John Whiteside

Usability Engineering: Our Experience and Evolution

Publisher Summary This chapter discusses the users experience and evolution of usability engineering. Usability engineering starts with a commitment to action in the world. It seeks to capture user experience within a context situated in user work and in a form useful for engineering. Usability engineering provides operationally defined criteria so that usability objectives can be used to drive an efficient and productive engineering effort, and it can lead to production of systems that are experienced by users as usable and that serve as a basis for the next generation of systems. When a system is built and delivered to users, interaction with it would affect user experience and would shift the background against which users evaluate that system in comparison with other systems. Therefore, as systems are built that provide new functionality with new levels of usability, the expectations of users would shift so that the whole cycle should begin again.

User performance with command, menu, and iconic interfaces

Performance and subjective reactions of 76 users of varying levels of computer experience were measured with 7 different interfaces representing command, menu, and iconic interface styles. The results suggest three general conclusions:there are large usability differences between contemporary systems, there is no necessary tradeoff between ease of use and ease of learning, interface style is not related to performance or preference (but careful design is). Difficulties involving system feedback, input forms, help systems, and navigation aids occurred in all styles of interface: command, menu, and iconic. New interface technology did not solve old human factors problems.

The natural language of interactive systems

The work reported here stems from our deep belief that improved human engineering can add significantly to the acceptance and use of computer technology. In particular, this report describes an experiment to test the hypothesis that certain features of natural language provide a useful guide for the human engineering of interactive command languages. The goal was to establish that a syntax employing familiar, descriptive, everyday words and well-formed English phrases contributes to a language that can be easily and effectively used. Users with varying degrees of interactive computing experience used two versions of an interactive text editor; one with an English-based command syntax in the sense described above, the other with a more notational syntax. Performance differences strongly favored the English-based editor.

How do people really use text editors

Keystroke statistics were collected on editing systems while people performed their normal work. Knowledge workers used an experimental editor, and secretaries used a word processor. Results show a consistent picture of free use patterns in both settings. Of the total number of keystrokes, text entry accounted for approximately 1/2, cursor movement for about 1/4, deletion for about 1/8, and all other functions for the remaining 1/8. Analysis of keystroke transitions and editing states is also presented. Implications for past research, editor design, keyboard layout, and benchmark tests are discussed.

Contextualism as a world view for the reformation of meetings

The foundations for research and action in the area of group work are examined. Four alternative “world views” are presented. One of these, contextualism, is discussed in depth. Its methodological consequences for research and implications for reform of group meetings are explored.

The Dialectic of Usability Engineering

Publisher Summary This chapter reviews a major theoretical issue underlying usability engineering that emerges when usability is defined in terms of user experience. Usability engineering is emerging as an identifiable design philosophy and approach to the building of usable software systems. Usability, ultimately, lives in user experience. Therefore, usability engineering must be grounded in experience. Engineering is commitment to action in the world. It is building artifacts economically according to specification and infinite time. Engineering always operates against a background of scarce resources, such as talent, materials, time; and money. Usability Engineering provides a collection of powerful tools to support this part of the process. Engineering involves building things. Almost hidden by the transparency of this truism is that engineering involves a commitment to action in the world. A commitment is a pledge to cause to happen, by a specified time, an event with shared, agreed upon conditions of satisfaction. Engineering, and more generally commitment, depends on interpretation against a shared background of meaning, in other words, against agreed upon goals and conditions of satisfaction.

Engineering for usability (panel session): lessons from the user derived interface

The focus here is on the lessons learned from the UDI project for building usability into the software development process. In the UDI project we attempted to engineer a usable system. That process involved:<list><item>defining an appropriate metric for measuring usability, </item><item>setting explicit levels of usability to be achieved </item><item>determining an appropriate methodology for building usability into the system, </item><item>delivering a seemingly functional system with an easily changed interface very early in the development cycle, and </item><item>recognizing the tentative nature of the initial design. </item></list> Using the UDI project as an example, each of the above principles will be discussed in detail.

Computer human factors in computer interface design (panel session)

Human factors psychologists contribute in many ways to improving human-computer interaction. One contribution involves evaluating existing or prototype systems, in order to assess usability and identify problems. Another involves contributing more directly to the design of systems in the first place: that is, not only evaluating systems but bringing to bear empirical methods and theoretical considerations that help specify what are plausible designs in the first place. The goal of this panel is to discuss four case studies emphasizing this role of cognitive human factors, and identify relevant methods and theoretical considerations. The panelists will present examples of prototypes or products to whose design they contributed, with the aim of characterizing the problem (or problems) they tried to solve, the approach to identifying a design solution for that problem, and evidence that the approach was useful. Robert Mack will discuss an editor prototype designed to get novices started doing meaningful work quickly and helping them to continue acquiring new skills, with virtually no explicit instruction. The prototype is being designed in large part by identifying key novice problems and expectations, and trying to design the interface to better accommodate these expectations. The first goal of getting novices started relatively quickly has been achieved but problems remain as novices try to acquire further text-editing skill. These problems — and solutions to them — are being identified through a process of iterative design and evaluation. Dennis Wixon will discuss implications for designing usable interfaces of the User-Derived-Interface project (Good, M., Whiteside, J., Wixon, D. and Jones, S., 1984). The project involved a simulation of a restricted natural language interface for an electronic mail system. The design process was driven by the behavioral goal of getting users started relatively quickly with little or no instruction or interface aids. Actual user interaction with the simulation coupled with iterative design and evaluation provided interface specifications. This prototype illustrates a number of techniques for bringing usability into the software engineering process. These presentations will discuss the role of empirical methods such as verbal protocol techniques for identifying user problems with existing computer systems (e.g., Lewis, 1982; Mack, Lewis & Carroll, 1983; Douglas & Moran, 1983), including variations aimed at identifying user expectations that may be able to guide design (e.g., Mack, 1984); interface simulations for studying user interactions again with the aim of letting user behavior guide interface design (e.g., Kelley, 1984; Good, Whiteside, Wixon & Jones, 1984), and iterative design and evaluation of interfaces, aimed at achieving behavioral goals (e.g., Carroll & Rosson, 1984; Gould & Lewis, 1983).