A Brief Introduction to Usability

Consistency and predictability are admirable qualities in both app interfaces and tech book series. That’s why I see the irony of opening this book with some abstract stuff—a bit of background, some conceptual material—instead of diving right into the how to get things done stuff that you’d ordinarily expect to find in a typical Take Control book.

However, you need the abstract stuff because this book is about understanding how and why your apps and devices act they way they do, and understanding that requires context. Don’t worry: it’s only a very little bit of background and barely a handful of concepts.

Specifically, this short chapter briefly explains What Usability Is, which has a lot to do with determining how you and your devices interact, and even more specifically, it describes What Affordances Are, which end up involved one way or another in nearly all of the mysteries you encounter as you use your devices.

What Usability Is

Usability is the field that studies how people use things, and it attempts to learn and to prescribe more efficient and effective ways to use them. As software and digital devices have become increasingly more important economically, so, too, has the field grown. Today, most major software and hardware developers have one or more teams of usability specialists working with the software and hardware engineers; in some cases, the usability specialists are engineers themselves.

Note: In the early days of the Mac, and even before, Apple had a usability specialist, Bruce Tognazzini, whose Apple Human Interface Guidelines literally guided the way that many Apple II and Mac apps interacted with their users.

Software usability specialists tend to do two sorts of things:

• Categorize interactivity methods and patterns: This activity trickles down to developers in a lot of ways. A fair amount of it comes directly from Apple in the form of software frameworks (for example, Apple’s UIKit framework), and as usability guidelines. It can also arrive indirectly—for example, in the form of the free apps that Apple provides. These apps, such as Pages and Keynote, not only give Apple’s customers useful software but also give Apple’s developers actual working examples of various interface methods and patterns of interactivity.

• Test (and evaluate) interactivity patterns and methods: It’s not a mystery why usability testing is big business: usable interfaces are profitable! A successful user interface means fewer user support calls and emails that developers have to field, and all those support calls and emails cost money. Usability studies generally focus on evaluating the following (you may want keep this short list in mind as we look at the various usability puzzles covered in this book):

  • How easy something is to learn

  • How efficient it is to get something done

  • How easy it is to relearn it after being away

  • How pleasant it is to use

The Takeaway: As random and arbitrary as some user interfaces can seem, most user interfaces don’t just happen. Lots of people, working hard and thinking hard, consciously and deliberately craft them. When interfaces fall short of perfection it’s seldom from want of trying. As Osgood Fielding III says at the conclusion of Some Like It Hot, “Nobody’s perfect!”

Everything Old Is New Again

User interfaces are how people and machines communicate. Once upon a time, before computers, and even before printed books, there was another field of study that attempted to categorize and make recommendations about communication methods. It was called rhetoric and every educated person in the Western world studied it.

Rhetoricians attempted to categorize the many patterns people used in speech and writing, giving these patterns names (like chiasmus and anaphora and homeotelueton), and they recommended good (and not so good) ways to get one’s point across. Spoken and written discourse was the user interface of pre-technological societies, and those who mastered it had a good shot at running the world.

Though today’s usability specialist is a long way removed from a toga-clad rhetorician of ancient Greece, they have much in common. Were Aristotle, author of The Rhetoric, to be bundled into a time machine and brought forward to a modern usability lab, he might very well recognize the bones of his ancient field peering out from beneath the face of usability analysis.

What Affordances Are

The term affordances looms large in the field of usability analysis. It refers to the actions that a user thinks are possible, that are afforded, usually, but not always, based on what the user can see: the term encompasses anything that an environment offers the user. For example, there are a lot of ways to open a door, but the presence of handle strongly suggests to a user at least one method by which the door attached to it might be opened.

The Mac interface, for example, teems with visible affordances, clues that something on the screen is clickable or draggable. Some Mac affordances are obvious because they resemble real-world objects, such as buttons you can click. Others you learn very quickly because they behave consistently from app to app, such as the visually distinct title bar on a window that you soon learn is the area you drag when you want to move the window.

When it comes to apps, the virtue of a visual affordance is that it gives you a target that you can click or drag in order to do something. The affordance doesn’t tell you just what clicking or dragging the target does, only that you can click or drag it to do something.

Unfortunately, such an affordance takes up screen space, and that’s a serious drawback on screens that don’t have much available space to begin with (hello, Apple Watch).

Today’s Apple devices and their apps offer many visible affordances, but they also offer what the voices in my head call invisible affordances, such as the bottom border of an iPad screen: nothing about the bottom of the screen says you can “drag up from below me to see other apps you have recently run” but you soon learn that dragging up from beyond the screen’s bottom border consistently has that result.

Many of the mysteries this book explores are just such invisible affordances.

Note: Usability mavens might call these things user interface conventions, but, honestly, doesn’t invisible affordance have just a bit more zing to it?

What Is Discoverability?

Affordances that allow users to do things are almost useless if users can’t discover that they exist. When you see a button on screen, you can guess that it is clickable, even if you can’t always predict what a click might do. But how would you know that a three-finger swipe to the left in iPadOS does something, let alone know what that gesture does?

In user interface design, discoverability is the quality in the design that helps users discover that a capability exists. Sometimes a capability is visually obvious, as is the case with an onscreen button labeled “Print.” Sometimes it is easily guessed because of quickly learned conventions: once you’ve learned you can drag to select text in a word processor, it’s easy to guess that dragging over onscreen text in other apps can select text as well—the capability is easily discovered.

In very general terms, the less likely you are to fumble your way to discovering how to employ a capability in an app, the less discoverable that capability is. Not every capability in an interface need be easily discoverable, but the more of an app’s capabilities that are hard to discover, the more frustrated its users are likely to be.