The Psychology of Why We Shouldn’t Judge a Book By Its Cover

I’ve got a quiz for you…

My friend, Chad, is very unorthodox. He has odd tastes in music, movies and art. He is married to a performer and has numerous tattoos. For fun, Chad likes to do yoga and visit farmers markets. An extrovert, Chad is always looking to take on a dare.

What do you think Chad’s occupation most likely is?
– Farmer
– Librarian
– Trapeze Artist
– Surgeon
– Lawyer

Based on that description, you probably guessed that Chad is a trapeze artist, right? After all, he fits with our existing thoughts of how a trapeze artist might sound.

However, that answer is wrong.

In reality, there are thousands more farmers than there are trapeze artists (and librarians, surgeons & lawyers). So based on sheer number of people in each profession, the correct guess to what occupation most likely we would find Chad, is farmer.

Thinking about it now, that answer seems obvious. Of course there are far more farmers than trapeze artists. No one would argue that.

So why did we just assume Chad flew through the air with the greatest of ease (instead of grew crops on the ground like lettuce and peas).

The answer can be found in what psychologists Amos Tversky and Daniel Kahneman call the representativeness heuristic.

A heuristic is a mental shortcut we take when making judgments. For every decision we have to make, we do not always have all the time or information needed to make a perfect choice. Because of that, we use heuristics, or shortcuts, to help make the decision. This happens without much thought and most of the time we don’t even realize that we are doing it.

But the problem is, just as a driving shortcut using a freeway can lead to a longer route, sometimes these shortcuts can lead to mistakes.

The representativeness heuristic is used when we estimate the likelihood of an event by comparing it to a prototype that already exists in our mind. For example, we seen a 7 foot tall man on the street and figure he probably plays basketball.

The prototype we are prone to choose is whatever happens to be the most common example we have in our mind of that particular event. Basketball players are tall.

The prototype of a trapeze artists might include an eccentric individual who isn’t afraid to take risks. So it makes sense that we would guess that occupation for Chad.

Unfortunately, we often overestimate our ability to accurately predict certain events. When we rely solely on representativeness to make judgments, we are likely to judge wrong because the fact that something is more representative does not mean it is more likely.

To put this in everyday lingo, I think this is similar to the old saying, “don’t judge a book by its cover.”

We judge a book (or a person or a situation) by the cover because that is the limited amount of information we have. If the book looks like what we have in our minds as the prototype for say, enjoyable, we guess that it would be fun to read.

But upon reading the book we might actually learn that it wasn’t very enjoyable.

That is an example of when our shortcuts, or heuristics, led us astray.

This post doesn’t have a moral or a lesson. It is simply something interesting to consider next time you are forced to make a snap judgment.

So remember, shortcuts can be quicker, but they aren’t always accurate.

Maybe the saying should be “It is quicker and easier to judge a book by its cover, but just know that you might not always be correct.”

But I guess that doesn’t fit as well on a bumper sticker.


Side note, Chad is a fictional person made up for the purpose of this post. The idea for this topic was inspired by a very cool (and free) online class called The Science of Everyday Thinking. Click here if you want to learn more.