Con­sider Linda, a 31-year-old woman, sin­gle and bright. As a stu­dent, she was deeply con­cerned with dis­crim­i­na­tion and social jus­tice and also par­tic­i­pated in anti-nuclear protests.

Which is more prob­a­ble? (a) Linda is today a bank teller; (b) Linda is a bank teller and active in the fem­i­nist movement.

Quick, what’s your answer?

If you answered (b), you are wrong.  At least you are in good com­pany (that’s what I answered the first time I saw this teaser in one of my Stan­ford Orga­ni­za­tional Behav­ior classes).

It is more prob­a­ble that Linda is a bank teller, which is a whole cat­e­gory, that she is both a bank teller AND active in the fem­i­nist move­ment, which is a sub­set of that category.

A recent Wall Street Jour­nal arti­cle explains the phenomenon:

Free to Choose, But Often Wrong:

“When psy­chol­o­gists Daniel Kah­ne­man and the late Amos Tver­sky con­ducted an exper­i­men­tal sur­vey in the early 1980s ask­ing peo­ple to answer this sim­ple ques­tion, they dis­cov­ered, to their sur­prise, that most respon­dents picked “b,” even though this was the nar­rower choice and hence the less likely one. It seems that saliency in this case, Linda’s pas­sion­ate polit­i­cal pro­file trumps logic.”

Related read­ing:

- Why Smart Brains Make Stu­pid Decisions

- Brain Teasers

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