Chapter OneHow humans (almost) universally perceive
PART 1: Perception principles
The first step in designing for your audience and its needs is to find out what makes people alike. How do most humans-those with normally functioning eyes and brains-perceive and comprehend information? Basic principles of cognitive psychology apply. Perhaps chief among them is our selective attention.
"The mind is not a camera," writes Stephen Kosslyn in his book Graph Design for the Eye and Mind. Although the camera captures everything within its frame, the mind captures only what it chooses to, especially in a crowded "frame" or scene. So what any two minds choose to capture in a given scene will vary. But you can learn to predict and, to an extent, control what they view in the "scenes" you design if you create and arrange their elements in line with inherent human behavior:
We humans look for and recognize patterns, and we expect them to mean something. We also notice interruptions in pattern, and expect those to mean something different from the consistent elements. We see what's bigger, bolder, or brighter as more important than what's smaller, lighter, or duller. And we look for order and unity, even trying to impose them where they don't exist. Anything that lacks order in visual displays tends to make us uncomfortable. So we mentally group individual parts to form a whole. (You might say we seek relationships among visual elements in much the same way as we seek relationships with other people.)
For example, you can see that parts-as-a-whole principle in facing pages of a magazine or newsletter with two or more articles that begin with a drop cap. Readers notice when the caps spell out a word, as in the illustration on the next page. Readers especially notice when the caps spell out a swear word. It happens more than you'd expect, so make sure you check before you send off the pages.
You might wonder why the designer, editor, or proofreader didn't notice and remove the unintended word before the audience could see it. It's probably because each person focused more on the details than on the big picture. It's also why many typographical errors in headlines and titles go unnoticed during proofreading. The mind also tends to actively "correct" for mistakes such as a repeated or dropped word. So it's also hard to spot a small supporting word (such as the) at the end of one line that repeats at the start of the next line in the column.
Basic principles translate into guidelines for designing content your audience members can perceive, which they must do before they can comprehend it:
Limit the content and elements in the design to what your audience needs; don't include everything you know (the principle of restraint).
Group related information to show it is related, and separate unrelated info.
Use space. Physically move the informational elements together or apart (the principle of proximity).
Use style-the size, face, style, color, and shape of elements-to show their relationships with other elements. Match related elements and contrast unrelated ones (the principle of similarity; also consistency and repetition).
Emphasize what's most important (the principles of hierarchy and emphasis).
Arrange information from most important to least (the principle of hierarchy or sequence).
Align elements with others to help the audience navigate through them (the principles of alignment, unity, and balance).
Make the content stand out clearly from the background (the principles of figure/ground and clarity).
Use clear and legible images (the principle of clarity).
Gestalt principles of perception
Some of the principles about how parts relate to the whole come from the movement of psychology known as Gestalt, which is German for "form." Gestalt practitioners including Max Wertheimer, Wolfgang Kohler, and Kurt Koffka began applying the ideas to human visual perception in the early part of the last century. Here are some of their principles and how I've interpreted-even sometimes stretched-them into practical information-design guidelines.
THE GESTALT PRINCIPLE OF SIMILARITY:
Make equal elements look equal
What Gestalt psychologists really meant by the similarity principle is that we humans tend to group similar elements into one perceptual unit. But in order to group similar elements, we must be able to recognize their similarity. Our ability to perceive patterns means we can discern obvious similarities and differences. We regard elements that look alike-such as article subheads that share a typeface, style, size, and color, for example-as being alike, having the same level of importance. So it only makes sense to emphasize similarities and differences with your design.
In much the same way, we regard elements that are obviously bigger as being more important, and those that are obviously smaller as being less important. In fact, size is the most noticeable graphic trait, writes Jacques Bertin in his book Semiology of Graphics. So people understand the different levels of importance implied by a size hierarchy of elements unless something visually "louder" distracts us. Defy those natural laws-by, say, reducing one section of type to fit the page-and you could confuse readers, who expect changes to mean more than a lack of space.
