Consider the following: Linda is 31, bright, single, and outspoken. She majored in philosophy at the university. As a student, she was deeply concerned with issues of discrimination and social injustice, and also participated in antinuclear demonstrations.
Is it more likely that Laura works at a bank? Or, is it more likely that she works at a bank and is active in the feminist movement?
Opting for the last option is prone to representativeness heuristic—the tendency to let the similarity of objects or events confuse one’s thinking about the probability of an outcome. Because the possibility that Linda is active in the feminist movement is a subset of a more inclusive category, the probability of her just working at a bank is simply higher.
Primary origin: Daniel Kahneman; Amos Tversky