Usability for Handheld Devices Versus Computers
Published: November 1, 2010
Many people now use different mobile devices—including smartphones, digital cameras, MP3 players, eReaders, and GPSs (Global Positioning System)—in particular contexts. How are users interacting with these devices when they are away from their computers? How does the design of a device—including the controls its hardware provides, its interaction models, and its form factor—determine the design and usability of the software applications that run on it? How can we understand user experience on the move? My new column Mobility will answer these questions and more—questions about mobile user experience, user interface design, and usability for small, handheld, mobile devices.
“The only important thing about design is how it relates to people.”—Victor Papanek
As companies progressively introduce more advanced technology in their consumer electronics products, handheld devices are taking up more and more of people’s time in their everyday lives. Are users interacting with handheld devices in the same way they interact with Web sites on their computers? What kinds of challenges are users facing when using such a wide range of handheld devices on a day-to-day basis? What should usability professionals take into consideration when studying usability for these different platforms?
One Hand or Two Hands?
The first big question to ask is, Do users need one hand or two hands to operate a device? Interacting with Web sites on a computer normally requires the use of two hands when typing on a standard keyboard and one hand when using a mouse or other pointing device. With the vast diversity of handheld devices, users often need to decide whether to use a particular device with both hands or only one hand. Sometimes this decision is contextually constrained. For example, people driving a vehicle have only one hand free when operating a GPS device. Sometimes this decision is culturally constrained. For example, smartphone users in Japan are accustomed to using their smartphones with one hand, because they’re often using their other hand to hold onto a handrail on a running train.
Whether we intend a device for one-hand or two-hand use can greatly impact how we design it—and, therefore, affect how people perceive its usability. Usability professionals should take this factor into consideration when planning test tasks and creating test scenarios.
A Standard Keyboard or Different Button Sets?
When users interact with Web sites on a computer, a standard QWERTY keyboard provides a consistent mode of interaction with which they are familiar. However, when interacting with handheld devices, users may need to operate each particular device either by using hard controls such as buttons or by manipulating controls directly on a touchscreen. Handheld devices come in many different shapes, with many different types of controls. For example, the Sony Reader and Amazon Kindle 2 have very different button sets. The Sony Reader features 10 number buttons, a five-way control, a home button, a back button, a read button, and a zoom button. The Kindle 2 has a QWERTY keyboard, previous and next page buttons, a five-way control, a menu button, a home button, and a back button. Although both companies designed their devices to provide a better reading experience for users, their designers certainly had different ideas of how users should interact with a digital reading device. Five-way controls make it easy to navigate up, down, left, and right. A QWERTY keypad makes it easier to type.
Lack of standardization adds to the frustration users sometimes experience when interacting with handheld devices of different types. Because of this lack of standardization, usability professionals must think of usability for handheld devices systematically rather than focusing only on individual buttons. Thus, while answering such questions as Do users understand how to use this particular button? could be informative, it might be even more beneficial to ask questions like Does a particular device’s entire button set facilitate the tasks users most frequently carry out with the device? and Can users successfully find their way around the device, or do they get lost in the set of buttons?
What’s a Device’s Context of Use?
People don’t use handheld devices within a vacuum. They’re driving a car and using a GPS. Or they’re riding a train and text messaging a friend. Or they’re on a trip and using a camera to capture the view. Or maybe they’re riding a bus and reading a book on a Kindle. Everything happening around a user coalesces to create a device’s context of use—an important part of the user’s experience of the device. The context, or the environment, in which people use handheld devices varies considerably and matters greatly in evaluating the usability of those devices.
For example, when users interact with a digital camera, they are usually trying to catch a good shot—perhaps a fleeting moment—and have very little time and attention for operating the camera. How well designers can optimize the design of the camera—ensuring users can easily push the right buttons without making mistakes—is a very important aspect of camera usability. When users are operating a GPS, driving is usually the highest priority task. The limited amount of attention users can give to a GPS requires that the buttons in its user interface be big enough to use easily within the context of driving. This is also why voice commands now play an integral role in navigation system user interfaces.
Methods for Studying Handheld-Device Usability
With these thoughts in mind, it’s clear that usability testing in a lab might not be optimal for studying handheld-device usability. When there is a designated lab testing environment participants must go to, they enter a testing mode from the moment they step into the lab. They start thinking about the testing facility, what’s going to happen in it, and what kinds of things they might experience during the test. I have heard participants make comments like “This is new…” or “I’ve never done this before…” when entering a usability lab. As soon as people step out of the lab, they again become their normal selves—and perhaps start to use their handheld devices in a completely different way from what they just told us they usually do.
Even if participants are completely at ease during usability testing and a user researcher has created a perfect test scenario, testing in a lab just cannot afford the type of richness a real-life setting can offer. The cultural and environmental elements of real life are absent. In a lab setting, it’s impossible to reproduce all of the ephemeral happenings of real life that affect the way people use handheld devices in their natural environments.
Ideally, it would be great if a user researcher could be an invisible shadow, following participants around without intruding on their reality. For instance, when a participant is struggling when trying to use a new GPS system while driving, the researcher could be sitting next to him and observe every problem he experiences. There are a couple of methods that let user researchers and usability professionals get closer to participants without intruding.
In-home or at-work visits are often superior to usability testing in a lab. When researchers go to places with which participants are very familiar, participants are more comfortable when demonstrating their typical daily usage of devices. Conversations between participants and researchers that occur in participants’ normal environments often help them to remember particular stories about using a device that prove to be very valuable and offer opportunities for great insights.
Short-term, longitudinal studies can also be very beneficial for studying handheld-device usability. Longer periods of observation let participants experience a device in a more relaxed and natural way, allowing more random accidents and issues to arise. Diary studies can also be effective if participants are sufficiently motivated to keep track of what happens during the course of each day throughout a longitudinal study. However, the retrospective nature of diary studies might not work for all participants. Some people find it difficult to sit down at the end of a day and think about what happened during the day. A diary on an actual device might be a good alternative. It could prompt participants to make short log entries whenever there is a need.
Users confront very different usability challenges on handheld devices from those they encounter when interacting with a Web site on a computer. As usability professionals, we need to consider whether a device is for one-hand or two-hand use. As we observe users interacting with handheld devices, it is more beneficial to think about a device’s usability systematically instead of focusing on the use of individual buttons.
Since context plays such an important role in the use of handheld devices, in-home or at-work studies; short-term, longitudinal studies; and diary studies are more suitable than conducting traditional usability testing in a lab.