The Linda Test – Conjunction Fallacy – Part 2 (Solution)

Can you pass the Linda Test? Almost 90% of Stanford students got it wrong. Last video I gave the full version that I called the Social Perception Test. Yes, I was trying to trick you. It gives this description of Linda, and these possible descriptions that you had to rank in order of how likely they were to apply. But really only 3 of these mattered. Pause and write down which of the 3 you think is most likely.

Ready for the answer?

This question set you up to fall for a cognitive bias known as the Conjuction Fallacy. Our brains are really bad at probability. As many of you may have discovered in college. But it’s not your fault-it’s built in.

90% of students said that Linda was more likely to be a feminist bank teller than just a bank teller. But that is WRONG. Even if you knew nothing about Linda, B is INCLUDED in A, and so CAN”T be more likely than it. Let’s say A was 20%. B can ONLY be less than 20%.

So do we make this mistake?

Professor Daniel Kahneman proposed it was due to something called the representativeness heuristic. WHen our brain is guessing at probabilities, it compares what’s in front of it to its existing mental models or stereotypes. Because Linda seems to be more representative of the category of feminist bank tellers than just bank tellers, that translates to thinking it more likely, against all actual rules of probability.

If you like learning how to think better, hit that follow button! I’ll be doing frequent segments on cognitive biases and how to spot them.