Mental Habits: Taking the Shortcut (Part 2)

In this new series of posts, I consider thinking habits that I call “mental shortcuts.” It will help to read the first post in the series before reading this one.

Why did you bet on Sequence Two when, if you only took a moment, you would have bet on Sequence One? Psychologists have an answer. Sequence Two looks like the kind of sequence that the die should produce. After all, the die has more green sides than red sides and Sequence Two has the most greens. Put another way, Sequence Two is more representative of how the die should behave over a series of rolls. So, it kind of makes sense to pick Sequence Two. That’s why hardly anybody picks Sequence Three. That sequence looks the least random. It is not a good representative of randomness. And you rely on representativeness to make decisions. We all do.

The “Linda Problem”

I have known Linda for a long time now. Let me tell you about her.

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.

Consider the following eight statements about Linda.

___	1.	Linda is a teacher in elementary school.
___	2.	Linda works in a bookstore and takes Yoga classes.
___	3.	Linda is active in the feminist movement.
___	4.	Linda is a psychiatric social worker.
___	5.	Linda is a member of the League of Women Voters.
___	6.	Linda is a bank teller.
___	7.	Linda is an insurance salesperson.
___	8.	Linda is a bank teller who is active in the feminist movement.

I would like you to arrange the statements from the least likely to the most likely. It is easiest to put a number beside each statement. The least likely statement gets a 1 and the most likely statement gets an 8. I left a blank beside each statement that you can fill in (pencil is probably best).

Did you give statement eight a higher number than statement six? In other words, did you rate statement eight as more likely than statement six? I did the first time I saw the problem. And most people do. But, as you probably guessed, that is wrong. Let’s see those two statements again:

Linda is a bank teller.

Linda is a bank teller who is active in the feminist movement.

There cannot be more feminist bank tellers than there are bank tellers! So, it is impossible for the “bank teller feminist” statement to be more likely than the “bank teller” statement. How did you make this mistake? Here is my description of your thinking:

Linda was a philosophy major. She was outspoken. She was concerned about discrimination. Linda looks like a feminist. Her description is representative of a feminist. You used your representativeness shortcut. So, the feminist bank teller statement looked likely.

Linda’s description is not representative of a bank teller. I certainly do not picture someone like Linda when I think of a bank teller!

You used your representativeness shortcut. So, the “Linda is a bank teller” statement did not seem likely. As a result, you rated the “Feminist bank teller” statement as more likely than the “bank teller” statement. You’re in good company, remember. I did it too.

Hold on a Second!

At this point you might be saying to yourself, “Hold on a second! I thought Ian said I am pretty good at making my way through the world. And I am pretty good because I use mental shortcuts. But Ian’s examples show how easy it is to make mistakes using shortcuts! Maybe I shouldn’t use shortcuts. But, then what?” You are absolutely right. I have been showing you how your representativeness shortcut works by showing you how it can lead to mistakes. There is a method to my madness and I will let you in on my reasoning once we have considered another important mental shortcut. Stay tuned …