You probably know this about me: I am a strong proponent of making employee communication simpler. Use plain language, I say while presenting. Cut words, I write in a blog. Reduce the number of messages, I sing in the shower.

What you may not realize is that my advice to simplify does not stem from a belief that employees are getting dumber. In fact, recent evidence points to the fact that we’re all getting smarter. For example, in the United States, IQ scores have risen steadily over the past century, according to this essay in The Wall Street Journal.

Writes James R. Flynn: “Advanced nations like the U.S. have experienced massive IQ gains over time . . . From the early 1900s to today, Americans have gained three IQ points per decade. In 1910, scored against today's norms, our ancestors would have had an average IQ of 70. By comparison, our mean IQ today is 130 to 150, depending on the test.”

What’s going on here? Mr. Flynn explains that we do so well on IQ tests because we are “new and peculiar. We are the first of our species to live in a world dominated by categories, hypotheticals, nonverbal symbols and visual images that paint alternative realities. We have evolved to deal with a world that would have been alien to previous generations.”

A century ago, Mr. Flynn writes, “people mostly used their minds to manipulate the concrete world for advantage. They wore what I call ‘utilitarian spectacles.’ Our minds now tend toward logical analysis of abstract symbols—what I call ‘scientific spectacles.’ Today we tend to classify things rather than to be obsessed with their differences. We take the hypothetical seriously and easily discern symbolic relationships.”

So if employees are so smart, why shouldn’t communication be complex? What’s wrong with writing at the 12th grade level, creating 700-word emails, building PowerPoint slides that look like diagrams of nuclear power plants?

Here’s what’s wrong: For busy, distracted employees, complicated communication creates a barrier to entry. People are so smart today partly because we are exposed to so many stimuli. We’re overloaded with all that intelligence-generating information. If something seems too difficult, we’re likely to put it aside for a later that never comes.

The shorter and more accessible you make communication, the faster you cut through the clutter. It’s just that simple.