What should code look like when we squint at it?

It’s the start of another school year, and my seventh-grade son is learning algebra. As I sat beside him to coach him through some homework the other night, I shared my favorite bit of wisdom about how to make math problems—even complex ones—simple and error-free:

Write the progression from known to unknown, one step at a time.

In my experience, the surest recipe for disaster is to short-circuit this rule. Collapse a few steps in your head in the name of efficiency, and you’ll forget a minus sign, or you’ll group incorrectly, or you’ll lose track of an exponent or an absolute value—and you’ll end up with a mess. You’ll have to debug your solution by slogging back through the problem from the beginning until you figure out where you went wrong.

It’s interesting—and maybe, profound—how nicely this piece of advice maps onto the design principle of progressive disclosure. The human mind is simply wired to perceive in broad outlines, and then to gradually clarify, a few details at a time.

Don’t believe me? Try a short experiment: draw this fractal.

Fractals embody the principle of progressive disclosure. Image credit: Fábio Pinheiro (Flickr).

I’ll bet that instead of laying down every pixel, like a printer, you immediately produce a simplification that captures the general shape as lines, with a lot of detail suppressed. You did this as a kid, when you drew stick figures and triangle+half-circle sailboats.

Artists sometimes squint to blur out what they don’t want to see, leaving only general patterns and colors. But coders never do, because we don’t expect code to work that way. Continue reading

Progressive Disclosure Everywhere

If you google “progressive disclosure,” you’ll get hits that describe the phrase as an interaction design technique. UI folks have long recognized that it’s better to show a simple set of options, and allow users to drill into greater detail only when they need it. (Thanks to James Russell–a brilliant UI designer–for teaching me PD years ago.)

But calling progressive disclosure a “technique” is, I think, a serious understatement. Progressive disclosure aligns with a profound cognitive principle, and its use is (and should be) pervasive, if you have eyes to see.

The Principle

Here’s my best attempt to distill the operative rule behind progressive disclosure:

Focus on essence. Elaborate on demand.

In other words, begin by addressing fundamentals without cluttering detail. When more detail is needed, find the next appropriate state, and move there. Repeat as appropriate.

Stated that way, perhaps you’ll see the pattern of progressive disclosure in lots of unexpected places. I’ve listed a few that occur to me…


The scientific method is an iterative process in which hypotheses gradually align to increasingly detailed observation. We learn by progressive disclosure.

Good conversationalists don’t gush forever on a topic. They throw out an observation or a tidbit, and wait to see if others are interested. If yes, they offer more info.

The development of a complex organism from a one-celled zygote, through differentiation and all subsequent phases, into adulthood, could be considered a progressive disclosure of the patterns embedded in its DNA. The recursive incorporation of the golden mean in many morphologies is another tie to biology.

A nautilus grows–progressively discloses–the protective covering it requires over its lifespan. The golden mean, repeated and repeated… Photo credit: Wikimedia Commons.

In journalism, the inverted pyramid approach to storytelling is a form of progressive disclosure. So are headlines.

Depending on how you’re reading this post, you might see a “Read more…” link that I’ve inserted right after this paragraph. Making below-the-fold reading optional is progressive disclosure at work. TLDR…

Continue reading