KNOWLEDGE AND THE KNOWER—PERSPECTIVES
COGNITIVE BIAS — HEURISTICS

*Human brain image credit: Neuroscience News*

Kahneman and Tvarsky

Daniel Kahneman and Amos Tvarsky became famous for their longstanding collaboration on heuristics—intuitive judgments, or pragmatic rules of thumb, that speed up and simplify our thinking. In their landmark 1974 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 empirical research in psychology toppled the assumption, driving prevailing economic models, that human agents always behave rationally. Tvarsky would have shared the prize, but he died in 1996. The Nobel is not awarded posthumously.

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

CLASS ACTIVITY I:
COGNITIVE BIAS SCENARIOS

Six scenarios have been carefully selected to provide students with a direct personal encounter with Kahneman and Tversky's findings.

Provide each student with a printed copy of the Questionnaire. Announce a timed five minutes for individual students to grapple with the scenarios and note their responses. Next, hand out copies of the Key for consolidation and conversation with a nearby partner.
Pdf. of the Questionnaire and the Key
Later, for a homework assignment, students should try them out on family members and at least one stranger.

—QUESTIONNAIRE—

SCENARIO #1

“Steve is very shy and withdrawn, invariably helpful, but with little interest in people, or in the world of reality.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?

SCENARIO #2

“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.

SCENARIO #3

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?

SCENARIO #4

“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?

SCENARIO #5

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

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

SCENARIO #6

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?

**Rare winter flood in Missouri that prompted many evacuations.**
*Photo credit: Jeff Roberson, AP*