Illusion of Explanatory Depth: Testing a Goal Plan Like a Zipper

On a scale of 1 to 7, how well do you understand a zipper? In the first study of Leonid Rozenblit and Frank Keil’s 2002 paper, sixteen Yale graduate students rated themselves on 48 devices and phenomena, then wrote step-by-step explanations of four of them, then rated again. Their confidence went down after writing. The researchers named this the illusion of explanatory depth: people feel they understand how things work with far more precision and depth than they do, and the feeling only breaks when they have to produce the explanation.

A goal plan looks like a good candidate for the same trap. The catch, which most summaries of the paper skip, is that it depends on what kind of knowledge a plan is.

Do plans count as procedures or explanations?

Rozenblit and Keil did not find that people overrate everything they know. In Study 8, 37 participants rated their knowledge of ten procedures, including baking chocolate chip cookies from scratch, tying a bow tie and driving from New Haven to New York City, then wrote the steps and re-rated. Ratings did not drop. Nobody expressed surprise at how little they knew. Knowledge of narratives (movie plots) behaved the same way, and facts, such as the capitals of 48 countries, dropped only a little.

So the claim “people think they know more than they do” is too broad. The paper’s claim is that the illusion is far stronger for explanatory knowledge, meaning knowing why a thing works, than for facts, procedures or narratives.

A goal plan is both kinds at once. “Wake at 6, run for 20 minutes, shower, work” is a cookbook procedure, and people are reasonably calibrated about those. But every plan also contains a causal claim that nobody writes down: that doing these steps, in this order, on these days, will produce the result. That claim is the explanatory layer, and it is where a zipper-style gap would live. The people most at risk are those who say “I have a plan” and whose plan is a list of steps with the because left implicit.

This is an inference, because no study in Rozenblit and Keil tested personal plans.

Why does explanatory knowledge fool us more?

The paper proposes four features of explanations that together produce the illusion. Each has a goal-shaped twin.

1. Confusing levels of analysis. Understanding the brake pedal of a car gives a rush of insight that leaks downward into a false sense of understanding the pistons. In a plan, “build a launch audience” is a clean, graspable top-level unit, and the rush of having named it leaks into the layers below that nobody has examined.
2. Environmental support. A zipper is in your hand and its parts are visible, so looking at it feels like knowing it. The goal version is a visible calendar, a gym bag by the door or a half-filled spreadsheet that feels like understanding because it is there.
3. No clear end state. You can test whether you know a capital city: you produce “London” or you do not. Explanations have no finish line you can check against, so self-testing is hard. A plan’s finish line is the goal itself, which is months away.
4. Rarity of production. We seldom explain how things work, so we have little record of failing to. How often have you actually written out how you will get from here to done, as opposed to naming the goal and the date?

The other half of the story is good news. After the drop, Rozenblit and Keil’s participants read an expert description and reported that their understanding rose sharply. The lowered rating was not general self-doubt. It was accurate, and it was recoverable.

Why does thinking about “how” shrink the illusion?

Alter, Oppenheimer and Zemla published a follow-up in the Journal of Personality and Social Psychology in 2010 (volume 99, pages 436-451). Across six studies, they argued that the illusion occurs because people use an inappropriately abstract mindset when judging how well they understand concrete things. People who naturally thought concretely, or who were pushed into a concrete mindset, showed a smaller illusion. Two further studies found the illusion for electoral voting, a social domain, not just machines.

In the reports I could confirm, one concrete manipulation was framing the question around parts. People were better calibrated when asked how a ballpoint pen’s parts make it work than when asked how a pen works overall. A second pushed participants to explain how they do everyday actions instead of why. I only read the abstract of the original paper, so I am not describing its effect sizes. The authors close by suggesting that the same abstract-representation habit may feed stereotyping, egocentrism and the planning fallacy, which they say are cases where people represent abstractly something that should be represented concretely.

The practical reading is simple. “Get fit by June” is a why-level sentence. A person holding only that sentence is in the abstract mindset the paper links to the illusion. The cure it points to is not more motivation but a lower level of description. For the forecasting side of the same gap, see the planning-fallacy post.

What does the test look like for a goal?

Rozenblit and Keil’s procedure had five beats: rate, explain, answer a diagnostic question, read an expert description, rate again. A goal version borrows each one.

Start by rating, before writing anything. One sentence for the goal, then a 1 to 7 rating of how fully you could explain how you get there, with 1 meaning you could only gesture at it.

Next, explain, with the because. Write the steps as numbered sentences, and after each step add one clause beginning “which works because”. That clause is the explanatory layer the 2002 data say we overrate. Where you cannot finish the clause, mark it.

Third, answer a diagnostic question. In the original, it was “how would you pick this lock?”, a question you can only answer if you know the parts. For a goal, ask the question the plan has to survive: what happens on the third day you do not feel like doing step one, and what is physically in front of you at that moment? Write the answer in steps, not in resolve. If the honest answer is a list of things pulling against you, Kurt Lewin’s method for scoring those restraints gives the list a structure.

For a plan that starts with waking up earlier, the diagnostic question is blunt: you are asleep at the moment of step one, so what gets you upright. If your written answer is “the alarm”, write down what the alarm does when you silence it. DontSnooze is one answer for iPhone owners, a 30-second window to film yourself awake and a photo from your camera roll sent to friends if you miss it. It covers that first step and none of the others.

Fourth, compare with someone who has done it. The expert step is the cheapest one to skip. Find one person’s written account of doing what you want, and lay your steps next to it. The gaps are free information.

Last, re-rate. If the second number is lower, that is the test working. The drop is not the thing to fix. The marked clauses are.

Does explaining the how change anything beyond confidence?

One more result is worth knowing about, as a contrast rather than a promise. Fernbach, Rogers, Fox and Sloman (2013, Psychological Science, 24, 939-946) asked people to explain a political policy in detail. Doing so reduced their sense of understanding, and in two experiments also left attitudes more moderate. That effect did not appear when people instead listed reasons for their preference. Listing reasons did not move either measure; writing the causal story did.

That contrast describes the common way goals are set. The usual exercise asks why you want something, which produces reasons, and reasons survive any amount of not knowing how. Moderate attitudes are not the aim here. The part to borrow is that explaining how, and listing why, are different acts with different effects on what you believe about yourself.

If you find the marked gaps are not missing steps but missing nerve, the hole may be about whether to continue at all, deciding in advance when you will quit is a different tool for it. If the plan stays unfinished because it feels impossible to write before you have made anything, the usual “make more, plan less” anecdote is the pottery-class story, which turns out to be a tale with no data behind it.

What to do with an hour

Pick the one goal you have described aloud most often and written down least. Rate it. Write the numbered steps with their “which works because” clauses. Answer the third-day question in steps. Re-rate and circle the clauses you could not finish.

The clause nearest the first step goes on the list first, since it is the one that gets tested soonest.