Clueless: The Illusion of Explanatory Depth

Learning By Doing

You've seen a bicycle before, right? Of course you have! You probably learned how to ride when you were a kid, although maybe it's been a while since you've last ridden. I'm guessing you're probably not a bike mechanic, but you are familiar with the general shape of a bike and roughly how it works.

To kick off this post, I would like you to do two things. First, I would like you to rate your knowledge and familiarity of bicycles on a scale from 1 ("I know nothing about bikes or how they work.") to 7 ("I have a complete understanding of how a bike works."). The second task requires a pen and some paper. Below is a partial sketch of a bike; however, you will notice that it's missing a couple of parts (Fig. 1). I would like you to finish my drawing. Specifically, I would like you to add the pedals, chain, and the missing pieces of the frame [1]. 

Ready? Let's get started.

Figure 1. Complete the drawing of a bike by adding the missing pieces of the 
frame, the pedals, and show where the chain goes (used with permission).

The answer to this task is probably parked in a bike rack not far from where you're sitting. But if you need to see an image of a basic bike, with no gears or brakes, here is a great example. Now that you've seen the answer, how did you do? Did you make any mistakes?

"I thought I knew more than I did."

Most people, myself included, walk around thinking that we have a pretty good understanding of the way the world works. But every once in a while, we are confronted with the uncomfortable realization that we don't know as much as we think we do. If I asked you to re-rate your knowledge about how a bike works on the same 7-point scale, would it go up, down, or stay the same? If I had to guess, I would say it probably went down. This task is likely harder than you thought it would be [2].

The reason it was so hard is because of the illusion of explanatory depth, which is the belief that you understand something better than you actually do [3]. The illusion doesn't usually happen with facts or procedures. In other words, we're pretty good at estimating when we don't know a piece of trivia (e.g., "When did Amelia Earhart become the first woman to fly across the Atlantic ocean?" ) or how to do something (e.g., "Take the first derivative of f(x) = 3x² + 4x - 5"). But with semi-complex mechanical objects (e.g., a lock or a crossbow), people are often overly confident when it comes to explaining how things work. 

How Does This happen? 

You might be asking yourself: How does the illusion of explanatory depth happen? 

There are several potential sources of the illusion of explanatory depth, but here are two. First, the illusion might arise from a confusion between familiarity and understanding. Since we have all seen many bikes in our daily lives, we come to think that we understand them. When we learn how to ride, we might also think that we understand how a bike works because we have experience interacting with them. 

Second, the illusion might be caused by the ease by which we can mentally simulate the mechanical device under question. For example, if you say, "Imagine a bike." I can do so easily. The detail of my mental image, however, is fairly sparse. The demands of the task don't require me to do anything more than envision something with wheels and a frame. Thus, my performance on the task seems adequate for the current purposes. Only when we raise the stakes do I stumble and discover my lack of understanding.

The S.T.E.M. Connection

The illusion of explanatory depth is a problem for education, partly because it seems inevitable. When you are learning something new, a necessary first step is to become familiar with the terminology and the concepts. You can't learn about the anatomical structure of a frog without first becoming familiar with the names of the organs. So what can be done about the illusion?

The most basic antidote for moving beyond a superficial understanding is to try and answer the question: Why? or How? Once you are tasked with explaining how something works, only then will you discover the gaps in your knowledge. It is both illuminating and humbling. Here are several examples that I've recently run into:

• When are you able to see a new moon? 
• Since the tension on a crossbow is strong, how do you draw back the cord?
• How do tumblers in a lock prevent the cylinder from turning? 
• How does a zipper work?
• Why does the toilet keep running?

The illusion of explanatory depth is strong, and it probably serves a purpose. We can't carry around knowledge of every mechanical device around in our heads. Otherwise, we would never have enough time to do anything else! But we also don't want to dupe ourselves into thinking we understand something when we clearly don't [4]. So the best treatment is to keep asking yourself: Can I explain what the parts are, where they go, and how they interact? In other words, keep asking yourself if you understand the way things work.


Share and Enjoy!

Dr. Bob

Going Beyond the Information Given

[1] The drawing task was taken from Lawson, R. (2006). The science of cycology: Failures to understand how everyday objects work. Memory & Cognition, 34(8), 1667-1675. I am grateful to Rebecca Lawson for allowing me to recreate Figure 1.

[2] Another good example of a deceptively difficult task – and one that we talked about in a previous post – is trying to remember what a penny looks like. We've seen hundreds, maybe thousands, of pennies. But it is surprisingly difficult to identify the real penny. Try it for yourself. 

[3] Rozenblit, L., & Keil, F. (2002). The misunderstood limits of folk science: An illusion of explanatory depth. Cognitive science, 26(5), 521-562.

[4] Kruger, J., & Dunning, D. (1999). Unskilled and unaware of it: how difficulties in recognizing one's own incompetence lead to inflated self-assessments. Journal of Personality and Social Psychology, 77(6), 1121.