User interface design is a subset of a field of study called human-computer interaction (HCI). Human-computer interaction is the study, planning, and design of how people and computers work together so that a person’s needs are satisfied in the most effective way. HCI designers must consider a variety of factors: what people want and expect, what physical limitations and abilities people possess, how their perceptual and information processing systems work, and what people find enjoyable and attractive. Designers must also consider technical characteristics and limitations of the computer hardware and software.
The user interface is the part of a computer and its software that people can see, hear, touch, talk to, or otherwise understand or direct. The user interface has essentially two components: input and output. Input is how a person communicates his or her needs or desires to the computer. Some common input components are the keyboard, mouse, trackball, one’s finger (for touch-sensitive screens or pads), and one’s voice (for spoken instructions). Output is how the computer conveys the results of its computations and requirements to the user. Today the most common computer output mechanism is the display screen, followed by mechanisms that take advantage of a person’s auditory capabilities: voice and sound. The use of the human senses of smell and touch output in interface design still remain largely unexplored. Proper interface design will provide a mix of well-designed input and output mechanisms that satisfy the user’s needs, capabilities, and limitations in the most effective way possible. The best interface is one that is not noticed, and one that permits the user to focus on the information and task at hand instead of the mechanisms used to present the information and perform the task.
The Importance of Good Design
With today’s technology and tools, and our motivation to create really effective andusable interfaces and screens, why do we continue to produce systems that are inefficientand confusing or, at worst, just plain unusable? Is it because:
1. We don’t care?
2. We don’t possess common sense?
3. We don’t have the time?
4. We still don’t know what really makes good design?
I take the view that the root causes are Number 4, with a good deal of Number 3 thrown in. We do care. But we never seem to have time to find out what makes gooddesign, nor to properly apply it. After all, many of us have other things to do in additionto designing interfaces and screens. So we take our best shot given the workload and time constraints imposed upon us. The result, too often, is woefully inadequate. I discounted the “we don’t possess common sense” alternative years ago. If, as I have heard thousands of times, interface and screen design were really a matter ofcommon sense, developers would have produced almost identical screens for similar applications and functions for many years. When was the last time you saw two designers create almost identical screen solutions, based on the same requirements, without the aid of design guidelines or standards (or with them as well)?
A well-designed interface and screen are terribly important to users. They are their window to view the capabilities of the system, the bridge to the capabilities of the software. To many users it is the system, because it is one of the few visible components of the product its developers create. It is also the vehicle through which many critical tasks are presented. These tasks often have a direct impact on an organization’s relations with its customers, and its profitability.
A screen’s layout and appearance and a system’s navigation affect a person in a variety of ways. If they are confusing and inefficient, people will have greater difficulty doing their jobs and will make more mistakes. Poor design may even chase some people away from a system permanently. It can also lead to aggravation, frustration, and increased stress. One user relieved his frustrations with his computer through a couple of well-aimed bullets from a gun. Another user, in a moment of extreme exasperation, dropped his PC out of his upper-floor office window. Poor interface design can also have a huge financial cost to users and organizations. A critical system, such as one used in air traffic control or in a nuclear power plant, may compromise the safety of its users and/or the general public.