And when people see bold type, they tend to recognize its emphasis, an understanding you'll defeat by boldfacing everything. When they notice color that's used consistently, the pattern can help to reinforce the element's meaning.
The guideline also applies to photos, with risks to the designer who violates it. Consider the head-and-shoulders photos (also known as "mug shots") that are so common in publications. Make the size of any such photos on a page or (two-page) spread identical. If you don't, the size difference could imply that the people in the photos have different levels of importance. Match the size of the head from the top of the forehead to the chin, not just the size of the frame. A small head in a big frame will look less significant than a bigger adjacent head even in a slightly smaller frame.
Also watch where you place photos of equal importance. Depending on the number of photos and what else is on the page, the photos at top left or center might look favored. Even arranging photos by alphabetical order of the people's names can't compete with the stronger nonverbal impression. But top-down placement does work for a photographic organizational chart in which position conveys each person's relative status. And, like it or not, some designers use the size-equals-importance code to enlarge just the director's photo, visually underscoring that person's status (and trying to flatter the one at whose pleasure they serve).
But do use size and placement to show the order in which readers should view photos. And use them to show how the photos rank with each other and relate to corresponding content. Plan a hierarchy of photos-from most to least important-as you do a hierarchy of type.
The similarity principle also extends to alignment. Align every element with something else in the frame to help viewers see the elements in the unified context of the whole. In particular, align related elements to emphasize their relationship and their contrast with other elements. Consider aligned contact info on a business card or an indented quotation within flush text. In both examples, grouped alignment reinforces the difference between two categories of type.
Similar alignment explains the value of a grid. That's a framework of invisible vertical and horizontal lines designed for placing type and images and reserving unfilled space similarly from page to page or project to project. A well-planned grid anticipates and accommodates the range of elements in the project while avoiding monotony. Adherence to a grid gives projects a sense of order and unity, and helps readers find things.
Pages designed without a grid tend to draw the eye from the content to the chaos. Think of the last slide show you saw in which the titles bounced with each new slide. Lack of alignment also annoys audiences of other forms of design, maybe most when they know something's wrong but not what it is.
THE GESTALT PRINCIPLE OF PROXIMITY:
Group related things
The principle states that we group elements that are close in space as a single perceptual unit. Here again, let's stretch the idea: We expect elements that are close in space to be more related than those farther away in space. So, for example, place:
titles, headlines, and subheads closer to the text they introduce than to any other text, especially what comes before. For example, reduced space under the subhead above shows its connection to this paragraph; extra space above the subhead shows its separation from the paragraph above it.
related photos closer to each other than to unrelated ones. For example, you'd group photos from an annual conference well away from the shot of your director addressing Congress.
photos near the text they relate to
captions near the photos they describe (close without touching)
THE GESTALT PRINCIPLE OF FIGURE/GROUND:
Make the content stand out from the background
We separate what we see into foreground (figure-for our purposes, the content) and background (ground). In information design, never ask the audience to work at telling them apart. Make the content prominently emerge from (contrast with) its background, and keep the background in the background, never intruding.
Low or no contrast, on the other hand, blurs the distinction between figure and ground. Edgar Rubin, a psychologist who studied figure/ground relationships, created the famous image of a vase within two human facial profiles. Looking at its re-creation, what do you see first, the faces or the vase? Notice that you can't focus on them both at once. To see the second one, you must shift your focus. So because it's impossible to focus on both figure and ground-or type and back-ground-at the same time, make it easy for the audience to focus on the type by playing down the background. (Escher's drawings, which also blur the divisions between figure and ground, are fascinating, but nothing to mimic in information design.)
EXERCISE: Make your own version of Rubin's vase using silhouettes of someone you know. Display the image near your work area to remind you to keep content clearly in the foreground and backgrounds clearly in the background.
You can achieve the essential design principle of contrast with:
size. Make type big enough to stand out from the background. (What if you want to discourage people from reading the "fine print"? Reconsider using fine print whenever readers need the info buried in it; they're on to that trick.)
