates, suicide rates, traffic accidents, assaults, domestic violence, and admissions to mental hospitals (Carroll, 2002). Research, however, has shown no good evidence that the phase of the moon is associated with increases or decreases in any of these. In other words, unusual behaviors are no more frequent on full-moon nights than they are on nights in which the moon is in other phases.

Given what you have learned in this lesson about the availability bias, why might people believe that unusual happenings are more frequent on full-moon nights than they are on nonfull-moon nights?
Suggested Answer

Question 8B-2
Use what you have learned about cognitive heuristics to answer the following questions.

(a) In Question 4-2 in Critical Thinking Lesson 4, you learned about Andrea, who dreamed that her aunt had died in an automobile accident. Later that same day, she found out that her aunt had been struck and killed by a car that same morning as she was crossing a busy street. Andrea now believes this dream to be proof that people can have psychic premonitions of the future. How might the availability heuristic and the difficulty with remembering the nonoccurrence of events be misleading Andrea into drawing this conclusion?
Suggested Answer

(b) Andrew is a 45-year-old white male, who is thin, of medium height, and introverted. He is very intelligent and reads widely in a number of areas (especially literature, science, and poetry). He loves to solve mathematical puzzles. As a child, he always had a few very good friends, but he was never a member of the popular crowd in school. Is it more likely that Andrew is (a) a professional philosopher, or (b) an airplane pilot? Describe how you reached your decision.

(c) Let's say that you had not studied at all for a 16-question multiple-choice quiz given in your chemistry course. Just before you started the quiz, your instructor told everyone that the actual sequence of correct choices was determined by a random process (such as flipping a coin), and that four questions had A as the correct answer, four questions had B as the correct answer, four questions had C as the correct answer, and four questions had D as the correct answer. Given this knowledge, which of the following sequence of choices is most likely to give you the highest score?

(a) ABCD ABCD ABCD ABCD
(b) ACBA DCDB ACCB BDAD
(c) AAAA BBBB CCCC DDDD

Suggested Answer

Question 8B-3
Students sometimes will conclude that a test must have been unfair if most people in the class did not do well on it. Although it is true that an unfair test probably would lead to a large number of poor grades, there are other factors that also could lead to the same result. For example, it may be that most people did not study sufficiently for the test. Nevertheless, students tend to ignore this possibility and conclude that a test on which the majority of people did not do well must have been an unfair test.

Based on what you have learned in this lesson, what error in reasoning are these students making? Explain your answer.
Suggested Answer

Question 8B-4
Alfred Kinsey was a researcher of human sexuality who, after World War II, published two very important books on the sexual attitudes and behaviors of American men and women. The research on which these books were based showed that, among other things, many more Americans expressed deviant sexual attitudes and behaviors than was commonly believed. Much later, it became widely known that Kinsey himself had some extreme sexual attitudes and engaged in some uncommon sexual practices (Jones. 1997). If a person, after learning this fact, rejected Kinsey's findings because, as the person might put it, "Kinsey was a pervert," what error in reasoning would this person be making?
Suggested Answer

Bibliography and References

Carroll, R. T. (2002). Full moon and lunar effects. Skeptic's Dictionary. Retrieved May 31, 2003, from http://skepdic.com/fullmoon.html

Engel, S. M. (2000). With good reason: An introduction to informal fallacies (6th ed.). Boston: Bedford/St. Martin's.

Gilovich, T. (1991). How we know what isn't so: The fallibility of human reason in everyday life. New York: Free Press.

Halpern, D. F. (2003). Thought & knowledge: An introduction to critical thinking (4th ed.). Mahwah, NJ: Erlbaum.

Jones, J. H. (1997). Alfred C. Kinsey: A public/private life. New York: Norton & Company.

Kahneman, D., & Tversky, A. (1973). On the psychology of prediction. Psychological Review, 80, 237-251.

Kunda, Z. (1999). Social cognition: Making sense of people. Cambridge, MA: MIT Press.

Piatelli-Palmarini, M. (1994). Inevitable illusions: How mistakes of reason rule our minds. New York: Wiley & Sons.

Porter, B. F. (2002). The Voice of reason: Fundamentals of critical thinking. New York: Oxford University Press.

Ruscio, J. (2002). Clear thinking with psychology: Separating sense from nonsense. Pacific Grove, CA: Wadsworth.

Sutherland, S. (1992). Irrationality: Why we don't think straight. New Brunswick, NJ: Rutgers University Press.