Daniel Kahneman (left) and Amos Tversky (right). Kahneman and Tvarsky are famous for their longstanding and highly productive collaboration on heuristics--intuitive judgments or pragmatic rules of thumb that speed up and simplify our thinking. In their landmark publication, Judgment under Uncertainty: Heuristics and Biases (Science; 85: 4157, pp. 1124-1131), they outlined their research program in a single ominous sentence: "In general these heuristics are quite useful, but sometimes they lead to severe and systematic errors." Kahneman won the 2002 Nobel Prize in Economic Sciences. Kahneman and Tvarsky's research findings in empirical psychology challenged (and have largely toppled) the unexamined assumption, at the core of prevailing economic theoretical models, that human agents always behave rationally. Tvarsky, of course, would have shared the prize, but he died in 1996. The Nobel is not awarded posthumously.   Almost everything that follows on this page is a direct borrowing from Kahneman and Tversky's original paper, and Kahneman's 2011 book, Thinking Fast and Slow. 

Daniel Kahneman (left) and Amos Tversky (right).

Kahneman and Tvarsky are famous for their longstanding and highly productive collaboration on heuristics--intuitive judgments or pragmatic rules of thumb that speed up and simplify our thinking. In their landmark publication, Judgment under Uncertainty: Heuristics and Biases (Science; 85: 4157, pp. 1124-1131), they outlined their research program in a single ominous sentence:

"In general these heuristics are quite useful, but sometimes they lead to severe and systematic errors."

Kahneman won the 2002 Nobel Prize in Economic Sciences. Kahneman and Tvarsky's research findings in empirical psychology challenged (and have largely toppled) the unexamined assumption, at the core of prevailing economic theoretical models, that human agents always behave rationally. Tvarsky, of course, would have shared the prize, but he died in 1996. The Nobel is not awarded posthumously.  

Almost everything that follows on this page is a direct borrowing from Kahneman and Tversky's original paper, and Kahneman's 2011 book, Thinking Fast and Slow. 


CLASS ACTIVITY I: HEURISTICS

Provide multiple copies of the following questionnaire. Students will initially work through the questions themselves; and later, for a homework assignment, will try them out on some family members and at least one stranger.

Again, I must emphasize that all questions are directly quoted (or appropriated, and very slightly tweaked, for use in this one-time, written survey without having additional lab equipment on hand) from Kahneman and Tversky's formidable body of research.

Printable pdf. of the questionnaire.


QUESTION ONE:
“Steve is very shy and withdrawn, invariably helpful, but with little interest in people, or in the world of reality. A meek and tidy soul, he has a need for order and structure and a passion for detail”

Is Steve more likely to be a librarian, or a farmer?


QUESTION TWO
“You have participated in a lottery at a fair, and have bought a single expensive ticket in the hope of winning the single large prize that is offered. The ticket was drawn blindly from a large urn and its number is 107358.”

When the result is announced the winning number was 107359. Do you think you would be more or less disappointed if the winning number was actually 207358.
 

QUESTION THREE:
“A certain town is served by two hospitals. In the larger hospital about 45 babies are born each day, and in the smaller hospital about 15 babies are born each day. As you know, about 50 percent of all babies born are boys. However, the exact percentage varies from day to day. Sometimes it may be higher than 50 percent, sometimes lower.”

“For a period of 1 year, each hospital recorded the days on which more than 60 percent of the babies born were boys. Which hospital do you think recorded more such days?”

 
QUESTION FOUR:
“Imagine an urn filled with balls of which 2/3 are of one color and one 1/3 of another. One individual has drawn 5 balls from the urn, and found that 4 were red and one was white. Another individual has drawn 20 balls and found that 12 were red and 8 were white.”

“Which of the two individuals should feel more confident that the urn contains 2/3 red balls and 1/3 white balls rather than the opposite?”

 
QUESTION FIVE:
When repeatedly tossing a coin six times the first two sequences were:
“H-T-H-T-T-H and H-H-H-T-T-T.”

Which sequence was more likely?
 

QUESTION SIX:
“In a discussion of flight training, experienced instructors noted that praise for an exceptionally smooth landing is typically followed by a poorer landing on the next try, while harsh criticism after a rough landing is usually followed by improvement on the next try.”

What conclusions would you make from this real data? Would your recommendation transfer to other training situations?

 
QUESTION SEVEN:
“Suppose one samples a word at random from an English text.

Is it more likely that the word starts with r or that r is the third letter?”


QUESTION EIGHT:
Recall and write down the last two digits of your phone number. 

Now estimate the “percentage of African countries in the United Nations.”


QUESTION NINE:
Consider the following scenarios:

  • “A massive flood somewhere in North America next year, in which more than 1,000 people drown.”
  • “An earthquake in California sometime next year, causing a flood in which more than 1,000 people drown.”

Which of the two scenarios is more likely?


QUESTION TEN:
“Linda is thirty-one years old, single, outspoken, and very bright. She majored in philosophy. As a student, she was deeply concerned with the issues of discrimination and social justice, and also participated in antinuclear demonstrations.

Which alternative is more likely?

  • “Linda is a bank teller.”
  • “Linda is a bank teller and is active in the feminist movement.”


QUESTION ELEVEN
In four pages of a novel (about 2000 words)

  • Roughly how many words would you expect to find that have the form ----ing (seven-letter words that end with “ing”)?
  •  Roughly how many words would you expect to find that have the form -----n- (seven-letter words with an n in the sixth position)?

 
QUESTION TWELVE

“Mr. Crane and Mr. Tees are scheduled to leave the airport on different flights at the same time. They traveled from town in the same limousine, were caught in the same traffic jam, and arrived at the airport thirty minutes after the scheduled departure time of their flights.

  • Mr. Crane is told that his flight left on time
  • Mr. Tees is told that his flight was delayed, and just left five minutes ago."

Who is more upset?

 

A rare winter flood in Missouri prompting many evacuations. Photo: Jeff Roberson, AP

A rare winter flood in Missouri prompting many evacuations. Photo: Jeff Roberson, AP

“Disbelief is not an option. The results are not made up, nor are they statistical flukes. You have no choice but to accept that the major conclusions of the studies are true. More important, you must accept that they are true about you.” (57)
— Kahneman, Daniel (2011) Thinking Fast and Slow. Farrar, Straus & Giroux, New York.
Salvador Dalí (1940) Slave Market with the Disappearing Bust of Voltaire. Oil on canvas. The Dali Museum, Tampa, FL

Salvador Dalí (1940) Slave Market with the Disappearing Bust of Voltaire. Oil on canvas. The Dali Museum, Tampa, FL