"color." Black type on a white background gives the highest, most comfortable contrast for sustained text reading. On the other hand, in many cases the same combination reversed (white type on a black background) emphasizes the background over the type. For graphics, favor cool, deep colors as a background for warm, bright colors. On signs, black on yellow is the best-projecting combination. (If you live in the United States, you've probably noticed a fluorescent yellow-green gradually replacing nonfluorescent yellow-orange on Pedestrian Crossing and other signs.)
weight. Make type heavy enough to be visible. Especially on low-visibility surfaces, typefaces with uniform stroke widths tend to achieve more contrast between figure and ground than those built from thick and thin strokes. (But avoid going so bold with type, especially in small sizes, that the enclosed space in the characters, such as the loop in the lowercase e, start to fill in.)
quiet, solid backgrounds. Understate your design's background because a loud one competes with reading the way loud background music competes with conversation.
Also avoid the temptation to put text on a shifting background such as a photo or a gradient screen, which makes reading as tough as listening to an inconsistent cell-phone signal. An evenly screened background also lowers contrast, as does heavily textured or colorful paper.
AN EXAMPLE OF GOOD CONTRAST
Consider the environment in which you'll deliver your message. High-contrast colors and type weight help make the poster in Color Plate 1 stand out against other messages on a subway car's cluttered walls. Although most of the background reverses, text is big, limited, and visible enough to hold its own, especially with its powerful uniform strokes. You might see the green against the black first, but you're more likely to read the higher-contrast bold white main info.
In the green panel on the left side of the poster, the color's brightness still takes a backseat to the black-outlined white images. With more and weaker (reversed or serif) type, it also would pose more of a reading challenge. But despite its reversing, the white paragraph on the black panel transmits more easily than it might have because of its bigger point size and limited words. Still, if you squint, you can see the background intruding on the shape of each letter.
MORE FIGURE/GROUND RELATIVES
Other principles work with contrast to affect the perception of figure/ ground. What's bigger or bolder appears to be more in the foreground than what's smaller or lighter (hierarchy). It also tends to appear closer to the viewer. Contrast's primary design partner is emphasis: making the most important elements in the foreground stand out from the rest. Every information design project, page, or view needs a focal point, an emphasis, an obvious place for the reader to start.
The principle of balance (see sidebar on pages 22-24) and the use of empty space also play into figure/ground. Extra space between elements tends to draw the reader's eye to where you don't want it-the background. So leave just enough space between elements to frame them, but not so much as to distract from them. And use more space to frame pages than individual elements. That way, the elements won't seem to be pulled off the page; the frame will look strong enough to enclose them.
THE GESTALT PRINCIPLE OF PRAGNANZ:
Simplify (appropriately) and give context
We look for the simplest possible explanation in any visual based on its-and our-surroundings. But that's too much work to ask of your audience members, so simplify for them, at least as much as it makes sense to do.
Adding principles of adult learning, we also look for context. When we see something new, we look for existing mental niches to file it in. Use that idea to choose and present content based on what's familiar to your audience. Content should begin where the audience's knowledge leaves off, and you should connect the two. And design should favor conventions, such as putting a Web site's logo in the upper right or changing the color of a visited link.
THE GESTALT PRINCIPLE OF COMMON FATE:
Viewers notice direction
We group lines and shapes that seem to be heading in the same direction. For example, on a bar graph, bars above zero are seen as one group, those below zero as another.
THE GESTALT PRINCIPLES OF CLOSURE AND GOOD CONTINUATION:
Viewers fill in visual gaps
Closure is when we mentally fill in any gaps in regular objects, such as circles, so we'll tend to complete a broken circle. Good continuation means that we group things that are on the same line or a curve. For example, we understand the graduated climb or decline of bars in a graph, and we expect the variation in graduated screens to mean something.
Let's go beyond the Gestalt meanings to show how continuation-like elements can help to unify projects. For example, a thick bar at the top of every page encourages horizontal movement-continuation, so to speak-through a print publication. In a Web site, a matching menu bar and logo in the same spots on every page form an implied connection and a path between pages. Those elements also impose continuity.