Brain teaser to test your cognitive abilities…and biases


Please con­sider Lin­da, a 31-year-old woman, sin­gle and bright. When she was a stu­dent, in high school and in col­lege too, she was deeply involved in social jus­tice issues, and also par­tic­i­pated in envi­ron­men­tal protests. Which is more prob­a­ble about Linda’s occu­pa­tion today?

a) Lin­da works as a TV reporter;

b) Lin­da is a bank teller;

c) Lin­da is a bank teller and active in the envi­ron­men­tal movement.


Quick, what’s your answer? a) or b) or c)? And in what pre­cise order?


First, ignore how you ranked a), as it is irrel­e­vant to this par­tic­u­lar exer­cise. The key is this: If you ranked c) as more prob­a­ble than b), you are wrong…and in very good com­pany. That’s what most of my Stan­ford col­leagues and I answered the first time we faced this teas­er, and it reflects a very per­va­sive cog­ni­tive bias, tech­ni­cal­ly called a “con­junc­tion fallacy.”

Sta­tis­ti­cal­ly speak­ing, by def­i­n­i­tion, it is more prob­a­ble that Lin­da is a bank teller, which is a whole cat­e­gory, that she is both a bank teller AND also active in the envi­ron­men­tal move­ment, which is a sub­set of that whole category.


To learn more about your brain and mind:

About SharpBrains

SHARPBRAINS is an independent think-tank and consulting firm providing services at the frontier of applied neuroscience, health, leadership and innovation.
SHARPBRAINS es un think-tank y consultoría independiente proporcionando servicios para la neurociencia aplicada, salud, liderazgo e innovación.

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