Cramming every point onto one slide guarantees none of them land

It seems reasonable to assume that if you want your audience to notice something important, you should make it stand out, and if you have several important things, you should make all of them stand out. Garr Reynolds points out why this instinct backfires: if everything is emphasized, nothing is. A slide where every column is a different bright color, every line of text is bold, and three images compete for attention gives the eye nowhere obvious to land, so it wanders and eventually gives up.

He draws on the work of Harvard psychologist Stephen Kosslyn, author of Clear and to the Point, who studied exactly this problem. Kosslyn's principle of salience holds that attention is drawn to large, perceptible differences, meaning the most important element in a design should also be its most different one, not simply its largest or most colorful. A background full of visible pattern or detail, Kosslyn warns, has too much salience of its own, and it will pull attention away from whatever sits on top of it, regardless of how big or bold that foreground element is.

Reynolds finds a five-hundred-year-old version of the same idea in the tokonoma, the raised alcove found in traditional Japanese rooms, where a single scroll or flower arrangement is displayed. Nothing else decorates the room. There's no clutter competing for the eye, because everything else in a traditional Japanese room was deliberately kept plain, which is exactly what allows a viewer to notice, and then linger on, the one object the room was built around. Reynolds notes that a powerful focal point doesn't need to be overbearing or fancy; emptiness around it is often doing more of the work than any decoration could.

The practical version of this, for a slide or a poster, is to decide in advance what a viewer should notice first, second, and third, and then use contrast deliberately to enforce that order, rather than hoping that adding emphasis everywhere will somehow help everything get noticed. As Reynolds frames it, every good visual needs a clearly dominant element that tells the viewer where to begin. Without one, the viewer has to do the work of deciding what matters, and most of the time, they simply won't bother.

Before your next slide goes anywhere near your software, decide on paper what you want a viewer to notice first, second, and third, the same way a traditional Japanese room is built around a single alcove display and kept plain everywhere else. Make that first element different from everything around it, whether through size, color, brightness, or position, rather than simply making it big alongside other big things. Keep your background as quiet as you can, because a busy background has its own pull on the eye and will compete with whatever you place on top of it. Once it's built, show it to someone cold and ask what they noticed first; if they hesitate or name something you didn't intend, you have too many things fighting for the same attention, and it's worth cutting until only one clearly wins.