The Science of Clear Writing

Plain language is fast, cheap, and effective.

Suppose you’re browsing writing guides and come across one that begins:

The widely unbeknownst method by which effective written communication can be achieved is through a process of meticulous revision, focusing on the reduction of each sentence to its core elements.

Now, suppose instead it begins this way:

The secret of good writing is to strip every sentence to its cleanest components.

The short version quotes the late great William Zinsser; the long one is my best attempt to overcomplicate the idea. If you prefer the short one, you’re not alone. Research shows that most people prefer plain language. And for a good reason: Plain language works.

Plain language is faster, cheaper, and more effective than the convoluted, bureaucratic language found in many organizations, including the US military. One study, for example, found that naval officers read a plain language memo 17–23% faster than the same memo written in bureaucratic language. The authors argued that the extra time spent reading dense writing costs the US Navy millions of dollars annually. Another study found that military officers were more likely to follow written instructions quickly and correctly when they were written in plain language.

The effectiveness of plain language isn’t just a matter of personal preference; it’s grounded in cognitive science. Plain language works because it reduces the mental effort readers need to process our writing, helping them understand our ideas quickly and easily. Writers who understand this science can improve their writing’s clarity and impact.

Memory, Large and Small

The science of plain language begins with human memory. Humans have two types—long-term memory and working memory. Long-term memory is vast. My wife, for example, remembers that one time I messed up two decades ago. The reader’s long-term memory is where we writers want our ideas to end up.

However, before ideas can make it to long-term memory, they must first pass through the funnel of working memory, which can only handle so much information so fast. When incoming information exceeds working memory’s capacity, the reader must either slow down to process all the information or continue reading quickly but miss some details. Neither outcome is good for writers.

Cognitive Load

To help readers read quickly and understand easily, writers must reduce the mental effort required to read their writing as much as possible. This effort is called cognitive load.

Incoming information (including writing) imposes three types of cognitive load: intrinsic, germane, and extraneous. Intrinsic load comes from the ideas and the knowledge required to understand them. Writers can’t reduce intrinsic load without over-simplifying ideas. If you’re writing about a specialized topic, a reader without the required background knowledge will struggle, no matter how simple the language is.

Writers can, however, reduce germane and extraneous load. Germane load is the effort needed to process and encode information in long-term memory. Writers can reduce germane load by presenting information logically and helping the reader connect new ideas with what they already know.

The last type is where plain language can help. Extraneous load is the mental effort required for everything that’s not intrinsic or germane. Sloppy formatting, irrelevant information, and distracting visuals increase extraneous load. But the real villain is needlessly complex language. Plain language, in contrast, reduces extraneous load, freeing up mental resources to focus on ideas.

Let’s look at an example. Below are two sentences covering the same topic. Both impose similar intrinsic and germane loads, but the first imposes a far higher extraneous load than the second:

The initial formulation of any written undertaking is, by its very nature, subject to inherent deficiencies, often characterized by inexactitude in articulation and a paucity in the development of conceptualizations.

Here’s the original quote from Ernest Hemingway:

The first draft of anything is shit.

Another example comes from Harvard professor Steven Pinker, who tells of how the warning label below failed to dissuade people from running their generators indoors:

Mild Exposure to CO can result in accumulated damage over time. Extreme Exposure to CO may rapidly be fatal without producing significant warning symptoms.

Things got better when the label was simplified:

Using a generator indoors can KILL YOU IN MINUTES. Generator exhaust contains carbon monoxide. This is a poison you cannot see or smell.

One of my favorite examples comes from William Zinsser in On Writing Well. In 1942, the US Government, anticipating air attacks on government buildings, issued this blackout order:

Such preparations shall be made as will completely obscure all Federal buildings and non-Federal buildings occupied by the Federal government during an air raid for any period of time from visibility by reason of internal or external illumination.

After hearing the order read aloud at a press conference, President Roosevelt said:

Tell them that in buildings where they have to keep the work going to put something across the windows.

These examples reinforce the research and demonstrate the obvious: Plain language works. If so, then why don’t more people use it?

Our Intuitions About Plain Language Are Wrong

The short answer is that using plain language is hard—much harder, in fact, than using complex language. Learning to use plain language is beyond the scope of this article, but you can find my thoughts in Military Review. Here, I’ll discuss why people don’t use plain language (beyond the fact that it’s hard to do).

People intuitively believe complex language is credible. In one survey, 78% of people said that using big words makes someone seem smart. Moreover, 58% admitted using a word to sound smarter despite not knowing what it meant.

These intuitions are wrong. When researchers ask about complex language, people say one thing. But when they read it, they change their tune.

One study, for example, asked people to read a passage and rate the author’s intelligence. Some received a plain language version of the passage, and others received a more complex version. Those who read the plain language version rated the author as more intelligent than those who read the complex version.

Another study on legal writing found that 80% of respondents preferred legal documents written in plain language. Counterintuitively, this preference increased with education, discrediting a common belief that educated people prefer or are more tolerant of complex language. The study also found that only 0.5% of people find complicated words impressive, while 60% find them annoying.

Plain language isn’t just a preference—it is a proven tool for better writing and communication. It makes reading easier to process, making readers more likely to retain it. Despite our mistaken intuitions about the value of complex language, the research is clear: Plain language works.