Description

Tendency for people to judge that a conjunction of two possible events is more likely than one or both of the conjuncts. 

Tversky, A., & Kahneman, D. (1983). Extensional versus intuitive reasoning: The conjunction fallacy in probability judgment. Psychological Review, 90(4), 293–315.

Task

Participants are given a scenario (e.g., the Linda problem from Tversky and Kahneman, 1983) and decide which of two statements is more likely. One of the statements ("Linda is a bank teller and is active in the feminist movement") is a conjunction that includes the other statement ("Linda is a bank teller").

Items (7)

Item ID: Linda

Scenario: Linda is 31 years old, single, outspoken, and very bright. She majored in philosophy. As a student, she was deeply concerned with issues of discrimination and social justice, and also participated in anti-nuclear. 

Option 1: Linda is a bank teller
Option 2: Linda is a bank teller and is active in the feminist movement 

Correct Answer: Linda is a bank teller 

Item ID: Bill 

Scenario: Bill is 34 years old. He is intelligent, but unimaginative, compulsive and generally lifeless. In school, he was strong in mathematics but weak in social studies and humanities. 

Option 1: Bill plays jazz for a hobby
Option 2: Bill is an accountant who plays jazz for a hobby 

Correct Answer: Bill plays jazz for a hobby 

Item ID: Colored Die 

Scenario: Consider a regular six-sided die with four green faces and two red faces. The die will be rolled 20 times and the sequence of greens (G) and reds (R) will be recorded. Imagine a hypothetical scenario in which you are asked to select one sequence, from a set of three, and you will win $25 if the sequence you chose appears on successive rolls of the die. 

Option 1: GRGRRR
Option 2: RGRRR 

Correct Answer: RGRRR 

Item ID: Scandinavian 

Scenario: The Scandinavian peninsula is the European area with the greatest percentage of people with blond hair and blue eyes. This is the case even though every combination of hair and eye color occurs. Suppose we choose at random 100 individuals from the Scandinavian population. 

Option 1: Individuals who have blond hair and blue eyes
Option 2: Individuals who have blond hair 

Correct Answer: Individuals who have blond hair 

Item ID: Grand Pix 

Scenario: Suppose Ivan Lendl reaches the final of a Grand Pix tournament. 

Option 1: Lendl will lose the first set
Option 2: Lendl will lose the first set, but win the match 

Correct Answer: Lendl will lose the first set 

Item ID: Rails 

Scenario: Because of the Italian Rail’s new policies aimed at encouraging voyages longer than 100 km, the number of passengers will 

Option 1: will decline by 5% on commuter trains and increase by 10% on long distance trains.
Option 2: will decline by 5% on commuter trains. 

Correct Answer: will decline by 5% on commuter trains. 

Item ID: Tennis Player 

Option 1: Sandy, an alcoholic tennis player, drinks for five more days after which she joins Alcoholics Anonymous. Eight months later, she wins a tennis tournament.
Option 2: Sandy, an alcoholic tennis player, drinks for five more days after which she joins Alcoholics Anonymous. Eight months later, she wins a tennis tournament. 

Correct Answer: Sandy, an alcoholic tennis player, drinks for five more days after which she joins Alcoholics Anonymous. Eight months later, she wins a tennis tournament.

Scoring

The total score is the number of problems answered correctly.

Source

Burgoyne, A. P., Mashburn, C. A., Tsukahara, J. S., Hambrick, D. Z., & Engle, R. W. (2023). Understanding the relationship between rationality and intelligence: A latent-variable approach. Thinking & Reasoning, 29(1), 1-42.