Book contents
- Frontmatter
- Contents
- List of Contributors
- Preface
- Introduction – Heuristics and Biases: Then and Now
- PART ONE THEORETICAL AND EMPIRICAL EXTENSIONS
- 1 Extensional versus Intuitive Reasoning
- 2 Representativeness Revisited: Attribute Substitution in Intuitive Judgment
- 3 How Alike Is It? versus How Likely Is It?: A Disjunction Fallacy in Probability Judgments
- 4 Imagining Can Heighten or Lower the Perceived Likelihood of Contracting a Disease: The Mediating Effect of Ease of Imagery
- 5 The Availability Heuristic Revisited: Ease of Recall and Content of Recall as Distinct Sources of Information
- 6 Incorporating the Irrelevant: Anchors in Judgments of Belief and Value
- 7 Putting Adjustment Back in the Anchoring and Adjustment Heuristic
- 8 Self-Anchoring in Conversation: Why Language Users Do Not Do What They “Should”
- 9 Inferential Correction
- 10 Mental Contamination and the Debiasing Problem
- 11 Sympathetic Magical Thinking: The Contagion and Similarity “Heuristics”
- 12 Compatibility Effects in Judgment and Choice
- 13 The Weighing of Evidence and the Determinants of Confidence
- 14 Inside the Planning Fallacy: The Causes and Consequences of Optimistic Time Predictions
- 15 Probability Judgment across Cultures
- 16 Durability Bias in Affective Forecasting
- 17 Resistance of Personal Risk Perceptions to Debiasing Interventions
- 18 Ambiguity and Self-Evaluation: The Role of Idiosyncratic Trait Definitions in Self-Serving Assessments of Ability
- 19 When Predictions Fail: The Dilemma of Unrealistic Optimism
- 20 Norm Theory: Comparing Reality to Its Alternatives
- 21 Counterfactual Thought, Regret, and Superstition: How to Avoid Kicking Yourself
- PART TWO NEW THEORETICAL DIRECTIONS
- PART THREE REAL-WORLD APPLICATIONS
- References
- Index
3 - How Alike Is It? versus How Likely Is It?: A Disjunction Fallacy in Probability Judgments
from PART ONE - THEORETICAL AND EMPIRICAL EXTENSIONS
Published online by Cambridge University Press: 05 June 2012
- Frontmatter
- Contents
- List of Contributors
- Preface
- Introduction – Heuristics and Biases: Then and Now
- PART ONE THEORETICAL AND EMPIRICAL EXTENSIONS
- 1 Extensional versus Intuitive Reasoning
- 2 Representativeness Revisited: Attribute Substitution in Intuitive Judgment
- 3 How Alike Is It? versus How Likely Is It?: A Disjunction Fallacy in Probability Judgments
- 4 Imagining Can Heighten or Lower the Perceived Likelihood of Contracting a Disease: The Mediating Effect of Ease of Imagery
- 5 The Availability Heuristic Revisited: Ease of Recall and Content of Recall as Distinct Sources of Information
- 6 Incorporating the Irrelevant: Anchors in Judgments of Belief and Value
- 7 Putting Adjustment Back in the Anchoring and Adjustment Heuristic
- 8 Self-Anchoring in Conversation: Why Language Users Do Not Do What They “Should”
- 9 Inferential Correction
- 10 Mental Contamination and the Debiasing Problem
- 11 Sympathetic Magical Thinking: The Contagion and Similarity “Heuristics”
- 12 Compatibility Effects in Judgment and Choice
- 13 The Weighing of Evidence and the Determinants of Confidence
- 14 Inside the Planning Fallacy: The Causes and Consequences of Optimistic Time Predictions
- 15 Probability Judgment across Cultures
- 16 Durability Bias in Affective Forecasting
- 17 Resistance of Personal Risk Perceptions to Debiasing Interventions
- 18 Ambiguity and Self-Evaluation: The Role of Idiosyncratic Trait Definitions in Self-Serving Assessments of Ability
- 19 When Predictions Fail: The Dilemma of Unrealistic Optimism
- 20 Norm Theory: Comparing Reality to Its Alternatives
- 21 Counterfactual Thought, Regret, and Superstition: How to Avoid Kicking Yourself
- PART TWO NEW THEORETICAL DIRECTIONS
- PART THREE REAL-WORLD APPLICATIONS
- References
- Index
Summary
The extension rule in probability theory states that if A is a subset of B, then the probability of A cannot exceed that of B. A special case of the extension rule is the conjunction rule, which states that the probability of A&B can exceed the probability of neither A nor B because it is contained in both.
Tversky and Kahneman (1983) demonstrated that under certain circumstances, people predictably and systematically violate the conjunction rule. In one study, they gave subjects the following description:
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 demonstrations
(p. 297).This was followed by a list of eight possible outcomes, each describing possible activities of Linda at the present time (her job, her interests, or both). Subjects were asked to rank order the outcomes by the probability that they describe Linda's current activities. Of the eight, one was representative of Linda (“Linda is active in the feminist movement”), one was unrepresentative of Linda (“Linda is a bank teller”), and one was a conjunction of these two (“Linda is a bank teller and is active in the feminist movement”). A large majority of the subjects (85%) rated the conjunctive outcome, “Linda is a bank teller and is active in the feminist movement,” more probable than “Linda is a bank teller.”
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- Heuristics and BiasesThe Psychology of Intuitive Judgment, pp. 82 - 97Publisher: Cambridge University PressPrint publication year: 2002
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